Tires bounce in burnout

Tires bounce in burnout and vibration before finish line .

Tire balance or driveshaft/u-joints?

Hoosier radials they are balanced and take a lot of weight
Driveshaft is Denny’s nitrous ready , been in car 10 years . Approx 500 passes and who knows street miles

hi

look close at tires for a build up of rubber and traction compound .

i may only be on 1 tire .

air psi also must be correct , higher is best for top end .

n20mstr- I suspect you have forgotten more than me but I spoke with a real good local driveline shop recently that did drag racing stuff- He said driveshafts do wear out. I don't know your power level but 500 passes is a decent number and it could be that it twisted and is now out of balance.

Tony, I'd be leaning more towards it being a tire issue. I've twisted driveshafts in the past and only had a vibration through 1st and 2nd gear...not noticeable anywhere else. Once in high gear, it smoothed right out. Had this happen twice.
Last year I had a slight vibration in 2nd gear only...turned out to be wear in the U joints. New U joints and it's smooth as silk again.

Its a small block duster street car . 400+ ? Hp . Runs 11 teens at 120. I think It’s the tires. I also think the driveshaft needs maintenance. It’s been in the car for ten years . He races multiple classes most times and like I said it’s got well over 500 passes on it most of them 11.50 to 11 teens . It’s a 3200lb street car . It’s got some street miles on it also .

He has balanced the tires twice now . On a spin balancer . I told him call Hoosier and see if he did something wrong . Maybe they can only be bubble balanced ? Or maybe something wrong with these tires. They take 9-10oz to balance .even tried moving them around on the rim

Check your tires for roundness. We see more and more tires that are egg shaped. And no amount of weights will offset it. I have a pair of MT drag radials that are so out of round that they will shake the fillings out of your teeth by 60mph.

Put the car on stands/ hoist. Run the car in low gear and look for oval running tire or wheel. It would not be unusual to see a powerful radial car to have bent wheels or axles.

If I had a tire that HAD to have that much weight....I'd throw it out.

I don’t know if I would say it’s “powerful” lol but it’s got an 8.8 from an explorer under it . Stock axles . We are going to run it on stands see what the tires rims axles are doing

I'd definitely do what Trendz suggested! I forgot to mention a couple years ago I also had a vibration that turned out to be twisted axles. Again, wasn't noticeable at speed. I found it by letting the car idle in gear on jackstands.
https://www.youtube.com/watch?v=u7en1p9e7iU

He has balanced the tires twice now . On a spin balancer . I told him call Hoosier and see if he did something wrong . Maybe they can only be bubble balanced ? Or maybe something wrong with these tires. They take 9-10oz to balance .even tried moving them around on the rim [/quote]

If I had a tire that HAD to have that much weight....I'd throw it out. [/quote]

Apparently you've never balanced a bias ply slick
Doug

If I had a tire that HAD to have that much weight....I'd throw it out. [/quote]

Apparently you've never balanced a bias ply slick
Doug [/quote]

As mentioned above, put the car on jack stands and run it in 1st gear and see if everything runs true. Tires are probably out of round.

Apparently you've never balanced a bias ply slick
Doug [/quote] [/quote]

nope.
that sound ridiculous

Just mounted and balanced these Brand New .... 7oz... I've seen that much and more, more times than not.

I have a old bubble balancer along with a really old(1950 tech.) mechanical tire mounting machine.
I replaced Hoosier, they have a bubble on one tire at the edge of the where the tread would be 13.5x32x15 W slicks on my S/P car this winter with a new set of Goodyear 15x33x15. I did all the work here in my shop and when it came time to balance the new tires I had a really hard time balancing these tires on my old bubble balancer, the rims are a old set of Monoque 15x15 with 3.5 inch back spacing.
I mounted and balanced the Hoosier and I don't remember having the same issue as these Goodyear, the Goodyears needed very little weight, maybe 2.5 to 4.0 ounces per tire so maybe their not bad. I have ran them in the 1/4 mile(147+MPH) with no issues that I noticed

WE HAVE A LOAD FORCE BALLANCER AND YOU CAN GET IT TO BALLANCE BUT THE LOAD FORCE MAY BE WAY OUT(EGG SHAPE). WE HAVE SEEN 25-50 LBS OF LOAD FORCE.