ls six

Just wondering if anyone has considered or even tried an SLA front end conversion?

I'm not talking about a Vette swap or some other approach that requires complete front end replacement.

I'm thinking of something more like whats available to the Sn95 and 05 mustang crowd.

Agent 47 and Griggs racing make kits for the Mustangs but theres nothing for the 3rd gen F body as of yet.


I was thinking of something similar to those kits but with a shock mount on the upper arm.

If it's done the way I envision the parts list should be relatively short, just the adaptor that attaches to the stock spindle, a fabricated upper arm and a shock that could likely be an off the shelf adjustable unit.

A new set of upper mounts might be needed to replace the stock strut mounts, backing plates or aditional brackets will almost certainly be needed at the UCA inner mounting point.

I think the stock LCA (or standard aftermarket replacements) and springs can be retained but a coilover setup is plenty feasable.


Ideas and questions are welcome.

AlkyIROC

Third gens have been around for a long time. If there was an easy way to convert from a strut front suspension to an upper and lower control arm suspension, somebody would have created a conversion kit by now.

There are kits available to convert to a coil over design but it still uses the factory style strut suspension.

What's wrong with the third gen strut design?

ls six

The Fox stang was around for nearly 20 years before someone designed a conversion for it and the SN.

Except for some details this is what I'm thinking of. http://www.agentfortyseven.com/racing/suspension.html

and http://www.griggsracing.com/article_...be8eef28eab49a



As for whats wrong with the 3rd gen strut... the same things that are wrong with every other strut in existance. Poor camber curve, poor feedback, lack of tuanbility, the tradeoff between poor traction and poor tire life (see poor camber curve above) compromised braking.


As for an "easy way" it wouldnt be any more difficult than it was for the Mustang, just a different set of measurements.

My concept is atleast half a complex as the Ford aplication however so it would infact be even easier (and cheaper).

hickman

I've been curious about this as well, hell wouldn't mind seeing a swap setup using vette parts either. Thinking that converting the front end would make the handling even better.

???

iTrader: (5)

i've wondered about putting a whole 4th gen front k member under a 3rd gen.

but thats as far as i've gotten lol. then you could use the rack and everything.

AlkyIROC

Doesn't fit.

???

iTrader: (5)

what doesn't fit?

just wondering if anyone has put research into it.

i happen to own both a 3rd and 4th gen. but have only got as far as measuring the wheel base and it looked the same. i meant to check the sub frame rails, but never did.

ls six

Essentialy everything from kust behind the fire wall forward is completely different.

It might as well be the front clip from an import grafted to a revised 3rd gen rear 2/3rd unibody.

There are plenty of smaller differences through out the rest of the chassis too but it's still practicaly a 3rd gen floor pan to the eye.

After I saw the 1st gen 4th gen hybrid I wondered if the 4th gen front clip as a whole could be grafted to a 3rd gen chassis but no the 4th gen subframe will not fit the 3rd gen unibody, not even close. The rack could be made to fit but it would be just like fitting any other rack, complete custom fit.

I do hear that one company is introducing a mini rack designed to swap with factory GM boxes. Since 3rd gen boxes are popular swaps for nearly anything else GM with a box I suspect it'll fit our cars just as well.

CodyFarncombe

I'm 16 and own a 1986 trans am and i was just wondering if it's possible to change from the trans am front end to a camaro front end? Like if you were to change the front side panels and the hood would the front bumper and everything bolt up? Or are the chassis different?

ls six

You'll have better luck starting your own thread or finding one that is related to what you are interested in.

This thread is about suspension fab work not cosmetic swaps.


I can tell you that there are several differences between the Camaro and Firebird unibodies. You will likely atleast be drilling out countless spot welds and swapping integrated pieces of the chassis to make it all fit like factory.

The rear of the cars are different aswell and that would be major surgery to swap.

iroc a 86 berli

well get to work on your design, or buy some coilovers and call it done, or u could just by a stang

ls six

Coilovers have nothing to do with it. They wont fix the struts short comings so suggesting that just shows how un-educated you are, if you have nothing usefull to say find another thread to troll.


