Bouncing problem

[Sparxx]

Hey guys need some help. New to the E bodies. Just got my 71 Challenger running and driving. Bought it in October. Swapped out the 318 for a 360 with a Haughes cam. Stock 904 and 8 3/4 but put new 3.73 gears in it. New rear leaf springs and converted it to 4 wheel disc brakes. Took it for a drive and it's bouncing. Like the tire has a bulge in it. All 4 tires are good and wheels too. Jacked it up and spun them and nothing is out of round. Any ideas? Posted this in the general area cause I wasn't sure where it's coming from.

[Scooter]

Hey guys need some help. New to the E bodies. Just got my 71 Challenger running and driving. Bought it in October. Swapped out the 318 for a 360 with a Haughes cam. Stock 904 and 8 3/4 but put new 3.73 gears in it. New rear leaf springs and converted it to 4 wheel disc brakes. Took it for a drive and it's bouncing. Like the tire has a bulge in it. All 4 tires are good and wheels too. Jacked it up and spun them and nothing is out of round. Any ideas? Posted this in the general area cause I wasn't sure where it's coming from.

If the wheels spin true it's not a bent axle or the like. Do you feel it in the steering wheel as well or just the seat of your pantelones? U-joints or driveshaft maybe?

[Shane Kelley]

It's going be a wheel/tire issue. I would take them to a tire store and have them road force balanced. That will expose any issue. What are the wheels your running? Some unilug mags can cause this as well.

[Sparxx]

It has new u joints in it. The front wheels are Keystone Klassics and I've had them on other cars before without issues (wheels and tires). The rears are Cragars SS and I just mounted and balanced them and road tested them before putting them on. The rears had different tires on the other day and it did it then also. So I doubt it's the rear tires.

[Sparxx]

All 4 wheels are unilug but they have the unilug washers and if they are not centered right shouldn't you see that spinning them? With the washers it would be pretty hard not to have them center correctly.

[Katfish]

Switch tires from front to back and see if anything changes.
Back in the 80s I bought brand new Cragar SS rims, car never ran right, tried everything under the sun and finally found out the rims were defective.
I'd suspect the rims.

[Sparxx]

Yeah that's not possible. The rear tires are 29x11/R15 they barely fit the wheel well. They won't fit up front. Also the 15" Keystones won't clear the rear calipers because of the rim design. I'm trying to find other vintage wheels for it but not having any luck. I'd like to run some Ansen slots on it since I can't use the Keystones. But finding some 15x10" slots aren't the easiest thing to do.

[Chryco Psycho]

BFGarbage tires ??
I have seen them balance perfect but 3/8" out of round
Never buy BFGarbage !!

[Sparxx]

No BFGs. Rears are Hoosiers. But even at that I've had 2 different sets of rear tires on it and both did the same thing. The fronts have been on my rat rod and had many miles put on them and no issues. I really don't think this is a tire or wheel issue.

[Chryco Psycho]

Can you tell if it si front or rear , steering wheel or butt feel ?
can you have someone drive behind & beside you ?
Could also be just bad shocks .

[RUNCHARGER]

Radial T/A's was my first thought but I see not. You can spin the front and rear wheels on the car (jacked up in neutral). With a screwdriver or other pointer near tread to see any runout. I don't like unilug wheels and wide tires accentuatse any problem.

[Sparxx]

Can't really tell if it's coming from the front or back. Or side to side for that matter. I'll maybe have to try having someone drive behind and beside me and see if they can see anything.

Runcharger no BFG radial TAs. I'm surprised everyone seems to hate those. I've had sets on my Mustang and a few other cars and liked them. No issues.

[Rich G.]

I jack the wheel about and inch off the ground and spin the wheel and look between the tire and the ground from the front and the side. Much easier to see if there is any runout that way.

[Sparxx]

Thanks everyone for your help. It was the tires. I was able to find a different set of wheels and tires to swap out the rears. They where the problem. Now I needed to find some replacements. Hopefully I'll be uploading and posting the build on YouTube before too long.

[Katfish]

Any idea if the problem was the tires or those Cragars?