Which diff ratio for M42?

[Cal]

I'm about to put an LSD in my car. Would you go a 4.1 or a 4.45 and why? Sounds like it might buzz a bit too high on the highway with the 4.45. It's hell slow with the 4.1 though.

[tjts1]

3.73

[Dj Buttchug]

dude no way. 4.10 is way quick. top speed sucks if thats what you mean. imo it depends how you drive.
I have a 2.93 in mine. the long gears are great for crusing

[tjts1]

Having to shift to 3rd gear before 60mph makes the car feel slow in the real world. It can handle taller gears no problem.

[e30huh]

there's a 3.46 for M42 for sale on the local craigslist.

http://washingtondc.craigslist.org/nva/pts/2058727263.html

[nando]

the top speed of an M42 powered car probably doesn't change or goes down with an excessively long rear diff ratio.

E30s are almost *never* gear speed limited. I don't get why people think a 4.10 or higher makes the top speed lower. I also don't understand the desire to go 120mph in 3rd gear..

[2002maniac]

I think 4.10 is the best for street use. 3.73 is sluggish and 4.45 is screaming on the highway. I've tried them all but would like to find a 4.27 to try out.
Nando, i redlined my m42 in 5th with the 4.10. It took a while to get up there though.

[Supadave]

I'm about to put an LSD in my car. Would you go a 4.1 or a 4.45 and why? Sounds like it might buzz a bit too high on the highway with the 4.45. It's hell slow with the 4.1 though.

slow on the top end or the bottom? I have a 4.10 lsd in my car, its great the only complain i have is high rpm on the freeway, wich really isnt that bad. With a 4.45 lsd would be sick doing autoX. I guess it all depends on your driven style and hp. Me myself would like a 3.73 when I'm done building my stroker.

[tjts1]

Perfect.


Why you would want be forced into 3rd gear before 60mph is beyond me.

[nando]

I'm not. my 2nd gear goes to a hair over 60mph. ;)

a 3.73 isn't bad and makes sense. but a 2.93? Those are smogger gears..

[trackjunkie21]

I'm not. my 2nd gear goes to a hair over 60mph. ;)

a 3.73 isn't bad and makes sense. but a 2.93? Those are smogger gears..

Don't forget that he has boost

[nando]

so? 2.93 is still retarded. how about a 3.25 or 3.55? What does 5th gear top out at with a 2.93, 200mph? What's the point of that? Why not convert to a 3 speed automatic while you're at it? :p

[Supadave]

dude no way. 4.10 is way quick. top speed sucks if thats what you mean. imo it depends how you drive.
I have a 2.93 in mine. the long gears are great for crusing

Are going to stick with the 2.93?

[tjts1]

I'm not. my 2nd gear goes to a hair over 60mph. ;)

With a 4.10 diff, not unless you're revving past 7300. And you speedometer is way off.

[nando]

Yes, yes, and no. It's dead on actually - verified with a direct VSS input to the ECU. ;)

but my tires are a little oversized. if they were stock size, the dash speedo would be about 4mph high. the ECU speedo wouldn't care though.