Al Weyman

Hi all.

I hope someone will be able to help me with this one. The car is an 87 Camaro IROC-Z a bit power mad with about 475 bhp and bags of torque, rear wheel drive, Steve Spohn Racing QA double adjustable coil overs at rear and their aftermarket torque arm,trailing arms and panard rod. Front end Konis revalved to Firehawk spec with Spohn coil over conversion.

My problem is the car simply will not hook up coming out of corners and is severly compromising the performance of this potentially fast saloon. Take Donington last Saturday for example, I turn on to the main straight from a highspeed right hander in third gear (4 speed box) as soon as I apply the power it just lights up the back wheels, change to top same thing and the rest of the field streaks away (I will try to add a bit of vdeo later in week). As soon as it finally hooks up in a straight line I quickly catch and /or overtake then I have the same thing coming out the chicane. I am now thinking of a locked diff but am a tad concerned it will break something as I have to run the standard 3rd gen axle (externally althogh internal mods are free) and pushing the thing about in the paddock with a locked diff may be a struggle. Also is a spool available for this axle?

Any help would be greatly appreciated also if any one has any experience of the best settings for the double adjustable QA's that would be a help. I still have the standard IROC-Z antiroll bars back and front, the car is a genuine IROC.

This is the only 3rd gen ever road raced in the UK to my knowledge in this near stock configuration and it should be quicker than my 2nd gen car but its not as I am loosing so much coming out the corners. Off the line its like a drag racer and will pick up at least four grid places every time.

sofakingdom

iTrader: (1)

Lower control arm relocating brackets



Adjust them so that the LCA points SLIGHTLY downward from the frame to the rear end (emphasis on SLIGHTLY), like in the pic; you will probably want the rear about ½" lower than the front, certainly no more than ¾". They will also affect braking and other features of handling so be prepared to do some chassis tuning.

Better LCAs, like in the pic, will help some too. Those are Lakewood ones. Basically that takes an extra unwanted spring out of a suspension member that's supposed to be rigid.

EGG

I saw your thread over at ten-tenths and was going to suggest visiting over here

BlackenedBird

iTrader: (5)

The relocation brackets are a very good idea, but so are tire compound/brands. Might need to review your tire choice & get a softer/stickier compound. And/or wider tires, if you can in your racing class.

And, of course, driver compensation. The biggest learning curve out there. When you know where/when a car he traction problems and adjusts their driving style for them. Once you get the chassis adjustments made, you can revise your driving style & hopefully use more throttle, more often,.

//<86TA>\\

iTrader: (14)

if you are serious, look into one of these.
http://www.unbalancedengineering.com/Camaro/

they have to be adapter a bit to fit a 3rd gen, as the 4th gens have a slightly different trans tunnel, but they offer much better corner exit traction, as well at traction overall. the guys over on FRAXX use these to great success.

what wheels/tires are you using?

GMan 3MT

iTrader: (4)

You say light up the tires, then mention considering a locked diff. Are you spinning both rears or just the inside one? What diff do you have right now? What anti-roll bars are you running? You may also want to post over at FRRAX.com (F-Body Road Racing).

slow305

iTrader: (2)

Anybody know what the hot setup is for A Sedan thirdgens? Seems like it would be an easy "fix" for Al. Also, +1 on what Gary said to post at frrax.com. There are bunch of people there who are racing 3rd and 4th gen cars.

From a gee-whiz standpoint, just curious as to what tires you run on the other side of the pond.

Pat

89_RS

What modifying would be needed for it? I've looked at those for a long while and that's been the only hold up for me that it won't bolt in.

//<86TA>\\

iTrader: (14)

the back of the tunnel is narrower in a 3rd gen, so you have to hammer the side of the tunnel to fit the "bolt in" one in. then yolu need to fab something to mount it too.

the race version apparently works, but you have to support it with a rollcage, or make somekind of other mount for it.

I used the basic idea and built one out of a heavily modified jegster torque arm with its saddle mount in the tunnel

89_RS

Think a mount that ties into the SFC's would do it for the weld in version? Add some Alston style inner SFC's that tie that mount to the rear LCA mounts seems to do the trick in my mind.

//<86TA>\\

iTrader: (14)

maybe, but the front mount has be be very strong, since under braking, there is a lot of force on it. not sure if you can do this by just attaching to the sfc's. But its a start, and im sure it can work.

As for the OP, it would be interesting to know if you are spinning both wheels or just the inside tire.

89_RS

OP, sorry for the thread jack.

86, hows some 1.5" x 1" or 2" x 1" .125 or .1875" tubing sound for the front mount?

Doug Phillips

Keep it simple, one thing at a time.

As already asked, are you spinning one wheel or two? When the rear is jacked in the air and you hand turn one side what is the other side doing?

