Now that i've got my car back on the road for the summer, i'm tinkering with it trying to chase down all the problems and address them. (Oh man, so many problems) I'm shy on cash for the next 2 weeks or so, so i'm just trying to get my ducks in a row here.

When accelerating hard, I can powershift from first to second, and it'll chirp. Now if i'm in a corner or something, it'll just "screech" and fish tail, but i'm talking in a straight line. I'm not getting a solid "screech", but the "chirp chirp" of wheel hop.

I have boxed LCA's with poly bushings. NO LOWER CONTROL ARM RELOCATION BRACKETS. I have 3.23 gears and a T10 tranny. Lets say a 350HP engine, for arguements sake.

I have 28" tall tires in the back, 275/60/R15's. They're crappy hard compound truck tires in my opinion, BFG Extentia T/A's, (walmarts proprietary version of the Radial T/A I think).
The tall tires lead me away from thinking about the relocation brackets, since I imagine the LCA is straight. I actually havn't really looked at it, I don't have a bubble level either...

Also, when wheel hopping, I can notice my shifter handle jumping. I put in a NAPA rubber tranny mount right before winter, maybe 200kms are on it.

I know there are a few experts on this subject with differing opinions (*cough*). I respect all opinions here, so what would you guys recommend I try first?

- Could this tranny mount not have enough strength? ie, should I go to a poly mount? Could the stamped metal tranny cross member be a weak point?

-LCARB's?

-Too hard of a tire?

Thanks

-J

 

It is definately shock and spring related. You do not have enough spring rate and the shock damper is not high enough-probably older factory or aftermarket somewhat replacement shocks I am guessing?
edit: I see KYB in your sig. The are not the greatest in damper force valve control- better than stock, but still could be the problem when combined with a factory spring rate and the car is leaned over in a corner inverting the outside LCA.
A note to you or anyone else experiencing such a problem and using LCA relocation brackets to correct this problem- It is the proper fix-HOWEVER- Only move the rear of the LCA's down one adjustment notch at a time until the problem disappears- Don't just weld them on and use the lowest setting- You can and probably will in most cases induce massive roll oversteer which is bad. Inverted will induce roll understeer but higher HP will also cause that to wheel hop. Keep the rear settings basically as high as possible without experiencing wheel hop- A general basic rule of thumb to follow.

 

Close,
Moog cc635 on the back, brand new (just like everything on the car, 8 months old, maybe 500km on it).
KYB gas-a-just on the back, again, new.

I thought drag racers use really soft stuff on the back to promote weight transfer?

Moog 5664 on the front, with KYB GR2.

Does this change your thoughts?

 

No it doesn't, those shocks and springs are too soft for cornering and the car is rolling over and inverrting the outside LCA inducing tirehop.No you do not waht soft rear springs on a drag car. You play with the IC Instant center and soft tall front springs to unload the front and pivot that load onto the rear without the rear lifting or squating.

 

oh ok, well i'm not too worried about cornering, the wheel hop I experience is only in straight line acceleration. In a turn I don't get any hop.

Either way though, you think it isn't a tranny mount problem, but a LCA mounting point issue? I should get those, and jump down one hole at a time until it clears up?

 

My appologises, I just reread what you wrote and I relized I misinterpeted it. I thought you were saying straight is fine but in a corner it screeches and goes chirp chirp- Not the case, my bad.So straight is chirp chirp wheelhop- Thats just the classic old need relocators to drop the angle of the LCAs slightly more so they do not squat and invert under thrust traction. Either way, its still a result of invertion under power and you'll need either stiffer springs not to invert as easy, stiffer shock compression valving not to invert an control hop, or simply just add relocation brackets and drop the angle until it stops if you desire to keep everything as is spring and shock wise.

 

Ok. Since my rear suspension is new, I don't want to replace it. I'll look at the LCARB's, since having more adjustability long term is good anyway.
Thanks.

 

i have always heard in rwd cars like ours you put the v6 rear suspension in to the v8s to shift the weight to the back of the car to make it hook up when launched. which is practical for your budget racer.

 

you want v6 front suspension.. soft front springs help it unload and transfer weight easier.. you dont want the rear to squat.. squat=tires initially wanting to lift=less traction

edit: LCARB's helped lift the rear in my ta.. i used to squat and wheelhop, now it lifts and goes

 

Using a 28 inch tire will not help the lower control arm angle, it will make it worse in two ways, one, using that size tire with out lowering the car back to level will shift weight foward and two, under acceleration the axle is sitting higher in the body than with a stock 26 inch tire causing the control arm angle to incline to the axle instead of a level or decline connection the the axle. Springs and shocks are just as important also.

