View Full Version : TR4/4A gear ratios, tr4a irs O/D???

12-01-2008, 04:57 PM
Please refresh my memory. Does the TR4a-irs with o/d run a 4.1 diff ratio? I just picked up a chassis with no rust but a bend in the back section and the trailing arms and irs diff were still attached. The car had O/D. 3.7 or 4.1??? next question is if its a 4.1 what should i ask for it? Thanks, Bob

12-01-2008, 05:30 PM
The standard ratio was always 3.7, with or without OD. The confusion arises because the optional 4.1 ratio was only available in combination with OD.

Except of course by special order <<GRAEMLIN_URL>>/grin.gif

And considering how many parts have been swapped around over the years, I wouldn't call anything conclusive, short of actually counting turns or teeth.

For example, my 59 TR3A had been factory equipped with the 4.1 axle, but came to me with 3.7 gears in it.

Sorry, no help on what it might be worth. The 4.1 ratio is popular with racers, but since quality new 4.1 gear sets are still available ...

12-01-2008, 06:22 PM
Randall, Thanks. I will count the teeth and see whats in there. I heard that the new gear sets were marginal at best. Bob