Re: Rearend strength vs size question...ATTN: Jon S.

From: Bob Tom (tigers@bserv.com)
Date: Fri Sep 24 1999 - 08:13:27 EDT


At 05:10 PM 9/21/99 -0400, you wrote:
>Does the size of a rearend directly correspond to its
>strength? <snip>
>Also, are rearends "rated" for a particular HP or torque?
>If so, where can I find these ratings? <snip>
> So, I definitely will be putting in a stronger rearend in the
>future, but I'm undecided as to what to use. Obviously, cost
>is a big factor, but I want strength too. I'd like to get something
>that'll be able to handle a thousand horsepower or so, rather than get
>something intermediate just to have to upgrade again later.
>Obviously I don't have anywhere near that much power now, but
>who knows what the future holds?

If you have the Oct.'99 issure of Mopar Action, take a look at
Race Tech, pp 74-75. His remarks are directed towards a car
with a weight of a '68 Charger.

It says that rear ends are rated by torque but doesn't mention
any spec. ranges. He says the ability of rear ends to take torque is
determined by 3 main things: vehicle weight, traction and
the engine's horsepower level

He says that the 8 3/4 should be totally fine into the low 11's
for a street/strip rear. Many well in the 10's and light cars
in the 9's still run them because it takes less power to turn than
some of the other popular rear ends on the market.

If you want to beef things up, go to a Dana 60 (NOTE: there are differences
in a car Dana and a truck Dana) and don't throw money into the 8 3/4.
Most failures of the 8 3/4 are in the ring and pinion gears breaking
teeth. Nothing can be done about this. Also, the mopar 8 3/4 does
not use a large pinion support on the front as well as a support right
near the teeth of the pinion gear although the 489-case 8 3/4 does
have the largest pinion bearings ever used in a passenger car rear end.
Carrier cap breakage is common too but only at very high power levels.

An option, for budget reasons, is to run an 8 3/4, get 35 spline axles
along with a 35 spline spool. By doing this, the axles are the same
for a Dana 60 so if you ever decide to switch, you'll be set on the
axles.

The tech editor did a story on most of the aftermarket and OEM goodies
for the 8 3/4 axle in the June '98 issue (I don't have this issue)
and the ed says that he'll have some lowbuck tips soon.

Bob, Burlington, Ontario
'97 FR CC Sport, 5.2L, 3.55 SG, auto., 15.268 @ 88.86



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