GIUBO vs. GUIBO vs. JURID JOINT vs. ?

[MMercury]

Nomenclature observations and a couple of related questions.


A recent question about the availability of a giubo with a seemingly experienced BMW parts man resulted in a frustrating exercise. In fact, despite using the language found in the shop manual, none of the people on the other side of the counter understood what I was describing until I said "black licorice-colored rubber doughnut."

FWIW, the shop manual agrees AND disagrees with TonyVelocewestS' take on the correct spelling of Giubo. The "3.75 amendment" uses the "GIUBO" spelling. The 3.75 amendment also describes the same part as "Giubo coupling/joint disc." However, the "1.76 amendment" lists Torque specifications for "GUIBO" coupling. Page 26-11/1 (10.73 Alteration") seems to describe the same part as a "rubber clutch."

For even more variety, the same manual refers to the reinforced driveshaft coupling - typically used with automatics - as a "Jurid joint." Should it matter (when ordering parts), the coupling has also been referred to as a "universal joint" and driveline "connector."

As I am currently concerned with a 1973 model, I will stick (probably to my detriment with parts personnel) with "giubo" and "Jurid joint." :wink:
___________________________


On a distantly related subject, using different nomenclature, E9'er-Steve asked about replacing the stock solid rubber giubo with a "thinner" Jurid joint. http://www.e9coupe.com/forum/showthread.php?t=1032 BMW P/N 26111107832 (giubo) versus BMW P/N 26111109603 (a.k.a. "Jurid joint").

Short of sticking with the original part, as suggested by a Pacific-based E9'er, the Jurid joint can be used with individual 7.5mm (.295") shims or spacers - per the factory. BMW P/N 26111109626 and 26111109907. The former is described as a spacer "ring" while the latter is merely described as a spacer. I am unfamiliar with the difference. See No. 16 below:

Some have described this as a common upgrade. The stiffer, reinforced-Jurid joint may transmit more driveline vibration (although I have never noticed any). Anecdotally (since I have never measured the parts), it appears far more tolerant of rough treatment and long lived. The benefit of OEM giubo’s extra vibration absorption seems minor when used with the inherently smooth running inline M30. Contrariwise, a buzzy M10 might benefit from the solid rubber donut.


Two questions:


1. Has anyone found a readily available and less expensive substitute for these spacers? I had a box of surplus aircraft-grade spacers (0.295" long) that worked well, but managed to misplace them. (Grainger? Make my own?)



2. Jurid joints came in several sizes with bolt patterns identical to the OEM giubo. The outside diameters can differ by about 35mm. Apart from reduced clearance, additional weight/mass, and possibly extra stiffness for the larger diameter joint - both fit. Anyone using the larger joint, experience any issues suggesting the smaller joint is the preferred choice? (I have used the smaller OD joint, but happen to have a couple of larger diameter Joints collecting dust.)


Thanks

 

[JhwShark]

Mercury Man,

It appears that the experience is limmited, and possibly related to time on the job versus type and variety of parts dispensed. I do not have answers to your questions. However on #2, I believe that the larger the couple the more it absorbs versus transfers power; I would want a mechanical engineer to help on this. The more rigid the more power transfers. It has been way to long sice I went to Engineering school.

On my former 2002's I only used the guibo coupling (that is what I called it) and they gave me the exact replacement. However that was over 15 years ago. I was aware of a stiffer type of coupling but wanted to stay stock.

I would believe that the stiff one would be better/quicker with power transfer due to more rigidity. I also aggree that it may transfer vibration if there is any balance issues, that could possibly degrade some items including welds faster on the older beasts. A possible downside to the rigid couple/Jurid is that it possibly puts more stress on the rearend at shifting and quick clutch release. The guibo would absorb some of the stress.

I also do not believe it should be refered to as a U-joint

 

[MMercury]

A "friend of a friend" recently asked me about constant vibration in his manual trans-E3 - after recently replacing the solid rubber giubo - twice. Given three teenagers with access to the car, it is not a stretch to wonder whether someone was experimenting with the car's acceleration capabilities at the expense of the drive train. Since the patriarch plans to keep the car, I suggested he try the stronger Jurid joint and planned to give him some spacers, I thought I had. That was the reason for the post.

I tend to agree that the solid rubber giubo acts as an easily replaceable “fusible link” that will take the brunt of abuse before more expensive parts will. (Operators of Automatic equipped cars do not ordinarily miss shifts or dump the clutch, as can happen with manual trans equipped cars.) I swapped giubos for the reinforced disks on a couple of cars many years ago and never had any problems. Naturally, even the reinforced “Jurid joints” do not last forever. They just tend to be more difficult to destroy and they do flex, providing a modicum of protection.


