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Autocrossing newly built coupe Aug 7th. ??

2K views 22 replies 8 participants last post by  Glenn 
#1 ·
I recently finished building my V-8 converted 92 coupe. :leghump:

I'm autocrossing it aug 7th and have a few q's. I really don't have enough gear for this cam, but I'm trying to get away with it for mileage purposes. My Question is, on some of the slower curves with 3.27's there's no way I can power out in second. How bad is it for my tranny to downshift into first. I know if I heel to toe it it willl be smoother, but I don't want to break my new toy.

Second, It seems like the steeda rear adjustable sway bar I put on made it too tight, and oversteers too easily. Is it possible I don't need it. I have it as loose as you can go?

Any input?
 
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#2 ·
First of all I always like to see fox bodies with newer stock wheels, looks good.

Secondly, I doubt you will have to downshift.

Third, be sure that the oversteer you speak of is not actually caused by your right foot.

Lastly, have fun and avoid the tendancy to overdrive.
 
#4 ·
Maybe I'm wrong, but the car actually feels too tight with it on. Not to spark up a "dangeros street driving lecture" but about three am the other night I spun out on an on ramp. I was pushing it pretty hard, but was'nt in the throttle that much. I held it at the same throttle, but at the end the turn tightend up a little she came around, and so fast there was no correcting it.

I know such street diving is stupid and dangerous, but sometimes adreniline overpowers brains. :shakehead

I did take into consideration that my other car is a much heavier convertable so it seems to have more traction, I just figured I'd see if it could be too tight.
 
#5 · (Edited)
Looks nice.No problem shifting back to first-I do it all the time. I now have a supercharged Mach 1 but I had a 89 notch and autocrossed and tracked it for 15 years. I found after many changes that I liked the factory swaybars with stiff bushings and my shocks set on soft. I liked being able to settle the car or steer the car by adding or decreasing the throttle. Too stiff in the rear will not let you get a good enough bite-IMO. Also, you make no mention of what tire you are using, crappy tires will feel like you are driving on ice. Get some sticky performance rubber like a Kumho MX or similar or a dedicated r tire for the track and you will notice a big difference.If you can't get traction-it doesn't matter what you do. I am no professional-but practice-practice-practice. You will get the set up right with time.

Another thing, I just remembered. That car is alot lighter in the rear than the front. If you adjust your weight bias by putting your battery in the trunk and autocross with a full tank it will feel more balanced.
 
#6 ·
I think you're using tight/loose the opposite of how most people do.
Tight=understeer=front end slips more than the rear=you see what you're going to hit

Loose=oversteer=rear end slips more than the front=you don't see what you're going to hit

I'd try autocrossing with the bar on, and bring tools to disconnect one side in case you want to see how it is without the extra rear bar. You might want to keep it disconnected on the street to reduce your tendency to loop it on exit ramps. ;)

Justin
 
#7 ·
Hey, great looking ride! I'll be looking for you in Deland on the 7th.

I wouldn't worry about making any changes until after you have driven it in an AX. As for the on-ramp episode, what happened is that you were in a body roll situation that put your rear control arms into what is known as "roll bind", it's a common problem with Mustangs. As the body leans the rear suspension bushings begin binding which in turn increases the rear wheel rate nearly exponentially. This gives you the "snap oversteer" Mustangs are so famous for. Fortunately there are some remedies for this.

Don't be too concerned about the 3.27 gear, I ran the stock 3.08 gear in my Cobra for about 6 months and it wasn't too bad. I don't think a shift to 1st gear will be needed, nor will it help. I have found that it usually only upsets the car and causes a loss of traction. If you want some pointers just give me a holler and I will ride along with you.
 
#8 · (Edited)
jeb said:
I really don't have enough gear for this cam, but I'm trying to get away with it for mileage purposes. My Question is, on some of the slower curves with 3.27's there's no way I can power out in second. How bad is it for my tranny to downshift into first. I know if I heel to toe it it willl be smoother, but I don't want to break my new toy.

Second, It seems like the steeda rear adjustable sway bar I put on made it too tight, and oversteers too easily. Is it possible I don't need it. I have it as loose as you can go?

Any input?
Enough gear for the cam is a little different for auto-x than for best street response or dragstrip usage, which is more what the cam mfr tables are based on. When you're cornering really hard, you simply can't use all the wheel torque that's available in 2nd, so you won't be at WOT from mid-corner anyway. Especially if you've got any tendency toward "looseness". That said, as you find ways to get better rear grip, you'll be able to use more rear gear. But whether that will be enough to make 1st gear actually useful is still less certain (time to make up and downshifts, making them where they don't get in the way of making other maneuvers, etc.).

You may be able to keep the Steeda bar - going up in front spring rate and/or front bar size are the kinds of things you'd want to be thinking about.

You wouldn't happen to have a lot of poly rear control arm bushings, would you?* Any more than one in each LCA or any in the uppers and you need less rear bar than OE, not more. Either that or a WHOLE LOT more front roll stiffness.

*On edit, apparently so, and in a way too stiff combination what with boxing the uppers and what I assume are some sort of boxed or tubular LCAs. (I didn't pick this up at first, since sigs don't show up on the reply page.)

