Seeking 5-speed conversion information

[Delia]

I've seen more than one way to do a five-speed conversion, and a recent thread has brought up guibo failure in these modifications. I'm looking for a relationship between the two more common types of mods and guibo failure using these two methods:

1. A U-shaped bracket that mounts to the existing four speed brackets in the tunnel.

2. Cutting off the brackets and relocating them farther to the rear of the car.

A question *might* be posed as who has had guibo failure with their five-speed conversion. Did they use method one or method two?

further, what were the problem(s), what was done to correct the problem(s), or is it ongoing an ongoing problem or problems?

My suspicion is that driveshaft misalignment causes premature guibo wear and subsequent failure.

I've had two five-speed conversions ('73tii and '74tii) and both of the guibos suffered premature wear compared to the ones mated to their original four speeds. I'd like to know how others have fared with their conversions.

TIA

D

[gwb72tii]

good question as i am doing this conversion right now.

i know aardvark sells a center support relocation kit to support the tranny in the original location. i believe it can be bolted into the tunnel.

[frank]

This is how I did the mount. It's a little different, but I've had no guibo or other problems in 8,000 miles.

[BLUNT]

ive got one of each but, 22k on the aardvark unit where you relocate the tabs in the tunnel and its been perfect. i made sure everything was straight though. then i have jakes bracket on my 69. it bolted up and everything was aligned perfectly right off the bat. i dont have any miles on the car yet but i dont foresee a problem as there is no stress to the guibo at all

[tyjoja]

I'm gathering parts for a swap at some point. I bought a bolt on bracket, the one you see for sale in the parts for sale section. It looks nice but I've heard that bolting these on the original 4 speed location works but can add a lot of stress to the mounting tabs which can eventually crack and break. Has anyone had any issues with these mounts? Thanks bob

[Guest Anonymous]

This is how I did the mount. It's a little different, but I've had no guibo or other problems in 8,000 miles.

Frank, your pictures remind me of a conversion I did almost two decades ago using two strips of .25" thick angle iron running longitudinally at the base of the tunnel. I stupidly had nothing to compare it to, except the recollections of seeing a wrecked rally car that may have been running a 262 trans and had skid plates. So, I used my imagination. The only thing that bothered me was drilling the bolt holes in a perfectly good floor. Otherwise, I figured the extra strength couldn't hurt anything other than adding a little extra weight. In 15 years, never had a bit of trouble and don't remember ever changing the rag disk.

Exactly long are your longitudinal supports? Are the rearward bolt heads behind the front seats or even further back? Care to share some of the details?

Thanks.

[conkitchen]

2. Cutting off the brackets and relocating them farther to the rear of the car.

D

So far this method has only produced one issue I became aware of.

The 5 speed was really tough to muscle into the tunnel due to the narrower dimension of the relocated brackets welded further back. They choked down the width such that the tranny had to be pressed up and in by the hydraulic jack. Super tight, but once the brackets flexed out of the way, it popped right in.

Another little issue is when cutting off the factory brackets for relocation, be careful not to puncture the floor pan with the chisel.

Cough, cough. ;-)

[Delia]

2. Cutting off the brackets and relocating them farther to the rear of the car.

D

So far this method has only produced one issue I became aware of.

The 5 speed was really tough to muscle into the tunnel due to the narrower dimension of the relocated brackets welded further back. They choked down the width such that the tranny had to be pressed up and in by the hydraulic jack. Super tight, but once the brackets flexed out of the way, it popped right in.

Another little issue is when cutting off the factory brackets for relocation, be careful not to puncture the floor pan with the chisel.

Cough, cough. ;-)

Yeah, well, get yourself some coughdrops...'cuz we're talkin' about a car that actually *runs* here, Dude!

D

[frank]

Frank, your pictures remind me of a conversion I did almost two decades ago using two strips of .25" thick angle iron running longitudinally at the base of the tunnel. I stupidly had nothing to compare it to, except the recollections of seeing a wrecked rally car that may have been running a 262 trans and had skid plates. So, I used my imagination. The only thing that bothered me was drilling the bolt holes in a perfectly good floor. Otherwise, I figured the extra strength couldn't hurt anything other than adding a little extra weight. In 15 years, never had a bit of trouble and don't remember ever changing the rag disk.

