Gauge

iTrader: (3)

Hey all,

I have a suspension issue, I believe, and I don't have clue one where to start looking for a solution. The car is a Procharged M6 and is probably making about 650 to the wheels now on 16psi. The suspension is mostly stock with LCAs, an adjustable torque arm and Bilstein HDs. Stock PHB, springs, etc.

The issue I have is that when I'm going down the track, the car tries to turn right. It's like the rear end is trying to walk to the left around the front of the car. I have to countersteer to the left while under load and then quickly center the steering when I let off at the traps. I've had a close call or two in the traps because I didn't center the steering quickly enough after letting out of it.

This seems to scale with torque. First gear is always the worst. Even if I baby it off the line and then nail it, it's pretty violent. I have a video that shows it a bit, but it's not too bad because this was on a slower build with me countersteering a lot.

Once in the past I thought I had an alignment issue (turned out to be the front tires cuz when they were changed, the problem went away), but NTB said my alignment was dead on. I thought maybe my rear end wasn't square to the front because the LCAs have some adjustability to them with the rod ends. I put the car in the air and measured with a plumb bob front to back on both sides and corner to corner. As I recall, it was within ~1/16" on all measurements. I assume I'm in good shape.

Anyone have any ideas on this? Maybe an adjustable PHB to center the rear end perfectly? Perhaps a Watts Link? LCA relocation brackets to limit the squat in the back?


VIDEO: http://www.streetfire.net/video/d1sc...8th_685754.htm

studderin

iTrader: (28)

truetrac?

Old Geezer

iTrader: (3)

Tires the same diameter?
Shocks working?
Suspension bind?

Dan / Wolfe Race Craft

iTrader: (3)

Check Bumpsteer

Heyfred

iTrader: (10)

May need larger rear swaybar and upgraged rear LCA.
Bushings probably flexing in the LCA.

Gauge

iTrader: (3)

To be perfectly honest, no idea. I wasn't the one who ordered it. The thing is like a spool, though. Peg legs real bad, and there's no one-wheel peal.


They're the same tires left and right, so I assume they're the same diameter. Same age, experienced the same conditions. Shocks are fine. Not sure what would bind up in the suspension. What should I look for?


I know what this is (thanks Google), but I don't know how to check it or resolve it.


I'm not sure about the rear swaybar. From the video, it doesn't look like the body or axle are out of level with the ground. It looks to me like it's an even squat and an even plant of the tires. However, your suggestion of the LCA bushings sounds plausible. What you can't see from the video (or any of the others I have) is whether the rear becomes out of square with the front tires under load. If one of the bushings has failed, then presumably that side of the rear end could be allowed to move forward more than the other screwing up my rear alignment. Hmmmm....

Gauge

iTrader: (3)

bump.

ElkySS

iTrader: (6)

mine does this too. iv got an eaton

Gauge

iTrader: (3)

If I had to guess, I'd say that's what I've got. That's the default carrier isn't it?

Mighty Whitey

Check your LCA bushings for sure. I worked on a 95 z28 that did same thing, it would pull to the drivers side under load, and get real squirrelly on decel right as you let off.

Ended up being the driver's side LCA bushings were totally shot, and the passenger wide not far behind.

Gauge

iTrader: (3)

I will check the LCA bushings and report back shortly. Thank you very much for your replies, guys.

Gauge

iTrader: (3)

Well, despite it being a good idea, I struck out. I took the driver side LCA off, and the bushing was hard as a rock still. No signs of cracking that I could see. I'm assuming it would have to be the driver side to cause the car to pull right so hard.

Any other ideas or answers to previous questions?

Sluggish

iTrader: (10)

Have you measured the gap from the tire to the front lip of the wheel well on each side to make sure the rearend is square.


Edit: Like this
https://ls1tech.com/forums/drag-raci...4-how-bad.html

wws699

iTrader: (3)

What tires are you running? front and rear... Hard to tell from the vid

Gauge

iTrader: (3)

Falken street tires in front. M&H 12x26x15 slicks in back.

wws699

iTrader: (3)

Thats your problem you cant mix match bias ply tires with radials. Very dangerous man..

Get some bias ply fronts

wws699

iTrader: (3)

Lots of guys run Bias ply fronts (skinney) and radials in the rear with no problem...

But if your running a 9.5" radial up front and a 10" rear slick your going to smack the wall..

You can run a skinny radial up front and a slick (bias ply) in the rear and be fine. But I wouldn't do it..

Hopefully that makes sense

https://ls1tech.com/forums/drag-raci...8-wipeout.html

^^^

^^^

Mighty Whitey

With the scenario you're having, I would check the passenger side.

If it's pulling right, I would think the pass. LCA is effectively shortening itself.

My friends car was shortening the driver side and pulling to the driver side.

Old Geezer

iTrader: (3)

"They're the same tires left and right, so I assume they're the same diameter. Same age, experienced the same conditions. Shocks are fine. Not sure what would bind up in the suspension. What should I look for?"

Measure the circumference @ the same psi. [Have you tried to swap the tires side for side?
Shocks may look "fine". Could well be 1 of the suspension binding points, if they are different rates.
Other bind points are as mentioned in other posts...
You can set the car on jack stands. [Under the body, not the axle.] Support the axle on a jack, drop the shocks loose, and raise/lower the axle to check for binding...

Gauge

iTrader: (3)

This seems like an unscientific way to measure, but I tried it anyway and found that the wheels are like 3/4" different relative to the wheel wells. That's bad. However, when I installed the LCAs, I measured the wheels front to back on both sides and corner to corner with a plumb bob, and it all looked good (to within ~1/16"). I'm going to check this again. Thanks for the suggestion.


I had this problem with a '72 Nova race car once. We didn't know the fronts were radials when we bought it. When we upped to power to about a 10.3 1/4, it was all over the place. The issue was that when the slicks would roll left and right, rather than the front doing the same, it would cut the opposite direction. The rear would sway driver side, and the front would cut passenger side, then reverse. It would oscillate back and forth getting worse and worse until you were either off the gas or in the wall. This doesn't appear to be what I'm experiencing. I have a consistent pull one direction.

Skinnies are in the works, though. Thanks for the suggestion!


You're right. She's still up in the air, so I'll give it a look see tonight.


I'll give this a shot. My money is on the rear end not being square at this point, so that's my priority. I'll check the tires, but the shocks might wait for now. Thanks for the suggestion.