Originally Posted by grouch
Do I need to mess with the basic original design of the rear suspension on a '49 Olds?
The goal is to have a car that's fun to drive occasionally, not a daily driver nor a dragster. The weight of the car means it will never be a sports car, so I'm not going to try to get it to corner like one. The heavy frame and lots of space up front begs for an engine with lots of torque, so I'll have to beef up that rear end.
Other than the differential and shocks, what's wrong (and what's right) with the original design? The radius arms(?) in the attached image are about 45 inches long.
I intend to make a 5" to 7" drop. The thing had 8-1/2" clearance under the differential, originally! Can this drop be achieved with this design, getting the differential up higher into the step of the frame, so that at normal ride height the frame itself is the lowest part of the car? Will that result in a ride so harsh it won't be a decent cruiser any more?
Here are a few thoughts from me. Back in 1959 I owned a '50 Olds Coupe. It had a '56 Olds engine, '38 Cad/LaSalle trans with Corvette shift linkage. Suspension was basically stock except for cut coils in the front to lower it about 3". I ran the largest rear tires I could get at that time (8.20-15) and the rear wheel wells were radiused (Full radius). You might consider this for ease of rear wheel removal if you do lower the car as much as you mentioned. That car rode great and although I never tried any high speed type road racing, it handled very nicely. I did have new shocks on it.
As to the strength of the rear end; I believe your '49 rear is the same as the '50. If that is the case, third members from both Olds and Pontiac up to 1956 will interchange. That third member/rear end assembly was "the way to go" at the time ('50's thru '60's). It was the "9" Ford" rear of that era and is plenty strong for the application you have described.