89 replies to this topic

[Lemons Rex]

Some friends and I bought and prepared a non-si 86 CRX for the 24 Hours Of Lemons. We entered our first race last fall and our best lap was a pathetic 1:10.73. A solid 8 seconds behind the leaders. Luckily, we blew up our engine and had to find another. We found an 87 integra for dirt cheap and stole EVERYTHING off of it. Engine, front brakes, rear brakes, front suspension cradle, etc. We got it started the day of the race, only kept it running for a bout 6 total hours or racing, but still managed a 1:05.31 for our best lap.

So we have a competitive car but we need to work on our handling and improve our durability. The main issue we need to solve is that we are getting no rear grip. We are going to lower the rear more, bend the axle for some camber, and maybe add a little weight back there. Remember, we can't really spend any more money on performance parts. Brakes, wheels, tires, and anything that counts as a safety item don't count toward our cost limit though. Hopefully you guys have some experience and ideas that will help. I'm a total noob when it comes to these cars, so don't hold back.

[Lemons Rex]

Here's an abbreviated list of stuff we are already planning on doing:

-Bend rear axle for camber
-Lower rear
-(maybe) Move front shock towers mounts back and in
-Make front shock tower brace
-Make Cold-Air intake
-Move and shorten main fuel line
-Tune? (is this possible/worth it?)
-Install cheap-o PhantomGrip knockoff LSD

Edited by Lemons Rex, 18 February 2010 - 09:28 PM.

[kaymo]

swap the integra torsions and tubes, the brakes weigh more according to scott, so dont use em. in fact i would think about gutting the rear brakes to save rotating weight since this is ONLY a race car, just depends on how much you think you need em

weld in some fender braces and strut tower braces. for some solid rear action, weld up the internal rear sway bar. if you are having trouble with rear grip, would filling the axle with some weight work better than putting in the trunk, since lower center of grav? just some things to think about


make sure to use the integra lower control arms as well, since if you dont you will have positive camber in the front.

did you use 3m window weld in the motor mounts? this will help your power stay on the ground and not wound up in the mounts

[kedwards]

I'd say weld-up the RR axle pivot bearing (like kaymo suggested) but I'd cut the internal rear swaybar, to save weight.

How about welding up the spider gears, instead of doing a limited slip?

Keith

[Lemons Rex]

We used the entire front suspension cradle from the integra so we have the torsion bars, control arms, sway bar, etc. We need the bigger brakes for passing since we don't have the hp that some of the bigger cars have. We considered welding the spider gears, but weren't sure what kind of problems that might cause. Has anyone done this? If so, please direct me to a thread so I can check out their results.

There is some debate in our team about what to do about the rear grip. I think we need to shift as much of our weight % as we can to the rear and tighten it up as much as possible. Some of our other guys (who have a lot of professional and semi-pro racing and driving experience albeit all in RWD cars) agree that we need to shift our weight distribution to the rear, but feel that we need to increase the amount of rear body roll in order to increase weight on the outside tire when cornering. Any thoughts?

[Rampage]

From what i've heard, you don't need to bend the axle to gain more camber.

Simply add some washers to the two bottom bolts of the the hub bearing to space it out a bit!

[cbstdscott]

"No rear grip" means you are getting over-steer? Is the back end of the car is stepping out, particularly under braking into a corner?

First off, shifting weight from the front to just in front of the rear axle is a very good idea. Putting weight behind the rear axle will induce a "pendelum" action that will increase over steer.

Second, understand the physics of thes cars. At rest, 60% of the car's weight is over the front wheels. Under braking maybe 90% of the car's weight is over the front wheels. If you trail brake into a corner, what little weight that is over the rear wheels gets shifted forward and the rear wheels have nearly lost all contact with the road.

Cliffs: Brake in a straight line.

Scott

[Lemons Rex]

We don't trail brake the car. In fact, I try not to use the brakes any more than I have to since it is an endurance race. Lots of heel-toe downshifts with a tap on the brakes right at turn in.

However, when I do turn in the rear just kind of slides. I guess that it's technically oversteer, but I also get understeer once I get on the throttle. This is being caused from the lack of a Limited-Slip. What I am virtually certain will happen once I install a LSD (or lock the diff) is that I will get great pull up front and zero grip in the back. Power induced oversteer. I know how to fix this in a RWD car, but FWD is a bit of a mystery to me.

[Lemons Rex]

did you use 3m window weld in the motor mounts? this will help your power stay on the ground and not wound up in the mounts

Yup. It worked a lot better than I thought it would.

[Screech]

if you are having trouble with rear grip, would filling the axle with some weight work better than putting in the trunk, since lower center of grav? just some things to think about

No Kaymo, adding weight to the axle is a very bad idea. You want to reduce unsprung weight anyway you can without making it unsafe.

I have welded my rear sway pivot bearing in my B20 hatch because it was bad anyway, works great.

[jsgprod]

However, when I do turn in the rear just kind of slides. I guess that it's technically oversteer, but I also get understeer once I get on the throttle. This is being caused from the lack of a Limited-Slip. What I am virtually certain will happen once I install a LSD (or lock the diff) is that I will get great pull up front and zero grip in the back. Power induced oversteer. I know how to fix this in a RWD car, but FWD is a bit of a mystery to me.

If you lower the rear it will ad more static weight to the rear of the car. If it's already loose, you're going to make it worse by adding more weight.
Are your rear tires the same size as the fronts? If not you should use a softer compound tire back there or run the same size. This being Lemons though, I would guess that you are using DOT tires with a minimum treadwear rating so that's out.

It also sounds to me like you have WAY too much rear roll stiffness. Be it by stiffer springs (you never mentioned what kind or rate you have) or a big rear anti-roll bar. I'm guessing you still have the original internal rear bar in the axle though, if so, you could remove it as has been suggested. Personally, I wouldn't do that though for what you're doing. I'd get softer springs first.

If you are still using the original CRX springs then I think there's something odd going on, it shouldn't be that loose. Especially with the Integra front suspension, that should make it push.

What I am virtually certain will happen once I install a LSD (or lock the diff) is that I will get great pull up front and zero grip in the back. Power induced oversteer. I know how to fix this in a RWD car, but FWD is a bit of a mystery to me.

Uhh...no, not unless you have it set up with some rear toe out. Which I have added into my car in some cases but in your case, I wouldn't recommend it.

So, what are you using for rear springs?
Jay

[kaymo]

i know someone with a welded diff, he needs a football field to turn 180

[cbstdscott]

a tap on the brakes right at turn in.

Try braking BEFORE turn in.

[RETROCRX]

Few suggestions.

Looks like you are very low in the front. Could you be bottoming the front causing wierd chassis pitch changes in a corner? Do you get stange understeer/oversteer oscilation from bouncing on the bump stops?

If it is just a statically oversteery car you can do some of the following

stiffen the front roll stiffness
Soften the rear roll stiffness
Stiffen front spring/damper combo
Softern rear spring/damper combo
Make sure front alignment is neutral to a small amout of toe IN
Same for the rear......Toe IN will make it more stable

I would first check the toe settings all around, I run with basically 0 toe an all 4 corners. Rear toe OUT will drastically affect the rear grip. I tried it once and the car was terrifying!!

Rob

Edited by RETROCRX, 19 February 2010 - 02:13 PM.

[rolandinacrx]

i don't no what to say without driven it, so what do you say