Guibo - Proposed Motormount rule

[chuck baader]

Question about the legality of substitution of the guibo. The stock piece (BMW) connects the drive shaft to the transmission and is made of rubber. The alternate is of aluminum with poly bushings to cushion the forces. Both perform the same function, but would the aluminum piece be legal? Is the guibo a bushing? Thanks for your imput. Chuck

[Greg Amy]

So that's what those things are called...whenever I needed one for the old Formula Ford I'd call the guy and ask for "that rubber coupler piece in the driveshaft..."

Chuck, I'd suggest unless it was offered on a same-spec-line BMW, it's not a compliant part...I'd certainly not consider it a suspension bushing...

[chuck baader]

Greg, all BMWs from the 2002 to current (I think) use the guibo. Spec line has nothing to do with it. Chuck

[Greg Amy]

Spec line has nothing to do with it. Chuck

If none of them use the aluminum version, then I suggest it's not a compliant part in IT.

[JeffYoung]

Legal under the new driveline mount rules in my view, so long as there is some squishy stuff in it.

[Greg Amy]

Legal under the new driveline mount rules in my view, so long as there is some squishy stuff in it.

Have those been approved yet?

[JeffYoung]

Out for member comment in Nov. fastrack. I suspect they will be on the books for next year, but that is just a personal guess.

[tac911t]

Legal under the new driveline mount rules in my view, so long as there is some squishy stuff in it.

The Guibo is not a mount, it is a driveshaft flex joint. It would be like replacing U-Joints with CV-Joints, or a solid shaft. Reading the Nov Fastrack, it states that the Rubber or other inserts can be replaced with other non-metallic inserts.

The BMW Guilbo that was on the E36 M3 I had (my only experience with guilbo's), was mostly a rubber piece, with metal strips inside for reinforcement. Sounds like the replacement part is mostly aluminum with a little rubber.

Is the intent of the aftermarket motor and transmission mounts is to include the driveshaft or halfshafts?

[JeffYoung]

To allow commonly available engine mount aftermarket inserts,
replacement units, or "window weld" like solutions without allowing solid metal or rigid materials or bearings that could
result in the driveline becoming a stressed member of the chassis, the following is permitted. Engine, transmission,
differential or any other driveline mounts may be replaced. Mounts may use only stock mounting points, must maintain
stock location and orientation of the mounted component, and must be non-rigid.Rubber or other inserts in stock mounts
may be replaced with any other non-metallic material

Well, you may be right. I think the intent was to allow replacement of anything rubber in the driveline. I would certainly vote that way. Chuck, you may want to comment on this on the rule so we cover it.

The Guibo is not a mount, it is a driveshaft flex joint. It would be like replacing U-Joints with CV-Joints, or a solid shaft. Reading the Nov Fastrack, it states that the Rubber or other inserts can be replaced with other non-metallic inserts.

The BMW Guilbo that was on the E36 M3 I had (my only experience with guilbo's), was mostly a rubber piece, with metal strips inside for reinforcement. Sounds like the replacement part is mostly aluminum with a little rubber.

Is the intent of the aftermarket motor and transmission mounts is to include the driveshaft or halfshafts?

[JohnW8]

"Flex discs (aka: the guibo) is a vibration dampener mounted on the back of the transmission. The flex disc acts as a buffer between the transmission's output shaft and the driveshaft leading back to the car's differential."

Sounds like its a vibration damper and part of what makes a BMW run so smooth. They're readily available. SO why change to an aluminum part with poly bushings when this will only transfer a harsher vibration through the driveline? Quicker response, like running a solid clutch disc as opposed to a sprung hub disc?

[GKR_17]

...engine mount... Engine, transmission,
differential or any other driveline mounts... ...stock mounts...

...I think the intent was to allow replacement of anything rubber in the driveline. I would certainly vote that way.

So if the intent was to allow the replacement of any rubber in the driveline, why include mount in the wording so many times? Good grief. Regardless, he's asking to replace a part made primarily of rubber with a part made primarily of aluminum (metallic). Not close to legal even under tortured interpretation.

