Yes, that's approximately my understanding as well.

Keep in mind too, that the torque arm in these cars is VERY long, so VERY little sliding action occurs. To put it into perspective compared to Milliken's drawing, he's showing a TA that's less than twice as long as the LCA; where ours is around 3 times.

But regardless, look farther:

So, where is the instant center at various LCA angles; and what is the effect on the tendency of applied forward-pushing power, to also produce vertical forces? (that being the driver behind wheel hop).... since putting the instant center produces the minimum tendency to produce vertical "rotation".


Looks to me like even if the IC is always in the vertical plane of the TA bushing, if it's too low (LCA angled upward from frame to rear), it's still going to have the EXACT SAME EFFECT as I've been describing all along; namely, the existence of a vertical vector as well as the horizontal one, tending to make the body roll (clockwise in the drawing), which is the same thing as the rear rotating counterclockwise. Whereas, is the LCA is angled so that it points DIRECTLY AT the TA mount (the way I've been describing that it should be done - angled slightly downward from frame to rear), the vertical vector goes to ZERO, because there's no rotating force.... in other words, NO WHEEL HOP. No vertical forces, no compression of springs, no need to add damping.

Eh?

No, I will not stop posting.

 

Sonix,

It should be inline with the sliding link, to matter what. Remeber, the IC is the motion summary, since there is not a fixed roting link there, you don't extend the plane, the motios is always going to be located along the sliding link, where that motion plane intesects the LCA's motion plane is the instant center.

Sofaking,

Yes, the instant center does effect the vertical forces, I never said it didn't. But, you are always going ot have those foces, not matter how much A/S you have, you still have other weight transfer, etc. You are always going to have motion, whenever you have motion, and springs, you have to have dampening to control that motion. When you can design a suspension, that has zero vertial motion, you let me know, I'll sign up to buy it from you.

That is my whole point. In your "method" you have to dial in so much A/S to to avoid a frequency in the suspension to stay out of wheel hop, that negatively effect 10 other things. I don't call that a solution. I prefeced my first comment with "assuming" in that, we are going on the assumtion, that the bushing are in good shape, there are no broke/bent parts, and that the geometry is close to where it should be (He put OE replacement springs on, gauren-f-ing-tee you his LCA mount is lower on the axle side, probably not by much, but a little. His dampers are the problem.

Now, I didn't dive into this deep before, but madmax brough it up, and it is very valid. YES you can overdampen this, if you have WAY too much bump resistance built in, it raises your effective spring rate, thus raising your sprung frequency, this will give the car a tendancy to be more prone to wheel hop. Same as worn out bushings do. Obviosly like anything else, you can over do dampers. Especialy in bump, and a lot of people do in rebound also, too much rebound and the car does funky things coming out of roll, but that is a whole diffrent thread.

 

I couldn't find the picture of the LCA's crossing the TA in my books, maybe I only read it online here.
FWIW this thread has a lot more info on this topic
https://www.thirdgen.org/forums/susp...arm-angle.html
And it's a sticky to boot! Makes ya wonder why anyone bothers arguing anymore.... hahaha

 

Hey Duracell- I thought it was the Energizer Bunny. Inside joke?

 

Its a long story around here on TGO. Goes towards the phase "keeps on going and going..."

Also the fact I have a Duracell battery Scuba tank and have had the nickname for years from that too. Its fitting hence the dual meanings- besides I am running out of creativity with callnames around here.
http://www.cardomain.com/member_page...52_64_full.jpg

 

Got it-check.
----------
Sure doesn't seem to take much to get a whole mess started round here-- does it?

 

so lets get really nuts here - I understand how spring rate and shock dampening control "hop". I also understand how lowering the lca's at the diff creates anti-squat, thus helping force the tires onto the ground during hard acceleration.

Sooo, if I were to lengthen my lca's, lets say roughly 2", and build a set of brackets that ran at a back angle from the axle tubes to maintain the factory wheel base length, would that not allow me to run a perfectly parrallel lca and still create anti-squat due to the rear of the lca trying to swing downward in reaction the the pinion trying to "climb" the ring gear? Plus, the longer arm would lessen the distance change through an equal range of motion, thus would lessen the possibility/amount of roll steer.

Could this make a more ideal lay-out for street/strip use, or am I missing something?

 

Sounds like a great idea. At first glance at least. Gonna have to let the old brain stew over it for a day or two, haha.

 

I can't see a reason why it wouldn't work. I was hopeing to get dean's opinion, but he's been banned again.

anyone else?

