Leaf Spring Pad Delete vs. Noise

[68Formula]

I had heard others removed their upper and lower rubber mounts.

I did this as well, and I'm getting noise as the suspension articultes over speed bumps (sounds like rubbing). But I can't be sure if it's due to the pads being removed because, in addition to removing the mounts I have also done the following:

Installed 1" aluminum lowering block
Added 4° leaf spring shim to correct pinion angle (rearend was also swapped)
Removed the bottom overload spring (it was not clamped to the other springs, and there were no isolators between it and the spring above)
New bilstein shocks
Disk brake swap
Reinstalled and adjusted the exhaust hangers


Just trying to get a feel if removing the mounts might be the noise source, if maybe it's related to the other changes. I almost wonder if in installing the shim, I overtorqued the spring bolt torque.

Anyone have experience with this?

[68Formula]

I should also mention the car was sitting on blocks for the past year.

[Rod]

I also have the leaf pads removed and a 1 inch block and no rubbing sounds, I also have rear disc and qa1 shocks, but I would think the rub might be the exhaust if you hear it on bumps because the rear end moves and the exhaust is stationary

[woody80z28]

I removed the pads on mine too and when I first did it there was a clunk on bumps and hard accel. Apparently the spring mount on the housing was just deep enough to keep the spring pack from clamping properly, because when I took it apart there was some scuffing on the leafs and the lower shock plate. I installed a 1/4" spacer block and it has been quiet ever since.

In your case the lowering block and shim should be plenty tall enough to keep that from happening...so I don't think that is the issue. Rod has a good point about the exhaust (or any other body-mounted component for that matter.)

[68Formula]

Thanks. Sounds like I need to focus on the exhaust.

[musclecarmatt]

i'm running lower blocks and no pads under my DSE drop springs in the rear....i driven over 2000 miles and no noises at all...and no problems...

[68Formula]

I may have loosened and retightened my leaf spring shackles with the suspension lifted (keep in mind the project was stalled for a year).

I'm going to try loosening everything and retightening.

What should be the proper shackle bolt torque?

[Rod]

I was trying to remember some issues with earlier builds, is it a rubbing noise or a clinking sound? if its a clinking/rattle sound on bumps it could be the rear disc brake pads, (you put on new rear disc) just reach thru the rim and see if there a little loose some SSBC and Right Stuff kits use the caddy calipers and the pads rattle sometimes(there free floating) I have even had the wilwood D-52 calipers pads rattle some in the rear

[Quickboat]

I may have loosened and retightened my leaf spring shackles with the suspension lifted (keep in mind the project was stalled for a year).

I'm going to try loosening everything and retightening.

What should be the proper shackle bolt torque?

Torque depends on the quality of the bolt used. My U bolts are 7/16 -20 likely grade 5 and the torque specs are 55 ft lbs. If they are grade 8 bolts fine thread torque goes up to 78 ft lbs.

In my 67 which came with the single leafs, it has the shallow pearches and the replacement springs were multi. So I incorporated U bolts instead of T bolts. I put a set of spacers between the bolts along side the spring pack to prevent any uncaptured leafs from walking. I dont like the idea of removing all of the rubber insultation, too harsh. Mine is clamped so tight I dont see any way of spring slippage, so what is the point?

https://static1.pt-content.com/images/pt/2012/07/P1020276-1.jpg

[68Formula]

It's not a clank or rattle sounds, it's like you're hearing the springs actually compress. Kind of like you were jumping on an old bed.

Quickboat, thanks for the information, but I was talking about the shackle bolts at the spring eyelet, not the U-bolts.

Also need to find out proper torque on the front eyelet, and the bolt that holds the spring pack together (had to switch to a longer one to add the angle shims). I can imagine if the spring pack bolt is too tight, it's not going to allow the leaves to slip relative to each other.

BTW, the springs are a few years old and do not have many miles on them.

[Quickboat]

http://www.morbark.com/service/belttorque.pdf

[Tony1968]

What is the advantage to removing the pads?

[MrQuick]

All I hear is screeching tires.


im with rod, look for rub marks. open up your trunk and have someone bounce up and down while your under the car with a rubber tube to your ear.

[Quickboat]

What is the advantage to removing the pads?

That was my question. I guess if your car is only used to race it would make things stiffer or more solid. But if you like to cruise with the wife anytime, harshness is not advantageous to her enjoying the ride quality. Nor me really. I want percise handling but not at the demise of driving quality. Stiff but not harsh, that is my goal....

[MrQuick]

In the OP's configuration he is lowering the car a bit. By removing the rubber/isolator you are getting a most positive contact between leafs and differential. Less flex. I doubt you will hear or feel any difference. At least I didn't.

[ryeguy2006a]

Before everyone flames me for bumping up a very old thread, I was doing my due diligence and using the search function. I found this thread that is discussing the exact issue that I'm debating on. Before starting another thread, I figured we could add to this one since there is good info. My question though that doesn't seem to get answered here is; What is the benefits to deleting the leaf spring pad? I'm considering it for my car to avoid any rear end movement. I'm getting some wear on the top of my differential tubes where the U-bolts contact. I tightened up the ubolts as much as I dared with the prothane pads, but they were squishing quite a bit. I'm wondering if I could either run a thin rubber between them, or just delete them all together with a thin steel or aluminum spacer.

Thoughts from the suspension gurus?

My current setup is a stock 1968 Camaro 12 bolt housing, 1/2" U bolts, Hotchkiss 3" lowering leaf springs and a set of Prothane leaf spring pads. Which I bought new three years ago and could use a replacement already.

[79T/Aman]

on first gen leaf spring perches you must have either run rubber pad or a 1/4" shim spacer or the leaf spring pin will touch the axle tube.

[68Formula]

When you say "rearend movement" are you referring to lateral shift, or the fact that the u-bolts are moving relative to the housing?

As far as lateral shift, eliminating the pads will not be as effective as a panhard bar or watts link, but it's one less variable that will contribute. And since it would be locked solid together, the loads should transfer to the springs, which should take away most of the micro-movement between the ubolts and the housing. Plus you wouldn't be over torquing the ubolts so much, nor have to replace pads every 3 years.

[ryeguy2006a]

Thanks PTFB. Could you comment on the benefits to deleting the leaf spring pad and running a solid 1/4" shim? I'd be interested to know your perspective.

68Formula, The movement I'm hoping to reduce is the rotational movement of the housing on the pad, or load transfer. I'm hoping to find the pros/cons of deleting the rubber pad and replacing it with a solid mount before I move forward with going away from the urethane pads.

[79T/Aman]

ryeguy2006a removing the rubber pad will reduce the ability of the rear end to articulate on the leaf springs, makes the rear end housing act like a big anti sway bar and increase roll rate, if you have stock or moderately soft leaf springs it can improve handling but if your springs are stiff it can go too far and cause oversteer.
So it's a matter of knowing what it will affect and testing.

[ryeguy2006a]

Thank you Dave! I do have stiff rear springs, so I think that the benefit of reduced articulation would be negated by causing the car to oversteer. Great explanation, I appreciate that.

[68Formula]

Thank you Dave! I do have stiff rear springs, so I think that the benefit of reduced articulation would be negated by causing the car to oversteer. Great explanation, I appreciate that.

Do you have an overload leaf (shortest bottom one which is not clamped to other leafs)? You could try to remove that for less stiffness. That would reduce the lateral stiffness for less oversteer, and likely allow better front/rear weight transfer when accelerating in a straight line. That's what I did with mine.