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OD - A-Type - Tough Question on Sun Gear End Float (long)

To: "Triumph List" <triumphs@autox.team.net>
Subject: OD - A-Type - Tough Question on Sun Gear End Float (long)
From: "Brian Sanborn" <sanborn@net1plus.com>
Date: Mon, 1 Jan 2001 10:53:43 -0500
Listers,

To anyone with experience in this OD rebuild.

I am in the final re-assembly stage of my OD rebuild and have hit
a problem with the Sun Gear end float.  I have a measured .042
when the allowable is .008 - .014.  All the parts are there and I
have made a very precise measurement of this using a different
method than the very rough one shown in the manual. I need to
close this up at least .031 to get to a median end float of .011

I measured my end float using the depth feature of a dial
caliper... first measuring the depth of the front case flange to
the back steady bush... plus the depth of the rear case flange to
the surface of the annulus... then add the thickness of the brake
ring. You can then subtract the length of the sun gear and its 3
thrust washers and the distance piece. The rough method used in
the manual using a feeler gauge, came up with a low confidence
number .049.  I needed a more precise calculation because this
number was not expected and didn't make sense.

I have not replaced any the bronze thrust washers because they
don't seem worn and are smooth... no marks.  You are supposed to
adjust this end float by swapping out the steel distance ring for
one of the alternate sizes... but they only come as big as .113
and the current one is .098... that is only a difference of .015.
Something else is wrong.

I am assuming that although the 3 bronze thrust washers look OK
they must have lost some thickness in the many years this OD was
in service. I am prepared to buy all new thrust washers if they
are available.  Is it the normal practice to replace these?

My thrust washer thickness measurements are:

Behind unidirectional clutch .116
At planet gear housing       .091
On top of sun gear           .095

Does anyone know the nominal thickness of these when new?

The other component that contributes to end float is the rear
steady bush in the front case.  The "brim" of this bush is .110
and does show some wear.  But,  I have read that the two steady
bushes can't be replaced because the parts are not available...
and if they were they need to be line bored. The manual says to
purchase a new front case if these are worn... not possible
anymore.

My only guess is that the 3 bronze washers have lost enough to
add up to the missing .031.

I know this is a complicated tough question but any advice or
experience would be very helpful in raising my confidence level.
I have talked with John Esposito at Quantum Mechanics about this
a week ago but for some reason he has not returned my call.  If
all else fails, I will order the new bushes from Quantum, TRF,
Moss or ORS (Overdrive Repair Services) in the UK and experiment.

Brian Sanborn
'62 TR4  CT16260L soon to be "O" - Groton, MA

My TR4 Restoration Web Site
http://www.net1plus.com/users/sanborn
E-Mail: sanborn@net1plus.com

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