I mean, I can't see much over maybe 2", as that would just be excessive. I also think that the materials used would need to be a bit heavier due to the added stress of being mounted behind the rear.

 

Why's that? I'm not seeing how that would add stress to it?

I was thinking about this for a bit, and yea it seems like it would work. You'd probably want to do the holes in a line going down and back, say maybe 5° back? That way it'd be straight down under acc. Under braking though?

 

Changing the LCA length won't really have any effect at all.

The ring/pinion thing also isn't the issue at all. Not connected in any way. All of that is going on INSIDE the housing; has nothing to do with the issue at hand.

I've about used up all the good ways I know to explain what's happening with this suspension design, but I'll try one more.

The design of the suspension links affects the "instant center" location. If these cars act like the "slider" design rear suspension, then the IC is located where a line drawn through the pivot points (bolts) of the LCAs, intersects a vertical line drawn through the torque arm bracket (on the tailshaft of the transmission). It's really irrelevant whether they act more like that, or more like a 3-link; the end results are identical.

The IC is the imaginary point at which the suspension ACTS LIKE it applies the forward thrusting force from the engine, to the body. Keep that concept carefully in mind. The suspension design and geometry effectively places the engine's accelerating force at that point.

The car's "center of gravity" is the point at which the car's mass ("Mass" is another word for "tendency to resist acceleration") ACTS LIKE it's all concentrated. It's not all concentrated right there, of course; the actual distribution of it, in particular whether it's all clustered near the center, or whether it's all out at the edges and corners, makes a BIG difference to the car's dynamic behavior. For a demonstration of that, take yerbasic thin styrofoam carton of a dozen eggs, and remove 8 eggs. Leave the 4 center eggs. The CG is DEAD CENTER inside that carton, right? Pick up the carton, feel how it feels, and how it reacts to you moving it around. Now move the 4 eggs to the ends of the carton. Note that the CG is in THE EXACT SAME PLACE, hasn't changed; dead center in the carton. Pick the carton up again, and move it around. Does it feel the same? If it doesn't, tell us how it felt different. But that's a subject for a different rant.

Now do a quick thought experiment. Imagine a box, a shoebox or something, sitting on a table, mounted on 4 nice sproingy springs at the corners. Imagine that it has a CG somewhere, and just to keep it simple, imagine that the CG is somewhere inside the box. Remember, the CG is the point at which the box's tendency to resist acceleration (force), is all concentrated. Now imagine that this box has an IC as well; that is, a point at which a force tending to accelerate (move) it, is also concentrated.

Imagine putting your left index fingertip at the CG, to hold the box still; and imagine taking your right index fingertip and putting it at the IC, and pushing on the box to the left.

What happens?

If the IC is a different spot from the CG, the box rotates, compressing some of the springs and extending others. The closer the IC is to the CG, the less it tries to rotate, which is to say, the less of an effect all of this has on the springs; in other words, the less motion there will in the "suspension" of our box. More specifically, if the IC is BELOW the CG, the box rotates such that the BOTTOM of the box moves in the direction of the applied force. If we view this thing from the direction you're looking at it from (the box's left side), it looks like it roates clockwise; the rear springs compress, and the front springs extend.

We call this condition "squat" when it's a car doing it. Obviously, it involves moving the suspension with respect to the car, just like going over a bump.

Now imagine that everything else is the same, except the IC is ABOVE the CG. Now, when you apply the leftward force, the box rotates COUNTER-CLOCKWISE; the force tends to LIFT the "rear" of the box.

When applied to a car, this is "anti-squat".

Now imagine that the IC coincides EXACTLY with the CG. Under this condition, NO SUSPENSION MOTION AT ALL occurs. The box does not try to rotate, and therefore the spring stiffness, damping, height, or whatever else, DOESN'T MATTER, and it DOESN'T HAVE ANY EFFECT ON THE BOX'S behavior. Eh?

When no suspension motion occurs, then THERE'S NOTHING TO DAMP; and you don't NEED shocks to control motion, because THERE IS NO MOTION. Clearly, this is the "perfect" situation, as far as suspension design for acceleration ONLY is concerned. Clearly this is not possible to achieve in the real world, but it's certainly possible to do better than the factory did, with minimal ill effects.

