diff ratios how do they work

kepp · Post by **kepp** » Wed Apr 12, 2006 1:50 pm

i have 3.7 diff ratios what would i need to do to give car longer legs thanks

Outback bloke · Post by **Outback bloke** » Wed Apr 12, 2006 2:33 pm

You can't get a taller ratio in a Subaru. If you want to make the ratio higher then all you can do is fit a taller tyre.

xaymaca · Post by **xaymaca** » Wed Apr 12, 2006 4:30 pm

Hmm, you hear about the Datto kids modifying Subaru diffs to suit their 1600's. Maybe you could get a taller ratio out of a 1600 (which is also an R160) and modify that?

Are you just wanting better fuel economy? Maybe you could look at engine modifications etc?

BaronVonChickenPants · Post by **BaronVonChickenPants** » Wed Apr 12, 2006 6:39 pm

The problem there Tim is the dato's are RWD in the suby you would still be stuck with 3.7 in the gearbox for the front wheels.

Jordan.

kepp · Post by **kepp** » Wed Apr 12, 2006 6:45 pm

so fitting 3.9 ratio would not effect the speed to engine revs i am not sure how the ratios is it 3.7 turns of the motor or the diff ?

BaronVonChickenPants · Post by **BaronVonChickenPants** » Wed Apr 12, 2006 7:00 pm

A 3.9 would make your revs about 200rpm higher than with the 3.7.

Jordan

Fang · Post by **Fang** » Wed Apr 12, 2006 7:27 pm

BaronVonChickenPants wrote:A 3.9 would make your revs about 200rpm higher than with the 3.7

ie - give it "shorter legs"

tim_81coupe · Post by **tim_81coupe** » Wed Apr 12, 2006 7:28 pm

The longest ratio I've ever seen in any R160 rear diff is 3.54, from a Liberty RS, but these ran a 3.7 front diff and a reduction drive in the gearbox. I've messed around with a few Datsun 1600's too, all I've seen have run a 3.7 final drive. Remember R160's only come in the sedans too - wagon 1600's have a live axle!

You could run the 3.54 ratio with a RWD conversion, I did this for quite a while, but it's very overrated. I found the EA81 didn't have the horsepower to accelerate on that ratio, the final drive is 3.7 for a reason

MUDRAT · Post by **MUDRAT** » Mon Apr 17, 2006 9:31 am

R160s are pretty much the most common IRS diff in Jap cars - Everything from the mighty Datto 1600 have them up to 180SXs and some Skylines. They're even found in the front of some Nissan pickups. As a result there are loads of options here.

The problem would be finding a high-ratio front diff to match it.