From what I recall, several later model BMWs, including M10, M30 and M series vehicles gravitated toward the reinforced "jurid joints," suggesting some logic in that direction. It is interesting that some of the more performance oriented vehicles used larger OD joints and included a separate vibration damper (See no. 3 below).

At one time (a few decades ago) BMW evidently recognized one style was smoother or provided for a more comfortable ride, at least for the 3.3L E3-limo. "In view of the risk of vibration being transmitted and causing engine noise (engine/transmission), use only propeller shafts with Giubo couplings." Yet one has to wonder how significant is the selection of flex disk given the thousands examples of Detroit Iron that merely had single piece driveshafts bookeneded with replaceable U-joints and transferred gobs more torque and horsepower than most M10 and M30's.

 

[x_atlas0]

I suppose something made from Delrin or other hard plastic could be machined up pretty quickly. This would be both stronger and still be the weakest link, so as to prevent hard part damage.

 

[Bill Riblett]

Two questions:
1. Has anyone found a readily available and less expensive substitute for these spacers? I had a box of surplus aircraft-grade spacers (0.295" long) that worked well, but managed to misplace them. (Grainger? Make my own?)

2. Jurid joints came in several sizes with bolt patterns identical to the OEM giubo. The outside diameters can differ by about 35mm. Apart from reduced clearance, additional weight/mass, and possibly extra stiffness for the larger diameter joint - both fit. Anyone using the larger joint, experience any issues suggesting the smaller joint is the preferred choice? (I have used the smaller OD joint, but happen to have a couple of larger diameter Joints collecting dust.)

1. A possible alternative to using spacers is to "lengthen" the driveshaft. The driveshaft coupling between the two pieces is splined. Back in the 80s when I installed a 5 speed, I had a spare 3.0CS automatic transmission driveshaft which was almost the correct length. Experimenting with loosening the splined joint, I discovered that I could gain the 3/4" or so I needed and it worked.

I was a little concerned about having less length in the splined connection, but it has survived all these years, including a few autocrosses, and this behind a modified engine with about 50 more horsepower.

2. My impression is that the smaller guibos seem to be made more sturdy and seem to hold up better. This is especially true in 2002 applications judging by the anecdotal experiences reported on the 2002FAQ forum.

 

[Bill Riblett]

I did the 5 speed conversion about 1987, so the details are a little fuzzy, but I know I did not move the diff. I do remember looking into using some sort of spacer at the guibo, but decided that if 'stretching' the A/T driveshaft didn't work I would just have my 4 speed driveshaft shortened.

 

[MMercury]

Far Afield??

I did the 5 speed conversion about 1987, so the details are a little fuzzy, but I know I did not move the diff. I do remember looking into using some sort of spacer at the guibo, but decided that if 'stretching' the A/T driveshaft didn't work I would just have my 4 speed driveshaft shortened.

This thread has meandered a bit from the original subject. I may as well ask, what style flex disk did you use on your conversion? The 4-speed giubo or the auto Jurid joint?

Since the initial post I have been reminded that many other Euro cars used driveshafts connected with flex disks of both styles: Jaguar, Fiat Mercedes and Volvo, to name but a few. Interestingly, some of these actually have a shield to presumably protect the giubo or jurid joint from exposure to oil AND to contain a decomposing coupling. This seems to be different from a much larger round heat shield. Strangely, I have seen many of these "guards" but they don't appear on the Realoem.

I suppose it can happen, but I have never experienced a giubo flying apart at speed.

This is pic of am E24 drive shaft coupling described as a "guard" to be distinguished from a "vibration damper."

 

[Arde]

My knowledge is limited to:

- Guibo is easier to pronounce than Giubo, so we use that, or flexi-disc.
- When the E9 had the automatic transmission we had the driveshaft joint rebuilt and installed a new Guibo, it was the rubber style.
- Upon the 5-speed conversion we put a different length rebuilt driveshaft and kept the recently installed Guibo.
- My E24 recently rebuilt driveshaft does not use a solid rubber Guibo, presumably because it is automatic.

