Setting up MK9 diff carrier bearings

[ian Staples]

Hi guys,
I would like some advice on setting up the diff carrier taper rollers end float/pre load. When i got my car to restore I pulled the gearbox apart ( I didn't check it)and when I went to reasemble it with new output and diff carrier bearings useing the same shims on the same side the diff locked up solid I had to put 20 thou shim under the main side cover to get the diff to turn. ( pinion backlash is ok) . I removed all of the bearings and removed the seals,these where 8mm wide and i thought the may have been stopping the output bearings from seating properly. I have machined the outside diameter of the old bearings to act as dummys and reassemble it with the same problem, I have removed 3 shims (about 20odd thou) to get it to turn. Reading the Hewland info I have( which I find very vague) it says "Now turn the pinion by hand to test the pe-load,adjust by means of shims untill satisfactory" The big question is what is the "satisfactory" preload. should I remove shims untill I get ,say 10 thou end float and then add 10thou shims plus a certain amount to give a set preload. Can anybody help me please . I hate guessing ,I would much rather have a mesurement to work to instead of "Satisfactory"

[Bob Coury]

Ian:


I ran into a case were the old inner races bearings were installed with an outer race of a different part # bearing. For that reason, the tapers were differnt between the inner and outer race. If that unknowingly happened to you , then you replaced them with the correct matched set and put in the same shims, you would have had a problem.

Now back to your question-I have only done this to two trannys-but I set the preload with a feeler gage between the side plate and the case per the Hewland spec. The backlash is then adjusted by moving the shims from one sideplate to another.

Search this forum for some tips.

[ian Staples]

I have just made up this arrangement in these photos to measure the diff endfloat. Ive taken 38thou worth of shims out to get 3thou endfloat. Unfortunatly, when I pulled the old bearings of the diff head, I never kept them. My new bearings measure 712thou thick so I am starting to wonder whether the old bearings were thinner as I can see no other reason for this problem but the big question remains: If I shim the bearings down to 0 endfloat, what is an accepted thickness shim to add to give the required preload?? Regarding the figure you mention about feeler blades under the side plate, I can find no referance to this in my Hewland manual which I have downloaded from Hewland. I am considering making up a wheel to fit onto my attachment so I can use a string and spring-balance to measure to pounds it takes to rotate the diff head. This is standard practice on some diff heads mounted in tapered rollers. I just need to find one so I can copy the specs and find the diameter I need to make my wheel.
Regards,
Ian Staples

[ian Staples]

Hi guys,
I have hunted around on the net and the closest thing I can find is a list of specs for a Webster transaxle from something like Taylor motorsport, As for diff preload it says "snug but if you want to mesure it 10-12 thou" now can I assume it's zero end float then add 10-12 thou ? Does anybody have a webster manual which may spred some light on the subject??
Regards Ian

[rickb99]

Ian,

What you stumbled upon with ".....from something like Taylor motorsport." Is actually Taylor Race Engineering. What many consider a VERY good source for setup info on the Hewland & Webster transaxles in the U.S.A. They are also quite helpful in these matters.

If you can spring for a phone call to them, I suspect you'll find more answers to your set-up questions in 30 minutes on the phone then you will in a week of posts here. I don't recall many if any posts about the specifics you're asking concerning the Hewland on this Forum.

Taylors web site:
http://www.taylor-race.com/

Or E-mail your questions too:
craig@taylor-race.com

or Scotty at scotty@taylor-race.com.

[ian Staples]

Hi guys, I'm impressed!! I emailed Craig taylor and he replyed very promptly he confirmed that the correct way is to remove all end float and the add 10-12 thou for the correct preload I have done this and every thing feels good ,
regards Ian.