 

Wheel hop is: you give it gas, the car gets a push going forward, the car tries to "squat" which is actually the rear end trying to compress the springs and lift itself off the ground, the tires lose traction and spin, the pushing force goes away, the springs push the rear end back down, the tires get traction again, the pushing force returns, the rear end tries to compress the springs, the tires lose traction, ..... about 6-7 times a second, in the rear suspension of one of these cars.

LCARBs fix it, where NOTHING else will. They repair the geometry that was defective for this purpose from the factory, and does nothing but get worse with age and modifications.

 

Ok yea. Only thing was, I know that when you lower your car, the geometry gets worse. I thought "raising" it, would be raising the rear axle and would help the angle of the LCA?
Well, either way, i'll grab some of Spohns $70 specials then brag I have spohn suspension, and see if it helps me out.

 

Raising THE CAR up off of THE AXLE helps somewhat; larger tires don't do that.

Lowering THE CAR causes this to happen, because THE AXLE stays at the same height, but the FRAME end of the LCA becomes lower.

Look at your car, let's say, from the left side. Look at the LCA. Imagine that the front attachment point (at the frame) is below the rear attachment point (at the axle). Imagine that you push on the axle from the right toward the left, trying to accelerate the car. What is that axle going to try to do?

Right... it's going to try to rotate UPWARDS and lift the tires off the ground. The car body can't "hold it down", because it only moves downward at the rate that gravity pushes it down; an acceleration of 32 ft/sec/sec. In English for any non-physicists that are reading whose eyes haven't glazed over yet, that means that the downward velocity of the car body increases by 32 feet per second, each second; at the end of one second, it's moving at 32 ft/sec, at the end of 2 seconds, it's moving at 64 ft/sec, at the end of 3 sec, it's moving at 96 ft/sec; etc. That also means, if you calculate it back toward smaller time increments, that at the end of one-tenth of a second (near the wheel-hop rate), it's only moving at the rate of 3 ft/sec; meaning that at the end of that first tenth of a second, it has fallen less than .3 feet, or less than 4 inches, assuming that the rear end has come completely up off the ground and the car body is in free-fall!!! And the real number is of course less than that, if the tires maintain any contact with the pavement at all. Is it any wonder that it hops?

Now imagine that the rear end end of the LCA is BELOW the frame end. NOW when you push on the axle, the axle tries to rotate DOWNWARD, which tries to plant the tires HARDER into the pavement. You don't want too much of that of course; ideally, you want enough of that to keep the tires from spinning, without shocking them so hard that the spring effect of the tires begins to dominate the rear axle's motion, instead of the spring effect of the suspension (at the track, this is called "hitting the tires too hard"). So it's a tuning adjustment, not some absolute "this angle is the perfect one" kind of thing.

 

I am not trying to harp on you(just trying to educate) so please don't take offense but 'NOTHING' is not true.


What most people do to their cars is before anything else is generally start adding HP to a completely stock and worn chassis & suspension. Now what happens is they then get wheel hop from a sagging and weak suspension and usually are not wise to suspensions in general. THEN, they come on here asking questions why they are getting wheelhop and I have seen MANY MANY other people just as you just did tell thenm the worldly fix of just adding LCARB's- This can be dangerous and usually IS very dangerous.
The factrory suspension even when new is not designed for that kind of HP and acceleration stress, nor is the chassis designed for the promotion of Roll Oersteer gain that is now happing to their chassis after they listen to you. Once they get off the gas and the car raises back up from the thrust squat, they are now twichcy and unstable due to the roll oversteer they just induced from bolting on LCARB's on to a car that would have been better suited NOT having them and merely just a stiffer spring and shock upgrade. This spring and shock upgrade would limit the car back to factory suspension articulation travel under the new greater forced applied and would keep everything working withinn the balance and handling perameters the chassis was engineered for- and in alot of case would not let the LCA angle invert under thrust that the old worn spring will allow, or the old worn shock is allowing , or both.


Please do not just tell someone LCARB's are there answer and NOTHING else will work.
Thanks, Dean

 

In my experience, wheel hop is most often caused by worn/crappy shocks and bushings. I found a poly TA bushing helped a little too. From what he describes it sounds like a normal chirp, its not supposed to screech. The screeching and over steer in the turn is probaly a weak posi or loss of traction. If i powershift or just shift hard i get a chirp and no wheel hop. My car is pretty stock, urethane, moogs and illuminas, with the poly TA bushing, and poly tranny mounts.

 

Well I don't have worn shocks, and they aren't exactly gabriels or monroes here. They're a relatively performance piece.
All bushings on the car are poly, Energy Suspension. TA, LCA, Panhard, sway bars. Except for tranny and motor mounts, those are new rubber ones.

