Rear suspension hop

[G Force]

I added 3 degree shims to the rear suspension in an effort to create  the proper drive line angles and reduce vibration problems.
The vibration is still there and now I also have a "Hop" affect in the rear suspension.
Anyone else ever experience this?? It s hard to believe that a 3 deg. shim can affect the ride dharactoeristics.

[Chryco Psycho]

are you using coilover shocks ?

[firefighter3931]

What kind of shape are your leaf springs in ?

Ron

[G Force]

The leaf springs are New and seem Ok. The gabriel shocks are also fairly new. I did not have or notice the Hopping before the shims were installed.

[firefighter3931]

The leaf springs are New and seem Ok. The gabriel shocks are also fairly new. I did not have or notice the Hopping before the shims were installed.

Which springs....super stock, hemi replacements ? How many leafs on each side ? Pinion angle will influence spring performance. Ideally you want 5-7* nose down with leaf spring suspension.

Ron

[Charger4404spd]

You have a pinion snubber?

[Chryco Psycho]

are the shocks coilovers or just regular shocks ?
coilovers create an ocillation ....or hop 

[G Force]

The shocks are not coil over style. The springs are Mopar Performance ( I do not know the amount of springs but i do know the passenger side has an extra spring). I did not have the hope befroe the 3 deg shims were installed.
I have a gear vender OD unit in the car so Im not sure if the 5-7 deg shims are still proper. I have a pinion snubber that now seems to work properly.

[Chryco Psycho]

coil overs ALWAYS cause hopping which is why I had to know , next I would try a square top U bolt & clamp the front section of the springs as tight as possible approx 1/2 way between the spring eye & the diff

[Ghoste]

What is the pinion angle with the shims installed?  The overdrive unit shouldn't be an issue.

[G Force]

I am not sure what the pinion angle is but I do know that there was no shims in originally. Now the mechanic put in 3 deg. shims.
I thought the overdrive unit causes the drive shaft to get shortened which changes from the stock angles 

[Chryco Psycho]

check the angle , it may not need the shims he added

[Ghoste]

How much shorter is the driveshaft?

[G Force]

How much shorter is the driveshaft?

I can only guess its approx. 12" shorter than stock. Im sure that would change the angle,, Right 

[Chryco Psycho]

it will change the angle slightly , it depends how high the rear of the car sits & how much angle the shaft is actually at

[G Force]

it will change the angle slightly , it depends how high the rear of the car sits & how much angle the shaft is actually at

New springs from Mopar performance Drivers side has extra leaf (stock)

[Chryco Psycho]

the U bolts shoild be new try loosening tthem off & removing the shims , see if the problem goes away or gets worse

[Steve P.]

Ask the shop that shortand your shaft how much they took out or call Gear Vendors. They can tell you the difference.. I don't think it's 12 "s.. That seems like allot.... I don't remember any talk about shims when I spoke to them about doing one in my 65' Coronet....

[Chryco Psycho]

which leaf springs do you have , possibly the springs are winding up & releasing / snapping straight & causin gthe Hop

[Steve P.]

G, I would like to know more about your car..

1)  Did you make more changes at the same time as the Gear vendors??

2) Is the cars stance more of a factory car or a 60's FUNNY CAR??

3) Anything different done to the tranny mount while putting in the GV unit??

4) Did GV recommend the 3* shims?

5) Any other changes and mods you have done during or after this mod???

[G Force]

Hi Steve,
1) No additional changes made at the same time the Gear vendors unit was installed.
2) The Cars stance is factory stock with the exception of the 17" after market rims and tires.
3) No changes made to the tranny mount .
4) Gear venders did not reccomend the 3 deg. shims. I had a vibration problem before the gear vendors unit was installed. I thought it was in the drive line so waited till the GV unit was installed  hoping the vibration would go away, It didn't.      I went back to the mechanic that installed the GV unit and asked him to look at the pinion angle, He recomended the 3 Deg. shims. The car now has less vibration with the 3 deg. shims ( still vibrates too much and is not acceptable) But now "Hops"  in the rear.
5)No other changes done during or after the Mod.
NOTE: The leaf springs and shocks are fairly new ( approx. 5,000 miles on them). THere were no shims in the car after the leaf springs were installed ( I do not know if they were there before the springs were changed).


G, I would like to know more about your car..

1)   Did you make more changes at the same time as the Gear vendors??