Go back to the "squat" condition. When this happens, the suspension is trying to move upwards with respect to the car, or if you'd rather consider it the other way, the car is trying to move downward with respect to the rear end. But the car can only fall JUST SO FAST; it's limited by THE ACCELERATION OF GRAVITY. This acceleration is approximately 9.8 m/sec^2, or about 32ft/sec^2. That means, that's how fast the car can accelerate downwards to "meet" the rear end. For the first instantaneous bit of time that the pushing force is applied to the car, it doesn't fall very fast; so during that time, the rear is trying to LIFT ITSELF UP OFF THE GROUND. When it does that, it unloads the tires. When it unloads the tires enough, they lose traction, and they start to spin. When they lose traction and spin, the pushing force goes away. When the pushing force goes away, the force tending to lift the rear also goes away. When the lifting force goes away, the energy stored in the springs while it was lifting, tries to push the rear back down. Eventually the rear is pushed back down far enough that it regains traction. Eventually it regains traction enough to restore the pushing force. When the force is restored, it begins lifting itself off the ground. It lifts itself until the tires lose traction and begin to spin. ..... about 7 times a second more or less.

Note that all of this analysis is based on the location of the IC; which is the point at which a line drawn through the pivot points of the LCAs intersects a vertical line through the TA bushing. The length of the LCAs doesn't change any of it, only the line through the bolts. So lengthening the LCAs won't help. The only thing that will help, is to relocate the IC to where it coincides with the CG, which in these cars, is done with LCARBs, since there's no way to move the frame end of the LCA UPWARDS. If we could do that, then it would be another option.

Until the IC is correctly located so that it is at or at least NEAR the same point as the CG, the suspension will be forced into all sorts of violent contortions by the application of power. That's what drag racers work on to get their cars to hook up and to leave with the least amount of their engine power being wasted on vertical motion in the body: once they get sticky tires on their cars, they tune the suspension to produce either a slight amount of squat, no squat at all, or a slight amount of anti-squat, according to how suddenly the power is applied, the "springiness" of the tires, and various other minutiae. Drag racers refer to this as how the car "hits the tires". Guys that have 6-cylinder cars and spend their Sunday afternoons in parking lots with cones hanging out with middle-age guys driving Miatas and Mini Coopers, no matter how tightly they can make their cars go around the cones, might not ever have to deal with this; but that doesn't mean it doesn't exist.

These cars aren't the only ones with this issue. This is not some kind of Internet buzzword that only people on this BBS have made up. A & G bodies for example have it(Chevelle and Monte Carlo, along with all of the other divisions' models built on those same platforms), except in reverse, as far as ride height is concerned. Their IC is located where the line through the upper CAs intersects a line through the lower CAs. With them, RAISING the car, as opposed to lowering it like our cars have trouble with, moves the IC downward and makes them hop, because the upper CAs are shorter than the lowers, and therefore their angle changes faster than the lowers. There's various fixes for those cars on the market, notably the Edelbrock "no-hop" bars. Again, Miata and Mini guys wouldn't be expected to know about how to build one of those cars, either; but people who build high-HP drag cars are intimately familiar with the situation.

Shocks and other damping techniques are nothing but a Band-Aid to be applied to the last little bit of the hop tendency, AFTER the suspension geometry has been corrected to minimize the hopping, or to control it to a specific desired amount. The first line of attack remains, FIX THE GEOMETRY; then damp out whatever residual imperfections remain. Not, take a car that yanks on itself every which way, and try to somehow damp all that energy storage and release. Go TO THE SOURCE of the problem and cure it there; not try to act directly on the SYMPTOM. Fence at the top of the cliff compared to ambulance / hearse at the bottom.

I just don't understand what's not to understand about this.

I also wonder what Dean did to get himself banned this time.... I would guess though, a direct personal attack on someone using foul language, as he did to me above, would have done the trick, if anything would. He must have really PO'ed somebody, I guess.

 

and damping dissipates energy, energy I'd rather use applied in a forward direction, instead of converted into heat. Thanks.

 

Keep typing buddy. I think you got all the major "buzz words" in there.

I am still waiting for real data, not your pathetic attempts at explaining what YOU THINK is happening. Show me one real source that gives data on Percantage of anti-squate as it relates to wheel hop. Just one is all I ask for. With most of the people with brains leaving this pathetic site, you may think you know stuff, but all you are doing is pulling out the same BS that has been tossed around this site for years. Really, get out all your suspension design books, all of your mechanical enginnering experiance, and find one refrence or equation that show the relationship between anti-squat.

All you are doing, is telling everyone to do things to their cars, that in auto design classes, they teach designers to avoid.

NAF, then don't use the energy to burn the tires. Your not going to hop the wheels if you dont' spin them. Easy solution.

BTW sofaking, ever talk about what happens to a suspension with large ammount of A/S after the initial launch??? guess what, you usualy have worse 60' times, because you completely unload the suspension once you get out of the hole from the intial launch. You have your head stuck up your *** if you really think that giving cars large ammounts of A/S is a solution to anything.

