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RE: IRS input flange/nut torque spec

To: "tr list" <triumphs@autox.team.net>
Subject: RE: IRS input flange/nut torque spec
From: "Randall Young" <Ryoung@navcomtech.com>
Date: Sat, 8 Mar 2003 07:28:34 -0800
> I can't find a spec for the slotted nut on the input (pinion) shaft of
> the 4A IRS diff in the factory shop manual.

I believe it's the same for the IRS and non-IRS diffs, which my factory
manual gives as 85-100 ftlbs.

> Taking it up to 85 or 100 lbs. seems to cause some drag.

There is supposed to be a very small amount of drag; there's a procedure in
the manual for measuring the drag and selecting shims to get just the right
amount (15 - 18 INCH pounds without the seal installed).

> Is 60 lbs. likely to cause a
> problem (60 to 85 lbs is about one slot on the nut)?

The pinion uses taper bearings that should have a certain amount of preload.
Too much or too little preload will theoretically reduce bearing life.

>  Can someone look
> up the torque spec for a TR250/6?

My TR6 Haynes gives 90-100 ftlb.  However, ISTR late TR6 were fitted with a
collapsible spacer instead of shims, these should never be torqued that
tight or it will ruin the spacer.  The very slightly higher spec is probably
because of the increased power of the TR6, my Stag manual give it as
100-120.

Randall

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