[6pack] Differential Health Metrics

[Jerry C Shaw]

Hi Robert
My mechanic friend says that if you jack up the car, thus immobilizing one 
drive axle, the free wheel should not have much play if you rock it back and 
forth before meeting with turning resistance. Mine has almost 3/4" at the 
tire stem circumference. He calls it pinion lash and says it's way too much.
Thanks
Jerry

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From: "Robert M. Lang" <lang at isis.mit.edu>
Sent: Wednesday, July 28, 2010 3:24 PM
To: "Jerry C Shaw" <slowtoaccept at yahoo.com>
Cc: <6pack at autox.team.net>
Subject: Re: [6pack] Differential Health Metrics

> Hi,
>
> The book has a set of procedures that you can use to measure the various 
> end-float and clearances in your diff. That said there's only a few 
> characteristics of the diff that can give you noise.
>
> Most obvious is lack of fluid. Don't laugh. I taken diffs out of parts 
> cars that we totally empty of gear fluid.
>
> Next is poor bearing preload, usually too tight. The pinion bearings, 
> particularly the pinion head bearing can howl. If they overheat the races 
> can gall and then they make a lot of noise. But this sort of thing usually 
> shows up right after a rebuild or right after a "sharp" grease monkey 
> decides that the pinion nut needs to be cranked down good and tight to fix 
> things and the bearing preload goes to hell when the collapsable spacer 
> (not available in all models!!) collapses.
>
> The diff carrier bearings can also gall, spin and otherwise make noise.
>
> There's also the loose ring gear, but that's more of a rattle unless a 
> bolt backs out far enough to lock the diff at which time it becomes a BANG 
> and then there's no differential action 'till you replace the darn thing.
>
> Now, there's settings for the pinion head height which controls the mesh 
> with the ring gear but that shouldn't change once the diff is set up 
> unless there's a major problem and there are side-to-side shims so you can 
> center the carrier, but those dimensions shouldn't change under normal 
> ops. There's also the spherical shims for the sun/planet gears but these 
> only seem to control backlash within the differential...
>
> TR6 diffs are all sorts of fun!!
>
> I also probably didn't answer your question. :-)
>
> regards,
> rml
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> Bob Lang              Triumph TR6!!            |  This space for rent
> 2010 NER Solo Chair                            |
> Voice:617-253-7438                             |  Cell: 339-927-4489
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