completed auto to 5sp conversion on 81 633csi, I have only driven it around circle driveway so do not know how its gonna feel on the road but a question; It has oem diff, believe its 3:45 and only one rear wheel spins/drives (r/r) and that makes it useless to drive if any snow on ground/driveway. Could not even move in/out of garage if any amount of snow on driveway, car would just sit there and spin r/r trying to move forward inch by inch,,,not that I drive it in Winter but,,,anyway I have a LSD 3:90 was planning to install, had done that on couple other older BMW's (Bavaria, 5'ers) and really liked it in those models, yep loose a bit of top speed, but really liked accell, etc and with 5sp which is OD anyway thought this might work well.
thoughts,,,
auto/5sp swap final drive ratio recomendation
Moderators: GRNSHRK, ron, bfons
auto/5sp swap final drive ratio recomendation
1961 Borgward Coupe
1981 633csi 43K miles
1998 M-Roadster
1968 1600-02
1981 633csi 43K miles
1998 M-Roadster
1968 1600-02
Re: auto/5sp swap final drive ratio recomendation
Up to you really. I changed my 3.07 to 3.45 and wouldn't go with a lower diff ratio than that for my tastes
Have a play with this gearing calculator. http://www.unixnerd.co.uk/revs.html
Have a play with this gearing calculator. http://www.unixnerd.co.uk/revs.html
'85 635csi JPS (RA2-66)
Re: auto/5sp swap final drive ratio recomendation
Depends on your driving requirements and vehicle specs. As I have 265/5 dog leg and S38B36 , and love highway/country driving, I chose to stay with the OEM 3.07. Loooooong legs
1986 635csi LOCUTUS / Arktis Blau Metallic / Pearl Beige / S38B36/ Close ratio dogleg 5sp
2002 E46 M3 / Topaz Blau Metallic / Black Nappa / 6 speed SMG software tuned / Bilstein PSS10 Coilovers / CMP RACP reinforcement
2002 E46 M3 / Topaz Blau Metallic / Black Nappa / 6 speed SMG software tuned / Bilstein PSS10 Coilovers / CMP RACP reinforcement
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Re: auto/5sp swap final drive ratio recomendation
I did a 5 speed swap with a 260 and kept the 3.45 from the auto.
For me it works great plenty of snap off the line and cruising @ 75 around
3000 ish RPM
For me it works great plenty of snap off the line and cruising @ 75 around
3000 ish RPM
86-635CSi
96-MB C220 SOLD
98-740i
71-Continental MK3
96-MB C220 SOLD
98-740i
71-Continental MK3
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Re: auto/5sp swap final drive ratio recomendation
I have a 5 speed OD gearbox in my '80 with the standard 3.45 rear axle ratio, but would love to go one step up to 3.64, if I could find one
Presumed that you have a sideloader diff
What model BMW had a 3.90 sideloader
For the record, at 3000 RPM in 5th gear, I'm registering 78 MPH
Presumed that you have a sideloader diff
What model BMW had a 3.90 sideloader
For the record, at 3000 RPM in 5th gear, I'm registering 78 MPH
Bobbo
1980 633 CSi Cypress Green/Pearl Beige
2017 X5 M Sport Xdrive 35i Carbon Black/Ivory White
2005 330 Ci ZHP Cabrio Imola Red/Bone/Black
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Re: auto/5sp swap final drive ratio recomendation
I have been rebuilding and selling diffs for a while and have found what I believe to be the definitive answer. 3:07 for a dogleg and 3:45 for an over drive box and of corse an LSD. For you guys with the later cars finding a lsd diff is not a problem as they are all over the place cheap. The killer is finding an early side loader diff for the pre 82 cars
81 Euro 635 M90 with motronic. Currently under a complete nut and bolt restoration. Pictures at
flickr.com/photos/bertsphotos.
flickr.com/photos/bertsphotos.
- 86_6series
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Re: auto/5sp swap final drive ratio recomendation
I stand corrected, GRNSHRK is absolutely spot on with MPH @ RPM
Don't remember what the hell I was looking at.
Don't remember what the hell I was looking at.
86-635CSi
96-MB C220 SOLD
98-740i
71-Continental MK3
96-MB C220 SOLD
98-740i
71-Continental MK3
Re: auto/5sp swap final drive ratio recomendation
I have a 3.91 diff in my car; I installed it when my car was still an automatic and left it in after my manual swap. First gear is very steep; you'll be shifting to 2nd before you're through an intersection. And at 80 mph the engine's turning about 3400 rpm so it's not something you'd want if you do a lot of long-distance driving. But other than that's it's all good; the car pulls much stronger in every gear and feels much more lively. Since I don't take the car on long trips, the highway revs don't bother me. If that's the kind of driving you plan to do, I recommend going with the 3.90.
1985 635CSi
1987 535is
1965 Impala SS
1987 535is
1965 Impala SS