Or mabe you would like to tell me what your problem is? Never mind, i really dont care

1MeanZ

iTrader: (9)

In theory the thirdgen front suspension is not really the hot setup, in practice it works very well. If the thirdgen front suspension was really that bad, then why do thirdgens handle as well or better than 4th gens? I'm not sure all the work is really worth it....

iroc a 86 berli

settle down there hott shlt, if your design is as easy as you say, why arent you fabbing them, instead of being hostile on a third gen forum, flapping your gums about mustangs.

coilovers are a great upgrade from the stock setup. if you dont think they are, well who's un-educated??

whats your problem mr. sensitive?

Norm Peterson

Coilovers are an upgrade in that a wider range of rates (in more closely spaced increments) and ride heights is possible. That still doesn't fix the geometry, particularly for lowered cars where the strut's front roll center drops by about double the amount of visible body/chassis lowering if left uncorrected.

You can "crutch" strut suspensions either with stiffer springs and bars or by setting lots of positive caster. With respect to caster, the current Mustang is up around 7°, vs the 3.5° - 5° numbers that I can find for the 3rd Gen F-body. Yes, these tweaks can be effective crutches (just ask some guy named Sam Strano who has both 3rd Gen F and S197 Mustang experience). But they don't eliminate the condition.


With respect to a SLA, I don't think the upper arm is the preferred place to mount either the spring or the shock (assuming that you can fit a shock of appropriate length under the hood/fender line). The UCA is shorter, and will travel over a greater angular arc as the suspension moves any given distance. One of the end results is a spring or shock motion ratio that varies more, not generally a good thing if it's a handling/cornering performance increase that you're after. C/O's off the LCAs ought to be the better way, and you might as well work that around/into the probable necessity for adding structure to carry the UCA loads from bump, cornering, and braking.


Norm

iroc a 86 berli

i understand the diff between coilovers and the short/long setup, however like 1meanz said, i dont see it as a big enough problem to be worth the extra work.
f bodys handle pretty well with a few mods anyways.
thats not saying i wouldnt like to see a set built and tested. i like seeing any kind of custom fab work.

Pocket

iTrader: (24)

Once you figure out an acceptable design with decent geometry that fits in the wheel well, fabrications shouldnt be too hard

Reuse the factory LCA, find a short double A arm spindle (any full frame car/small truck), reuse the factory spring

Build a similar mount that welds onto the K-member or inner wheel well and build an adjustable upper control arm using a generic balljoint and threaded tubes

The reason you dont see this made and mass produced are from two reasons

Aftermarket liability, if the geometry isnt universal to all cars offered the consumer base will be narrow and sue happy when they are too dumb to install/adjust it correctly

Application specific, those who actually need this setup just go out and build it. They dont need some company to sell it to them since what the company sells likely wont fit their needs 100%, thus making it unattractive

Ill give a likewise example: 4 link rear suspensions
Is there a 3rd gen kit? No
Do people still use them? Yes
They buy a universal kit and build it to their needs, just like you could never pull Stephen's rear and put it directly in Shagwell's car. They're both 4 links from 3rd gens, but the application is too specific

ls six

Thank ypu to all the members with helpfull input

In reverse order...

Pocket: I did plan to re-use the LCA, I'm trying to keep the parts list small and cost down.

Pluss I believe I can use the factory shock mount position left vacant in the 3rd gen aplication of the arm.

The same arm is used in several GM cars and trucks with SLA suspensions.

Mounting the upper portion of the shock may be tricky and require dropping the sub frame. Not the best option but proabably doable.

iroc: Thats the only reason I'm going this route, I'm a fan of home fab solutions and it's something I enjoy. I'd like to offer it to the community but even if there are no takers the learning proccess is well worth it.

Norm: You have it exactly right with your "crutched" statement. If you only focus on a single aspect of a cars performance a strut can be made to perform nearly as well as a good LSA, but with compromises in ride, wear, stability etc.

This is more of a cake-and-eat-it-too endevor.

I was looking at the early Mustang and related cars that had the spring mounted on the UCA, not exactly a handling dynamo but it shows it can work.



Recently i did a lot of "eyeballing" with respect to fitting the up-right from a 4th gen along with a fabbed upper arm and bracket mounted under the top of the strut tower but clearance between the upper and the tower is tight even with a stock height car like mine. ( for any one thinking about the added stress to the tower I would use large backing plates for the brackets and a triangulated tower bar at the least, coilover's can apparently cause the towers to distort or fail)

iroc a 86 berli

cool, lets see em come together. hell if they work good, i might try them!

ls six

I'm looking for a set of LS1 up rights to use for the mock up.

