I bought an 88 with a 4cyl 5speed that is on its way out. Locally for sale is an 86 complete rear frame and 6cly 4 speed. Is that a straight bolt on? Or is the rear frame on the 88 different? Itd be nice to drive it while building a new motor/trans combo on the original frame.
The subframe attachment points are the same. The location of the upper strut mounts are slightly different, the 88 is farther forward and inboard. It will bolt in, but you may have rear alignment issues.
In the final analysis, you want the 88 subframe- Solid mounted so it acts like a reinforcement for the body, and a much improved suspension design.....
If you want, use the 86 subframe to hold the engine trany until you're ready, then pull the 88 frame out and just quickly transfer the engine/trany to it and ....install....The only difference in mounting is the actual engine mount and bracket on the right side at the "front" of the engine.
So you are looking at installing an 86 rear cradle with V6 and 4 speed into an 88 coupe that was a 4cyl/5 speed?
In this scenario, the cradle will bolt in and you shouldn't have much issue with adjusting the rear camber. You will need to use the 88 struts for the upper spring hat (bolt pattern) and smaller diameter springs to fit the 88 strut towers, but you shouldn't have any issue dialing in the proper rear camber. The issue with camber is installing an 88 cradle in an 84-87 chassis.
Assuming you get the engine harness, ecm, shifter cables, shifter, etc from the donor chassis, it is mostly plug & play. You will need to add a fuse to the ING 2 location, remove the hose barb on the top of the water pump and install a cap, install a V6 fuel pump, and be willing to live w/o backup lights and parking brake until you swap back (unless you want to run the wires needed for the backup light switch moving to the console vs. being at the transmission and swap out the chassis side parking brake cable. You can reuse the 5 speed shifter, but you won't have a reverse lockout (unless you buy one of my bolt on units!)
The '88 Fiero has a completely different suspension and brake setup from the earlier years. Plus you're going from 4-cyl to V6, which means changing out the engine wiring harness, ECM, fuel pump, fuel lines, coolant lines, etc. IMO, that's more trouble than it's worth. You might be better off just renting or borrowing another car while you fix your Fiero. Or maybe find another '88 4-cyl to donate a drivetrain.