Have you lowered the car? Are your LCA brackets sitting pretty level?

Tire choice and air pressures?

//<86TA>\\

iTrader: (14)

to the pm's!

Al Weyman

OK thanks for replies sorry to not get back sooner I will try to answer questions but not necessarily in order asked.

1. Tyres are a Toyo 888's wide section 275x35x18 we call them a trackday tyre over here and are a semi race tyre and not road legal, quite good and I have to run them.

2. I have the Spohn Racing fully rose jointed lower arms and their drop brackets I could try dropping to the lower hole they are currently in the centre hole.

3. I am not sure if its both wheels spinning but have checked operation of factory LSD and its within limits (30 ft lb from memory).

4. I built this car many years ago when still a current model and also race a 2nd gen so i am fully conversant with driving style as I have done many many races over the years in both cars, my 2nd gen on leaf springs simply hooks up better.

5. I have the Spohn racing Torque arm which I fitted after finding the standard arm bolted to the gearbox (I have a Muncie fitted) was working the tail housing loose. I am disappointed with the piece as its both heavy and I fail to see any advantage over stock apart from running from the cross member also the bulk of the thing made it impossible to run dual exhausts so have had to siamese the system into a 3 inch pipe, not ideal although sounds cool and a lot quiteter and does satisfy the noise police over here who have become very strict lately so maybe not a bad thing.

6. I have QA dual adustable shocks with 300 lbs springs the kit supplied by Spohn that I am not sure how to set up and think I was better off with the IROC Bilstiens and standard springs cut down.

7. I weigh 270 lbs fully kitted up and dont think my bulk helps too much as our circuits are predominantly right hand turns and I am sitting on the wrong side and this is where I am having the problem. To me it feels like as i plant the throttle the car is leaning and the torque arm instead of squatting jacks the car up making the wheel go light. I really hope the video comes out from incar and I can show you what I mean as you will see I am seriously backing out the gas, I cannot even through the rear end out under power just wheel spin.

I like the look of that torque arm kit I wish that was out a few years back when I bought the Spohn one which I recon is a good drag race piece but a compromise on a road race car.

Al Weyman

Oh forgot one thing, I am using the stock IROC-Z anti roll bars back and front.

Al Weyman

opps sorry tyre pressure set at 35 pounds cold last weekend.

slow305

iTrader: (2)

Springs are cheap/easy to replace, so personally that's where I'd start. I'd go lighter in the 150-200 range (or buy multiple pairs of different weights).

Also lower tire pressure in the rear (free mod ). In my 250-hp autocross car on 295 Hoosier A6s, I'm at 28 in the rear when warm.

Pat

BlackenedBird

iTrader: (5)

Try dropping the spring rate, for better weight transfer coming out of the corners. I've never seen anyone go with 300s in the rear of a 3rd gen.

You could consider adding some weight to the passenger, to help balance the car left to right. While it does seem counterproductive to add weight to a car, the better balance could be more of a help than the extra weight be a hindrance.

Base91

iTrader: (1)

Nothing to do with the thread but I learned to ski in Watford.

GMan 3MT

iTrader: (4)

I'll echo what has been said. The highest conventional spring I've heard used in the rear is a 275. Mine are 200s right now.

I know the R888's like a slightly higher cold pressure, so 35 may be in the ballpark for the fronts, but does seem a touch high especially for the rears. I would do whatever is possible to get off the R888's. From what I've found, they don't like a high slip angle. If you slide around much, then they get greasy very quick, which causes you to slide the tires more, which...

I've ran on Toyo RA1's, then R888's, and now back (thankfully) to RA1's. 888's fell off after a handful of laps.

//<86TA>\\

iTrader: (14)

i agree with the springs, they are too much. people using rear spring rates close to and above that, have lowered the panhard bar/rear roll center, requiring the change.

Al Weyman

I must confess I may have got the spring rates wrong but am pretty sure thats what they were at the time of purchase I will look through my notes or measure up. It does feel pretty stiff on the back and way stiffer than my 2nd gen which has Rancho leaf springs (uprated) and Koni shocks. I have a feeling this may be some or all of the problem. I dont recall having this problem when usingthe standard IROC springs and shocks. A friend has a good stock of springs so maybe I will have a play although testing over here is an expensive problem. Here is a shot of the car http://www.cadart.com/Images/IROC%20at%20Mallory.jpg

dannyboyemt

subscribed

RBob

iTrader: (1)

Sounds like it is jacking on the panhard bar. This happens in right hand curves with our 3rd gens. I hate the feeling/result it gives as left hand turns do not exhibit the jacking.

An easy/inexpensive fix would be to lower the panhard bar (relocation kit). A better fix is to use a Watts link such as Strano's.

