Rear Wheel Hop!!!!!!!!!!!

[69 GTS Clonvertible]

Ok I installed the new S/S leaf springs and re-installed the adjustible pinion snubber and test drove it this morning and everytime I start out from a dead stop and get going buy letting the clutch out I can't let the clutch out all the way untill I am going fast enough to not get the rear axle to hop and have the snubber bounce against the floor pan. I have to keep feathering the clutch or dump it and rip up the road.
So what's the problem here?
How far away from the floor pan should the adjustible snubber be?
I have the snubber all the way down right now and it is about 2" taller than the stock snubber.
Bill or anybody with suspension experience please HELP! I need to get this resolved before the show next weekend.
Thanks,
Shawn

[b569rr]

I came to a height of 3/4" on my Road Runner. That way I don't hammer the body on normal driving. But it is close enough that when I dump the clutch the snubber hits the floor and plants the tires.

Before the snubber I had bad wheel hop. With the snubber the 12" wide rubber just smokes but no hop. 

[Blvedere]

Almost sounds like your gear ratio is to high. What is your final gear ratio?  Rear end gear and tire size...

[69 GTS Clonvertible]

I came to a height of 3/4" on my Road Runner. That way I don't hammer the body on normal driving. But it is close enough that when I dump the clutch the snubber hits the floor and plants the tires.

Before the snubber I had bad wheel hop. With the snubber the 12" wide rubber just smokes but no hop.

Tom,
I just went out to look at the distance from the snubber to the floor pan and from the very top of the rubber snubber (which looks like a triangle) It was about 1 1/2" away with full weight of car on suspension, so I raised the snubber up 1 hole and now it is about 1/2" from floor pan. I can pass my large fingers between the top of the rubber and the floor pan. now I just need to let it cool down some so I can tighten up the snubber bracket with some washer shims because it apparently is thinner material than the original and iis loose but the bolts are torqed at 200 inch pounds.
I will testit again latter today,
Thanks,
Shawn

[NYrr496]

Your pinion angle may be a little off now with the new springs. That's what the adjustable front hangers were for. How's the car sit? You can adjust pinion angle with wedge shims.

[69 GTS Clonvertible]

Almost sounds like your gear ratio is to high. What is your final gear ratio? Rear end gear and tire size...

Not sure what the gear ratio is in the trans , I believe it is a stock 69 A-body non-Hemi 4-speed, it does not look like the case was ever taken apart. it was in the car when I purchased it, besides it was doing just fine when I had the old saggy springs in it.
The rear end gear is 3.23-1 sure grip and tire size is P215-70/R14.

[69 GTS Clonvertible]

Your pinion angle may be a little off now with the new springs. That's what the adjustable front hangers were for. How's the car sit? You can adjust pinion angle with wedge shims.

it sits very close to the same height before doing the mods about 1 1/2" higher.
Before doing all the mods (brakes, axles, springs) the floor pan sat on the adjustible snubber, because the springs were old and sagging.
If adjusting the snubber up does not work than, what about flipping the front spring hangers over so that the hanger pivot bolt hole is at the top not the bottom?
Wedge shims?

[*DB*]

Are you sure what you're hearing is the snugger hitting the floor, & not the shocks being fully extended & yanking the rear up? What rear shocks does it have? If they're A-body length shocks, it's a sure bet they're too short. Truck length shocks would work better. HD truck shocks would probably be even better yet.

I've seen it a few times: The car would launch, go a foot or two, then wheel-hop or go into smoke. They'd fight, & change things (raise snubber, lower snubber, remove snubber, change pinion angles, change tires, change tire pressures, load & unload one or both torsion bars, & more) for months trying to fix it, then finally go with longer shocks & the car would work.

[oldkimmer]

Are you sure what you're hearing is the snugger hitting the floor, & not the shocks being fully extended & yanking the rear up? What rear shocks does it have? If they're A-body length shocks, it's a sure bet they're too short. Truck length shocks would work better. HD truck shocks would probably be even better yet.

I've seen it a few times: The car would launch, go a foot or two, then wheel-hop or go into smoke. They'd fight, & change things (raise snubber, lower snubber, remove snubber, change pinion angles, change tires, change tire pressures, load & unload one or both torsion bars, & more) for months trying to fix it, then finally go with longer shocks & the car would work.