 

Hi, Dean #2!!!

Who ever said anything about ???? (your English, not mine) Sure, you can do that WRONG, just like you can do just about ANYTHING wrong; doesn't invalidate the reason for doing the RIGHT amount of it. Which is of course, to get the IC and the CG to be at about the same place, so that the application of engine power doesn't send the suspension into violent oscillation.

Keep typing buddy, you just make yourself look more foolish with every reply. Suits me just fine though. Foul language won't make you any more truthful, accurate, or "right" than Dean, and it won't make getting the suspension geometry CORRECT, instead of trying to hack a work-around with shocks, any less the right thing to do.

 

Foolish, I made point after point, with quotes from sources. You have yet to site any actualy source, or show any real information. I am done in this thread, it has very much run its course, anyone reading it has all the information to make the descision on their own. If they want to listen to the DUMB advice you are giving them, telling them to use relocation brackets on a stock car, that will give them roll steer problems, and likely hurt their 60' times also, then good for them. You reminded me why I left TGO to begin with, and why I am sorry I came back to post. The people like you who have no real know how, giving out poor advice is sad. For all the newbies, welcome to TGO, home of the misinformation, due to tools like this guy.

 

Geez Dewey you have a bad day? You guys can't take this so seriously, I don't think anyone on here is going to take this as the lords gospel and endanger themselves due to some internet suggestions - if it is as dangerous as some think.

Also, having a BSC in mechanical engineering doesn't give yourself any additional credibility to me. I know that I was one of maybe 5 mechanical engineers in my graduating class who could identify a crankshaft, let alone know what it does. Sad, but they don't teach a whole lot of automotive or IC engine stuff in mechanical engineering. I'd trust a mechanic with bruised knuckles over a fresh mechanical engineering graduate from my experience.

Anyway, sofa, you really dragged that horse out of the barn and beat the (non-living) stuffing out of that with your longer post up there. I think we've all got the concept here, those that are still reading by now at least

Do you (anyone?) have any thoughts on the suggestion above? The length of the LCA isn't really the gist of it. We all know that under power the rear will try to rotate, and a *real* torque arm will flex a bit, and let it rotate up, hence some people adjust their TA to be a -ve value. Ok, so instead of lining up your bolt holes *directly under* the rear axle, such that any rotation of the axle will swing that bolt hole forward (and in that arc - upwards), bolting your LCA to your rear axle (with custom brackets), that put it slightly behind the rear axle. This way when the rear axle rotates, the mount hole will go in that arc forward, but also down more. How would that work?

 

My reply was to Shagwell re. extending the LCA brackets rearwards, and why that won't work; coupled with yet one more attempt to explain the mechanics of the design issues involved, in a language and using a visual that would be easy to grasp for anyone of any educational background whether technical or not.

The main problem with moving the pivot hole rearward like that, is that then, the car will wheel-hop under braking (which they do anyway, because the rear of the car already tends to lift). With force applied the opposite way, the rear will tend to rotate the OTHER way, which will tend to LIFT it off the ground, which of course is not good. It's kind of like cambering both your front wheels the same way to favor turns in one direction: sure you can do that, but it will cost you in th eother direction. A better approach is to make the suspension NEUTRAL to accelerations applied in both directions, rather than biasing it one way or the other. IMO.

Sonix, I apologize if there seem to be other people who JUST DON'T GET IT, and think they know everything there is to know about this because they read a book once and can quote it, and just feel like, for whatever reason I can't fathom, they just HAVE TO get on here and try to smear anybody that offers sensible advice; but strangely enough, haven't offered ONE SINGLE SHRED OF ADVICE on how to get to the source of the problem and CURE it as opposed to hacking ineffectively at the SYMTPOM with cubic $$$. I'm not completely sure what I'm apologizing for, because I didn't make those people act that way, I can't change them, and I have no choice as to whether they continue to act the way they've been acting; but FWIW, I apologize. For them, on their behalf, if not for anything I did.

I would WELCOME any constructive, informative, lucid, logical, mechanically and mathematically rigorous, hate-free, alternative explanations of why these cars wheel-hop, without a bunch of know-it-all "I 'know' more than you do" type of personal attacks. I'd like to know why it is that there are SO MANY manufacturers offering this simple, cheap, easy-to-install part instead of selling $1000 shock packages that they could make A WHOLE LOT more money on, if that was REALLY the solution to the wheel-hop problem. And most of all, I'd like to know what to do about it, besides spend $1000 on shocks covering it up. Which so far, is the ONLY alternative suggestion to geometry correction that's even been offered.

