[TR] J-Type Overdrive oddity

Randall TR3driver at ca.rr.com
Sat Nov 8 14:57:40 MST 2014


> A much renowned small British oil producer and distributor 
> recommended 80W90 
> GL4 gear oil for my TR but recommended 20W50 engine oil for my MGB.
> Work that one out if you can!

Which overdrives?  They aren't all the same.  The J-type pretty much didn't care, it would run in whatever the gearbox maker
specified.  Probably work fine with sperm oil! <g>

For the A-type, Laycock always said to use non-detergent motor oil.  Standard-Triumph started out saying "whatever", then switched
to the Laycock recommendation, then around 1960 switched back to only GL4 gear oil (GL5 didn't exist back then).  The story as I
heard it (from an old dealer mechanic who got it from an old factory engineer) was that they felt they had fewer (warranty) failures
overall using gear oil, even though that was opposite the Laycock recommendation.

But, AFAIK, MGB never had the A-type.  And evidently, their gearbox held up OK with motor oil, so that's what they used.

The important point, I feel, is that neither type of oil is going to cause instant overdrive malfunction.  If it doesn't work at
all, there is something else wrong.  It's possible that using the wrong oil might make it wear out faster, or more apt to break
thrust washers or whatever; but changing oil isn't going to fix those problems once they have happened.

Randall


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