engine and drivetrain 5 Spd Trans and Driveshaft Question

[GirtAllerton]

I've run into a problem with a 5 spd trans conversion. Getting ready to shorten the drive shaft but it appears that the 4 bolt end of my orginal 4 speed driveshaft will not mate up to the 4 bolt flange on the 5 spd trans that I purchased. The center hub of the 4 spd shaft with not fit into the 5 spd flange. From the the forums it looks as I cannot use the flange from the original 4 spd trans as it will not fit the 5 spd spline. I have not pulled the original flange off to try.

No one had mentioned this problem with the swap. DO I need to find a front end of a 5 speed drive shaft to make this work?

Help with the info and possibly the part is greatly needed.

Searched but couldn't find a definite answer.

Thanks guys.

[TobyB]

No, the 4- bolt flange for the 2002 continued into the 320 5- speed unchanged, so it should work.

 

Basic question, I know, but you do not mention a guibo.  Do you have one in there?  Gizzer #10, below.

 

If so, is it that the pilot shaft's not going into the socket on the driveshaft?  You can take that apart-

maybe there's something in there that's preventing it from going in all the way...

 

hth

 

t

Edited August 22, 2015 by TobyB

[jgerock]

What year did your 4 speed tranny originate? Could be fine versus coarse splines on the output shaft.

Clarification : the flex disc would be the same but if you are swapping the output shaft flange, there are differences

Edited August 24, 2015 by jgerock

[Mike Self]

IIRC both fine and coarse spline output flanges use the same guibo, so the bolt pattern must be the same.  The coarse spline shaft and flange failed on my '73 many years ago and were replaced with fine spline parts; the guibo was good so it was re-used.  

 

I thought at least some of the E21 5 speeds used a three bolt flange--and it doesn't mate up with the 3 bolt driveshaft used on automatics.  

 

Hope that helps.

 

mike

[M3M3]

there should be no issues with 4 to 4 bolt flanges.  need pics of your problem.

[TobyB]

 

I thought at least some of the E21 5 speeds used a three bolt flange--and it doesn't mate up with the 3 bolt driveshaft used on automatics.

Yeah, they did, and there are at least 4 different 3- bolt flanges in use by 1983.  And more thereafter.  BUT the 4's all stayed the same, as far as anyone knows.

 

t

[jgerock]

Tough to diagnose without seeing what you are dealing with. Maybe your guibo needs a hose clamp to get the 8 holes lined up to accept the thru bolts.

Also, some output shaft flanges have been mangled by exploding flex discs (guibos).

[TurkisM2002]

Hey everyone, got a question related to this topic. I'm also doing the 5spd/m20 swap. I've got a 3.91 LSD out of an e21as well.

 

Question I have is on measuring for the driveshaft. I've take a measurement from the diff to the trans. Do I need to subtract the thickness of the guibo before shortening the shaft?  

 

I've got the original driveshaft out of my '73 and one from an E30 325. I think they're both 4 bolt....

 

 

Thanks

[TobyB]

Well, yes, if you plan on running a guibo!  Measure flange- to- flange with the diff in the center of the 'adjustment' slots, then subtract the thickness of your target guibo.

 

You know, as I was typing that about 3- bolters, I was trying to remember what was on the E30.  And failing.  There's a 'big' one

on a lot of earlier cars and a 'small' one that came after (with that harmonic dampner thingy, I think)

but is it 4 bolts?  I just don't have a visual memory, and the E30 is up on the trailer.

 

t

[TurkisM2002]

Well, yes, if you plan on running a guibo!  Measure flange- to- flange with the diff in the center of the 'adjustment' slots, then subtract the thickness of your target guibo.

 

You know, as I was typing that about 3- bolters, I was trying to remember what was on the E30.  And failing.  There's a 'big' one

on a lot of earlier cars and a 'small' one that came after (with that harmonic dampner thingy, I think)

but is it 4 bolts?  I just don't have a visual memory, and the E30 is up on the trailer.

 

t

 

 

Ha ha. yes of course. I was curious to know if there were any other variables to consider in the measurement besides the guibo.  I need to take a look at the drive shafts I have to see what the ends are....

 

4 bolts at the diff end and possibly 3 at the trans end? I need to go into the basement.

Edited August 24, 2015 by chrisracer79

[TobyB]

Yeah, I think that's right.  And no, there aren't any other variables.  But it's not trivial to measure the driveshaft length exactly right- I've messed it up at least once.

 

t

[jgerock]

When measuring, note the location of your differential on the subframe and make sure the mounts for the subframe are up to snuff.  Measure thrice, (have it) cut once.   

[GirtAllerton]

Guys, Thanks for the help. I finially got to my mechanics to see what was going on. Simple mistake no guibo when they were first looking at it. We got it straight today and the drive shaft measured to send out. Best to admit our errors no matter how simple. It happens on a year plus project. Thanks for the input, I thought that I was facing another it doesn't fit problem.

[TobyB]

I'm glad it was that easy.  If you're not used to the BMW way, that rubber donut thingy doesn't make a damned bit of sense, as almost no- one else used them at all, unless they were British AND nutters...

 

t