rwd and rear antirollbars

[johnny yuma]

Al-would the Camaros be fairly short for their width compared to other race sedans? A longer car on a given track width will tend towards oversteer in a pendulum effect,but a stubbier car to understeer.

[dtype38]

Al, I would have to say after following you round at the Brands track day, I thought you were underdamped at the back end, possibly just at one side. Each time you changed gear and got back on the power, the back end did a really quite noticable corkscrew. I've only ever had that when one of my rear dampers lost its oil. Also, there is distinct lift at the back under braking, and squat under acceleration. Perhaps it might be worth a try backing off the ARB a bit and going for a bit more spring rate to keep it under control.

And, spookily possums, that raises another point about anti-roll bars. That being how many people seem to use quite soft springs with huge ARB in the name of traction. Is there any possiblility this might be inherited from the modifications done on high end road cars when "performance suspension" is fitted. The thing is, if stiff springs were fitted to a road car the ride on the M1/M25/M27 (choose nearest motorway), or average "A" road, would be horrendous. So the springs have to stay soft... and to give that "flat in the corners" feel, and a capacity for higher cornering speeds, uprated ARBs are fitted. Not sure this applies to track cars though.

[Al Weyman]

Dtype, since then and for the Brands TRC round (as seen on the Eric Falce video on Rods site) I fitted fully rose jointed trailing arms and a fully rose jointed panard rod and the rear does seem more stable however...... I think you are quite correct in fact I hope you are and looking at the video and the way the car felt I have ordered all the proper stuff from Sphon Performance in the States, proper springs, double adjusting shocks and other exotica and I am not goig to take it out again till these parts are fitted as a visit to the barriers was imminent.

Believe it or not all that was modified from stock IROC suspension was a trick torque arm from Sphon, all the springs and rear shockers were stock IROC road car with Konis on the front re-valved to Firehawk spec (a series for these cars in the US) so it was not surprising it was not right.

[dtype38]

Nice one Al. I'm not familiar with the different versions of setup for your car, but a change to a complete integrated setup from one performance supplier has got to be a big step in the right direction. Let us know how you get on :-)

[Al Weyman]

Thanks Dype, I looked at it that way myself, its not much good going to Ledas or some other UK company as they would have no experience with these models in fact as I am the only one mad enough to race one of these things overhere it seemed the best way forward.

[norman-normal]

The best info on roll bars as well as, all things that affect production car handling is: 'HANDLING!What it is and how to get it" by Roland de Marcellus. He is the founder of ADDCO Industries Inc. I got my copy for $5. in 1998 at: 700 East Street Suite 1
Lake park, Florida 33403 Tel 1 800 338 7015

[Al Weyman]

Addco, that manufacturer of fine anti-sway bars eh? I have one of their products bolted to the back of my car, nice bit of bling (gold anodised finish)as it happens and one of the competitors commented I should have a nice bit of undercar lighting to show it off, cheeky sod!

[greenamex2]

Al, you're a CHAV!!!

[norman-normal]

I feel cheated! those in my cressida are only grey.

[Al Weyman]

must have been a bit of favouritism from Summit Racing for being a good customer:-)

[TwoWheelTerror]

As its my car lol I suppose I should post. This car will just be used on track. Ride height is set at 3 inches off the ground. In a track car can use stiff springs to control body roll and removing the ARB stops the inside rear lifting through the corners. Thats my theory anyway.

It also was fouling the area where I want to mount the coilovers...

[grichie87]

Originally Posted by TwoWheelTerror

As its my car lol I suppose I should post. This car will just be used on track. Ride height is set at 3 inches off the ground. In a track car can use stiff springs to control body roll and removing the ARB stops the inside rear lifting through the corners. Thats my theory anyway.

It also was fouling the area where I want to mount the coilovers...

Any ideas onthe ARB set up on my race Nova its RWD and I have a adjustable rear ARB fitted. I think this is the way to go, but a explanation of why and how it works would be helpfull.
Any help would be a bonus
Thanks

[Al Weyman]

Probably because it induces a rear wheel lift that in turn will loose grip on the back negating some of the severe understeer you will get with that FWD model.

I thought I had overdone the antiroll bar on my yellow car at Thruxton yesterday as I spun it at the chicane on the second lap of practice but and if felt a bit tail happy in the wet conditions however it transpires oil was dropped there and I must say in the race although I did not push it with a leaking and failing master cylinder and a binding clutch (need me brains checked for even taking it out I know) it did not feel at all bad but the track was a lot drier and the oil had no doubt been mopped up.

