Final Drive Ratio for E36 LS1 swap

[sprbxr]

For those that have done the swap, what final drive ratio is optimum?

Justin

[rao]

You will never get agreement on optimum. I went with 3.46 and am happy with the choice

[GMW364i]

I'm running 3.23:1

0-60mph in 1st gear

[JoeZ]

I rock 3.73 and love it

[E36LUVA]

Are you guys using the large case M3 diff. I've heard of using the 8.8 from an explorer or mustang cobra with a modded subframe. Which would be better.

[JoeZ]

Are you guys using the large case M3 diff.

I'm using a regular ole e30 diff, with an e36 M3 dual ear rear cover and speed sensor wheel.

[325bob]

With that much low end torque I would get the lowest(numerical) possible, if you can spin the rear tires you have too much gear! I think Andetti said it best, if you can spin tires from 1 turn to the next, you have too much HP.!

[bimerok]

I'm running 3.23:1

0-60mph in 1st gear

what engine and tranny do you have?

[Thaniel]

You will never get agreement on optimum. I went with 3.46 and am happy with the choice

Agree there will never be agreement

I'm running a 3.9 LSD as it was in the car when I bought it. I don't feel any need to change. Yah it'll spin the tires pretty easy but any taller gearing and I am not sure I'd use 6th on the free way.

Oh the diff appears to be a 325i not an M.

[JoeZ]

With that much low end torque I would get the lowest(numerical) possible, if you can spin the rear tires you have too much gear! I think Andetti said it best, if you can spin tires from 1 turn to the next, you have too much HP.!

They'll break loose on you over 100mph if on cold tires and you're not smooth with the fun pedal. I find this gearing fun, and never find myself annoyed because I have to shift too much or anything like that. Keep in mind that both 5th and 6th are overdrive and 4th is your 1:1 (whereas in most BMW's 5th is 1:1)

[GMW364i]

what engine and tranny do you have?

LS1 and T56

7200rpm redline and 2.66 1st gear = ~62mph in 1st gear.

Something to remember about lots of torque and big displacement, it is very easy to control the power with the throttle. Wheel spin can be what you want for the most part. I find I can easily spin the tires through 100mph if I want, but that it is easy to launch hard with very little wheel spin as well.

It will get ~30mpg on the highway as well, which is nuts for a 6.3L V8. City not so good but it's mostly the drivers fault...

[bimerok]

LS1 and T56

7200rpm redline and 2.66 1st gear = ~62mph in 1st gear.

Wow... what did you do to the engine to be able to handle 1200 more RPMs? Did you replace all the rod bearings/bolts and all the valve springs?

[GMW364i]

Wow... what did you do to the engine to be able to handle 1200 more RPMs? Did you replace all the rod bearings/bolts and all the valve springs?

Initially just valve springs and rod bolts and a camshaft on the stock bottom end, but since it's been built with into a 383ci stroker, forged crank, rod and pistons. Which still goes to 7200rpms.

300+lb/ft torque at the wheels below 1800rpms to past redline and available the instant you hit the throttle.

[Redy 318Ti]

im using 3.73's

[Demon Speed]

Pretty sure my car still has the stock M3 gearing (3.23). I'm wondering how this will be for a 5.7L LS1 with a big (232) cam, stock heads, and aluminum flywheel. I guess I'll drive it for a while and see how I like it. But yea very tall gearing with the T56.

http://xse.com/leres/bin/gearratio?t...le=45&wheel=17

[bimerok]

Actually, I think 3.23 was one of the ratios offered for T56

[Demon Speed]

Actually, I think 3.23 was one of the ratios offered for T56

I think the autos had 3.23 rear gear ratio in the F-bodies. My T56 99' TA had a 3.42 rear from the factory.

[MikeJTR]

I think the autos had 3.23 rear gear ratio in the F-bodies. My T56 99' TA had a 3.42 rear from the factory.

One thing to consider about the E36 is that it is lighter and more aerodynamic than the F-body.
Also, the E36 tire is shorter the the tires used on the F-body, effectively raising the numerical rear axle ratio.
If you are running a stock LS1 with the F-body T56 (0.5 6th gear) the 3.23 or 3.38 rear axle ratio would probably be a good compromise between fuel economy and performance.
If you are using the GTO LS2 transmission, you may want to use a 2.93 or 3.15 rear axle rato because of the .56 6th gear, and the shorter first gear, compared to the F-body T56.

[Demon Speed]

One thing to consider about the E36 is that it is lighter and more aerodynamic than the F-body.
Also, the E36 tire is shorter the the tires used on the F-body, effectively raising the numerical rear axle ratio.
If you are running a stock LS1 with the F-body T56 (0.5 6th gear) the 3.23 or 3.38 rear axle ratio would probably be a good compromise between fuel economy and performance.
If you are using the GTO LS2 transmission, you may want to use a 2.93 or 3.15 rear axle rato because of the .56 6th gear, and the shorter first gear, compared to the F-body T56.

I have an F-body trans. I'm considering going to a shorter gear b/c I'll be tracking this car. Hopefully though with all mentioned above the 3.23 will be a good match.

[GotCone?]

anymore input on this guys?

I've got a spare 3.15 and am contemplating trading it for a 3.91 to better suit the LS-1 and T-56 f-body gearing.

[JoeZ]

I rock 3.73 and love it

anymore input on this guys?

I still feel the same

[sbeckman7]

sounds like I should be fine with the 3.25 that came in my e28


edit: Wow, I really should have checked the date on this. Sorry..

[Tongboy]

this threads old, there was a more recent one and the consensus was a lot more towards the high 3.x ratios- in the e36 the 3.91 is unquestionably the best ratio

[sbeckman7]

hmmm. does that still apply to a 1500lb car?

p.s. I quite enjoy your thread! may have some questions to ask in the future

[Tongboy]

weight doesn't so much matter- it's all about putting the power down, with the torque of hte ls you can spin even double that weight of car easily in most gears with a 3.2 ratio rear end.