The LT1's will work just fine and are common but if it dose work LS1 brakes are prefferable

One of the pair I got my LS1 brakes from is broken so I couldnt do any on road testing until I got another.



In the mean time I came up with an idea that may be unique!

It involves attaching the ball joint end of the upper to the chassis with the bushing end attached to the spindle / up right.

Depending on specifics I can get any king pin angle I want and avoid some of the clearance issues I'm dealing with now.

Norm Peterson

Reversing the upper arm on a steering "axle" will be neither stable nor have good geometry. It will still want to "steer" about the two balljoints, which would now be situated at a rather crazy front view angle, and you'd be relying on the steering to prevent the tops of the knuckles from flopping over. Reversed A-arms work on an IRS because toe control (think "steering") is provided by trailing links or fixed length toe control links rather than links that require driver strength to maintain in position.

What you could do is fabricate an adapter that bolts to the strut suspension's knuckle and has an upper ball joint of some sort either fitting into or bolted to it. Factory Five has done this for some of their kits, and I think they've had a couple of iterations that defined slightly different SAI's. I know that the idea had been considered long before that (think Fiat X1-9 time frame).

You end up with a short-knuckle design, which tends to favor camber gain at the expense of higher control arm load levels. It should fit inside the barrel of any wheel size that you can get big enough tires of recent technology in.

Then you need a to make a place to attach the chassis side pivots to that fits the geometry you want, and more than likely do a little bumpsteer tuning.


Norm

Pocket

iTrader: (24)

I would avoid the 4th gen spindles as they are very long. You will have to cut them down to do much of anything on the 3rd gen LCA

I would avoid flipping the control arm as well, the spindle pivots about the balljoints so moving a balljoint in would drastically change the steering angle and it would change progressively as you turn farther

deadbird

I hate to say you are wrong.... But, Fatal88 did it a good while back (like 5-6 years)...

https://www.thirdgen.org/forums/auto...times-has.html

I'm not saying it's a weekend job but, it can be done and has been.

I've seen the 4thgen grafted to a 71 Camaro (which I have the parts for) and a 77-79 (forget year specifically) Firebird as well.

ls six

Deadbird: I was reffering to the 4th gen subframe attaching to the 3rd gen unibody, Fatal88 grafted the entire front clip including a portion of the unibody.

At that point nearly anything is possible, I have seen early Mustang bodies on late Mod motor Cobra chassis as well as Miata chassis. And ofcourse theres a company making 69 Camaros with 4th gen underpinnings.

Pocket: I would use the 4th gen spindle as-is, thats where the clearance issues come into play as the upper arm ball joint will tend to hit the outer portion of the strut tower top plate with out clearancing.

Norm: I'll try to get a basic schematic of what I mean but it's rather similar to a combination of the Mazda Millenia and Infinity G20 front ends.

I dont see geometry being the issue though as the upper arm is not actualy being swapped end-to-end as you think. The ball joint is still outboard and the bushinged portion inboard it's just the mounting points and the static angle of the arm thats required thats different.

Most older SLA setups as you proabably know exibited massive positive camber gain from the factory, the space available in the 3rd gen strut tower would tend to require that sort of setup.

But by affixing the balljoint to the chassis and the inner pivot point to the spindle you can turn positive gain into negative gain with all the components in nearly the same relative location.

As for controling the lateral movement of the upper portion of the spindle thats where the Millenia comes into play as a point of inspiration.

They were equipped with a similar suspension as the 4th gen but with 2 upper links rather than a single upper arm. This lent the car some interesting dynamic castor properties.

I'm also looking at Fords new "revo-knuckle"

deadbird

Ha! I suppose you got me there lol.

Norm Peterson

I'm definitely going to need a picture (I'm online at the office, with all of its corporate internet filtering, so if there already is a picture, please ignore this). With the exception of one rather ancient British arrangement, I don't see how you can avoid having the ball joint at the knuckle as significant rotation about two axes needs to happen there (steering rotation and knuckle to UCA angle as the suspension moves is bump/rebound). Cylindrical bushings are intended as single-axis pivots only, with sufficient compliance to allow a limited amount of multi-axis rotation or other minor wobbling to happen, without being able to control it.

