View Full Version : Different Differentials

05-09-2005, 04:43 PM
I was wondering if some of TR guru's out there could explain something to me. I bought a used TR6 differential a few months ago to replace the unit on my TR250. The original unit has a lot of lash, so much so, that I get a knocking sound whenever I let the clutch out. I did have it checked by a local "furrin cah" mechanic and the support pins are good and solid. I was looking at my shop manual yesterday to get a grip on what I need to do and noticed under the fluids required that the TR6 diff takes 3 pints of GL4, where the TR250 only 1-1/2 pints. Why the difference in the differentials? I thought they were the same unit? /ubbthreads/images/graemlins/confused.gif How do I tell how much to put in? Do I just keep filling until it starts to run out?

05-09-2005, 06:13 PM
Hi Dave,

I think some of the later car diffs just have a different rear cover. That might account for the additional fluid required. I am pretty sure there was also a vertical baffle added inside the cover at some point, to better direct oil flow up over the crown wheel.

I'd fill to the overflow point.

Yes, GL4 is important. A bit harder to find around here, it seems. GL5 is mostly what the shops stock, but is a definite no-no in our old cars.

Does the diff have a drain hole for easy oil changes? I ask because I found out from postings here on the Forum that many TR6 don't (also the gerabox) and while it's out of the car would be a great time to add a drain hole. It was a 3/8" NPT tapered pipe threaded hole on the earlier cars, with a square-headed plug to match... which is available from all the TR vendors... or for a lot less at your local plumbing store. The latter will usually give you a choice of steel, brass or galvanized finishes.



05-09-2005, 10:40 PM
You are right, Alan. I had both units side by side tonight and my original unit has the early rear cover and bracket and definitely will not hold as much oil. However, I now think the unit I bought on e-Bay is in worse shape than my original one. The reason I think so is because (1) there is a bit of slop when I grab the crown wheel and shake it from side to side (there is none on my original unit) and (2) when I grab both inner driving flanges and rotate them back and forth there is more slop in the replacement unit than in my original one. Now there is no oil yet in the replacement, so maybe that could account for some of the looseness, but I'm not so sure that would account for it.