I suspect that you'll still be a little loose at auto-x even if you remove the rear bar entirely.


Edit #2 - you absolutely NEED to do something about redistributing your roll stiffness. Either more up front, less in the rear, less poly in the rear or modify what you have, or some combination. Driving a car that can turn and bite will not lead to your having confidence in it, and you'll get tired of driving it like you were a driver's ed student so it won't. This isn't a lecture - you've seen what can happen, and how fast. Now think 'wet roads'.

Norm
 
#9 ·
I forgot to mention that for now I'm running the Goodyears that were stock on an 04 GT. And the signature in my post is for my convertable.

In my coupe I'm running Steeda comp springs, poly flca bushings, bilsteins, c/c plates, strut tower brace, a big fat steeda front sway bar, and s-f connecters. In the rear I have the stock sway bar, steeda adj sway bar, and upr poly bushed u&lca's. I don't think I can find a bigger front bar, and my front springs are 850/1050#'s, so I'll probably pull it off for now, and If I have a problem with it pushing, I'll throw it back on for the next event.

As for not having enough gear, I fear I may not have enough low end grunt in second gear to power out of a turn on a course as tight and low speed as deland. Below 2500rpm it's kind of flat. In my vert with 3.55's I think I only got into 3rd once.

Anywho, we'll see how it goes.
 
#10 ·
Hey Jeb,
your car looks great in silver. Just wanted to say hi and welcome to Auto-x, you'll love it.

Just to give you an opinion, In my eyes, 2nd gear with 3.27 gears at Deland is exactly what you want. Sometimes you can even rip 3rd for a short period of time at Deland. But most of the time, 2nd is all you need. I pull it as soon as I can. And, with Deland's 180 turn through the tire wall, I have been able to throttle steer with just a little bit of drift to line up the usual return slalom spot on....

As for the down shift to first, uh, I totally agree with Glenn. But in my case, I hae the Tremec 3650 ( pretty sure thats what I have ) and I am TERRIFIED of a downshift to 1st. I am affraid of synchro damage. I think you might have a beefier trany than mine though. BUt , just as GLenn said, its too upsetting with the car. Just brake earlier, so you can get on the throttle earlier... besides, you already know that rear end snaps around....keep it in the higher gear and away from all that dangerous torque.

Im not the fastest, but my mustang is completly stock, ( a 03 GT ) and have been known to coach people to drive faster than I. :rolleyes:
 
#11 ·
jeb said:
In the rear I have the stock sway bar, steeda adj sway bar, and upr poly bushed u&lca's.
I think we may have located the problem with your spin-out on the highway on-ramp. Those UPR rear arms are absolutely horrible for cornering. I say ditch them in favor of something that works better. The urethane at all four ends is killing any compliance in your rear suspension as pointed out above by Norm. I would sugest something with a solid bushing at the axle end and a 3 piece urethane at the chassis end and swap the uppers out for stock arms. I'm sure you can find some drag racer that would be very happy with the UPR arms and in turn you would be much happier with something else.
 
#12 ·
Jeb,
Listen to Glenn he knows his tuff on the road course. He is very informative and is helpful on giving pointers on what to do. I have a 94 Cobra with a stock motor and rear gear and stayed in second the whole time after I shifted into it. However, I'm a novice and still have a long way to go. Good luck and have fun.

Thanks and God Bless,
David
 
#15 ·
jeb said:
Do you think I would be better off running 245/45 nitto drag radials in the rear, or the goodyears
I drove my wife's 02 GT at Deland on the stock Goodyears. I didn't know a tire could suck that bad! Grant you, they were 3 years old but they had absolutely no grip at all. You could run the DR's but you would push all over the place. If you can adjust to a bad push you would most likely be faster with the DR's, but it would take a lot of patience to drive it.
 
#16 · (Edited)
The extra rear grip and push from the DRs will tend to compensate for the looseness from all that rear poly. Call it a band-aid fix, and I suspect that the poly will eventually win out anyway, but at least you'll be going faster when it does. A good thing at auto-x, maybe not so good on the street.

Norm
 
#17 ·
I did'nt get my tires ordered in time, so I am going to run the goodyears this sunday. I think I could compensate for the push by adjusting the rear sway bar. Right now it's all they way loose, and seems to be too much.
 
#20 ·
I wanted to go but thanks to a really hard physics II final the following week I was stuck studying and plus moving out of my apartment. You'll see me at some of the upcoming events. How did you do Glenn?
 
#22 · (Edited)
My best run was 42.88 which wasn't terrible. But the car had nasty oversteer. I picked up four cones the one run. I'll eventually go with some kumho victoracers, but I've done enough spending for now. I don't know if I'll run next month. The heat was brutal. I thought I was going to pass out with my helmet on. If I do run next time, I'm going to ditch the rear sway bar, and see how that goes.

I'm a ford man, but I love this car
 
#23 ·
The oversteer was from those non-compliant bushings in the rear. Removing the sway bar may help...a little. You really need to address the issue directly instead of putting a bandaid on it.

That picture is of "Fast" Phil Currin, the car is well sorted and fast. I managed to edge him out by .01 second back in May. He more or less smoked me in this month in my daily driver.
 
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