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Posted by rkj 
rkj
August 23, 2011 08:20PM
So, my 87 325 auto blew another guibo, a few weeks after it was replaced. The thing I don't know is if the auto box guibo have direction arrows like the stick cars have. I have a feeling my guy might have missed this.

Anybody?
August 23, 2011 08:53PM
Quote
rkj
So, my 87 325 auto blew another guibo, a few weeks after it was replaced. The thing I don't know is if the auto box guibo have direction arrows like the stick cars have. I have a feeling my guy might have missed this.

Anybody?

I have no direct experience to go on but if the manuals is directional then so too should the auto be.

Chances are that it was put in backwards...unless Janet has been taking it up to redline then throwing it into drive sad smiley
rkj
August 23, 2011 09:34PM
Quote
Archeo-peteriX
Quote
rkj
So, my 87 325 auto blew another guibo, a few weeks after it was replaced. The thing I don't know is if the auto box guibo have direction arrows like the stick cars have. I have a feeling my guy might have missed this.

Anybody?

I have no direct experience to go on but if the manuals is directional then so too should the auto be.

Chances are that it was put in backwards...unless Janet has been taking it up to redline then throwing it into drive sad smiley

That's what I thought too, I couldn't see one and not the other.... but that arrow is, I forget now, direction of the bolts or something? but even if it was installed backwards I wonder what effect that would have on it getting tore up in a few miles.

Janet?, around here, we call her the wrecker!
August 23, 2011 11:38PM
I have no experience here but general physics, but I can't imagine a guibo installed backwards would fail in a matter of weeks. There is no reason it should do that. My thinking would be that it's experiencing increased stress. I'm sure someone would have noticed a bad transmission mount or center driveline support bearing? that would be my guess for quick guibo failure.

-----------------------------------------------------------------------------------
1989 - E30 - M20 - Manual. Approximately 270,000 miles
2000 - E46 - M52TUB28 - Manual. Approximately 110,000 miles

rkj
August 24, 2011 07:20AM
Quote
Earendil
I have no experience here but general physics, but I can't imagine a guibo installed backwards would fail in a matter of weeks. There is no reason it should do that. My thinking would be that it's experiencing increased stress. I'm sure someone would have noticed a bad transmission mount or center driveline support bearing? that would be my guess for quick guibo failure.

Hey Tyler

The trans mounts were checked on the first try, when the shaft was down. My friend (Jack) saw the mounts were sagging a touch but choose to not replace them (I've got to cure him of that!) and there is that arrow on the guibo (that's gotta mean something, however, I don't know exactly) so maybe he missed that one.... One thing I was very upset with was, the center bearing I sent him with the car was returned to me unopened. I'm sure he felt the one in there was serviceable but at 175k I wanted a new one!

I've gotta give him a call now and run a few things by him :eyes:

Thanks guys, Rick
rkj
August 24, 2011 01:21PM
Well, I had an interesting talk with my guys at Bav this morning; Bob, at customer service went right down and got a guibo for me and checked it out (for an auto box). The first thing he said was, if I didn't tell him about the arrows he wouldn't have seen them and he would've put it in either way, but on closer inspection he did see them and also that it was built up on the torqure sides of it so putting it backwards will rip it to shreds in no time.... Mystery solved.

I talked to Jack this morning about the center bearing and if he saw any arrows on the guibo before he put it up there; he said he didn't (without any hesitation) see any but would check it when pulling it down, and he had no problem putting in the center bearing even though the old one was tight. At 175k it's seen it's duty cycle-

I was glad to hear Jack was being honest and also about the info at Bav so hopefully this time all will go well :eyes:

To recap, this time; transmission mounts, guibo and check the center bearing that we just put in, new guibo and center bearing.

Sometimes, doing it yourself is easier! I wish I wasn't sooo old eye rolling smiley
August 24, 2011 01:46PM
I forgot to mention the other thing I might suspect: A guibo with a manufacturing defect.

It makes perfect sense that a guibo would be directional so that the side that experiences more torque can be reinforced. But that's the thing, it only experiences more torque with increased frequency, it's not as if the reverse direction doesn't experience any torque. Any time the car goes into reverse, or you "engine brake" (though not as common on an auto), or slam on the brakes, it's going to put torque on the guibo in the reverse direction.

It being an auto I would expect less "sudden" torque than a stick car. Heck, I throw my car into reverse on a steep hill all the time to back into my driveway. It's steep enough that the car manages to roll an entire inch before my amazing clutch skills (:dance:) kick in and the car lurches backwards up hill. My guibo has certainly withstood this without failing in the last few months. I can't imagine an auto putting more stress than that on a guibo in the forward direction.

Now, if there was a manufacturing defect AND the guibo were installed backwards, I might expect that to exaggerate the defect. Naturally, any additional stress added due to a failing center bearing would only hasten its demise.