[DavidM]

The flex-disk/guibo has nothing to do with mounting the transmission. It's more part of the drive-shaft. On my car, the flex-disk IS part of the drive shaft. The flex-disk is bolted between the main shaft and a little stub axle that slides into the transmission. When I ordered a new drive shaft it included the flex-disk and little stub axle. My interpretation would be that the flex-disk must be stock.

I would disagree that the intent of the new rule was to allow replacing anything rubber in the driveline. The intent was to allow replacing rubber mounts. That is entirely different.

David

[chuck baader]

Ok, I would not call this a drive line mount...it has nothing to do with mounting the motor or transmission to the chassis. I think that would have to be the test for a mount. I think it to be more of a bushing but BMW (real OEM) actually refers to it as a universal joint.

"Flex discs (aka: the guibo) is a vibration dampener mounted on the back of the transmission. The flex disc acts as a buffer between the transmission's output shaft and the driveshaft leading back to the car's differential." John, where did you get that definition? And yes, I would like to use the aluminum since the bushings in the aluminum piece are stiffer than the stock guibo. Chuck

[JeffYoung]

Well, since I helped write the rule I can tell you that for me anyway, the intent was to allow replacement of rubber devices in the driveline that wear out with harder materials.

What if any is the performace advantage of allowing this other than reduced maintenance?

The flex-disk/guibo has nothing to do with mounting the transmission. It's more part of the drive-shaft. On my car, the flex-disk IS part of the drive shaft. The flex-disk is bolted between the main shaft and a little stub axle that slides into the transmission. When I ordered a new drive shaft it included the flex-disk and little stub axle. My interpretation would be that the flex-disk must be stock.

I would disagree that the intent of the new rule was to allow replacing anything rubber in the driveline. The intent was to allow replacing rubber mounts. That is entirely different.

David

[JeffYoung]

Because no one specifically thought of guibos when we were writing the rule.

What is the down side to this? Why all of the grief? If we are allowing folks to change rubber bushings pretty much anywhere else on the car, why not here?

So if the intent was to allow the replacement of any rubber in the driveline, why include mount in the wording so many times? Good grief. Regardless, he's asking to replace a part made primarily of rubber with a part made primarily of aluminum (metallic). Not close to legal even under tortured interpretation.

[Harvey]

Jeff:

If you are saying that the NEW proposed rule for motor mounts would include any and all rubber items within the drive line to include the BMW guibo then we ALL should start writing letters in against this NOW because this is going to get even MORE out of hand then even I expected.

[chuck baader]

Jeff, I did not glean that "the intent was to allow replacement of rubber devices in the drive line" from the current proposed rule. Be that the case, wording needs to be changed slightly to indicate this. Chuck

[chuck baader]

Below are the two items in question. Chuck[IMG]file:///C:/Users/Admin/Desktop/Pictures/images.jpg[/IMG]

[Chip42]

Because no one specifically thought of guibos when we were writing the rule.

What is the down side to this? Why all of the grief? If we are allowing folks to change rubber bushings pretty much anywhere else on the car, why not here?

Jeff, I see replacing driveline joints (that's what this is) as a really quick trip to creepsville. follow the logic: U- and CV joins will be next as they are of the same category of mount. axle and prop shafts connect to these joints, then to hubs and drive flanges... all of these are fragile on SOME cars. warts and all, right? there are some bushings in shifters and steering racks and columns, too...

IF an exception is to be made for "sloppy" joints, like rags and guibos, then that should be a very specifically worded rule with clear definitions. I'd agree that we have a ruleset that places these types in left field, but disagree that they are covered by the mount rule or that "joints" in general should be open / not stock or equivalent.

[JoshS]

I don't think guibos are included by the new rule, nor do I think they should be. They are part of the driveline, not a driveline *mount*. During all of the ITAC discussions in my tenure, the idea that something like a guibo should be included never came up and I think the idea is crazy to lump them in with the mount rule.