69 Firebird 350 coupe, GM 8.5, 10 bolt corporate 74 Nova axle. Switched from 5 leaf to 4 leaf trans am springs.
Bought leaf springs from ESPO, I asked about leaf spring stack height and they said t was not an issue. Installed this weekend all new parts from ESPO and went for a ride, came back and I could see the axle moved a lot on the leaf springs.
When I installed the axle I did notice that the perch and the lower plate bottomed out pretty easily. Looks like I need a spacer or taller pad? I want to make sure the spring and perch and springs are locked together so this doesn't happen again.
Are you running with or without the rubber pads on each side? Is there a rectangle piece underneath the last leaf as part of the spring pack, or just all 4 leaves? Pics would be nice.
I run without the rubber isolators, but I have a 1" drop block (also added a wedge to correct driveline angles), so mine is proud.
Speedway motors sells drop blocks in increments of 1/4" if you just want to add a little bit without a whole lot of drop.
I used both rubber pads in each location. Underneath the spring stack there is very thin rectangular piece of sheet metal that doesn't appear to add any thickness, not sure why it is there. Is this a type of slip sheet should I mount them with out the rubber insolators?
I'll look at speedway motors to see what they have. Any negatives to not having the rubber insolators? I was thinking about getting away from them. Without the rubber insolators I would think it would be easier to lock the pieces together
The rubber should crush down to the point where it is not a factor when you tighten the nuts down. This is very important!!!You must make sure that the center thru bolt of the spring locks into the hole in the upper spring perch when you cinch the nuts down or it wil move on you. Most of the bolt heads are smaller than the hole so there is a built in spacer ring in the spring pads that make up the difference. The bottom plate on the spring is there to take up some of the thickness you lose when you go from 5 leafs to 4.
I had poly isolators, but removed them on a recommendation from others when I did my rearend swap. It feels more stable without them, and I noticed no difference in ride quality.
