Re: 7.5 vs 8.5" Diffs


Posted by Traveler on April 03, 05 at 13:13:37:

In Reply to: Torsen(tm) Paydirt posted by Frankenbiker on April 02, 05 at 14:40:47:

:buy a Torsen differential for a Camaro/Firebird directly from GM.

: P/N 12471371 Gears 3.23+
: P/N 12471372 Gears 3.08-

Camaro / Firebird were all 7.5" during the era I was racing. Last years might have been stronger. There was a Dana44 bolt-in for F bodies (Like SLP used).

7.5" might be OK in an S-10 but is too weak for a Sub or Tahoe. I also found that at 4.10 ratio the gear teeth could not take the full output of a healthy 350 very long. Cut back to 3.73 and thus reduced the stresses and it lived until I sold it. That 7.5 had the Auburn cone clutch arrangement. They sold a race version with stronger preload spring but cautioned it was almost not streetable on wet pavement. Can't band aid a bad design.

The 8.5" 10-bolt that the Tu Buick used was a 3.42 and was plenty strong for 400HP. Did wear out the RR axle at the bearing tho. Eaton plate posi in that one. Ruined syn diff oil in 15 - 20K miles; both amsoil and m1.

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