You mentioned further lowering the rear pivot of the trailing arms. Be careful with this as it can cause snap-oversteer. Dean has a bunch of posts about this, although under various user names (make searching more difficult).

You are right about these cars not being the same a leaf spring suspension. Night and day differences.

RBob.

Al Weyman

Thats exactly what it feels like around right handers, left handers feel a lot better, where do I get the relocation kits from or has amyone fabricated their own and have details? I think a spool or a better diff would also help enourmously but I do also feel the problem is more complex than just the diff not locking propererly as even with a fully open diff it shouldnt be as bad as this.

Al Weyman

Not the Watford where I live thats for sure!

91camarosRS

iTrader: (5)

I don't know if this would help, I but talked to a couple scca guys racing these cars and they didn't run a rear anti-roll bar. They said they felt it defeated the point. It would bring up to inner wheel causing wheelspin. JUst something cheap you might wanna try? Or go with something softer?

91camarosRS

iTrader: (5)

Or don't turn right lol

RBob

iTrader: (1)

After additional thought on this, I'm not sure that the panhard bar relocation would be enough to solve the issue. With the racing that you are doing going right to the watts link is the better choice.

With that here is some links & info. Panhard bar relocation kit:

Jegster 41055
http://www.jegs.com/i/Jegster/550/41055/10002/-1

Strano's Watts link:

http://www.stranoparts.com/partdetai...ID=0&ModelID=9

And a short thread on it with customer feedback:

http://www.ls1tech.com/forums/suspen...atts-link.html

RBob.

Doug Phillips

I did not see where you mention what front spring rate you use but for sure change the rears rates out. That is way to much spring in the rear of the car. I am running 750/150 now but it depends on the size of your bars also.

Springs are easy, change them out for 150 or so and see what it does. I do not recommend doing other changes at the same time, you will not know what each change does.

What are your pressures hot? Shoot for 35/30 hot on the 888s and go from there.

Base91

iTrader: (1)

Yes indeed. There is, or was, a dry slope somewhere around there. But it was 30 years ago!

Base91

iTrader: (1)

I don't understand. It seems like no anti-roll bar would allow more roll which would unload the inside wheel even more making it more likely to spin that wheel. With LSD the inside wheel shouldn't spin on its own but if it's unloaded you lose the traction from it. How about a bigger anti-roll bar to keep the inside wheel down? More oversteer?

Roostmeyer

iTrader: (3)

For handling you want the control arms to be slightly angle down rear to front. Having them angled slightly angled up increases the instant center, a good thing for accelleration, but causes the loaded tire to toe out with roll.

It will unload the front inside wheel more by disconnecting the rear sway bar, leaving more weight on the inside rear.

I've tried it on my old 1.6 miata and it does do wonders to eliminate inside wheel spin. By the time you add enough rear spring to balance the car out though most of the advantage is lost. I still thought the car was faster with a small rear sway bar and most of the roll control from the springs.

With a solid axle though I can't see trying to get all your roll control from the springs alone since you don't get as much roll control.

30lb's of preload seems really low for your posi, does your car have the 9-bolt or 10-bolt? I know I've got over 85ft/lbs (lugnut torque) of preload on my 9-bolt with properly shimmed cones and an washer under the cone spring.

I've got 300lb springs in the car for about 4 more hours before some 250lb'ers come from landrum. With 1200lb front springs, WS6 sway bars, and a lowered panhard bar the car was real loose. I would suggest the lowered panhard bar just for the consistency it will give you makes it easier to drive the car at the limit.

Al Weyman

Yeah I have taken the rear A/R bar from the 2nd gen car as it was a bit leathal in wet or slippery conditions but i did find the thing was binding I also went smaller on the front bar as i was running a TransAm bar, it seems what most of the 1st Gen racers over here dont run a rear bar. My tyre pressures would probably have got to 40psi hot bit I didnt have time to check as had a head gasket sealing problem.

Here is a bit of incar from a race I did at the new Snetterton circuit a few weeks back you may get a feel for the car from this, I wasnt trying too hard as it was a fresh engine and I had to start at the back as I had a qualifing problem and had to hold back at the start as the race organiser said we couldnt race till we went past the start finish line and I had a novice on my inside so had to sit behind her. This race was a bit of a Libra race and not the series I generally run in. http://www.youtube.com/watch?v=5BYtz3llQ_M

GMan 3MT

iTrader: (4)

Sounds to me from the video like that's inside tire wheelspin, mostly on the right hand corners. RPM's go up, car doesn't look to really step out as it would if both tires were losing traction. A better diff (older T2R), or Auburn would help. Until then, patience and a light throttle foot is all I can suggest. I've never been a fan of 'just throw more expensive parts at it' and completely redesigning the suspension.

Interesting combination of hardware out there. I'd love to take my Camaro out to Knockhill, a few miles away from my Grans.

