5 Speed mounting tabs - Are mine wrong?

[///mChris]

All these 5 speed discussions have brought up my own. I had someone (who will remain nameless) weld in new tabs to fit my 5 speed 15 years ago.

I've always assumed that the 5 speed tabs for the 5 speed not only needed to be 3.6" further back, but also a bit lower.

Is this incorrect? I'm restoring the car and would like to correct any issues.

[jgerock]

Instructions in the BMW Blue book say to measure from the bottom of the frame rails up to the flat crossmember surface of the (2) mounting tabs. Distance should be 3.149" (80mm).

See section 23 00 005 (installation of five speed gearbox)

[jerry]

i have 2 5 spd conversions under my belt so far. i merely mount them in the same plane as the existing brackets, the requisite distance back. has worked for me so far. i typically clamp some flat steel bars to the existing tabs using c-clamps, verify that they are equi-distant from the top of the tunnel, more or less, and make my mark.

[jgerock]

i have 2 5 spd conversions under my belt so far. i merely mount them in the same plane as the existing brackets, the requisite distance back. has worked for me so far. i typically clamp some flat steel bars to the existing tabs using c-clamps, verify that they are equi-distant from the top of the tunnel, more or less, and make my mark.

Some cars may be different - mlytle's '75 2002 seemed to have the original tabs welded in at an odd angle. He used the 80mm measurement method and new brackets bolted to the car. The driveshaft alignment is much better than before.

[02Les]

All these 5 speed discussions have brought up my own. I had someone (who will remain nameless) weld in new tabs to fit my 5 speed 15 years ago.

I've always assumed that the 5 speed tabs for the 5 speed not only needed to be 3.6" further back, but also a bit lower.

Is this incorrect? I'm restoring the car and would like to correct any issues.

Correct me i'm wrong, but doesn't the gearbox slope slightly down hill toward the centre bearing? If so, and the 5-speed box is longer, then the mounts would need to be a tad lower. Maybe the 80mm measurement in the BMW Blue Book takes this into consideration.

[eurotrash]

All these 5 speed discussions have brought up my own. I had someone (who will remain nameless) weld in new tabs to fit my 5 speed 15 years ago.

I've always assumed that the 5 speed tabs for the 5 speed not only needed to be 3.6" further back, but also a bit lower.

Is this incorrect? I'm restoring the car and would like to correct any issues.

Correct me i'm wrong, but doesn't the gearbox slope slightly down hill toward the centre bearing? If so, and the 5-speed box is longer, then the mounts would need to be a tad lower. Maybe the 80mm measurement in the BMW Blue Book takes this into consideration.

I just went through this as well. My question, while measuring and drilling, was if the 5 speed they are referring to is the dogleg, and if its the same length as the OD trans? And then if it really matters..?

[tjones02]

All these 5 speed discussions have brought up my own. I had someone (who will remain nameless) weld in new tabs to fit my 5 speed 15 years ago.

I've always assumed that the 5 speed tabs for the 5 speed not only needed to be 3.6" further back, but also a bit lower.

Is this incorrect? I'm restoring the car and would like to correct any issues.

Correct me i'm wrong, but doesn't the gearbox slope slightly down hill toward the centre bearing? If so, and the 5-speed box is longer, then the mounts would need to be a tad lower. Maybe the 80mm measurement in the BMW Blue Book takes this into consideration.

Yes, the 80mm measurement is correct, has the brackets roughly on the same level compared to the 4spd one, just farther back. My bars that I've made to bolt to the original 4spd ears have a slight Z bend in them. I have found many orig 4spd ears in the wrong place and adjust my bars accordingly every time. Even then I sometimes need to shim the trans slightly up or down from 80mm measurement to have the guibo properly aligned. I always check that the guibo can spin without any twist or binding and adjust the trans hight up or down accordingly.

All 5spd conversions I've done land either right on or within a few mm of the 80mm measurement when aligning the guibo for straight spinning. Some had dented frame rails, others are bent cars, while the majority have been pretty much right on 80mm.

The "factory" 5spd brackets are a bit narrower than the 4spd ones because the tunnel is narrower where they mount. I have used 4spd ones in a pinch, but the trans has to be shoved past the then narrower gap.

Your tabs appear to be 4spd ones welded in the wrong place.

The original factory 5spd ears are available new. part# 41 12 1 808 830 and the current list price is $15.71 ea! There are even two in the Ontario CA warehouse!!! Go order them from your favorite local BMW Dealer and have them a few days later!

http://realoem.com/bmw/showparts.do?model=ST18&mospid=47127&btnr=23_0781&hg=23&fg=15&hl=129

Here's a link to c.d.iesel's 5spd 80mm picture scanned from the factory manual....

http://s226.photobucket.com/albums/dd318/cd02md/?action=view¤t=025SPEEDCONVERSIONpart1.jpg

I have recently been using the 2002Haus crossmembers and shim the trans up accordingly for Guibo straightness. A few properly sized washers between the top of the rubber trans mount and the trans works well. I like using Rob's bracket on cars that I do not want to modify from stock, where drilling or welding or otherwise modifying the original body in any way would be very harmful.

http://2002haus.com/archives/276

Cheers & HTH,

[///mChris]

I think the choice of bushing might also make difference here. I believe 320i bushings were thicker. Does anyone recall this?

[jgerock]

I think the choice of bushing might also make difference here. I believe 320i bushings were thicker. Does anyone recall this?

I think the 320i tranny mount and the stock 02 mount are the same thickness (NOT 100% sure). The stock 02 mount is more flexible.

[DanOKC]

Automatics have tabs at different height, if I remember correctly, if that car was an auto, that would explain it.

[tjones02]

I think the choice of bushing might also make difference here. I believe 320i bushings were thicker. Does anyone recall this?

I think the 320i tranny mount and the stock 02 mount are the same thickness (NOT 100% sure). The stock 02 mount is more flexible.

Yes, you are correct sir, same height. The 320 trans mount is a standard upgrade.

[///mChris]

My 1600 is not an automatic. I'm guessing this alignment is the reason why I go through so many guibos!

I'll cut off the other ones and redo it. To clarify.. Distance further set back from the old mounts is 3.6" toward the rear of the car. Correct?

[jgerock]

My 1600 is not an automatic. I'm guessing this alignment is the reason why I go through so many guibos!

I'll cut off the other ones and redo it. To clarify.. Distance further set back from the old mounts is 3.6" toward the rear of the car. Correct?

If I were doing this, I'd mount the tranny to the engine with the bracket and mount at the back (leave off the clutch to make this easier during the fitment stages), lift up the tranny using a jack, then mark the (2) bottom holes for the crossmember mounts (then comparing the 80mm dimension to the bottom of the framerails). The 3.6" difference (or so) between the 4 speed and 5 speed O.D. trans length is just a number. Your results may vary (just like the driveshaft length when doing this swap).

Wish a bunch of us were there to help you (really - this stuff is fun to me).

Inside the garage on 12/19/2009

Outside the house the same day

[M3M3]

check page 5/6 of my m2 thread for info/pics on the bracket install.

http://www.bmw2002faq.com/component/option,com_forum/Itemid,50/page,viewtopic/t,345762/postdays,0/postorder,asc/topic_view,/start,0/

i actually mounted the tabs 88mm above the rails instead of the factory 80mm...and still had to raise back of tranny with a few washers.

[Lorin]

You want the transmission to be in a position that the output flange is square to the flex disc with the rest of the driveshaft straight. Any measurement is trying to achieve this or as close to this as possible.