Exactly long are your longitudinal supports? Are the rearward bolt heads behind the front seats or even further back? Care to share some of the details?

Thanks.

The car is away in a shed for the winter so measurement will be a problem. I will try later today. No new holes were drilled. We just used original mounting points and drive shaft support, the bracket was designed to span the space between them.

[jgerock]

The car is away in a shed for the winter so measurement will be a problem. I will try later today. No new holes were drilled. We just used original mounting points and drive shaft support, the bracket was designed to span the space between them.

Frank -

Interesting arrangement - it should be plenty strong using those (4) points.

Just curious about your long brackets at the center support bearing mount. Did you install the bearing assembly before the bars were bolted in? My reasoning is that the CSB will make the driveshaft lower at that point (out of alignment).

[frank]

Interesting arrangement - it should be plenty strong using those (4) points.

Just curious about your long brackets at the center support bearing mount. Did you install the bearing assembly before the bars were bolted in? My reasoning is that the CSB will make the driveshaft lower at that point (out of alignment).

The picture does not show the final installation. The bearing was installed and then the support bolted on after. I don't have a photo of the final setup.

[tjones02]

While I do not have any personal experience with the U shaped bracket... yet. But it went through extensive testing before being put into production. I will be installing a few this year and will take some measurements then.

I have in the past moved the 4spd brackets back, but have found them to stick out to far causing trouble in shoving the trans past them. The factory conversion brackets are narrower for this purpose.

I have also had experience with Ireland's and Top-End's brackets and found that how they bolt through the floor makes it more difficult to install and remove them when clutch or trans repairs are necessary. One person operation is very difficult with these. And their alignment leaves some to be desired as well.

So, there are currently two ways to go about installing 5-speeds that I like.... The U bracket, and.... using a pair of factory style conversion brackets.... If you do not want to cut, drill, or weld on your precious '02 then I would look into the U bracket, BUT if you want the best alignment and fit then use the factory style ones.

I believe one of the key factors in driveline alignment with the 5spd conversions is using the factory method of locating the height/level of the brackets at 80mm up from the frame rails. I know bent rails etc. are a factor here as well, but I have had success with this method in the dozens 5 speed conversions that I've done. Once the 80mm is established everything can be installed and the driveshaft spun to see if there's any flex in the guibo. If there is some than washers can be used as shims to level everything out. I have also seen and like the factory driveshaft alignment bar be used to line everything up perfectly.

I also like very much to use the 3-bolt flanges so that the 6-bolt 320 "624" guibo can be used. A key to this is using an OEM factory guibo (Lemforder), many of the aftermarket ones (Febi) are a little too large in diameter and hit the shift rod.

The other key factor that I have found is properly measuring the driveshaft length for each car. I have done it both ways, and had success with both, but I believe the best way is to measure each car.

There are currently a few places to get the factory style conversion mounting ears.

Factory ones are available under part# 41 12 1 808 830 are currently available from BMW at a list$ of around $18 each.

Double 02 Salvage has copies of the originals made and sell them for a very reasonable price.

Lee's are stainless and might be difficult to weld in place, but look beautiful.

http://www.bmw2002faq.com/component/option,com_forum/Itemid,57/page,viewtopic/t,334354/

AND one of the best sources of info is the Bimmers.com/02 site http://www.bimmers.com/02/upgrades/transmission.html

Cheers and HTH.

[yeewiz]

and then there's the Metric Mechanic bracket. a "U" in the vertical plane. picture attached

[Delia]

I'm still hoping those of you who have five-speeds in your cars would share some things about how well your guibos have stood up to the conversion.

Tell us how many miles you've covered with your five speed -- and --depending on which method of conversion you chose, how many times you've experienced guibo problems like excessive wear, cracking or failure.

So, if you are using Aardvark's kit, how's it working out? Any guibo failures?

-or-

If you cut the mounting tabs and rewelded them farther back in the tunnel, have you had guibo problems? And, if so, what did you do to correct them?

I'd never seen the MM mount. Does it use the exisiting mounting points?

D

[BillWilliams]

Birthday girl.

I think this is the MM mount, it was eating guibos until I ground it apart and re-welded it to make it hold the transmission straight.

The mount cantilevers off of only ONE mount.

I have the tabs relocated on P2 and the orange car - no problems