 

Sofaking.

I did offer several alternatives. 1) Bushings, worn and sloppy bushings have an big effect on this. 2) PROPER dampening. Correcting geometry is one things, altering is a diffrent. Just like drop spindles are used to correct the geometry.

What I am saying is that, the original poster was asking about his STOCK height car. with higher rate spings. In this case, the problem is not that he lowered his car, and the geometry changed. The problem is that he raised the spring rate, causing the sprung masses frequency to change. Yes, using relocation brackets is going to change thigns, yes the car may or may not have wheel hop problems after he does them, but it also changes a lot of other things, and that is why I would say to get better shocks. Not $1000 worth of shocks, spend $200 on new shocks that are up to the task of actualy controlling the motion of the higher-rate, higher frequency springs.

As I said before, it is stupid that this thread is still going. You made you point, you made it 19 times, with way more words than anyone wants to read. The information is there, let people make their choices. You are unwilling to open you mind to the idea, that maybe what you have read for years on TGO, is maybe not right, and maybe not the best solution. I prefaced my statement, with assuming the bushings are good, and the geometry is in the ball-park of where it should be. (he had a stock height car, so the geomitry should be fine).

The fact that you keep argueing without making a point, or without any real information to back up your point, is why I think your a tool.

Sonix, yesterday I was in a bad mood, I am not in a great one today, I am just tired sofaking.

--John

 

What could it mean if my arms are a little in the up position and I still don't have wheel hop? I have stock springs, tight new poly bushings and I think adjusted to stock length. spohn TQW arm and so on.... I used to hop stock, now it is all gone. My car has new KYB AGX shock set to 6 of 8, 8 being the hardest. No wheel hop ever, not under HARD braking and 0 under hard hard accelerating... Just curious, since my arms point a bit up towards the rear....

Am I just lucky that I found a combination of parts that don't hop? Whats my deal....

 

Dennis, I think you hit the nail right on the head; you're just "lucky". Most of the rest of us have fought this problem for as long as we've owned our cars, which is 20 some-odd years in my case.

 

Dennis,

It means just what I have been saying the whole time. You have good firm bushings, and proper damping, thus no wheel hop. I also have my control arms just ever so slightly up. (maybe 1/4"-1/2"), and even with the higher rate springs I run, I have it dampened properly so it doesn't hop either.

 

Shagwell,Extending the LCA's about 2" wolld in fact help a tad. the extra length of course would slow the wheel hop frequency. Longer the better- But at a cost- it is extra weight.Yes you are also correct as the pinion rotates upward in thrust it would just 'slightly" counteract the squat initially for about a 1/4" maybe depending on the mount distance of the LCA from the axle radius centerline- the longer the LCA is extended, the longer the mount arm is and the greater the angle of the mount arm exerting downrad force. THis again can come at a cost if the LCA comes into contact with the axle tube under suspension unload at any time- you could bend an LCA or just cause wheel lift in cornering . THis is an extreme example, but I am just empashizing the ill affect of having it too long and come into contact with the axle.Ultimately, the amount of work and unsprung weight added, compared to the minimal gain is really not worth it. It would have an initial affect under thrust slop, but then just go right back to how the original worked in the rest of the articulation. The longer arm does make the articulation angle stay more constant- this is the real change.Braking would gains or losses would be nil. The gain of the antisquat on mount angle would be counter balanced on the loss of squat on the braking rotation of the axle.Not worth it in my opinion.

 

You are a dumbass and just need to stop now. That egg crate example explains 'polar weight'.G()D help us.


ps- DW told me this weekend you need to Boogity, boogity, boogity your dumbass outta here son.http://www.cardomain.com/member_page...2_152_full.jpg Thats funny right there.

 

I can't understand why such a calm person with such people skills is constantly being banned....

C'mon Dean, lighten up here. That was a good example of polar weight, he just didn't use that phrase. I imagine thats why he eluded to "a topic for another rant".

 

That wheel hop might just be from the torque arm mount. have you checked it?

 

Hi Dean!!! You back looking for some more, or what?

Yes I'm perfectly aware of what the egg crate experiment is an example of. Glad to know you are too.

Thanks for being so cheerful. positive, helpful, informative, and otherwise generally an asset to the human race!!! Not to mention, one of the best verifiers of the truth of what I say; every time you re-register just so you can light into me AGAIN, it just goes to show that the truth must really hurt.

See you around for a couple more days!!!

 

Well I already spent $200 on shocks. I have Koni Reds in the back and they are on the toughest setting. And I was under the impression the springs were stock for an IROC. The torque arm is good.