Hopefully it all gets sorted out. I'm guessing a new bearing installed the correct direction and you'll be good for another 100K easy smiling smiley

-----------------------------------------------------------------------------------
1989 - E30 - M20 - Manual. Approximately 270,000 miles
2000 - E46 - M52TUB28 - Manual. Approximately 110,000 miles

rkj
August 24, 2011 08:38PM
Quote
Earendil
I forgot to mention the other thing I might suspect: A guibo with a manufacturing defect.

It makes perfect sense that a guibo would be directional so that the side that experiences more torque can be reinforced. But that's the thing, it only experiences more torque with increased frequency, it's not as if the reverse direction doesn't experience any torque. Any time the car goes into reverse, or you "engine brake" (though not as common on an auto), or slam on the brakes, it's going to put torque on the guibo in the reverse direction.

It being an auto I would expect less "sudden" torque than a stick car. Heck, I throw my car into reverse on a steep hill all the time to back into my driveway. It's steep enough that the car manages to roll an entire inch before my amazing clutch skills (:dance:) kick in and the car lurches backwards up hill. My guibo has certainly withstood this without failing in the last few months. I can't imagine an auto putting more stress than that on a guibo in the forward direction.

Now, if there was a manufacturing defect AND the guibo were installed backwards, I might expect that to exaggerate the defect. Naturally, any additional stress added due to a failing center bearing would only hasten its demise.

Hopefully it all gets sorted out. I'm guessing a new bearing installed the correct direction and you'll be good for another 100K easy smiling smiley

The stick cars have a different guibo, and I'm guessing the auto cars are much less beefy in the reverse torque application. But, the auto cars still have the arrows (and built-up areas) so if it's installed backwards it will rip out easily. Bottom line is, if it were installed correctly the first time it would've stayed fine, even with the old center bearing and tranny mounts. Should be interesting when it comes time to pay the bill....


I'll report back :wavey:
August 26, 2011 02:05PM
Pelican Parts has a tech article on replacing the guibo/flex disk. see http://www.pelicanparts.com/bmw/techarticles/E36-Guibo/E36-Guibo.htm

Figure 14 and 15 in that article show the arrow moulded into the side of the guibo. They say, "The rule of thumb is that the arrow shows which way the mounting bolts are pushed through the flex disc."

The red arrow in this photo points at the moulded arrow.

August 26, 2011 09:59PM
I still think Janet has been popping wheelies winking smiley

Looks like the arrows don't have anything to do with rotational direction but rather fore/aft mounting because the guibo probably has a lip; as seen on the rear; and none on the front(to fit nicely with the balancer that seems to be missing in this pic).
rkj
August 26, 2011 11:11PM
Quote
Archeo-peteriX
I still think Janet has been popping wheelies winking smiley

Looks like the arrows don't have anything to do with rotational direction but rather fore/aft mounting because the guibo probably has a lip; as seen on the rear; and none on the front(to fit nicely with the balancer that seems to be missing in this pic).

I went down tonight and picked the car up, Jack had the old guibo (2 weeks old) and it was ripped up badly but still intact. One of the things I noticed was built up areas of rubber in between the mounting holes that I think mean something as far as torque direction is concerned. I'll get it and take pictures on Monday or Tuesday. This car never had the guibo's surrounding drum, and I've seen other Thirty's without them too.

The car runs and drives tight with it's new parts; guibo, nose bearing, tranny mounts and the center bearing. Hopefully it will stay that way...
August 27, 2011 02:57PM
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"The rule of thumb is that the arrow shows which way the mounting bolts are pushed through the flex disc."

The red arrow in this photo points at the moulded arrow.
Each bolt runs through its own metal sleeve moulded into the rubber guibo. Obviously without a metal sleeve the rubber would just be crushed as the bolt is tightened.

I'm thinking it makes a difference which way the bolts are inserted because, when tightening, you should hang onto the bolt so it doesn't turn, while turning only the nut to tighten the connection. That way only the nut rubs against the metal of either the driveshaft flange, or the transmission output flange, while the bolt head is held immobile without turning against the metal sleeve in the guibo.

Otherwise if you do it the other way around, holding the nut while turning the bolt, as the connection is tightened you would end up twisting the metal sleeve inside the rubber guibo, possibly weakening or even tearing the bond between the metal sleeve and the rubber.

Another reason for inserting the bolts in the direction shown, is that over time the bolts will inevitably seize solid into those metal sleeves and you won't be able to pull them out again when the time comes to change the guibo. If the bolts go first through the metal yoke of the driveshaft or transmission output shaft, and then seized solid through the metal sleeves of the guibo, you'll never be able to remove the guibo. But if the bolts run through the guibo, and then into the metal yoke, as long as you can still undo the nuts it doesn't matter if the bolts stay rusted into the guibo as you can dispose of that as a single unit and replace it with new bolts and a new guibo.

Wadda ya tink of that theory?
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