As far as UCA inclination goes, that's what you need to play with in order to reverse the direction of camber gain (my '79 Malibu falls into this category, at least in 2-D). Note that a tall knuckle won't give a lot of camber gain (either way, + or -) without using either extreme arm inclinations or upper arms that are much shorter than the lowers.


Norm

ls six

Heres what I came up with in five minutes

It's crude and dosnt show the fore aft link that needs to be in or near the king pin axis but you can see how the camber gain works and that it might offer a bit of extra clearance above the tire that the 4th gen up right takes up.

<img src="http://www.gliffy.com/pubdoc/1831770/M.jpg"/>

soultron

iTrader: (2)

Well for starters, does anyone have a picture of a bare stock K member?

Norm Peterson

I must still be missing something.

If that odd "upper arm" is fixed to the knuckle at two places, and the knuckle is fixed to the LCA by the (lower) ball joint, how is the whole business able to move in bump/rebound?


Norm

rayar

iTrader: (1)

I have thought about doing this but instead of useing 4th gen spindles I think G-body or S10 spindles would be a better option. Use your stock lower A-arms Then just get some fabricated upper A-arms from a circle track supplier and build some mounts that would weld to the top of the K-member You can also buy mounts from circle track suppliers. You would need to cut and brace the subframe above the K-member to make it all work but don't believe it would be that difficult. The brakes are the same so you could bolt on your stockers or whatever big brake kit you allready have. You can use the springs you allready have and Good adjustable performance shocks for G-bodies are allready available and I believe could be made to work with the K-member and stock lower A-arm very easily.

I quit with the idea because I didn't know what to use for upper A-arm length or how much angle to have, or how much antidive to put into the upper arm mounts. I could have copied the factory G-body or S10 stuff but just wanted something better then that and I am not knowledgable enough about suspension geometry to build something from scratch and expect it to work correctly. I don't think it would be hard to build but getting all the angles right could be tough.

ls six

The outer most point is attached to the chassis not the spindle.

Just imagine a typical upper arm setup but attach the balljoint to the chassis directly above where it would attach to the spindle and move the inner pivot from the chassis to a redesigned knuckle.

But dont get too caught up in that idea, it's just something that popped into my head one day.


rayar: I have thought about the G body/S10 spindle and the setup you described.

My choice of spindle would be (and may still be) the late B body piece.

My first issue is I want it to be a bolt in solution and the other is that if you look at any of the vehicles above you'll see the upper arm mounts well inboard of the F bodystrut tower/unibody sheetmetal and I believe shortening the arm enough to avoid major surgery would cause major camber gain issues.


I'm centering on a medium legnth spindle setup (taller than stock but shorter than the 4th gen) to allow the upper arm to mount high enough to clear the bulge of the K member and attach to a bolt-in bracket using the upper strut holes and the existing holes just above the unibody lower frame rail but with out driving the balljoint into the strut tower sheetmetal.

I'll check out the B body spindle as it is taller than the F, G and T body parts but I suspect I'll still need to machine an adaptor for the stock spindle to rais the upper baljoint enough.

Norm Peterson

Could you use circle track tubular upper arms (they come in a variety of fixed lengths and there's at least one adjustable version)?

I think the steering arm on the "B" knuckle sits lower at the tierod hole than it does in the "G" version. IOW, common bumpsteer kits won't work because they go the wrong way. But maybe you can get enough positive caster to bring the arm up enough. Be sure to check out the length of the steering arms, as a longer arm will slow the overall steering ratio and limit how tight the car can turn with the steering at full lock. I think the "B" is a little slower but I don't know by how much.


Norm

rayar

iTrader: (1)

I didn't get into all of the measuring requied but in my mind it looked like every thing would work. My car is not a street car so I would have removed most of the front subframe, strut towers and fenderwells. The K-menber would have then been tied into the subframe connectors and also tied in with the cage. The K-member itself looks very similar in dimensions to the front frame section of a G-body so it should work.

The B-body spindle was also a thought and one of the tricks the G-body guys use to obtain over 1G of cornering power but without the proper suspension geometry knowledge this was all just a dream. I also decided that some of the fastest CP cars in the Nation are sill running struts so if they can make it work then so can I.

ls six

I can tell you that the 4th gen arm is significantly shorter than the 3rd gen piece.

