Leaf Perch Pad - Above or Below Spring?

[First Bird]

In the shop now, installing new leafs. This axle has muli-leaf perches. Each perch can be filled perfectly with the spring and one urethane perch pad.

Question:
Does the pad go above the spring - between the axle perch and spring?
OR
Does the pad go below the spring - between the spring and the shock plate?



This might be a no brainer but I'm getting different answers from good sources.
Mr. Pozzi says below spring.
Tech at GW says above spring.

[avgasman]

I've tried all three ways and the best is NO pad. Axle perch to leaf to shock plate.

[First Bird]

Thanks for the advice Dan. That's great you have tried all three ways! I'll take your advice. BTW these are GW L-2 leaf springs. I'll put the spring right up on the axle perch then. Is there any reason not to use a 1/2" lowering block as a solid spacer between the spring and the shock plate? I was thinking of how I could make a solid spacer, but then I thought: wouldn't it be easier to buy one already made (and cheap)? I'm not looking to lower the car. With 2" drop leafs and the Herb Adams Mod, it doesn't need to go lower.

[ArtosDracon]

You'll probably run into a problem with the pin on end end of the block. Why do you need a spacer there? Just to move the shock mounting plate down for better shock travel?

[First Bird]

The spacer is to take up the space in the Multi-leaf spring perch. The perch is 2.10" deep. The springs are 1.625" thick. If i don't take up the space in the perch, the springs will be able to move up and down. They will not be clamped. As for the pin, I think that can stick through the hole in the shock plate. Please let me know if I misunderstand anything. Thanks

[Rhino]

I guess it could come down to your desired ride height. If it's between the spring and the axle, it will lower your ride height by the thickness of the spacer. Any other place wouldn't have any effect on height.

[68Formula]

I guess it could come down to your desired ride height. If it's between the spring and the axle, it will lower your ride height by the thickness of the spacer. Any other place wouldn't have any effect on height.

Except that without the pads he needs to make up a .475 gap. So the .5 lowering block should only drop it .025" from where it is now with the pads. Visually it's a wash.

[Ishmael]

I thought there was one above and one below. Why wouldn't you want them in there?

[First Bird]

I've decided to do it like this: axle, GW 2" drop leaf, .500" aluminum spacer, shock plate. This should allow solid clamping. Rubber front eye bushings, urethane shackle bushings.

Normally there is a rubber pad above and below. When I started this thread I had urethane pads to upgrade. I thought only one pad would allow clamping of the spring, but after doing the install, it looks like I was wrong. If I stayed with urethane I would have needed to use a pad above and below. But now, after alot of internet research and advice from the forum I've decided to go another way.

I don't want flex between the axle and spring. It appears to me that best hookup (increasing anti-squat and reducing spring wind-up) happens when the axle transmits forces directly to the spring. I'm not worried about stance. 2" drop leafs and HA mod should lower rear 2.5". Removing a .455" thick urethane pad from between the axle and spring will raise stance that amount. So net drop will be 2" and I'm OK with that.

[avgasman]

The extra space in my setup is taken up by the two 4 degree shims. I replaced the stock GW through-bolt with one about a 1/2" longer to ensure positive engagement in the perch, and shock plate.

There's about a 1/4" gap between the perch and shock plate.

I torqued the U-bolts to 65 lbft and re-torqued after a few hard miles.

[First Bird]

Dan, Thanks again for the solid advice. I appreciate it. I'll do that longer through bolt - Grade 8 or better. Isn't it funny how obvious things are after you do them. I hadn't factored in pinion angle shims. Now I understand how you didn't need any spacers. I'll measure pinion angle tomorrow

[First Bird]

Dan, Thanks again for the solid advice. I appreciate it. I'll do that longer through bolt - Grade 8 or better. Isn't it funny how obvious things are after you do them. I hadn't factored in pinion angle shims. Now I understand how you didn't need any spacers. I'll measure pinion angle tomorrow.