What diff is in your M42 car?

[cabin]

I bought mine with a 3.73 LSD and proceeded to swap it out for a 4.10 LSD.

I just swapped the 4.10 out last weekend in favor of a 2.93 LSD, but the car is no longer powered by an M42 :)

[Ryann]

I put 3.73's in both of mine since I drive 126 miles round trip for work. Driving between 70 and 75 puts the rpms just over 3k. Much nicer then 4k with a 4.10. I definitely wouldn't go any lower since there are a few hills along the way between Sutherlin and Eugene that the m42 would really struggle on.

I'd like to do this too. It drives me nuts to be up over 3k @ 65-70 mph.

[YetiX]

Its better for the autox IMO. 2nd gear runs out further, dont hit the rev limiter as much as i did with the 4.10

80mph w/ 410 = 4k,
80mph w/ 3.73 = 3500

win win

I hear you on the freeway and hitting the limiter in 2nd during the autox. I swear mine spends half of some autox's on the damn limiter. How is it off the line in 1st though? Is ok?

[tjts1]

I hear you on the freeway and hitting the limiter in 2nd during the autox. I swear mine spends half of some autox's on the damn limiter. How is it off the line in 1st though? Is ok?

AutoX ing with a 3.64,I don't notice any difference in 1st. I still managed to spin both tires with RT615s. 2nd to 60mph+ really makes driving around most courses a lot easier. I think 3.73 is the ideal ratio for autoX. You'll never touch 3rd.

[Hick]

You have more torque and horsepower going to the wheels at any given with a shorter diff though (assuming you're in the same gear). I've never been at an auto-x where I needed to shift up to 3rd.

True but M42s are not known for torque, so it does not hurt much. Ive run several that hit 3rd. Tjis season ive been running my friends 325is, at one event i was hitting middle of 3rd (around 80mph)

I hear you on the freeway and hitting the limiter in 2nd during the autox. I swear mine spends half of some autox's on the damn limiter. How is it off the line in 1st though? Is ok?

1st is just about the same. Im telling ya, its a better set up. I think i was one of the first guys to swap to 373 from the M42 dudes i know, local and internets.

[KenC]

We need to test these different diffs Top Gear style. 8)

My 4.44LSD eats other diff's children.

[LowR3V'in]

I voted 2.93 just to let you know.
Forgot I was in m42 section.

[Matt-B]

4.10lsd, came with car

[bmwm42]

4.10 Medium open diff cause thats what it came with when i got the car and yes i know they normally came with small case diff mine has 8 bolts which means it a medium one lmao

[e30BMart]

have a 4.10 open diff ordered a 4.10 lsd but my garage got a 3.73 locked, ill try it and see if its that big a deal.. uphrade?

[e30BMart]

After two days I can say that the 3.73 have less kick, but over 4000 RPM is still fun! the locked diff makes the car feel safer or more planted somehow aswell

[KenC]

Locked as in welded? We have a welded diff on our track car, but I'd HATE to have one on the street.

[e30BMart]

Locked as in welded? We have a welded diff on our track car, but I'd HATE to have one on the street.

no I meant lsd

[///digitalme]

3.91 vlsd on my car great upgrade from the crappy 4.10 I had. I can do 65 on 3rd which is nice. I daily my car so it is better than having to shift every 5 seconds

[bmwm42]

car switched to economy mode downgraded to 3.73 and loving it especially on the highway....id rock a 3.46 or taller if i could find one cheap enough lol