I know the A and G body folks use the B body spindle for various reasons so I'll look to them for insight.

rayar the F body K member is all but identical to the G body frame section that the suspension bolts to but the problem for me and anyone not looking to make huge modifications to the F body is that the stock G body mounting point for the upper arm is directly on top of the frame over the spring pockets. This is exactly where the lower frame horns on the F bodys unibody exist and that's also the only point where the K member attaches to the car.

By the time the lost structure was replaced and the bracketry fabricated you could have front halved the car using available kits from any number of sources.

Norm, I'd likr to use an off the shelf piece if I could but all those arms are built asuming a stock inner mounting point. That either puts the arm right through the strut tower sheetmetal and possibly the lower frame horn or puts the ball joint so far out I'd never be able to dial all the positive camber out.

I'll be moving the inner pivot outboard atleast 1 1/2 to 2" so I'll likely need the arm to be atleast that much shorter than a stock piece.

Between the shorter arm and the higher than stock (for an A,G or T chassis) I'll find the ideal camber curve.

The B body spindle is mostly used for it's higher balljoint position since the GM front ends from the 50's through the late 80's dosnt allow the inner joint to be lowered.

Right now I'm going with the model of a B body spindle + a shorter control arm countered by the neccesary raising of the inner mounting point.

Just the B spindle would be great if I could mount the inner pivot in the G body position and everything else could be off the shelf.

rayar

iTrader: (1)

Like I said, my car is not a street car so cutting most of subframe away isen't really a problem as long as I have the K-member properly braced. I have allready built my suframe connectors so they are also welded to the K-member but realize that I am still getting the majority of stiffening from the subframe so it really is scary cutting into that. I would also need to build brackets for the steering box, sway bar and radiator so it would be a big job. Basically I would end up cutting off everything in front of the firewall.

Sure I could do an aftermarket option but there are 2 problems. First is the 10% weight penalty in CP for not useing the factory K-member. It would then be considered a tube framed car in C-prepared so if I do that I might as well buy a used tube chassis(Trans Am or GT1 road race car) and build off of that. The second is expense, I am sure any aftermarket option would be around $3,000. If I use G or B body spindles and tubular upper A-arms I would have less then $500 into it including all new ball joints and tierod ends.


What I am wondering is if the subframe can be notched and boxed above the spring pocket enough to fit the upper A-arm and still not lose any strength, Maybe welding some rectangular tube above the boxed section. I just don't know if it's more trouble then it's worth since Struts can handle very well.

ls six

You could definitely do a notch similar to what the lowrider and mini truck crowd dose especialy if you tie it into the roll cage.

If I recall though the bolts that tie the K member into the lower frame horns ( I assume that is what you call the sub frame? Its integrated into the unibody so technicaly yhe 3rd gen dose not have any sub frames, atleast if we are calling the K member a K member) and if they are too close together you might not have room for the arm mounts.

If your class wont allow you to modify the K member with weld on or bolt on A arm mounts you can attach inverted mounts to the notched portion of the frame horn.

You could simply cut a hole in the strut tower sheetmetal (or remove it since it would no longer serve a structural purpose) and attach the upper arm to the top of the frame horn but unless you raise the balljoint an equal or greater amount youll get major positive camber gain.

rayar

iTrader: (1)

Really since I am staying strut this is all just dreaming. C-prepared would allow me to grind, cut, weld, drill, lighten or completly redesign the factory Subframe or K-member, but I can not replace those parts without recieving the 10% weight penalty.

There is no doubt in my mind that i could build it but a good chance it would work worse then my strut suspension. I still find the idea interesting

Norm Peterson

Only because for years that was pretty much the only option. There are better answers now (check out www.scandc.com - from mild to pretty wild).


Norm

Norm Peterson

But you can modify them. 17.1.B and 17.2.C allow local notching/clearancing/etc., in order to accommodate allowed modifications. You just need to avoid failing to conform to any clarification that might exist (I didn't look that far) or the appearance of creating a "tortured interpretation". I would think that local notching & reinforcement at the UCA attachment points only would pass muster as long as its extent was held to reasonable limits.