Yes, definately. Punching it in a corner gets me fishtailing and burning rubber. More of a fun pasttime then a way to get around the track the fastest But that's kinda besides the point. I was just pointing out the chirp-chirp-chirp isn't a "screech", ie, wheel HOP, not purely burning rubber. If I was just burning rubber when I powershifted, I would be concerned about getting better tires that gripped, and maybe upgrading/adjusting suspension in the back. Or i'd just be happy I have that much power, and leave it at that. But the cyclic chirp-chirp of dreaded wheel hop is what bothers me. (and the movement of the shifter handle )
I'll go to LCARBs first then, and see if that helps me out. If it does, but I still notice a large movement of my shifter handle under power, then i'll go to a poly tranny mount, and eventually a non tranny mounted torque arm.

 

They may be new, but the KYB's arent exactly well known to be stiff shocks but rather soft/weak so they offer little damping capability. A stiff spring can only do so much. If the suspension is going to compress, it will, and if the shock cant control that motion you end up in a cycle of uncontrolled spring action or wheelhop. Might try getting some other shocks and see what happens then. Rears arent that expensive.

 

Thats the only part of these cars I still think "what the hell where they thinking when they engineered that". In my opinion, that is the very first weak link that sould be fixed on these cars by means of a crossmember mounted TQarm in some fashion (many different aftermarket choices).Sonix, Even though you springs are new, I still question if they are stiff enough for you motor application. So agin, if you do get the LACRB's, just make sure you first onlu go one hole down at a time to see if that helps eliminate it. You want them to be as high as possible without having wheelhop. If you have to go too low- ESPECIALLY if the car is not lowered- then the springs are not stiff enough rate.

 

Well, almost pointless to reply to someone who's been banned, but maybe someone else can answer me on this one then;

not a lot of choices out there for rear springs, and I thought Dean was an advocate for progressive rate springs.

Anyone know of any rear springs that are a stiffer rate than the 5665 straight rate, or a stiffer rate than the progressive cc635's? I'm not sure how those progressive cc635's are rated, or how to compare them to anything else...
I'm just looking for knowledge for now, I don't think i'll be swapping in new rear springs for a little while yet.

 

http://www.speedwaymotors.com/p/5878...1andquot;.html

anything from 150 to 300 lb/in.....knock yourself out.

 

Well i'll be damned, guess I just don't hang out in the right circles to learn about this stuff.
5 1/2" ID, with pigtail to fit on the axle end, and 11" free? I'm guessing the stiffer the spring, the taller the rear would sit eh?
What's the stock rear spring rate? I *think* it's around 130lb/in?
That's a good price too, $44 per spring, $90 a pair, that's about what stock springs cost... Interesting.

 

The shifter is moving because when traction is lost the engine settles back down into the mounts. - The motor torqueing over is caused by the rotational force of trying to turn the ring gear. If the gear turns freely(no traction) the motor has little reason to twist over.

My car hooks very well on Eibach sprotlines and cheapy Monroe Sensa-junks. I do have a fully built suspension system including LCARBs though. Sofa is right on about the lca angle. Taller tires do nothing for the angle of the lca relative to the rest of the chassis.
- Tires may be a big part of your issue. If you're just past the threshold of traction they may hook & unload.

HPE is/was Dean. I think at this point he is forever banned from this site. He does have some solid information/expertise, but he's a bit overly opinionated which seems to get him into arguements and eventually banned under ump-teen different screen names.

 

Ahh, that's what I was wondering about the shifter, thanks.

That's right, you're the one who does the 5000RPM clutch drops and gets 1.6x 60's on street low profile tires right? The secret is in the high negative pinion angle and the LCA adjustment? Boy, anything over 2000RPM dropping the clutch in first gear just lights 'em up with me, it's annoying actually.
Well, i'll focus on my other thread in reference to my blown tranny/clutch... *cough*.

 

i know how that feels.. for me, it happens in second as well.. i have a video on streetfire with me "dumping" at around 2k.. not even sure if it was 2k.. i just revved it and let the rpms fall and dropped clutch.. then floor


oh, i just added another post on your thread too

 

Yeah, I'm the guy beating all hell outta some T5's. Cars' been down for about 2-1/2 years now, but I'm finally able to get some work done. I'm shooting for 1.4x 60's on 17 drag radials. Yes, LCA angle and pinion angle have been key, but the more options you have for tuning the more chance you have to find traction.

- I don't get on the boards much anymore with the outside sales job. - I caught some of your other post. I'll check into it more here.