[cutrone]

While loading up my car Sunday @ Norwalk , my 12 yr old son says "Dad why is your left rear tire BALD and your right rear still has half tread " ?

I'm running M/T drag radials 295/55/15 . They have about 50 passes on them . No street miles.

Rear suspension is stock ,boxed lower arms, adjustable uppers, stock style sway bar,Comp 50/50 shocks . Air bags in rear 0 psi since installing sway bar. Pinion angle Not verified.

Left rear c-clip elim leaks a bit ( left rear brake shoes greasy) probably no holding power there.

Any insight as to why tire wear is that drastic on left rear ?

Here is a couple vids from Norwalk and is looks like both are spinning hard during burnout

Click on pic for video


click on pic for video

[TinInjun]

Totally normal. Right side wants to lift, left side wants to plant harder.

[Pearlbluebird]

I rotate my slicks after 10 to 15 passes to get double the wear life for that same reason.

[66bonne]

Originally Posted by Pearlbluebird

I rotate my slicks after 10 to 15 passes to get double the wear life for that same reason.

Cutrone: Are you running the DRAG radials or the ET STREET radials ? ET STREETS can't be rotated [as you probably already know].

Personally I've had several sets of the ET Streets and have not encountered the problem you are having.

While I don't have an answer to your question...I love watching your videos !! Man, you've got that Darksider flying !!

Thanks, jim

[PontiacMatt72]

left wants to plant, and right lift??

I'm tryin to understand this... when launching and the car goes to twistin, the left front is usually the side that raises the highest (or tries to anyway). so it makes since to me to say the right rear is the one planting the hardest... but maybe the rear end is doing something different than the body/chassis?

[vin63]

Originally Posted by cutrone

While loading up my car Sunday @ Norwalk , my 12 yr old son says "Dad why is your left rear tire BALD and your right rear still has half tread " ?

I'm running M/T drag radials 295/55/15 . They have about 50 passes on them . No street miles.

Rear suspension is stock ,boxed lower arms, adjustable uppers, stock style sway bar,Comp 50/50 shocks . Air bags in rear 0 psi since installing sway bar. Pinion angle Not verified.

Left rear c-clip elim leaks a bit ( left rear brake shoes greasy) probably no holding power there.

Any insight as to why tire wear is that drastic on left rear ?

From the tire size you noted, it sounds like you're running the ET Street Radials. Regarding your left side v. right side tire wear, you're probably experiencing the affects of the stock suspension and the inherent counter rotation of the chassis to the rearend housing (body roll)...this applies more tire pressure on the left side. Also, the ET Street Radials don't require much of a burnout.

[Jim Hand]

The left front lifting is primarily due to the engine torque twisting the left front up.

But as noted above, that same torque is twisting the drive shaft CW (looking from the front). And as the tires are essentially trying to not rotate. That combination of twist into the rear end with the tires not turning easily, makes the complete rear end try to twist in the same direction as the drive shaft - left tire down and right tire up. With less weight on the right tire, it spins easier and that is where your rubber went!

My wagon has about 52% of the total weight of the car on the rear tires. When it launches, the front lifts which in turn allows the rear tires to sort of steer the car. I run only one air bag and it is in the right rear coil. I also run an anti-sway bar and have the CE shocks set for stiffest compression. Before I added significant power with a fresh and slightly larger engine, I ran 14# pressure in the air bag and that kept the right tire down and getting equal traction as the left tire. And the car launched straight even though there was not much weight on the front tires to provide good steering.

After adding the power, the wagon started drifting to the right at launch. The added power was overcoming the equalization pressure of 14# in the bag, and the left tire was getting more traction which pushed the car to the right. The solution? I increased pressure in the bag to 18# and that was enough to compensate for the increased torque into the rear end. It now launches dead straight. In fact on a clean track, you could almost turn loose of the steering wheel at launch!

Try this: Leave the left bag with only 1-2 # (to prevent pinching or damage to it but not to lift or pre-load it) but air the right bag to 12-14#. You will launch straighter and probably a litte harder at initial hit. But be aware that 14# will tend to lift the right rear of the body slightly but that is what provides the pre-load to prevent uneven traction. I have never seen any need for a bag in the left side of a factory four link (unless the springs have totally collapsed!

Watch this launch video and notice the right side of the bumper is a bit higher then the left due to the 18# preload. Watch closely at actual launch and you will see the left front come up, just as yours does, but the rear stays almost level. Also notice the rear does not squat down over the tires - the fender lip stays almost the same height at actual launch. That is a result of the max resistance to shock compression - rather then letting the body squat down over the wheels/tires, it is applying the full body load onto the tires at initial hit.

http://www.youtube.com/watch?v=8GHYx...elated&search=

Good luck.

