Rear End

[MacDee]

In one of the other threads, Jeff W queried about which rear end I might be using when I swap out my tired 170/slug-o-matic for a fire-breathing 200 with C4. I stated that I was intending to stay with the its wimpy 7-inch rear. There are actually some specific reasons I say this, so I would like to present them here and wait for a barrage of feedback....

It all starts with the Dodge Dart I had in my youth. It had the "Power Pack" 273 V8 with hot cam, 4-barrel and dual exhaust (after-market). It had the wimpy 6-cyl rear end (MoPar, of course) and I never had a lick of trouble with it. As I recall, if you had the V8 with a manual trans, you got the 8-inch rear, but the engineers at Chrysler apparently believed that the auto trans would make it unnecessary to use the heavy rear in that application. Also, as I remember very clearly, that motor had very weak low-end torque. It was a dog until the tach reached 4000 when it took off like a bat [from the depths of darkness]!!

With the cam I've selected for my 200 build, I'm expecting a performance curve very similar to that old Dart. It's going to be a little weak in bottom-end torque. Although I know I should not compare FoMoCo and MoPar components directly, I kinda am, and am thinking the little rear end should be adequate assuming I don't get too rambunctious with it (Neutral/Drop burnouts?). Further, with the weak low-end torque, I'll need a fairly short gear. The rear I've got is 3.20:1, which is a pretty good ratio for this cam. If I were to locate an 8-inch with 4-lug axles, it would probably be a 2.79 or something and I would feel a need to have it re-geared to be compatible with my motor.

Next, the wimpy little rear end is, of course, lighter than the 8-inch. Lighter is Better (...if it'll stay Together!).

Finally, I also got the rear end and drive shaft from the '67 Mustang that supplied the engine and C4. It had the wimpy rear end also, and, as far as driveshaft modifications are concerned, I think I may only need a length adjustment of the 'Stang's driveshaft as I believe both ends of it are correct for my application.

Okay...

Let me have it!