right front wheel lock up

[Gene's98GTS]

I have a modified 98 GTS and use it at the track. It has been lowered, has dual adjust shocks, single front and rear adjustable links, monoballs, with 1100 lb rear and 800 lb front springs. I am continually flat spotting the right front tire, as it locks (no ABS) well before the left front, even after the car has been corner weighted. Any ideas?

 

[Chuck 98 RT/10]

Without ABS there is always a chance of locking up no matter how well weighted the car is. Have you had it scaled with you in it? What are the four corners weighing in at with you in the driver's seat?

Are the shocks ride height adjustable?

Alignment can also cause a wheel lockup.

Also seems like you have a lot of spring.

But even with everything perfect, without ABS you'll need to learn to threshold.

 

[99 R/T 10]

Get Tom's rear calipers! They will help stop the lockups.

Look for Tom, F&L GoR

 

[Gene's98GTS]

Chuck,

I have ride height adj shocks (snake oyl) and the cars been lowered about an inch with about 3/4 in. of rake. The car was corner wighted/ race balanced with the equivalent of my weight in the seat. I'm hearing it may have too much spring, with Cory at Snake Oyl suggesting 600 F 800 R. Alignment is same R and L, about -3 degrees of camber. I get the feeling the springs are so stiff that the chasis is flexing unevenly, or maybe the sway bar links aren't adjusted evenly. Let me know what you think.

Thanks for any info.


Gene Quirini

 

[Gene's98GTS]

Right now I'm running the Stop Tech big brake kit, which seems pretty good. It is not bias adjustable however.

Gene

 

[ViperRay]

You driving the course clockwise?
That's the one that'l lock up more often.
You like to trail brake some?

Happens to me toooo much

 

[ViperRay]

What pads you runnin'?
You might try something in the fronts with less bite.

 

[Chuck 98 RT/10]

Is it a fast track or a slow track? Regardless, -3 is big camber. Drop it to -2.5 or even -2.

Springs are cheap. Try the 600/800.

Vray's suggestion about less bite pad will help.

As said before though, you will always be able to lockup a non-ABS car. You need to lay on the brakes hard at high speed and back off corresponding to the drop in speed.

 

[Ulysses]

My car will lock up the passenger front before the driver's side. I've heard the same complaint from several others. Some good fixes already mentioned.

 

[Gene's98GTS]

The course is clockwise, and yes I like to trail brake on the slower turns to rotate the car. I'm running performance friction pads pfc 01 - which I love, but will consider others, except Hawk pads which chew up rotors- any suggestions?

Gene

 

[Gene's98GTS]

I'll try the camber suggestion. Thanks.


Gene

 

[ViperRay]

When I switched from Brakeman 3's to PFC 01 up front I too began locking inside front wheel.

I'm sure Chuck is right about using better pedal modulation to avoid this (hopefully with more time for me).
In the meanwhile, I may switch back to BM3's... can mash the pedal harder without lockup.

I suspect a properly modulated pedal with PFC 01 can stop you a little better than BM3's but all I know is I RARELY flatspotted with the BM3's.

I agree -3 camber is too much... definitely decreases the patch size.
If you track your car at the same place all the time, you may want even less camber on the inside compared to the outside wheel.
Most of us get same settings on both sides but that's because most of us don't have the means to get different settings for each track.

Try to take tire temps (get someone to help you) and see what's going on at each wheel. If you look at the flatspotted tire you will see that the spot is on the very inside of the tire.

 

[Gene's98GTS]

Ray, have you lowered your GTS? If so did you change any of the rod ends or shange sway bars to optimize the cars lowered geometry? Snake Oyl sells sway bars and a "bump steer kit" for the rod ends which sound interesting, but I don't know if it will solve any of my braking issues. I also notice my car doesn't like high speed L to R or R to L transitions- seems to wait a bit on the loaded side initially and then "snap" over to the newly loaded side. Any help?

 

[ViperRay]

I have an adjustable front sway bar but this will only help to minimize push in mid turn (which these cars are prone to do).

My GTS is lowered, yes. Problems in transitions like you describe are usually correctable by changing the shock settings.

If your shocks are adjustable for bump and rebound (which I think you indicated above) you can play with these settings.
For a quicker weight transfer on turn-in, you would want to decrease the compression setting (resistance) on the outside wheel (and/or decrease the rebound setting on the inside wheel).

Also, the shock settings will affect the effective corner weighting while cornering (as opposed to static corner weight).

This is complicated business. Considering that shock settings, ride height, spring rates, sway bar stiffness, camber settings, etc. all interact with each other, it's no wonder that professional teams spend megabucks testing and adjusting.

I think this is part of the fun of tracking your car and helps me to learn about all these suspension parts and their effects on handling.

Taking tire temps though is the ultimate measurement of the appropriateness of your settings.

Good luck and have fun!

 

[Gene's98GTS]

Thanks. If I only had a team of mechanics and maybe an engineer I could get serious about this weekend hobby!

Gene

 

[Chuck 98 RT/10]

Get active with some local clubs. There are always a few motorheads around that are happy to go to the track with you.

 

[Gene's98GTS]

Chuck, Thanks for the info. If you're ever around Joliet, IL come run with me at the
Autobahn Country Club. Nicely laid out tracks, very safe and fun. We could compare cars/notes.

Gene

 

[Chuck 98 RT/10]

Man, I've been wanting to run ACC since it opened. Viper Days had it on their tentative schedule but never materialized. Get some vids sometime.

 

[Gene's98GTS]

I'm a member at ACC, and if you're interested you can certainly come as a guest to drive. Check out the video of Jr from SVS...http://www.svspower.com/images/upload/video_53_0.wmv

Gene