Al Weyman

Yeah there certainly was, it was a support race for a 6 hour endurance held at the new Snetterton Circuit and some friends of mine were putting it on and had invested loads of money to stage it so I just done my bit to support it. BTW The Porsche 917 Sports car was a replica lol! Mind you it still had a flat 6 Porsche engine and looked the part.

I think you may be right about the diff not pulling its weight a racer friend of mine is also of the same opinion because as you say I cannot get it to step out. I am also limited to what I can do in the regs where I generally run the car. So Watts Linkage and the Uncoupled Torque arm are out as I had to plead with the committee to let me run the Spohn TA and got special permission on safety grounds and I only got it approved as it was basically a similar length and operating system as original. I should be able to get away with repositioning the Panard rod and it certainly feels like there is an unstable jacking effect at the rear. OK so getting back to the diff any suggestions. Basically the rules state I can do internal modifications in the back axle but must use the original case. So in essence I can fit another complete diff or a spool. Has anyone used a spool on these cars and is one available, I am concerned the axle could not take the punishment if fully locked but prepared to be told differently. The current diff is the standard IROC LSD is there anything I can do in there to beef it up?

If I cannot get the car right within the parameters of the club regulations I may have to concider running it in another series where the chassis rules are more flexible but that would be next season as they are 40 minute races and I need a bigger fuel tank to go the distance.

Al Weyman

I don't believe this, I just measured the rear Spohn supplied springs and I swear I was correct when I said previously they had recommended 350's, well I have used an online calculator and here are the figures maybe someone could confirm them. Overall diameter 2.5", spring wire diameter .443, 9 three coils and thats giving me a rate of 385lbs FFS!!!!! Even if I add half a coil for luck thats 365lbs. I think I had better measure what they have supplied me on the front unless the front and rears have got mixed up somehow but I am sure the coil overs came assembled but may be wrong.

The panard bar is way off level so I will order that Jegs kit if they will ship to UK but I have the lower control arms correct with a slight incline towards the body.

Just checked front they appear to be 625's with .5 wire diameter. I seem to recollect ordering something like that up front but front feels stable so just ned to try those lighter springs and panard rod relocation kit now and go on from there.

sofakingdom

iTrader: (1)

A spool is not a good idea for any car that has to turn corners.

Which diff do you have; 9-bolt or 10-bolt?

Al Weyman

Ths standard one that came with the 86/87 IROC-Z I used to think that but I own a Penske 2nd gen IROC race car (awaiting renovation) and they used a spool on the road race circuits and a slipper on the ovals which I was surprised about.

sofakingdom

iTrader: (1)

Both models were "standard" on that car.

Which one do you have?

Al Weyman

To be honest I am not sure but not the Aussie one, I have fitted Zoom gears so must be pretty standard it looks just like the 2nd gen 10 bolt but a tad smaller.

RBob

iTrader: (1)

If you had to remove 'C' clips to get the axles out then it is the standard 7.5"/7.625" 10-bolt.

If you had to unbolt retaining plates at the axle tube ends to get the axles out then it is the Aussie 9 bolt.

I too am surprised to hear that Penske used a spool in a road race car. Just doesn't make sense. I had a locker in my car for a while, and one had to be careful to not lock it up on a corner. Have a Torsen now which is better for handling.

RBob.

RBob

iTrader: (1)

Here is a good thread on the panhard relocation:

https://www.thirdgen.org/forums/susp...n-bracket.html

Dean (using RTFC this time) also covers other aspects of setting up the tail end of the car.

RBob.

oramac91

iTrader: (5)

Is there a road racers form?Want to get into road raceing?I live on east coast.

Al Weyman

ops got that wrong its 2.5 inches ID not OD so reusing the caluclator I came up with around 200 to 225 ball park and 340 to 350 fronts so not a great deal to be gained by going much softer sorry Mr. Spohn. Yes it has the c clips same as the 2nd gen. BTW has anyine had a axle break while using disc brakes, will the caliper stop the wheel going for a walk?

BlackenedBird

iTrader: (5)

http://www.frrax.com/rrforum/

//<86TA>\\

iTrader: (14)

they may be a little better than a drum, since the abutment brackets will hold the axle a little, but they will probably still break the mounts and come out if you put enough force on them.

oramac91

iTrader: (5)

Ty black!!!!!!!!!!!!

Al Weyman

A mate of mine that races in my club but different championship and rules has a brute of a car probably the fastes car the club has ever seen, its an Aussie V8 Touring car Ford Falcon late model but fitted with a 7 litre engine anyhow he runs a spool in that and keeps telling me I need one, another guy in the club has the worlds fastest Sunbeam Lotus and he also uses a spool. Is a spool available for the standard axle?