Jim Hand

[TTA850]

Your not running a spool are you? That will wear them unevenly. Also check your alignment and that the rear is square. A buddy had a car that would get around 30 passes out of a set of radials before he went and aligned everything which doubled tire life.

As for normal, I've got 80 passes on my current set, 26 passes at Norwalk alone, plus about 1000 street miles and while they are well worn they are worn evenly.

HTH,
Steve

[adam woodmancy]

Nice thread.. I just noticed this problem 1st hand last week on my footbrake car with 255/60 m/t radials. Left side had a 5" patch with nylon showing.. nothing on the right. Car has a full spool so I was wondering what was up.. now I know. Thanks guys

[Silver Judge]

Originally Posted by Jim Hand

The left front lifting is primarily due to the engine torque twisting the left front up.

But as noted above, that same torque is twisting the drive shaft CW (looking from the front). And as the tires are essentially trying to not rotate. That combination of twist into the rear end with the tires not turning easily, makes the complete rear end try to twist in the same direction as the drive shaft - left tire down and right tire up. With less weight on the right tire, it spins easier and that is where your rubber went!

My wagon has about 52% of the total weight of the car on the rear tires. When it launches, the front lifts which in turn allows the rear tires to sort of steer the car. I run only one air bag and it is in the right rear coil. I also run an anti-sway bar and have the CE shocks set for stiffest compression. Before I added significant power with a fresh and slightly larger engine, I ran 14# pressure in the air bag and that kept the right tire down and getting equal traction as the left tire. And the car launched straight even though there was not much weight on the front tires to provide good steering.

After adding the power, the wagon started drifting to the right at launch. The added power was overcoming the equalization pressure of 14# in the bag, and the left tire was getting more traction which pushed the car to the right. The solution? I increased pressure in the bag to 18# and that was enough to compensate for the increased torque into the rear end. It now launches dead straight. In fact on a clean track, you could almost turn loose of the steering wheel at launch!

Try this: Leave the left bag with only 1-2 # (to prevent pinching or damage to it but not to lift or pre-load it) but air the right bag to 12-14#. You will launch straighter and probably a litte harder at initial hit. But be aware that 14# will tend to lift the right rear of the body slightly but that is what provides the pre-load to prevent uneven traction. I have never seen any need for a bag in the left side of a factory four link (unless the springs have totally collapsed!

Watch this launch video and notice the right side of the bumper is a bit higher then the left due to the 18# preload. Watch closely at actual launch and you will see the left front come up, just as yours does, but the rear stays almost level. Also notice the rear does not squat down over the tires - the fender lip stays almost the same height at actual launch. That is a result of the max resistance to shock compression - rather then letting the body squat down over the wheels/tires, it is applying the full body load onto the tires at initial hit.

http://www.youtube.com/watch?v=8GHYx...elated&search=

Good luck.

Jim Hand

Great info Jim, thank you again for sharing. Some of your info about air bags reminds me of a post I read by Hard Timess (Mr. Truman Fields). Even though he's an F body guy, he also raced an A body Pontiac & wrote advice similar to yours in another post about 3 years ago here on PY. I remember reading that & I went out & got a passenger side air bag, installed it and inflated it to 15#

[cutrone]

Thanks for the replies everyone .
Mr. Hand , I appreciate the great info ,thanks for explaining that and posting video.

About a year ago I upgraded power and started to notice that my car would steer to the right when launching . So, after doing some searching on here, I installed air bags in coils.
Inflated rt side to 15# and 4# in left.
Launched perfectly straight after that.

Fast forward to the track outing before Norwalk...

The track was HOT and the starting line was not very good . NO Traction !
Not being very experienced , I started trying different things to find traction .
I let out all the air in the air bags (didn't help ) . I forgot, and left them with no air in either one for the Norwalk race . DUH !

I will put 15# in the rt side like Mr.Hand advised and rotate tires for the next outing.

Thanks Again .

[TTA850]

M/T drag radials are directional and I don't believe you should rotate them.

[ta man]

Originally Posted by TTA850

M/T drag radials are directional and I don't believe you should rotate them.

You would have to dismount and remount them.

[TTA850]

Thanks ta man, feel kinda dumb now lol but I honestly never thought to go through the trouble to do that then again I've never had an uneven wear issue.