2) Is the cars stance more of a factory car or a 60's FUNNY CAR??

3) Anything different done to the tranny mount while putting in the GV unit??

4) Did GV recommend the 3* shims?

5) Any other changes and mods you have done during or after this mod???

[Steve P.]

Did your problems start with your rims??  And what rims were on it BEFORE you put the 17s on?

I ask because of unilug problems.. Centering imbalances, heavy wheels, lots of problems can cause wheel hop.. You need to go back and figure out when the problem started and what made the change.. Any chance you still have the old wheels and tires?? Maybe switch back and see if the problem is gone..

[BlK03Hemi/70RR]

Has the driveshaft been balanced?

[G Force]

Did your problems start with your rims??   And what rims were on it BEFORE you put the 17s on?

I ask because of unilug problems.. Centering imbalances, heavy wheels, lots of problems can cause wheel hop.. You need to go back and figure out when the problem started and what made the change.. Any chance you still have the old wheels and tires?? Maybe switch back and see if the problem is gone..

The Rims and tires are balanced. I had custom cetrifical ceter hubs made so the wheels set on the spindles perfectly centered. alot of the new rims rely on centering  and mounting the wheel with the lugs only.
The wheel  hop started when I put in the 3 Deg. shims.

The drive shaft is new and balanced.

[Ghoste]

I'd be rechecking the angles then.  With and WITHOUT the shims.

[G Force]

Ok I found the Problem  It turns out to be that the Pinion snubber is setting too close to the body ( approx. 1/2") not giving enough suspension travel. I have it adjusted all the way down. I am now thinking I may have to Modify the bracket somehow to get it lower. 

[74Charger]

How far should the pinion snubber be to the body?  Is it different for street use verses track use?

[Chryco Psycho]

I like it touching at the track , you probably need a couple of inches even if the roads are decnt where you are

[Ghoste]

Yep, even with new springs and a couple of inches, mine bangs on rougher dips in the road.  I'm not talking about potholes either, just the average dips that you wouldn't ordinarily notice.  Your suspension travels a lot further and a lot more often under normal use than you would ever think (which is good, that means it's doing it's job).

[RD]

it will change the angle slightly , it depends how high the rear of the car sits & how much angle the shaft is actually at

New springs from Mopar performance Drivers side has extra leaf (stock)

glad you found out what it was, but if I am not mistaken, the passenger side is the side to receive the leaf springs with the extra leaf.

[Ghoste]

Correct.  Nor should they significantly alter the ride height unless the old ones were really worn.  Even at that, you'd have to set the car up to the worn springs for it to cause a problem by switching to new ones.

[G Force]

Turns out to be the mechanic had the pinion snubber adjusted to close to the body and didnt allow the suspension to travel.

[Mike DC]

The GV unit would definitely shorten the shaft, but I'm not sure if that's really supposed to affect pinion angle or not. 

Ideally the angle of the tranny and the rearend aren't supposed to be too far apart.  So pushing the tranny & diff closer together (GV unit) would definitely increase some angles, but I would expect it to just increase them both equally and net you zero changes in the ultimate situation.  The only difference would be that the standard recommended angles for a B-body setup would no longer be relevant to your situation.

And then, what angles are we talking about?  Drag-race angles or regular street driving angles? 

There's one angle that's ideal for the car to cruise at.  For a street car, you just set it there and you're done.
But for a drag car, you're supposed to set the pinion a few degrees too far down.  So when the drivetrain is under load, the engine torque will be forcing the pinion angle a few degrees unnaturally UPWARD . . . which will put the pinion angle where it should have been in the first place.  So the pinion angle is correct when the car's under full-blast power and it's wrong the rest of the time.

 

[G Force]

Hi Mike ,  I called Gear Vendors and they said it would change the angles. But as you mentioned it may not be enough to create a vibration.  The Gear vendor Rep said the angle should be approx. 1/2 degree from each other. and not totally zeroed out.
I measured my angles and the happen to be off by approx. 1/2 degree ( according to my measurments    )
I am just trying to get it to the point that I don't get vibration on the freeway. Not interested in the drag strip performance.
The standard 5-7 degree does not apply to my car any longer tdue to the  Gear vendor unit. The mechanic I brought it to put in 4 degree shims and said that its the best it can be ( but I still feel the vibration).

Thanks for your reply!