Norm

rayar

iTrader: (1)

I was under the impression that anything could be done to the factory parts. I now some of the Fox bodied Mustangs have heavily modified K-members wth a upper A-arm and are very legal in CP

There used to be pictures somewhere of Bill Headlie's 1970 Boss 302 clone C-Prepared buildup but I can't find them anymore. His car is really a tube frame car but retained the factory unibody subframe and even went through great lengths to repair the rust in it that I assume was in effort to keep it legal, Not one suspension part bolts to it. Kinda tortured interpetation of the rule but I know he didn't recieve the 10% weight penalty. Would it hold up under protest? I am not sure. I am sure that the early mustang the Mike Maier used to win CP this year is set up very similar but I could be wrong.

paul_huryk

The best and easiest way to get a SLA front suspension is to front half the car (like the 1st gen and Nova kits) and eliminate the strut towers and wheel wells. A lot of work, yes; but you can get dead on geometry without having to band aid factory parts. Class restrictions aside, this is one good avenue to take. I do like coil overs in the front - as long as you replace the A-arms and the K member also.

As someone said, you can get modern sports car handling with some intelligent parts selection - why go buck wild crazy when you go well above the point of diminishing returns?

Norm Peterson

The problem in this specific situation is that mods like those incur a 10% weight penalty. Keep in mind that while the car may actually remain streetable and is possibly even licensed/insured/etc., in order to be used in that way, that is not the prime purpose of a CP car. It's a competition car, built within a framework of rules that would sound odd to anybody not familiar with them. Trust me, the ruleset limitations aren't anything at all like drag racing rules.


Because in order to rise toward the top in autocrossing, precisely what you do is explore as many of the class-legal "diminishing returns" as you can. Positions are gained or lost over run time differences as low as 0.001 second out of 50 or so (and at the National Tour/National Championship level there can be a significant difference in contingency $ payout).

Most anybody in the sport purely for the fun of it isn't going to be running in the Prepared category; you'll mostly find them in various "Stock" or "Street Touring" classes, where the relatively few allowed modifications are essentially bolt-on in nature. Prepared is where fairly seriously re-engineered and custom fabricated chassis work starts showing up. One-off suspensions with non-OE geometry fabricated from scratch vs "lowering spring & strut/shock" kits and what-not. You have to apply a different "yardstick" to the folks in the "serious fabrication classes" than you do to the street car driver who occasionally shoes up to run through the cones.


FWIW, I've been running in Prepared mainly because some of the mods I have chosen to do for my street vehicles put me there, IOW not class-legal in Stock, Street Prepared, or Street Touring. But I like the greater freedom and the opportunity to try to engineer something to work better than the OE compromises do anyway. Limited-prep classes - where you might worry about the legality of things like your air intake or your wheel width/offset - just isn't my cup of tea.


Norm

ls six

Hey Norm, the link wouldnt work for me so I went to the site direct and looked around. I'm not sure what part(s) you are reffering too but the modular balljoints caught my eye.

I have seen spacers that go between the ball joint and spindle (for the mustang and the strut Mazdas like mine) that relocate the balljoint pivot but I was always concerned with stregnth.

There are also tapered inserts but I dont believe those offer the range I need.

I'll add the range offered by modular joints to the equasion when I figure out the angles I have to work with assuming a B body spindle.

If I can avoid the hassle and expense of fabbing an adaptor for the F body spindle I'll be very happy.


How dose this sound... an upper control arm either fixed or adjustable with bushings or heim joints depending on the app, bolted to a bracket that simply bolts to the stock upper strut mount lacation along with the available hole just above the K member.

Best case scenario that would be all as far as the "kit" goes with the owner providing the spindle and an off the shelf shock.

Though I have a feeling it may require a custom short body shock. In that case I could either provide the shocks in the kit or reffer the buyer to the manufacturer to buy direct.

Norm Peterson

CAUTION: OFF-TOPIC RANT IN ROGRESS!!!

Turns out that if you either paste or type a link into a post on this board, you cannot then go back and boldface it to make it stand out more (even though you still get the pointing finger cursor when you hover over it). This differs from other sites that I belong to.

Oh yeah, I fixed the link, so it works now. Just so nobody has to go back to find it, here it is again.

http://www.scandc.com/


Norm

rayar

iTrader: (1)

The ball joints are interesting and got me thinking about some ball joints I used to see for Circle track use. The ball joint was basically Heim joint in a housing. There where different housings to replace different Ball joint applications. It had a long stud with with a taper on one end that went into the spindle and You could adjust the height of the ball joint with spacers. It looked to be pretty trick but I cant find then anymore.

