Auto diff same as manual ?

pzs · Post by **pzs** » Fri Jan 17, 2014 9:06 am

Have 3.9 diff ratio on rear diff, in I assume the front diff is the same? It is a auto g/box. Will this auto diff fit into a manual g/box with 3.77 diff? I am running 14 inch wheels on my every day car, and drive in sand and hills so I am thinking that a lower diff ratio in my manual would be better....if diffs swapped over?

YouTube · Post by **El_Freddo** » Fri Jan 17, 2014 2:30 pm

The rear diff is easily interchangeable. The front diff auto to manual is completely different so there's no possibility of swapping to the 3.9 from the auto into the manual.

There are manual gearboxes with the 3.9 diff ratio - typically found in the '85/86 and early 87 L series.

Cheers

Bennie

NachaLuva · Post by **NachaLuva** » Fri Jan 17, 2014 4:37 pm

pzs wrote:Have 3.9 diff ratio on rear diff, in I assume the front diff is the same? It is a auto g/box. Will this auto diff fit into a manual g/box with 3.77 diff? I am running 14 inch wheels on my every day car, and drive in sand and hills so I am thinking that a lower diff ratio in my manual would be better....if diffs swapped over?

It goes the other way, a higher diff ratio allows the engine to rev higher for the same car speed. I have 4.11 in my Foz & if I went to a 4.44 would get much slower crawl speed. But would be revving the rings off it at highway speeds

steptoe · Post by **steptoe** » Fri Jan 17, 2014 7:02 pm

Hmmmmm, careful how you ask and listen to some of us.....series 1 L Series 3 speed auto ran 3.7:1 rear diff , with...are you ready ...??? a 3.45:1 diff in the front. Pretty sure was 3.45 but certainly not same as rear.

Sounds like you wanna know if you can flog the front diff from an auto and shove it in the front of a manual box. Wish I'd thought of this - pinch 3.45 for the front and er...flog a 3.45 independent bum from a yuk ....Triumph ....err...no thanks. Nice idea though

pzs · Post by **pzs** » Fri Jan 17, 2014 10:12 pm

steptoe wrote:Hmmmmm, careful how you ask and listen to some of us.....series 1 L Series 3 speed auto ran 3.7:1 rear diff , with...are you ready ...??? a 3.45:1 diff in the front. Pretty sure was 3.45 but certainly not same as rear.

Sounds like you wanna know if you can flog the front diff from an auto and shove it in the front of a manual box. Wish I'd thought of this - pinch 3.45 for the front and er...flog a 3.45 independent bum from a yuk ....Triumph ....err...no thanks. Nice idea though

That's what I was thinking ,take the front diff out of the auto and put it in the manual with the 3.9 rear. Not possible by the sounds

YouTube · Post by **El_Freddo** » Sat Jan 18, 2014 12:46 pm

pzs wrote:take the front diff out of the auto and put it in the manual with the 3.9 rear. Not possible by the sounds

^ That's correct

Best option would be to find an EA 5spd box with 3.9 diff ratio or fit an EJ gearbox with 4.11s or 3.9s to match your tyre size. Best thing I've done is change my diff ratio (on top of other good things!) to match the 27s I'm running.

Cheers

Bennie

RSR 555 · Post by **RSR 555** » Tue Feb 11, 2014 3:06 pm

From memory, the front auto diffs are different to the manual front diffs.

When you say lower diff ratio.. do you want lower RPM or higher torque for offroading?

pzs · Post by **pzs** » Tue Feb 11, 2014 8:29 pm

higher torque for off road and 14 inch wheels

RSR 555 · Post by **RSR 555** » Wed Feb 12, 2014 1:11 am

Then definitely look for a 3.9 ratio EA82 gearbox unless you want to spend some big dollars and change to 4.1