 

Right; you need LCARBs.

Looks like we've come back round to where we started before these other guys decided that they didn't like what I had to say, let alone ME, for whatever reason. Too bad they didn't read what you had to say in the first place, and that this thing turned into a giant p***ing contest and entriely ceased to be helpful to anybody. As I said above, I apologize on their behalf (since no apology seems to be forthcoming from them).

 

I just can't understand how somebody who claims to be such a smart person can waste so much time out of their oh so important life with childish games. I can't see how somebody that claims to have so much tech knowledge would want to spend their time repeatedly joining the same site to have the same arguement, to get banned all over again.

 

I am sometimes on the computer alot anyways for other reasons and it takes but about 2 mins to reregister and answer email questions. Its fun and a nice break inbetween work and research.

atc3434, why do you waste your time coming in here then? I gave you my reason, its fair I hear yours?

I happen to be home today working on car projects. I have actually already placed 3 orders on line, one of them being from Hawks- a TGO sponsor. I wil be out working on a car project for about 4 hours and will be back in for another break to eat and screw around on the computer, then I am out for an appointment and then back to work on my project till about 11:00 pm tonight. I am busy, but everyone needs breaks.

 

Fair call.

I've actually learned a lot from this little pissing match, my eyes were opened to roll oversteer, and we really got inside LCARBS and dampening, which I understood but enjoyed the dialog on. I'm still re-reading (here and other sources) about the IC, haven't totally wrapped my mind around the concept. I'm on here a lot at work, don't have time for internet play at home, so I post a lot. I've got a nice auto-x third-gen, and I'm always looking to improve. I draw specifically to this post because I'm amazed how fast you manage to re-register and start right back in...

 

I do not try and be an ***, but when I am provoked like Sofa making comments like he did calling me into this when it first started, I re registered and came in to set the facts straight and give helpful knowledgeable advice. This kind of crap he's now doing to Dewey with the aka dean 2 is childish also. I am guilty, but I did not start the crap- yes I do add my imput but I ALSO BASE IT WITH FACTS and whenm I am challanged and the other party doesnnopt bring the facts- I will belittle them. THis crap causes people to waste money- I try to stop that and give people factual info to base decissions on.
,p> This banning thing has gotten way out of control and is a joke. People constantly think I have been banned all 500 times from 500 different assults- thruth is it dates back to a vendetta a few moderators have against me. THe latest is actuall provoked from me staing factual reasons why UMI stb would be a PITA for an alignment mechanic to work around. THat made him look bad? whoops, but it is a fact andpeople looking to buy it need to know that before the spend their money. I am sure a mod banned me to shut me up.

 

BobItzaboy: You are right on that. That UMI piece is junk when it comes to getting an alignment. i don't see how UMI didn't see that when it was designed... Kinda makes me feel like other parts might not be well thought out. I am sticking with spohn whenever I can.

Good stuff seems to come out of BMR although I don't have anything from them right now.

As for LCRB, like I said before, I don't have them and DON'T hop at all.

-Spohn arms, tubular adj. kind.
-Hotchkis panhard rod.
-Stock springs.
-Spohn adj. TQ arm
-KYB AGX shocks

No special attention given to stop hop problem. Just bought parts, slapped them on and the problem doesn't exist for me.

If you guys want, in a few days when it stops raining here and I have some free time, I can heat up the drag radials and set the rear shocks to full soft and see if I get hop... Maybe I will, I will try smashing the C5 brakes too to see if I get braking hop. The front struts are already at the softest setting.

 

Dennis,

It may be that adjusting them up higher could also give you hop. Especialy on those shocks, that also adjust bump valving and reboung valving at the same time. As your bump valving goes up, it raises the sprung frequency.

As I said, the key is having "proper" dampening, not too much, not too little.

It will be an interesting test though, I look forward to seeing your results.

 

All you have to do is remove it to align it. I don't see why that is so tough. Get your vehicle aligned and then install it.. its pretty simple. Align the vehicle, install STB. Install strut tower brace, if you need a alignment remove it and then reinstall it. The slots are long enough that you can reinstall it in the EXACT same location. It isn't rocket science. We thought about this, because *you* don't like our design on this perticular item all our items are incorrectly designed? Right.

You guys complain because you have to drill holes in your vehicle and then you complain when you don't.Seems like a lose/lose situation for us.

 

I have two videos of this weekends racing I shot of a VW Ghia I was helping with. What it shows if you look closely is how just one simple thing like tire grip change can completely throw off the cars launch ability and foul up the suspension. This is a VW of course, but the same priciple applies to any car when it comes to bad articulation angles and how the car hopped bad from over exerting the intended coil rate and planned travel.

