Oversteer help

[pontiacgp]

Nice looking car and it brings back some fond memories running a metric. It's great that you joined and it's fun trying to set a car up and not even get dirty...lol

Are you not allowed to run a front hoop with your cage set up? It'll protect the rad and add some stiffness to the front chassis clip. With those springs your getting get them rated so you know what you have. Since your limited to the tires you can use are you permitted to get tires shaved? Do you run a rev limiter and with the final drive of 693 what are you reving at the end of the straight?...that is a pretty strong set up for a track that size with the restrictions you have with the tires and setting the car up.

 

[ReQ]

We are allowed to run bars in the front of the frame, as long as they do not connect to the main cage, basically the only limits on roll-cage we have, only 2 bars can run through the firewall, one for drivers foot protection and one for chassis support, but neither can be forward of the bellhousing

cannot X or brace the frame under the floor pan and the rear downbars cannot be connected to one another, the front of the frame has quite a bit of support and protection for the radiator, when we got the rolling chassis it had giant 24" wheels/tires on it, whoever owned it cut the frame to clear, so the front had a lot of flex, you could bounce on one of the front frame forks(not sure the proper name for this) and watch it flex, so we had to plate and brace the frame just ahead of the firewall on each side, they cur the rear as well although not as much, bracing there was much easier

http://i.imgur.com/M3FYN.jpg

once it was all said and done, the front was very stiff, we do think that it may suffer if it ever does touch the wall, as a result of the frame being cut.. who knows, it could fare better because of the extra bracing

the car was built pretty well overall, our first time with a RWD but not our first build, this one went rather smoothly too, so much more room for me in this car, was always pretty hard to get the seat low enough for my 6'1 self in a little FWD 4cylinder, I like to keep my head/helmet as far from the roof as possible, everyone comments that I look like a little kid sitting in this car


almost forgot, I do not run a rev limiter and it does not turn very much more than 6500rpms, hard to tell exactly right now since its such a handfull, really need a memory tach in this car, but the engine seems to shrug it off with no problem, heads and cam are still working at the end of the straight, we did not want to throw at lot of money at the engine so we decided to make up for it other places, we have a lot of engine rules in this class.. but we very rarely get teched on engines, so I will be putting this stock 350 against some real hammers, scat cranks and world product heads abound

 

[pontiacgp]

sounds like you have a good car to work with and it sucks if no one gets penalised if they are running outside the rules. That ruins competition..

here's the last metric we ran..

and this is what we ran last year..

 

[ReQ]

very nice cars, I really wanted to run a Camaro, but this metric car is what became available first, still looking for an f-body with an LT or LS-1, since we are allowed to run factory fuel injection if the car came with it, and I want rack and pinion steering

bit off topic.. so forgive me please but...

I thought I would quickly share what I did for a clutch pedal, seems there are a lot of different setups for getting a clutch pedal in a g-body, I dealt with this problem as well, of course

first I tried to mount a clutch pedal from a 95 Mitsubishi Eclipse outside of the factory bracket, which was the basic setup I found through google searches, it worked but there was a noticeable amount of play and the position was just, off somehow for me,(not to mention we mounted the master cylinder too low trying to clear the brake booster and had no leverage and bent the pedal ) so I decided to go about it another way

http://i.imgur.com/GdV8A.jpg

used a brake pedal from another g-body, cut the pad off and heated the pedal with a touch, bent it to the correct position and went to work on getting both pedals inside the factory unmodified bracket

i measured and cut the bearing housing(round tube the bolt goes through) on the top of the pedal, basically shaving little by little off until the two pedals together, were the width of one originally, the plastic bushing/metal bearing setup would no longer work (too much play for pedals so close) so I decided to do a bit of a redneck engineering solution

found a 1/2 socket that would very nearly fit through the pedal, and with lots of time sanding/grinding on the socket and pedal housings, I got the new "bearing"(AKA butchered socket) to fit as perfectly as possible, drilled the socket out so it would accept the factory bolt for the brake pedal, and bolted it all back together

http://i.imgur.com/lJnLV.jpg

pedals were too close for my liking, so I removed more of the bearing housing from the pedal on the opposite sides, thereby moving them apart and used washers to make up the difference, once its all bolted together tight and in the car, there is NO play what so ever in the pedals, has a very "machined" feel which is so much better for the brake pedal

we are also running manual brakes without a booster so the clutch master cylinder would fit under the brake master cylinder, retainer cap on the brake master cylinder, and adjustable stop keep the rod from falling away on the brake pedal, had to make a cap since all we did was remove the boost from the power brakes, seems to work just fine, I like the extra required force on the brake pedal a long with the new "no play" feel, clutch is still kind of stiff, but completely acceptable for getting on and off the track

