engine and drivetrain 5 speed overdrive install ? 4 bolt to 3 bolt

[skelatons]

Will be starting install of 5 speed OD today,but have 1 ?.What's involved in changing from 4 bolt output/input flange, to 3 bolt?I have a 3 bolt flange from a m20 engine,will that work?The manual I have does not say anything about this,can anyony help.Thanks.

[colorobo2002]

for those flanges.

[skelatons]

You are correct,they are not the same part #.I think that is because one is three bolt and the other is 4. :~))

[Mike Self]

tranny is the same flange as the one used on an E-30...if so, you're in business; if not you'll need to find an E-21 flange--shouldn't be too hard to do...

mike

[skelatons]

4 bolt flange from the 02 4 speed is too large (inside diameter) for the E21 5 speed.4 bolt flange from M10 E 21 5 speed,and 3 bolt flange from M20 5 speed are inter-changeable.Nut holding flange is 30mm.Need a thin walled deep 30mm socket or this other tool for which I don't know the name for.I'll try and post a pic of it later.

[TobyB]

I found it to be easier to just have the nose of the E21 driveshaft (3 bolt)

welded onto the driveshaft. It has to be cut anyway...

t

[winstontj]

Will be starting install of 5 speed OD today,but have 1 ?.What's involved in changing from 4 bolt output/input flange, to 3 bolt?I have a 3 bolt flange from a m20 engine,will that work?The manual I have does not say anything about this,can anyony help.Thanks.

You're in Germany - so what 5-speed are you using? I believe all 5-speed OD units from E21's had 3-bolt output flanges. (could - and probably am wrong though) You'll need to have your driveshaft shortened also and the flange switched there too.

Take the driveshaft out of whatever car you took the 5-speed from. If you took from an E21 it should have 3-bolt driveshaft and tranny (6-bolt giubo). Measure about 1,000 times to make sure and send the forward e21 section (or at least the first 25cm or so) in to the driveshaft shop with the 2002 driveshaft. They will cut and re-weld to the proper length and use the 3-bolt flange. Remember that the giubos are different thickenesses so it's important to measure many times....

I believe it's a 29 or 30mm thin wall deep socket that you need to remove the output shaft nut. then change the seals and you're all set. Only the E21 flange will work on the E21 boxes. I don't know anything about the CR 5-speed boxes...

Best of luck!

It is crucial to get your driveshaft lined up perfectly. I used a section of 48" (a little longer than a meter) pipe and hung it from the driveshaft about 5cm below with zip ties. Then I used a caliper and a coin to make sure that the distance betweeen the pipe and the driveshaft was the same throuought the length of the shaft.

Also leave the bolts out of the giubo and line everything up. the driveshaft will mate up to giubo without falling out. Next put everything in neutral and spin the driveshaft. Look to see that the three flanges are staying pressed up against the giubo. if any of the flanges seperate out from the giubo you are not level or lined up properly. get the flange lined up with the giubo perfectly so there is no deflection at all when it rotates, then space out and level the center bearing. I had to loosten my rear diff and slide it forward a few mm to get everything lined up to my liking - now there is no vibration, the giubo is not cracking and the car drives MUCH smoother than before I installed the 5-speed.

Again, best of luck

[skelatons]

I believe all 5-speed OD units from E21's had 3-bolt output flanges. (could - and probably am wrong though)

Yep,you got the first one correct,you are wrong.The 5 speed that I am installing,came with a 4 bolt flange.I swapped it over to a 3 bolt today.

You'll need to have your driveshaft shortened also and the flange switched there too.

You're pretty good at this,wrong again.:~)Varco kit,so driveshaft is shortened with 3 bolt flange.

Measure about 1,000 times to make sure and send the forward e21 section (or at least the first 25cm or so) in to the driveshaft shop with the 2002 driveshaft.

I know you have no way of knowing this,it's not my first 5 speed conversion.5 speed sport is currently in the car,just changing it for the OD 5 speed.

I believe it's a 29 or 30mm thin wall deep socket that you need to remove the output shaft nut. then change the seals and you're all set. Only the E21 flange will work on the E21 boxes.

winstontj-You got part of this one correct!Pic below will show what I used to remove the nut.Transmission is new (not used) along with a new diff (same as above)that I got from the parents of a tuner that is no longer with us.And I know the story probably better than most,having talked with his mom.Will say nothing more about that for others that can maybe guess who I'm talking about.So,tranny is new ,and no need to change the seals.

Only the E21 flange will work on the E21 boxes.

I'm with you on that one.Today,having removed the flanges from 3 different gearboxes,I would say that is good info.Old 4 speed box for practice,M20 5 speed for the three bolt flange,and the 4 bolt flange from the new 5 speed.M20 and M10 5 speed flanges can be swapped,as I stated in the above post.

Not trying to bash you or anything,'cause I know you are learning just like me.I've picked up a few things reading your posts on various subjects.Thanks for the well wishes TJW.