We expected the car to have a tad of wheel sin off the line and have the suspension set accordingly with the rear spring rate and shock damper for the grip coeficiant and weight transfer. We launched at 8lbs in the rears here but the track temp was colder so it slipped perfect and went. Good squat and weght transfer, fronts lifted and carried sitting down smooth and settled before 2nd gear maintaining the 6000rpm launch.

http://www.youtube.com/watch?v=8dD3mnsoTGw

Now the whole point here- With just a tire pressure change UP TO 12psi for more wheel spin because we gathered info that the track was heating up and grip was exceptional- we should have gone even to 14-15 because it did not slip enough and bogged down. Watch here how HARD it bit. SO much that the rear suspension articulated way too much and the car dipped and then hopped- this was not intended but IS A GOOD EXAMPLE how just a tire grip change can make the suspension travel work in a greater articulation range and into a realm of trouble causing problems. The unexpected grip caused the back tires to come off the ground twice because the spring rate was too low for the grip level

Relocation brackets would not have helped us here becasue we are traveling way too far from parallel to begin with both up and down. Higher spring rate and dampers would control this extra grip.(Thats not an option but not important for this discussion, this example is just to show how grip can change suspension performance)

http://www.youtube.com/watch?v=RLjxxMu-Qb4
Now for those that are curious even thought this is non 3rd gen related can read on. These tires are way too much for this car. 8.5 inch slick and it should have 7inchers on it. It was biting way too hard and we should be down in the 6-7psi range with them. Going larger like this we could easily stiffen the torsion rate slightly and up the damper rates for a very good fix, HOWEVER, this car does not have the power to launch and hold the rpms with that much grip and bogss down below 5000rpms. The better option is to go to the smaller 7 inch slicks which are easier for the little motor to rotate on top end for speed and also still has plenty of grip while allowing a tad of wheel spin to keep the rpms above 5k on lauch. It seems to like 6500 range for launch.

The lesson here is, things have to be married. we found out 8 1/2 inch slicks are too big and not a good marraige. 'ITS NOT ALWAYS THE SUSPENSION THAT CAUSES SUSPENSION PROBLEMS'

Weight of the car is another important factor I have not mentioned here either. Some thirdgens experience wheelhop with the same springs that other 3rd gens do not with the same settings basically BECAUSE one car is heavier than the other and/or th etires are gripping better or worse or the surface is the cause (rough asphalt you last had wheel hop on maybe) many different factors, but weight is a biggy difference. GTA's can be as much as 500 lbs heavier fully loaded than some light non optioned Camaro's.

 

My guess is those tight bushings. Friction between the bushings and the sides of the brackets is essentially a damping term that's having a larger effect than the rotational stiffness of the OE bushings had as supplemental springs. I'm not familiar with Spohn's torque arm, but if it's shorter than OE you'll have more anti-squat than with an OE TA. And if it's attached at the chassis end by a short link, the IC construction follows the link axis rather than being perpendicular to the torque arm itself (which is close to but not precisely the same as vertical, BTW). Quite possibly by enough to overcome that "wrong-way" LCA angle in terms of the final anti-squat number.

With respect to shocks, stiffer springs require greater damping from the shocks, at least on the rebound side. Otherwise the vertical tire loading varies more during spring extension, which varies the available traction more.


Norm

 

learning alot here, just posting so i can come back and read up on it later.

 

I don't have near enough time to keep up with this stuff.....

My reason for possibly lengthening the lca's is because I am building a tube chassis for my car. I am also putting a 8.8 ford rear in, so there will be no more work envolved with building a longer arm than a shorter arm. I see where it could result in squat under braking, but it shouldn't be noticable if I dial enough squat out of the front during braking and a the proper compression stiffness on the rear shocks. The longer arm would result in less angle change through the same range of motion, therefore would be less likely to cause any roll steer. What I'm thinking is to make the rear mounting point square with the back of the axle tube, instead of straight down from center. The mount tabs on the rear obviously have to be long enough to avoid contact between the lca and the axle tube, or you would need to build curved lca's, thus requiring even heavier/stronger material for the lca's(I see no point in this). What I'm attempting to do is dial in more weight transfer for the intial launch, w/o creating ill handling geometry at rest/ride angle.