probably would not work this way for a street car, unless you can get a clutch master cylinder that will clear the beak booster AND be high enough for mechanical leverage, trust me when you mount the clutch master cylinder near the bottom of the pedal and then try to use it... it does not work I was lifting myself out of the seat pressing the clutch, and trying to release it gently was impossible, the moment you relax your leg a little it would just throw your foot up, never would of guessed how much force was really at play here

also, we are running a hydraulic throwout bearing, so no slave cylinders needed

if anyone wants to know more I could try to help out, sadly I did not take any photos during the actual construction, I was in a bit of a rush and kind of upset that all the work I put into the first setup went to waste, not completely finished in the photos either(this turned out longer than I envisioned, oops)

 

[pontiacgp]

you could hang the clutch pedal outside the housing. I have an F body clutch pedal that I added 3/4" to since it was too short on my street car and the pedal is on the outside of the metric housing. I use the hole for the cruise control wires for the F body master and I have a Howe hydraulic throw out bearing

is that track your on a one groove track or does it have a lane on the high side?

 

[ReQ]

Not sure what a one groove track is, I assume you mean the width of the track and the surface across the width? it is possible to run 3 wide on this track but not advisable, the surface is pretty uniform no matter what groove you run

ignore the legends car, this is the only picture of the track I have, this is the back straight

http://i.imgur.com/FAgP3.jpg

you can kind of tell, the banking is a bit inconsistent, kind of progressive in some parts and more linear in others, difficult to tell when your on the track, but still important to understand

also, I just picked up some rear springs, friend stopped by on his way home and gave me a 150# and 175# 11" rear springs, not exactly what I want but right now anything is better than bottoming out, going to see if these will work for now, that way I can buy some front springs and rear shocks, he also returned my stagger gauge so I can actually check it this time, rather than running what everyone else does

track is open Thursday for test and tune, hopefully I will get some things sorted out then, pretty sure just getting the car up high enough is going to help a lot, I always figured the lower the better.. guess there is a such thing as too low

 

[pontiacgp]

That's a nice track and I was a little high on the spring rates I suggested. That 1/4 mile track looks more like a 3/8 mile track, they must have measured the inside edge of the track. And your revs at the end of the straight make more sense to me now. For the front springs I'd try an 850- 900 on the right and 700 - 750 on the left. The back I'd try 200 right and 180 left. Do you have adjustable shocks?

That track looks to be the same size we ran the metric and we ran a soft spring large bar set up and the car was able to pick up positions going into the corner without over driving the corner

By a one groove tack it means everyone races the low side and no one drives the high side cause it doesn't work for some reason. If the banks are inconsistent it makes it harder to set the car up.


your testing and we havn't even started on the car for next year...

 

[UMI Sales]

That's a nice track and I was a little high on the spring rates I suggested. That 1/4 mile track looks more like a 3/8 mile track, they must have measured the inside edge of the track. And your revs at the end of the straight make more sense to me now. For the front springs I'd try an 850- 900 on the right and 700 - 750 on the left. The back I'd try 200 right and 180 left. Do you have adjustable shocks?

That track looks to be the same size we ran the metric and we ran a soft spring large bar set up and the car was able to pick up positions going into the corner without over driving the corner

By a one groove tack it means everyone races the low side and no one drives the high side cause it doesn't work for some reason. If the banks are inconsistent it makes it harder to set the car up.


your testing and we havn't even started on the car for best year...

+1 on PontiacGP's spring rates. They're very similar to what we had success with. The most important thing is to get KNOWN values in there and then check the balance.

Can you get the corner weights measured at test-n-tune day? It would be very helpful to have that data.

ramey

 

[pontiacgp]

another thing is get a tire temp gauge so you can list the inside, middle and outside of each tire immediatly after a run. List the number of laps you have done as well on the chart so you can see what changes the car goes through with the number of laps you do. That will tell alot on what the car is doing.

 

[UMI Sales]

another thing is get a tire temp gauge so you can list the inside, middle and outside of each tire immediatly after a run. List the number of laps you have done as well on the chart so you can see what changes the car goes through with the number of laps you do. That will tell alot on what the car is doing.

Excellent point. I have every session's tire sheets from every time I was on the track. On our late model we could get RF, RR and LR tires average perfectly equal. On the LF our best was 10 deg F cooler. We kept tuning to get that LF up but ran out of time (our track went dirt, ugh!).

Another tip I got from a Goodyear engineer. Don't use an infrared pyrometer. The probe types give better data because you're getting into where the rubber is working.

ramey