T bucket front wheel hop

Fellers,
I'm helping a friend with his bucket. From the beginning, his front wheels hop uncontrollably at a little above 40 MPH. I have checked everything I know to check. Balanced rear tires, front tires ,changed tires, no better. I put shocks on it today and same thing. I don't know what else to do and I've built a bunch of t Buckets. Everything is tight, no front end wobble drives great up to about 40 then the wheel hop that actually broke one of the front hairpins. anybody got a thought.
Jackie

 

Too much toe in, wrong caster angle.

Dave.

 

Thanks Dave, but set the caster and toe in, no change. Had too much caster so I reset it. Toe in was ok. Drives great, up to about 43 MPH.

 

Did you check radial and lateral run-out on the rims?

 

you running bias plys?

 

Yes sir. The shop that balanced the tires (and I trust them) checked them all. One rear wheel had a very minute bit of run out but not enough for a problem. I'm stumped.

 

Try checking it while they are mounted on the car.

 

The rear tires are 16 inch M/T and when running off the ground, they run smooth enough with no out of round appearance. Had other tires on the rear and they did the same thing. I think it has a demon! LOL

 

Yeah on the hub wheel balence, some times the hubs are the problem....


....Roach.

(Not many shops know how)

 

Are you sure you don't need a steering stabalizer/panhard bar.

 

I don't think a steering stabilizer or panhard bar would help. Doesn't shimmy at all, just hop. I may have to find a shop that can balance on the car so the hubs are balanced too.

 

what hubs are on it? are the mounting studs concentric with the bearing bores? weird huh?

 

measure the wheelbase on each side of the car. I'm guessing one side is 1/2" longer than the other. Adjust the split wishbones

 

How about a few pics?
There's some pretty smart cookies around here

 

What do you consider "ok toe-in"? This sounds like toe-in.

I'll wait for your answer then tell you what mine is.

I've had a T Bucket for about 5 years and the couple times when I had wheel hop, it was bad toe-in.

 

The car has GM disks on the front and Chevy 10 bolt rear. I measured the wheelbase and the front and rear end is within 1/8 inch of square. The front brakes seem a bit tight when spinning the tire off the floor. Not much but not exactly a free spin either. I still think it's coming from the rear tires. Gonna balance them on the car tomorrow. I'll keep you all posted.

 

There's only one cure find a shop that balance the front wheels while they are on the car.

 

Hey fred, how's it going! The bucket has 1/4 inch of toe in. Of all the buckets I've built (6) all wanted a different toe in or out setting. One drove perfectly and best with 1/2 inch of toe out. Never understood that. Only trouble I ever had with bad toe was shimmy. This one doesn't shimmy at all, just hop. If you've had wheel hop caused by wrong toe, maybe I'll try that.

 

I'm not sure how measuring the wheelbase is related to toe-in, but mine is 1/16". Anything more or less and my nose end bounces like Cameron Diaz.

Here's a quick and easy way that works for me. I take a good steel tape measure. Go to the front of the car. Clip the tab in a middle tire tread, in the middle (from top to bottom) of the tire. Measure across to the same spot in the opposite tire. Write that measurement down. The do the same thing on the back side of the tires. Compare measurements and adjust accordingly.

Some T guys set it by crossing a string from one corner of the frame to another, but that won't work if your body is on. There's a few ways to do it, but that way works for me.

Try it. It's free and only takes a few minutes. It will work.

Edit: Yea, I've had what you discribe and toe-in fixed it. 1/4" seems high and 1/2" seems crazy! Something in construction may have caused it to be that high. Try going smaller.

 

I'd also rebalance the tires. Maybe even recheck your spindle nuts. These types of suspensions aren't complicated, but everything has got to be in tolerance.

 

bent axle? jack it up and run it, see how the rears look in motion on the car

 

too much air pressure

 

My 27t hot rod is very sensitive to tire pressure in front. To much or to little will send it into a bouncing frenzy.

 

I've heard guys talk tire pressure before, but I've never had that issue. I change my tire pressure a couple times a week. Kinda depends on the roads I'll be on that day. Hell, I even carry a portable compressor, so I can change it on the side of the road.

But, what ever works, eh?

 

Another vote for tire pressure.

Had the same thing happen to my car once. I went insane trying to chase it down. Toe in, toe out, checked caster, checked to make sure the axles were both square to the frame (and to each other), balanced wheels, balanced the drums, etc. . . did everything I could think of.

I added 5 more pounds of pressure to the front tires and it went away.

 

But how does that work? Tire pressure chnges as you drive. Cold tires are low and increase a few pounds after driving. Are you guys pulling over and changing pressure every 20 miles? I think it would take a DRASTIC tire pressure change to cause wheel hop. Not a couple pounds.

 

Mine too. Front tires are 44lbs, rear MTs are 16lbs. 5 pound difference up or down and I become a Whammo Superball.

 

44 in the front!? Damn. What brand? Doesn't ride hard?

 

Just some import brand 165r-15. The rating is 44 pouds max. I tried 32 for starters and was all over the place. Someone told me to try the max pressure and I did and now straight as an arrow. The rears REALLY bounce if I'm 20 or more.

 

Could be wrong here, but it seems to me that jacking the pressure up to the max allowable, on a light weight car, is only making the tires so hard there is no bounce left. I don't think the high tire pressure is solving whatever is causing the bounce, it's just keeping it from doing it. Kinda' like putting solid rubber tires on. They won't bounce either, unless they are severely out of balance. May be worthwhile to look at a good set of shock absorbers.