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Re: Differential rebuild

To: "mjmullin@juno.com" <mjmullin@juno.com>
Subject: Re: Differential rebuild
From: Mitch Seff <ms6453@optonline.net>
Date: Thu, 12 Oct 2006 11:14:54 -0400
Hi Matt,

I recently went through what you describe. My vibration was from 55 mph 
& up. I went through the usual steps making sure all my drive train 
components were in order. The strange thing about it was , although it 
was always present, it was not always consistent. Some times the 
vibration was more noticeable & other times very slight. Eventually I 
could hear a rhythmic thump when I shut the engine & coasted from 20 mph 
down. The last differential I cracked open was twenty five years ago on 
my 240Z with an R200 LSD. I kept blowing the little spider gears. I 
really have never rebuilt a differential completely before my TR6.

Following your thoughts on being mechanically able but unfamiliar & 
wanting to save a few bucks, I pulled my trusty Bentley manual & started 
to read up on differential voodoo. As always I got plenty of help from 
this awesome list. After disassembly & inspection I replaced the axle 
bearings, seals & a missing fiber washer behind one of the sun gears. 
The carrier bearings & pinion bearing looked perfect as well as the 
pinion & ring gear. I checked clearances and reassembled the unit . It 
felt buttery smooth but after installation and a test run I still had a 
vibration. The slop was gone & the unit was quiet but the initial 
problem was not gone. To satisfy my male ego I'm going to blame it on my 
not changing the side carrier bearings & pinion bearing. It was a short 
cut I should have not taken. The pinion bearing is the more likely 
culprit but I wasn't about to keep dropping the exhaust, differential 
for repairs & making this a weekly event until I mastered differential 
rebuilding. Just on a side note here...........The case spreader was not 
necessary to remove the carrier. Dick Taylors suggestion of gently 
prying the unit out with a pair of bars or screwdrivers on either side 
worked perfectly.

I had to make a decision that you will come to as well. I could 
eventually get the original unit sorted out and get on the road. I 
wanted more than that. Because of other performance upgrades I have made 
the Nissan LSD differential was looking very attractive. It would solve 
all of my fears about reliability,performance and smoothness. It was 
competitively priced against a TRF rebuilt but is capable of handling 
more HP, and abuse. The Nissan unit  has been designed , constructed & 
manufactured with modern technology & materials. If you USE your car and 
like to drive it allot & hard you can not compare the two units. I was 
definitely not prepared to spend the money , especially after just 
installing the HVDA 5-speed,  but I'm glad I did. The LSD is an amazing 
difference. The car is so much more capable through a turn it's hard to 
believe. It's quiet & smooth. The installation was straight forward & is 
no more difficult than installing the stock unit. If you have a stock 
4-speed you will have to shorten the driveshaft.  The HVDA Toyota trany 
is longer so the stock driveshaft can be used.

I am aware that some times the budget just does not allow but in this 
case I would wait until it did. Many things in the car may break in the 
future but I doubt it will ever be the differential.  There are some 
pics on my signature link if your interested.

-- 
Mitch Seff
Oceanside, N.Y.
75 TR6 SC
http://www.triumphowners.com/384




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