That brings up my question. Could you fab some A-arms to use a 3/4 rod end at the BJ location, drill out the spindle to 3/4 inch and use a long bolts with different length spacers between the A arm and spindle to adjust the roll center or is this a bit to much backyard engineering and not safe? I think it would work well on a autocross or short track car but I would have some reservations doing it on a street car or something that see's higher speeds.

rayar

iTrader: (1)

Here it is, It's called a mono ball.
http://www.hrpworld.com/client_image...22_hdr_2_l.jpg

ls six

Thanks for the link rayar, I knew there was bound to be something like that out there but I too would be leary of putting that on a street car or a fast open track car especialy if it were set at a high point in the adjustment range.

The higher the joint is adjusted the more shear load is placed on the stud, and with she short arm I'm looking at now forces will already be higher than normal.

For any car I own I would atleast want the spacers to be large enough in daimeter to sit flush with the machined top of the spindle to help distribute the load through more of the stud to the spindle rather than forcing the tapered portion to take it all. I can really see that thing snapping off near flush with the spindle top.

Your idea sounds ok but I wouldnt get rid of the taper, with the taper the stud is actualy 2 different fasteners doing 2 jobs. The tapered side retains the stud it's self in the spindle while the rod end side takes the lateral loads imposed by the suspension.

Forsing a sinkle piece to exist under significant tension and ask it to also resist significant shear loads is asking for a failure.

Look at it this way, with the tapered interface you can torque down the joint to the spindle but the upper portion be it a heim joint or a ball joint is under no load at all untill it is installed with the arm its self. With no taper you would have to over size it significantly to guard against failure.


Since I'm realy confident with the B body spindle I'm wondering if the Impala guys have done the LS1 brake swap, even if they have done it like we have with the F body rotors I'd rather be able to install the 2 pot calipers on the B body spindle with it's stock rotor. I believe it's the same diameter (12") but that the B body rotor is thinner. I'm willing to give up a bit of thickness to maintain the stock offset, I'm not going bigger than 12" either.

Replacement alloy B body calipers would proabably be good enough but I already have my LS1's lol.

rayar

iTrader: (1)

Well it looks like the studs are also available seperatly but I would say it's 5/8" by the looks of it. My rod end idea would still work but I would be more comfortable useing a 3/4 rod end. The Good news is it looks like they have the common lower GM mono ball so it would be a bolt in deal with out fabbing anything.

ls six

I would really suggest trying to lower your LCA balljoint if it wont incur any penalty, especialy in a strut car.

If you didnt know lowering a car significantly beyond stock can cause various issues among them is a camber curve that is just plain wrong.

As designed the arm is at a slightly downward angle from the bushings to the balljoint, this causes the balljoint along with the bottom of the spindle and most importantly the bottom of the tire to move out slightly as the suspension moves through it's arc.

This has a small but real effect on camber but when the arm starts out allready through most of it's arc it spends more of that arc past the dead horisontal position and after that point the wheel it pulled in at the bottom. That works against the camber gain you want to see under compression.

Since struts have issues with camber gain as they are losing this little bit can be a real problem, The typical bad compromise is to dial in lots of static camber, but that leads to yet more problems that I dont really need to get into here.

The same situation with an SLA suspension is similar but much more complicated, but normaly people are happy to shorten or relocate the upper arm for a near ideal curve and call it good.

BIG_MODS

iTrader: (9)

I don't think the 3rd gen geometry is horrible. I calc'd out the camber curve:


No one has validated this, its just my calcs, so it could be wrong.

Sometimes its hard to figure out someone elses spreadsheets, but if anyone wants to have a look be my guest.

I wouldn't change to an SLA just to have an SLA. If I were to do it I'd combine it with a lighter, optimized k-member. Much lower ride height. Stock a-arms wouldn't have a chance of going back on and I don't like the clevis style arms shown in the link from Norm. Since the fenders would need mod'd the wheels would be moved forward ~2" for better weight distribution and more stability and I'd increase the track width. I'd use a coil over because it packages easy and makes mounting brackets simple. I'd move the LCA mounting points as far inward as possible to maximize the LCA length for better geometry. Steering geometry would need to be looked at closely and it might be easier just to go with a rack and pinion and find a way to dodge the crankshaft damper (dunno, I'd have to think about it some more). A lot depends on the spindle design and I'm not sure if a factory spindle (G body etc) has enough drop, enough height, and the best location for the tie rod. Sure it would work, but there are compromises with it.

EDIT TO ADD: also, reduce scrub and eliminate the wheel spacer.