6 speed conversion

[E30_Crazy]

Any proven/popular 6 speeds I could slap in my pre-facelift 87 325i tech1? or would it be pointless since I've already got the close ratio? I just feel that it has more to go when gets to the end of the 5th gear... I have a feeling that there is much more to it, anyways. Like driveshaft mod (shortening?) rear end mod, etc. Anyone with info, tried searching wiki but no avail.

TIA

[StuBeeDoo]

driveshaft mod (shortening?) rear end mod, etc.

Intriguing. What's it all about? I'm curious.

[E30_Crazy]

driveshaft mod (shortening?) rear end mod, etc.

Intriguing. What's it all about? I'm curious.

Oh, just thought I remembered something somewhere about having to get driveshaft shortened to fit between the 6 speed box and rear end. Trying to get all the details/possibilities I can.

[E30BeemerLad]

Load of buggering about. Change the diff for a lower ratio if you want lower rpm at motorway speeds

[E30_Crazy]

It's not necessarily needing lower rpms at motorway speed.... so much as hitting an extra gear to overtake my mates Mazda6. I could just barely keep even with him at about 5k in 5th with my 4.10 welded. haven't tried lately, but I'm sure I'd creep by him with the LSD (3.73 came in tech1 sport? or 3.93?). I wanted to be able to creep up on him, then drop into 6 and "See ya", lol. But if you say it's a lot o' work, I'll leave it alone I guess, unless someone can throw out some new, more simple way??

[E30BeemerLad]

If you're running a 4.10 on a 325 then no wonder you are running out of revs.

1st gear must be a joke.

I think the sport box only has 1st & 2nd as close ratios, the rest are same as any 325 Getrag 260 box.

[drewjak]

from what i can see from the link below 325 260 boxes have same ratios,
i have a 4.10 in my 325 never had any problems with it to be honest but its true what you say about top end it feels like another gear would go nicely, but then i guess your diff would`nt like it very much and go bang maybe.

http://e30world.com/specifications/BMW-E30-specs-table

and for the record 1st gear is ok i think as long as youve got a quick shift and bruce lee like reactions its not to bad

[E30_Crazy]

If you're running a 4.10 on a 325 then no wonder you are running out of revs.

1st gear must be a joke.

Yeah man, 1st gear was redline at arond 15-18 mph! Don't need to worry about it anymore though, I busted that welded 4.10 at santa pod a couple weeks ago.... First time at the Pod, first time on a track to get a run time, and first run of the day for me... Dropped the pedal on 1st gear, and got a good jump on the big 5 series next to me, threw it into 2nd, and...... nothing..... Bouncing off the redline until I realized that I wasn't slipping; I was slowing down..... And then came the humiliating tow off of the track. So, anyways, likeI posted earlier, I have the LSD that came with tech1 sports back in it now. Much more economical

[Brianmoooore]

, I have the LSD that came with tech1 sports back in it now. Much more economical

And actually insurable.

[E30_Crazy]

Really? How? You mean that it won't detract from the legitimacy of my cars' insurance, or that I can actually insure my diff separately???

[Brianmoooore]

I find it VERY unlikely that any insurer would knowingly insure a car for road use that has been fitted with a welded diff.

[N00b]

I find it VERY unlikely that any insurer would knowingly insure a car for road use that has been fitted with a welded diff.

I agree. Welding up a diff is only done to effectively ruin a cars ability to corner properly by making the car step it's rear out more often and with less provocation.

[e301988325i]

Any proven/popular 6 speeds I could slap in my pre-facelift 87 325i tech1? or would it be pointless since I've already got the close ratio? I just feel that it has more to go when gets to the end of the 5th gear... I have a feeling that there is much more to it, anyways. Like driveshaft mod (shortening?) rear end mod, etc. Anyone with info, tried searching wiki but no avail.

TIA

On topic, you should find an E36 M3 Evo box bolts to an M20 somehow or other, likewise an E46 320d 6 six box.

However, they cover only the same gear ratio range as the wide ratio E30 box,

ie 1st = 1st (non C/R E30 box)
and 6th = 5th

so no extra gear so to speak. I have links if required.

[E30_Crazy]

On topic, you should find an E36 M3 Evo box bolts to an M20 somehow or other, likewise an E46 320d 6 six box.

However, they cover only the same gear ratio range as the wide ratio E30 box,

ie 1st = 1st (non C/R E30 box)
and 6th = 5th

so no extra gear so to speak. I have links if required.

But even so, being six gears, would you get a quicker acceleration being "worth the trouble?"

[Eddie25]

+1 on just swapping the diff.

The 325 has plenty enough torque to make use of the longer ratio and not effect acceleration.

I have a 3.91 LSD on mine and thats a bit too low for me at motorway speeds its churning over more RPM's than I would really like it to be. I would say the 3.73 is the best all rounder for the 325.

[e301988325i]

Gear....5 speed.....6 speed E30 C/R E30 Stock
1.........4.23:1.......4.35:1.......3.35...........3.83
2.........2:51:1.......2.50:1.......2.03...........2.20
3.........1.67:1.......1.66:1.......1.36...........1.40
4.........1.23:1.......1.23:1.......1.00...........1.00
5.........1.00:1.......1.00:1.......0.81...........0.81
6...........N/A.........0.85:1

But there is a closer option, using 5 series U.S. spec boxes, search for 'm20 close ratio gearbox options'

see page 10 for ratios

http://www.unofficialbmw.com/images/05% ... veline.pdf

and here page 8 M3 six speed ratios

http://www.kinmak.com/downloads/doc/m3t ... mplete.pdf