               

[69 GTS Clonvertible]

Are you sure what you're hearing is the snugger hitting the floor, & not the shocks being fully extended & yanking the rear up? What rear shocks does it have? If they're A-body length shocks, it's a sure bet they're too short. Truck length shocks would work better. HD truck shocks would probably be even better yet.

I've seen it a few times: The car would launch, go a foot or two, then wheel-hop or go into smoke. They'd fight, & change things (raise snubber, lower snubber, remove snubber, change pinion angles, change tires, change tire pressures, load & unload one or both torsion bars, & more) for months trying to fix it, then finally go with longer shocks & the car would work.

The shocks are not fully extended when full weight of car is sitting on the suspension, when I replaced the springs yesterday the rearend and new springs were hangnig from the frame rails and I had to use the jack and push the rear end up about 1" to get the shocks to go on........after jacking the rear end up, about 6 to 8 inches more, so that it has the full load of the car on it I removed the jack stands out from under the frame rails just in front of the torque boxes, then trounced on the rear bumper to see if it has good shock travel, and yes I believe it is the snubber because I can hear it slapping against the floor pan especially because the new snubber needs a few washer shims on the bolts to snug it up to the differential, and is loose right know and when it was slapping against the floor pan I could here it moving around with a "ping" "ping" like metal slapping against metal.
Thanks for the info though, I'll give it a try if it still happens after doing the snubber adjustment,
Like NYrr496 said on another post do one at a time or else you won't now which item fixed the problem.

[NYrr496]

I don't want to confuse one adjustment with another. I have a problem of not always being clear. Yes, you can flip your front hangers, you'll have to file the frame holes a little so they'll bolt up. That will help tailor the height as will the two hole hangers. Once you have the height where you want it, you'll need to measure your pinion angle. ( the pinion's relationship to the driveshaft ).  You can tailor that by placing 2 degree wedge shims between the spring and the housing. This is how you get the pinion pointed down a couple of degrees. I think Competition Engineering sells them in packs.

[*DB*]

The shocks are not fully extended when full weight of car is sitting on the suspension, when I replaced the springs yesterday the rearend and new springs were hangnig from the frame rails and I had to use the jack and push the rear end up about 1" to get the shocks to go on........after jacking the rear end up, about 6 to 8 inches more, so that it has the full load of the car on it I removed the jack stands out from under the frame rails just in front of the torque boxes, then trounced on the rear bumper to see if it has good shock travel, and yes I believe it is the snubber because I can hear it slapping against the floor pan especially because the new snubber needs a few washer shims on the bolts to snug it up to the differential, and is loose right know and when it was slapping against the floor pan I could here it moving around with a "ping" "ping" like metal slapping against metal.
Thanks for the info though, I'll give it a try if it still happens after doing the snubber adjustment,
Like NYrr496 said on another post do one at a time or else you won't now which item fixed the problem.

It doesn't matter if the shocks are OK at ride height. Those springs cause the rear to rise A LOT! I guess the best way to know how far it's rising is to have someone video it. You may be surprised, & find that the rear is going up like 6". Heavier shock can slow something like this, but not stop it from happening.

Also be aware that adding & subtracting spring clamps on the rear half of the springs can help you tune the suspension also.

Another thought I had was that you might be feeling clutch chatter, but if you're not having any trouble when you slip the clutch gently, then it shouldn't be the issue.

Remember, we're dealing with a clutch car here, so everything is happening faster & more violently than with an auto trans, so your rear springs will be heavier & you'll need more shock dampening to keep things under control.

So, get your snubber bolted down tight, see what happens, make some snubber adjustments, see what happens, take the snubber off, see what happens, etc, and I agree with NYrr496: ONE THING AT A TIME! 

Good luck!

[69 GTS Clonvertible]

Ok.............I tightened up the snubber and adjusted it. then took it out for a drive and no more wheel hop or chatter heres a new pic of it.



and 2 old pics sitting on snubber




notice the location of the rear wheel and wheel opening on all.

[A13Dart]

 *DB* is right,  You absolutely need to use long shocks with SS springs.  I don't remember the extended measurement off hand, but Mopar Perf and rancho make shocks for use with SS springs. The Mopar Perf SS shocks for a manual trans A-body have a bigger rod diameter too.