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9\" rearend questions

1049 Views 4 Replies 5 Participants Last post by  RPM
I am about to invest in building a 9" rearend for both street as well as open track events. Currently, my 67 Mustang has an old tired, leaky 9" rearend with the small-sized bearings, 28 spline axles (non-tapered) and 3.00 open gears.

-Is there any difference in durability and/or performance between the small bearing vs the large bearing axles?

-Since I plan to drive this car in open track events, should I step up to 31 spline axles when I'm building the new rearend?

-Does anyone out there run a Detroit SofLocker? If yes, does the SofLocker really make less noise than the original Detroit Locker?
Quote from the Detroit Locker website: "The Detroit SofLocker employs a pre-load spring pack to keep the drive and driven members engaged and dampens this noise. The pre-load does not affect the speed differentiation function when required while turning corners. The Detroit SofLocker provides the same performance of the Detroit Locker with reduced noise." hhhmm?

The bottom line is... I want to build a rearend that can handle the abuse, but if it's really not necessary, why overbuild?

Thanks for your opinions,


ps: here's some engine & trans info (if you want it):
351w (425hp / 400 ft lbs)
T5 w/G-Force gear set
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Keep the housing, buy 31 spline axles, Moser makes 31 splines that use the same size bearing (inner diameter and outer diameter). I would look at buying a center section already built rather than putting one together yourself and paying someone to set up the gears. I bought a strange nodular case 9 inch housing with daytona pinion support, 1350 spicer pinion yoke, 31 spline locker and 3.75 richmond gear for under $700 and it was barely used. It's overkill but still cheaper than piecing one together.
I run 31 spline Mark Williams Master Line axles with small bearing ends. The axles are thicker at the bearing than the "large bearing" axles. I had the housing custom made so I could keep my existing brakes.

The soft locker is a nice piece, been racing and driving on one for about 5 years now. I don't turn a lot of corners with it now but it's never given me any specific grief. I put 4.56's in the pumpkin last year and everything inside still looked new. Overbuild = peace of mind.

Here's what I did:
If you are going to do any open track stuff, I would upgrade to the large bearing ends as it will allow you to go with the tapered roller bearings which are light years ahead of the small bearings.
dittos f15. my brother did that and narrowed it a bit at the same time.
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