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C4 Independent Rear Suspension Conversion - Feeling Independent

The trials and tribulations of successfully converting a third-gen to C4 independent rear suspension

Apr 7, 2011
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For those loyal readers who happen to love third-gens, you may very well remember Jeremy Snyder’s ’86 IROC that appeared in the April ’10 issue (Love At First Flight). In said story, it was eluded that Jeremy had intended to swap in a Dana 44 from a C4--a swap done a few times before, but with little notoriety. For your average Joe working out of his garage, this task may seem monumental if not impossible. But for a guy with an engineering degree that fabricated his entire exhaust because he’s "a cheapskate," all it takes is time...and he is all too happy to share his experience of doing what corner carvers (like him) consider, "the ultimate upgrade." As you may recall, previously Jeremy was utilizing a stock 10-bolt with an LS1 fourth-gen’s limited-slip differential, a modified stock Panhard bar, Jegster torque arm, and J&M lower control arms. All of those items would be saying bye-bye.

gmhtp 01  C4 Independent Rear Suspension 2/26

Before we begin, here is some insight from the man himself as to why he did this swap. "My 383 stroker makes a little over 500 ft-lb torque. After a few years of abuse on the street, autocross, and a hard track day, my stock rear axle was starting to leak from the pinion seal. The Zexel Torsen posi I had installed years ago didn’t have enough bias ratio to spin both rear tires under a hard corner with my road race slicks on. I was looking to upgrade my rear suspension and upgrade to a stronger rear gear set, so I didn’t have to worry about grenading my stock diff. Bolt-in 9-inch and 12-bolt rear axles are very expensive and much heavier than the stock rear axle, and I didn’t want to spend tons of money on an axle that would damage my handling. I could fab in a Ford 8.8-inch axle like some have done, but again, that was a large amount of fab work for zero performance gain. If this was a drag car the choice would be very different."



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