This may be unrelated but highlights the difference between direct coupling at the clutch and a torque converter. As a 5-speed the car had a hesitation where it was impossible to maintain constant speed, you could either accelerate or slow down, but trying constant RPMs lead to jerky hesitation specially at low gears. The issue was solved by re-jetting the Webbers, but was masked for years in my opinion by the torque converter in the automatic transmission. Viscosity coupling is probably more flexible than a rubber Guibo, so a solid solid joint downstream is OK.

 

[Bill Riblett]

This thread has meandered a bit from the original subject. I may as well ask, what style flex disk did you use on your conversion? The 4-speed giubo or the auto Jurid joint?

Since the initial post I have been reminded that many other Euro cars used driveshafts connected with flex disks of both styles: Jaguar, Fiat Mercedes and Volvo, to name but a few. Interestingly, some of these actually have a shield to presumably protect the giubo or jurid joint from exposure to oil AND to contain a decomposing coupling. This seems to be different from a much larger round heat shield. Strangely, I have seen many of these "guards" but they don't appear on the Realoem.

I suppose it can happen, but I have never experienced a giubo flying apart at speed.

This is pic of am E24 drive shaft coupling described as a "guard" to be distinguished from a "vibration damper."

I don't remember which I used on my E9 5 speed conversion, but I think it was probably the 'guibo' type as opposed to the 'jurid' type, as the former is thicker and I was looking to make the driveshaft "longer".

I can't get under the car very easily at present to check what is there.

My 86 635 had one of the vibration dampers (second picture) which came apart! Getting rid of it didn't make any noticeable difference.

The 2002FAQ forum has lots of dialogue about Guibos and failures are common. Failures of the 'guibo' type seem much more common. I have seen quite a few which were badly cracked and a couple which came apart in large chunks. This seems to be much less of a problem with E9s. I wonder if the 'jurid' type have some sort of fabric reinforcement, like the steering couplings?

 

[MMercury]

"Rag Joint"

The 02 forum has lots of dialogue about Guibos and failures are common. Failures of the 'guibo' type seem much more common. I have seen quite a few which were badly cracked and a couple which came apart in large chunks. This seems to be much less of a problem with E9s. I wonder if the 'jurid' type have some sort of fabric reinforcement, like the steering couplings?

I think 02's tend to have more giubo issues for several reasons, not the least of which is an engine that vibrates more than the M30. Many 02 owners also neglect to fix chronic oil leaks that managed to coat everything including giubos. Some of the same owners literally beat the hell out of their cars until they drop. (Drive it like you stole it?) Then, there is the design of the smaller 8-hole giubo that has many places for the rubber to separate from the metal components.

You are probably aware that the same 6-hole automatic jurid joint for the E9 autos fits the later model 02 autos(ZF 3hp12 trans). I used the same one for almost 15 years. If I am not mistaken, most E21 5-speeds used the bigger 6-hole giubo configuration as used in the E9.

Look up "rag joint" and you will find many examples of steering couplers. :wink:

 

[MMercury]

This may be unrelated but highlights the difference between direct coupling at the clutch and a torque converter. As a 5-speed the car had a hesitation where it was impossible to maintain constant speed, you could either accelerate or slow down, but trying constant RPMs lead to jerky hesitation specially at low gears. The issue was solved by re-jetting the Webbers, but was masked for years in my opinion by the torque converter in the automatic transmission. Viscosity coupling is probably more flexible than a rubber Guibo, so a solid solid joint downstream is OK.

There may be good reason for calling the automatic a "slush box." No doubt it can hide many engine ills, including lean misfire. This may be no longer the case, if you were to use a more modern auto trans with a locking torque converter. Even with the stoutest of drive shaft connectors, the auto trans may not last long or continue to hide any engine issues if the car is repeatedly launched or slammed into gear at engine speeds well past the converter's stall specs. It makes for dramatic effect though (Go Powerglide?)​

Since this thread started with nomenclature observations, there are many other common names for driveshaft coupling: "Rag Joint," "Jurid Coupling," "Febi Flex disc" and good old "driveshaft donut." (I assume there is even a common reference in sign language.)

There have been a number of ways to transfer torque to the driving wheels, all of which take their place in history. Solid rubber giubos seem like a logical progression from belting leather and it is not much of a stretch to conclude the reinforced rubber or urethane is the current apogee of these connection types. Obviously not as strong as a CV joint, spicer joint or metal U-joint, the rubber giubo has its place. It is simple, elegant, lightweight, and requires no maintenance (until it fails).

Per the photos: Jim Clark pondered them; some evidently attempted to strengthen them with metal cladding; Triumph and Matra used them; and some trucks probably use the larger sizes.

Sorry, could not resist.:roll: