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TR4/4A TR4A IRS Diff Capacity


Jedi Warrior
Country flag
Drained and refilled my differential last weekend. Haynes manual as well as other sources says capacity of diff is 0.9 quarts. However, it easily accepted 1.5 quarts before it started flowing out the fill hole in the side.

Any thoughts, comments?



Great Pumpkin - R.I.P
Imperial quart vs US quart ?


Darth Vader

TRF shows 1.35 US quarts for a TR6 differential which should be the same as our TR4A IRS diffs.

I did check my Bentley manual and the owner's manual and they both show .9 US quarts although they don't specifically spell out whether that's for the IRS differential or not.



Jedi Warrior
Country flag
Thanks, and yes, mine was the Bentley manual, not Haynes. Sorry about that. Lists 0.9 US quarts. So does the Moss catalog.

Under routine servicing, the Bentley manual states to periodically top-up the differential right up to the fill hole until fluid begins flowing out that same hole. That's always what I learned. And sure enough, it was 1.35 to 1.50 US quarts, as you say.

Agreed, TR4A IRS and TR6 differentials are the same unit.


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