As for the pinion climbing the ring gear; traction is a tires' resistance to rotate. This translates into an axles resistance to rotate. This resistance to turn causes the pinion to "walk-up" or "climb" the ring gear. The tq arm keeps the diff from twisting backwards, but is forced to react from it's front mount, thus the diff travels downward from the car(basically climbing the gear, w/o moving the car). Spring rate and shock valving control this motion, forcing the tires to begin to rotate in reaction to the pinions rotation, causing them/the diff to move forward. The diffs' forward motion is transfered to the car through the control arms. The straighter the control arm angle, the more energy is used to move forward. The lower the rear of the control arm, the more it is used to continue front end lift/weight transfer to aid in traction. A car with more traction will require less weight transfer to maintain traction, therefore more energy will be available to move the car forward. Tire grip, suspension geometry, spring rate, shock valving, and power all dictate a vehicles traction level. A higher powered car will require less front end lift to maintain enough weight transfer to supply the required traction. - Back to the old saying, " an underpowered car goes up". It takes more power to move the whole car than to lift the front. If a car stands up, you have more traction than power to move the car.

All that said, I see where an lca that runs upwards toward the rear could result in the initial reaction of the diff to slide the tq arm forward on the slider, thus allowing the lca's to twist upwards even more, all of which would result in a loss of traction. An appropriate spring rate and stiffer shock compression could negate this, but would not be idle for forward traction as you would have to go overly stiff, thus negating the engine's ability to apply the suspension to help the tire maintain grip.


hummm... the more I think about this, the more I think anti-squat should be dialed in with tq arm length, pinion angle and spring/shock rate.

am I getting closer or loosing ground from over-thinking?

damb...now I'm gonna have to uncover the 'bird and check my lca angle. The car's been down 3 years now, I can't remeber exactly where everything is set to.

edit - hey I figured it was my turn to have an overly long reply

 

bump



did everyone give up on this thread due to the arguements? - Let's grow up and keep this going, there's actually some really good info in this thread about the lay-out/function of our rear suspensions....

 

Not really. But given the last lengthy post's date (Halloween), work suddenly getting busier, and me getting ready to make a weekend getaway I'm not ready to comment yet. I need a little time to make sure I understand what you meant (which may differ slightly from that which was actually typed).

My initial thoughts revolve around the idea that with longer LCAs the anti-squat generally changes less rapidly as the rear ride height varies. I'm not sure what happens with respect to pitch, though.


Norm

 

Can't speak for "everybody"; but I did.

 

yeah, and since my broke azz can't currently afford e-net at home(24yrs old, $1700 mortgage payment) I only get on from time to time.

I'ver read some of your posts in other threads, and it seems you have some solid/good knowledge of suspension systems - I'll await your reply.

Anything from Dewey or Dean?

 

I need to reread what your wrote. I'm at work right, hopefully I can sit down and read the whole thing tonight at home.

Any chance you could do a quick drawing of what you have planned, I get most of, which is moving to a longer control arm, but some of the other changes, I am not so clear on what you are describing.

I do have to ask some other question to preface this. What is the porpuse for the car, are you building a tube-frame drag racer? Road-racer? Silverstate?

--John

 

Dean already answered awhile ago.

 

what I was questioning was if my long description/theory on how this system works is correct. I have a fairly solid understanding of how suspension will react, and I believe that is correct for our tq-arm system, just trying to verify that with some of the "gurus".

I also should note that I have realized why I shouldn't dial out too much front end squat under braking. No road/track surface is perfect, thus the suspension must be loose enough to properly react to bumps/dips. Too much anit-squat in the front under braking could cause the entire car to be upset when an "irregularity" in the surface is encounter. - That said, I still believe that extending the LCA slightly behind axle centerline should not cause any major issues during hard braking IF you are running the appropriate springs/shocks.

As for the use of my car. To put a name on it, street. It will get drag raced, it will get thrown around an auto-x course from time to time, but mostly it will be my "off-work toy". I just got fed up with my 4001# curb weight and the general issues associated w/ a convertible uni-body. By the time you elimintate enough flex to make the car handle/respond well, it's just too heavy. So, I decided that a tube chassis w/ about 3-4" engine set-back('96 dash, I have room) and custom suspension could get me down to around 3000#'s w/o having to toss my a/c, stereo, power windows, etc. Plus, the over-all rigidity of the car and the custom coolness factor.

 

Nope, the diff does not teeter totter forces from the front of the tq arm and force yhe diff downward under throttle in a counter action. The diff always wants to rotate upward. Sounds to me that you are referencing the front tqarm mount and the diff as if there is a link pivot in the center of the tqarm.

 

My wording was off. That's basically what I was trying to say. The diff wants to rotate upwards in response to the pinion/ring gears. The front mount of the tq arm will not allow the diff to rotate, so the diff rotates downward from the front mount point.