Preloading a BMC Salisbury Limited Slip

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Bob Hess

Well-known member
Got an old one in great condition. Any of the old guard out there know how to preload one of them? Thanks!

Bob
 
Hi Bob, if you dont get a definite . I'l check the factory Jag book.
Call me, I have some other stuff you may have interest in. MM
 
Protech Racing":1zjs6hcg said:
Hi Bob, if you dont get a definite . I'l check the factory Jag book.
Call me, I have some other stuff you may have interest in. MM
Click to expand...

Thanks! Will do.

Bob
 
Original factory methodology for the C-BTA1226 Salisbury involve machining of specific locations in/on the casing. This also required relocation via shimming of the assembly to regain proper backlash and engagement location. What I've ended up doing over the years with mine is replacing worn Belleville washers or cutch pieces with new. Also adding/removing steel shims behind the axle drive cogs where they slip into the carrier (inside the carrier). Cut these from steel ends of oil cans when oil came in cans, but use the steel from brake clean cans these days. The shims can be used to get whatever break-away torque the driver feels gives the car the desired response. I tend to use 65-75 lbs as my preferred value. Just make sure to use the right gear lube. A number of the older synthetic gear lubes were not suitable for the Salisbury type clutch pack limited slips. My preferred LS gear oil was the old Dryden 75w-90, but these days it is Valvoline in the white bottle, still 75w90.

See you in FL next month :)

PS: Vizard discussed this some in his first book on How to Modify your Mini.
 
Thanks Mike. Sounds workable to me. Been running the Red Line 75/90 in them for the past 10 years. Is that a good substitute for your Valvoline?

Bob
 
If this is truly the old "Factory BMC" Salisbury type (Red primer color looking) with about 8 bolts around the opposite end from the ring gear flange to hold the unit together, then you will likely find the Belleville washers, clutch rings, friction plates and the spider plate in the center. If that's what it is, then everything I said above is valid. Never been in a ramp type diff before, so can't speak to them. I believe those were only a Mini item and were an adaptation of a ZF diff innards by Jack Knight.
 
Mike.... I'm getting smarter by the day! I've got 2 units pictured on the left and it explains why there is only 12 lbs of "preload" on them. When I bought them 25 years ago they were advertised as Salisburys. They work like a charm in both our race car and our autocross car. I've had them apart to clean them and didn't see any method to adjust them that wouldn't screw up their operation. Guess I'll keep running them and come back to you when the Quaife and Tranex units need adjusting. Thanks! Appreciate the extra effort.

Bob
 
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