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TR6 Last TR6 differential question


Great Pumpkin

You must get the nut torqued properly and then, if necessary, go just hair beyond or back, to allow the slot in the nut to align with the through hole in the pinion gear. Then the pin will slide in.

That is why the nut is "castled". To allow several slots to align with "one" through hole, without loosing the applied torque needed to keep the parts assembled properly.

Good luck,


Jedi Warrior
I have a clean hole through both the nut and the pinion but I am just being an idiot and I keep bending the cotter pin when I try to get it to go in.

can you use wire?


Great Pumpkin
NO you CAN NOT use wire, nor are you being an idiot by doing this for the first time and having an issue that we all have done in the past at least once. You have something blocking the hole or you are not completely aligned properly.

Try coming through from both sides to see what is misaligned or blocking you in the through hole.

This may sound silly, but, you do have the correct size cotter pin, I assume?


Great Pumpkin
<div class="ubbcode-block"><div class="ubbcode-header">Quote:]My thought exactly [/QUOTE]

I'm not a bit surprised. Great minds think alike.


If your cotter pin keeps bending, get a new one. Being bent or being the wrong size have the same effect.
Go to an auto parts store and get a little plastic container of assorted cotter pins. It is will worth the couple dollars spent.


Great Pumpkin

I can see that you are new here, and with all due respect to you, we do not post responses slanted in that direction on this forum. We welcome everyone and answer every question with the philosophy that we are all here to learn from each other. There is no expert here or anywhere that has all of the answers, so we try to use a learn by encouragement method rather than sarcasm.

I sincerely hope that you will understand the way that it is here and not take offense at my comment.



I only bring it up because its a red flag. The Triumph uses 2 types of pinion setups the crush sleeve and the shim. They are designed to put the proper preload on the pinion bearings both backing off and tightening the pinion nut will change this and can cause problems. Thats why I suggested proper help in this matter. Please forgive my blunt response but I am really trying to help here.



Great Pumpkin

Very good points indeed and well taken. Hopefully the installation was done properly and the preload will not be affected by any manner of slight adjusting. As I mentioned earlier, there is only a small amount of movement allowable to get to the proper alignment slot in the castled nut.

Unfortunately, upon reassembly of these or any differential it becomes nearly impossible to hit it dead on the money when you apply the needed torque to get the preload set and to get the slots aligned perfectly at the same time.

Probably better odds at hitting the lottery.

And thanks for the details in your explanation about the two types of setups.


Great Pumpkin

These are standard size cotter pins available at any hardware or automotive shop. You want a pin that will fit "snugly" or actually fill the entire ID of the through hole and traveling far enough of out the nut to allow the bending of the pin ends.


Jedi Warrior
I bought a bag of assorted size cotter pins and I couldn't find one that fit.

Since I had to order a clutch master cylinder rebuild kit, I figured I would just add the pin on.

I also figured that I would take the differential in to a shop to make sure that it at least appears right and I didn't mess it up to bad. Just to have a second set of eye double check it.


Jimbar-OUCH you wrote-

"if you need help with a cotter pin what are you
doing working on a differential? I'd suggest seeking
professional help on this."

There are those among us who have either no professional
help available or are limited to cash $$ availble to hire professional help.

The BCF is all about DIY and decent folks teaching guys
like me who know nothing about TRs how to fix our cars.

meaning no disrespect- I've been the BCF site TR6 idiot
for a long, long time and my 69TR6 is now running after being stone cold dead for 15 months. Yes, I needed help
with cotter pins as well.


Tinster in no professional help avaliable Puerto Rico.
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