[R59]

As this is a rallycross car we're talking about, you need bite out of the corner, which is quite often achieved by means that make use tarmac racers flinch. Take a look at some of the US Dirt Oval racers - their Late Model Stock Cars, or World Of Outlaws, where you'll see the cars almost twisted like a corkscrew. Also, look at autograss cars, you can learn a lot from their setups. They are soft as ... but did you see them in the live action arena at the Autosport show - wow!.

Denis - your rear anti-rollbar - what bushing/bearing material did you use. I was remembering the problems that the RAM F1 car had (a cheap copy of a Williams!) and it used to suffer snap oversteer, and was a pig to set up. The rear bar was bushed with nothing more than bronze bushes, which when warm, would snatch and grab, rather than glide nicely.
Changing it to the same as the Williams, or Lotus of the day, needle rollers, fixed that problem, and with a few other improvements (fixes to the design), Bob Berridge went on to win the TGP series with the RAM.

Worth looking at!

Rob.

[greenamex2]

Everything from standard Toyota rubber to polyurethene and rose joint drop links.

Always to same story.

[R59]

That could be your problem then.... Might be worth replacing the bushing material with needle rollers.

Rob

[TwoWheelTerror]

slightly inaccurate first post in that the 309 in question is an ex rallycross car. Its being build to hopefully meet the rules for the DTRC rather than to compete on dirt

[Notso Swift]

Originally Posted by racing59

Also, look at autograss cars, you can learn a lot from their setups. They are soft as ...
Rob.

... butter?

[marcush.]

the question should never be ARB or not it should read :how do I get more grip.
What helps today may be useless tomorrow because of different conditions.
may it be weather ,track,driver ,car or whatever.

[Lukin]

Congrats for introducing semantics to a good thread. How do you increase grip with changing conditions? I'm sure you should grace us with your thoughts to put everyone in their place.

[marcush.]

first of all:
a tyre wish has no contact to the road cannot contribute to the total grip of the car.(effectively a tyre in the air halves the load bearing capacity of that axle!)
The tyre is load sensitive in developing grip.If you put more load on the tyre the corresponding grip is not going up in the same way.this tyre characteristic is not linear and the non linearity is different for different tyres as well.
The tyre is as well sensitive to slip angles vers vertical Load....another factor in our little equation....

so it makes a lot of sense to try and get the tyres stuck as evenly to the ground as possible and at favourable angles at most of the time....most people do not realise that ALOT is in the flex of components in the car .
BUT:if you get rid of the flex ,it´s the driver that is going to bring in the heat into the tyre ...or not.

[TwoWheelTerror]

I read somewhere last night - that as you increase the stiffeness of the chassis and spring rates that the ARB should be reduced

[norman-normal]

Stiffer springs will cut down on body roll; but thats not the springs job. Springs were used for that purpose early in motor racing simply because we did not know about anti roll bars, the sole purpose of witch is to control body roll, to allow the use of softer springs, that will allow the tires to maintain contact with the surface, in spite of, surface irregularities.
If you have a corner wheel lifting you need to increase the compression resistance on the opposite corner. Think of it as if it is like a chair with four legs: if one leg is a bit short it will rock, under stress, lifting the opposite leg. This is what an ARB does, It corrects the short leg. Att the risk of sounding un-American I must say that springs are 'shock absorbers', thats all they are designed to do. Before springs came in to use, there was no such thing as body roll, springs introduced the problem.
Pardon me if I sound too preachy but, I have lived this stuff and I hate to see the same mistakes made over and over.

[greenamex2]

Originally Posted by norman-normal

If you have a corner wheel lifting you need to increase the compression resistance on the opposite corner.

Err, like increasing the spring rate on the opposite corner?

[norman-normal]

No, if you are lifting an inside rear, it can be corrected by stiffing the front ARB.
Very stiff springs like very high tire pressures are generally destructive to the whole vehicle: ball joints, wheel brgs, dampeners and things start falling off or coming undone.
Keep in mind that the suspension is a system, so if you change one thing you may need to change another system component to take full advantage of the first change.
The great thing about ARB's is that they allow you to have a supple suspension while keeping the car nearly level. If you look at old photos of race cars (even F1) they look like they are trying to roll over, and they had very stiff springs.