Leaf spring pads
 

Hi All,

I'm changing my rear end on my 67 Firebird.
Should I use the rubber pads or ditch them?
Maybe just the one between the axle and spring?
I am using CalTraks.

Thanks,
RIck

Hi Rick. On my 76 Trans am I left them in top and bottom when I first restored the car. Later on I bought a Moser 12 bolt rear-end, and removed them all-together. I still have my muilt-leaf springs on the car. I used spacer plates from Calvert to set the springs in place. I also have a set of Caltracs on this car.
I did the same on our 68 firebird. On this car it has a 12 bolt rear-end with split mono leaf springs and a set of Caltracs. I removed the rubber spacers also. Makes it easier to set pinion angle on both cars. The only thing that is crucial in all this, is the bolt in the center of the spring needs to be retained in the center of the axle. In one of the cars I made a bushing that fit the lower bracket hole to center the leaf spring bolt. In the perch on the axle I use a spacer that accommodated the bolt in the spring, and welded the spacer in the perch. This is a link to Calvert site shown some of the lowering blocks I used.
https://calvertracing.com/product-categories/parts/
I also installed U Bolts around the axles down through the perch to the bottom plate, washers and double nuts and torqued. Hopefully this make some sense.
The other thing that is very important is the crush of the leaf spring in the perch. The bottom plate snugs up against the bottom of the perch and clamps the leaf springs and blocks in place. You want to make sure you don't bottom out the plate on the perch, before everything is torqued. You may have to install a spacer to take any slack up.

Hi Chuck, Good info, thanks. But I failed to mention I replaced the rear springs with multi-leaf years ago. I also bought the Moser 12 bolt that is now installed. I only used one pad between the ford style perches and spring. I also used 1/2" U-bolts. My only issue now is I only have about 3/8" of space between the tailshaft seal of my TKX and the yoke while the car is on the 2 post lift. Hopefully it opens up a little when I put the car on the ground. I am waiting for 1/2" pontiac black center lugnuts to show up.

That good. Having one rubber pad between the perch and spring is no big deal. Either way it's still all good. The rubber pad does help center and hold the leaf spring in place. You can check it every so often to make sure nothing is moving. Keep an eye on the you bolts nuts. I double nut mine. I also used the wider nuts designed for rear axle U bolts.
On your spacing on the driveshaft to the seal of transmission, you may have to have the driveshaft shortened. You'll have to put the car on the ground so see where your at. I believe with the car on the ground the driveshaft yoke will push into the tranny more. Seeing you have a 2 post lift the rear will be hanging down? I think the consensus is the drive shaft yoke pushed all the way in to tranny, then pull it back approx 3/4" to 1 inch.

Those Moser 12 bolt rear-ends are a beast. Very well built. What gear did you go with? Also, out of curiosity what U joints are you running in your setup? 1350? You said your also running Caltracs. Makes for a very nice rear end setup. We have this setup on both cars. Running the Firebird at low 10's at the track.

Here is a good read. https://www.motortrend.com/how-to/ho...th-driveshaft/

Hi Chuck,

I ordered the 1350, my driveshaft and trans are 1330 from Siverlite. I ordered 3.73's and the truetrack, my original was 3.55, the new overdrive should work well. We have a good power train shop in the area to cut it. It sucks I have to cut my new driveshaft .5 " oh well all good. What are you running for an engine, thats a good time.

Thanks for the info. I have 3.73 in my T/A and a TKO-600. I really enjoy it. The Firebird has an IA2 engine. Did 789 H/P and 700T. It's alot of fun.