Guibo replacement

Sven

Sven

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So I got the winter bug to fix a few things on my coupe - replacing the guibo (rubber donut, flex disk).

The one on there was the typical stock type guibo. It was bought 3 years ago and has about 12,000 miles on it. From the photo you can see it has not held up well.

Per SFdon's recommendations I replaced it with a more modern type. Because it is about 10mm thinner I also needed to use the next size up transmission flange. There is an even longer one, but that will not work because the transmission shaft pin is not long enough to engage the driveshaft properly. The photo compares the old and new setups having the same net thickness. You will need to get 10 mm shorter bolts (60 mm) though. The old guibo uses 70 mm bolts.

Guibo part number: 26.11.2.226.527
Longer flange: 23.21.1.228.038 ?? (from the 260/6 I think) Don can you please confirm?

Thanks,
 

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I can't remember, doesn't the drive shaft adjust on the splines enough to make up the difference?
 
Sven said:
I replaced it with a more modern type. Because it is about 10mm thinner I also needed to ....
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Why not just put a 5mm stack of washers on each side of the new giubo? Seems simpler than changing the flange and worrying about the transmission shaft pin engaging the driveshaft.

I can't believe how quickly your old giubo deteriorated. While you had it for only 3 years, perhaps it had sat on a distributor's shelf for many years before that.
 
Why not just put a 5mm stack of washers on each side of the new giubo?
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Yes, you could do that. I initially was going this route.

can't remember, doesn't the drive shaft adjust on the splines enough to make up the difference?
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In theory, yes, but you are limited by the mounting slots for the center support bearing. The splines are behind the bearing. Also, the depth of the hole in the front of the driveshaft would likely not accommodate another 10 mm of the transmission shaft pin.
 
It looks as if the deteriorated guibo is a different style than the original? How about putting the correct (original?) style guibo in. I've done a few Bavaria's, a few 02's and now 3 e9's and on the really old original guibos I have seen some cracks but never saw one as bad as your picture. If, of course, you have a more powerful engine, say around 240-250 HP, then you may be stuck going Don's route.-not sure if that was of any use-
 
Sven...was the failed guibo made by goetze?

I was recently told that you should only use a guibo from BMW ($150) which are made by Goetze (stamped on the rubber) and that all others do not last. Am about to replace mine, also.
 
This is good to know because I plan on renewing mine plus the center bearing just in case prior to cross country trip next year.
 
Peter - the Bavaria's and coupes I have worked on all have had this style of guibo (like the cracked one). Automatic's might be different?

BP1 - I could not find any markings on the guibo.
 
Looking again at the photo of the new, stronger Giubo, I had a thought:

The thing is asymmetric - it has three thin sections alternating with three thick sections. So it would have more torsional stiffness when twisted in one direction than the other. E.g., when going forward, are the thin sections in compression while the thick are in tension? Or visa-versa? Are there assembly instructions that specify how you phase the giubo relative to the two yokes?

Why else would they have designed it that way?

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Careful Sven - looks like your Guibo is upside down. It will unravel that way.
 
Don - I have it installed one hole rotated from the position in the photo. The "arrows" pointing towards the respective flanges on both the transmission and driveshaft.
 
Yes, so the drive force from the engine is transmitted to the shaft via the thicker portion of the guibo (except for reverse and engine braking).
 
Sven said:
Yes, so the drive force from the engine is transmitted to the shaft via the thicker portion of the guibo
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Sorry, but that wasn't clear. Did you mean: When going forward, the drive force from the engine is transmitted to the shaft

- with the three thicker sections of the giubo in tension, while the thinner sections are in compression (my guess)

- with the three thicker sections of the giubo in tension, while the thinner sections are in compression

I'm guessing that the elastic properties of rubber aren't symmetric between tension and compression. That rubber offers less resistance (measured in force/area) in tension than in compression. So the giubo engineers designed the part with alternating thick/thin cross-sectional areas to achieve the same displacement for a given amount of torque.
 
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Yes, you answered your own question much better than I. I am not sure about the variation in compression and tension of the materials being the reason for the different thicknesses so that they contribute equally to the forward drive force. I was assuming they needed a certain thickness for the material to handle the tension of driving the car forward and then a certain thickness to supply reverse and engine braking forces.
 
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Another twist to the gumbo question was the choice between the newer 30mm unit and the older 45mm unit as related driveline shudder as discussed here http://www.e9coupe.com/forum/showthread.php?t=17913. The newer unit you are looking at to replace the one with the nasty split requires drilling out the end of the drive shaft or shortening the output shaft of the transmission (hope I got that right) if using the Getrag 5spd.

I have had the newer guibo - installed correctly- develop splits in under 20,000 miles though nothing like the one Sven has posted. Thought it might have to do with my driving habits.

No simple choices it seems.
 
There are 3 possible guibos....
Early grenade, late and M version.
Later guibos don't grenade- they are filled with cord.
Don't put the later ones on backwards- they unwind!
M guibos are 35mm and they never fall apart :)
 
sfdon said:
There are 3 possible guibos....

Early grenade, late and M version.

Later guibos don't grenade- they are filled with cord.

Don't put the later ones on backwards- they unwind!

M guibos are 35mm and they never fall apart :)
Click to expand...


So how do you tell which is the right way to put these on so they don't unwind??
 
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