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I recently purchased a new (used) rear end w/ 3.70 gears to replace my 3.08 rear w/ a bad posi. I've done some research and want to make the rear as stable as possible, aid in traction and eliminate wheel hop and from what i can tell solid mounting the rear crossmember to the frame is the best way to go. In the chevy power book (see attached) it says to "Replace rubber mounts with steel plates" as well as "Replace with aluminum spacers" for the snubber attaching the rear to the frame. all seem pretty straight forward since im removing the rear anyway. I'll also replace the U joints on the driveshaft. 2 questions:
1. Is there anything im missing while im there? the rest of the rear is all new (coilovers, control arms, 1/2 shafts, smart struts)
2. does anyone make the parts in the images to solid mount the rear?
Mine is still using stock sombrero bushings with the aluminum support plates.
Gotta be careful with the nose bushing. I used a polyurethane one for a good while and it punched a perfect circle through the frame mounting bracket. Just like you used a big hole punch. I made a much heavier frame bracket out of 5/16" steel plate and then used a poly again with no issues.
It always amazes me that that one point is what lifts the car. That has to transfer the torque through the crossmember to the frame rails. Not knowing much else I would be watching those welds back there, but it does look pretty sturdy on a C3.
The C2 chassis however lacks the diagonal bracing so the kick up welds would see more stress wouldn't they?
I'm just musing about this no real concerns, my car lifts a bit but not like that.
Somebody on the C2 forum used a picture of my frame to make this point - see arrows.
I guess that's why at one point they were making those "traction bars" for the C3 but never really caught on all that much (Jim's car seems to be doing all right without...)
Van Steel makes a crossmember lowering kit.
Delrin bushings in 3 spots.
2 Sombreros, and front lower diff mount.
Get this kit from Van Steel.
I just installed it on my 73.
If you do solid mount your rear differential or use Van Steel’s kit, check your pinion angle before and then after the changes to insure you space the front snubber to the frame correctly.
Changing the pinion angle could lead to vibrations and problems down the road.
You can buy the same angle finder I used from Harbor Freight for about $5.00 or download the app on your phone.
Solid mounting the rear crossmember
