any reason why no one makes a non-rubber flex disc?

[scooper]

I know the OEM rubber one is supposed to dampen vibrations and it should be inspected every 10k miles or so. For such a wear item, why doesn't someone make a poly, nylon, or aluminum piece? Just curious...

[EricP]

Because the OEM piece works. People have tried and failed to make a replacement that doesn't rattle the fillings out of the driver. It's like having solid motor mounts but worse from what I have heard. You WANT rubber there.

Inspecting every 10K miles sounds majorly overkill as well, do you inspect your motor mounts every 10K miles? I wouldn't worry about it.

[Dricebrug]

Because it takes up harsh "jerks" and extends the life of the differential. Not to mention without or with a solid one... your teeth would end up on your floor mats.

[dRock13]

the car in my sig has solid motor mounts. smooth as a top. I have the same question, it isn't undoable.

[scooper]

Ok thanks guys. Is there any short cut to replacing the guibo without taking off the exhaust first? I know then you're supposed to take off the heat shield then the transmission cross member. Then you're supposed to drop the drive shaft. I guess all these pieces need to come out or else you can't get a wrench on the hex bolts for the guibo? Also, is it imperative to replace the hardware? I was going to do it this weekend but I thought I should get new hardware.

On another note do I need to get another blower motor clip if I'm replacing the motor entirely? Another thing I need to do this week/weekend...Thanks!

[Brent 930]

I tried a solid guibo and it doesn't work.

Some people have done short cuts replacing the guibo but I don't recommend it.

[Junk]

I did always wonder why other cars I drove had no guibo and why would it make more noise in the BMW? (other than the diff is kind of bolted to the body). I have seen some aluminum guibo pieces somewhere.. I stayed with rubber since my m coupe diff has a bit of a clunk (input flange play)

[Mad Dog 20/20]

it should be inspected every 10k miles or so.

Who told you that?

They usually last 50k+ miles, easily.

[scooper]

Hey Garrett,

Just going by the pelican parts DIY...(inspect at 10k intervals)...Guess I should take any short cuts then. Will I need another floor jack and/or jack stands to help support the exhaust system? I'm guessing yes since it's better to have it supported while the bolts come out.

[BMWManiac]

Who told you that?

They usually last 50k+ miles, easily.

I would even say you could put it on the 75K - 100K maintenance requirement. 50K seems on the very low side.

[NeilM]

They usually last 50k+ miles, easily.

Sure, but they should still be inspected much more frequently than that. If you expect 50K miles life and you inspect at 50K and it's still OK, you're not going to want to wait until another 50K miles have passed for the next inspection. By then you're on borrowed time, to say the least. Catastrophic giubo* failure isn't pretty.

Neil

* Giubo is the correct spelling, pronounced "jew-bo." It's a giunto (Italian for joint or coupling) developed and patented by the Italian engineer Antonio Boschi (1896-1988). Hence Giunto Boschi, or giubo.

[Hova]

http://www.revshift.com/shop/index.php?_a=viewProd&productId=76

E30 though.

[Mad Dog 20/20]

Sure, but they should still be inspected much more frequently than that. If you expect 50K miles life and you inspect at 50K and it's still OK, you're not going to want to wait until another 50K miles have passed for the next inspection. By then you're on borrowed time, to say the least. Catastrophic giubo* failure isn't pretty.

Neil


By that logic, one could claim that drive belts (or ANY wear item) should be inspected every 500 miles . . . that is - once they have 150k miles on them.

I have never heard of a sudden catastrophic guibo failure. Guibo's, usually very gradually fail over the course of about 10-20k miles (ie, @ 50k+ miles, they begin to gradually degrade and may become disfunctional at 70k+ miles). First they develop tiny stress cracks in the rubber, then, much later, chunks of rubber begin to come free from the Guibo, then much later, the threads in the rubber are exposed and then later still, the threads begin to fray. At some point along this failure process, the driveshaft will begin to vibrate badly, and then finally it will begin to contact the shaft tunnel in rather dramatic fashion under acceleration.

The guibo is something that you take a peep at every once in a while, like when you do a SSK, exhaust, clutch or tranny fluid, etc. Its generally not something anyone needs to "keep an eye on" or inspect every 10k, unless its already near/exceeded its life expectancy.


I would even say you could put it on the 75K - 100K maintenance requirement. 50K seems on the very low side.

Agreed.
But I have seen them develop cracks at around 50k miles, especially on cars that see a lot of drivetrain abuse or FI'ed cars.

[99MPower]

I've seen solid alum guibos on turbo cars, and its not pretty, as in, the vibrations are BAD

[Ritt]

I've wondered about this myself. I had an S13 240sx, which in stock form is very similar to the E36 in terms of drivetrain mounting. Two motor mounts, tranny crossmember with rubber isolator, two-piece driveshaft with guibo and carrier bearing, and rear diff. In fact that diff had no bushings, but was solid-mounted to the rear subframe...

Anyway, I had a one-piece steel driveshaft on that car, which effectively eliminated the guibo and carrier bearing. The car was actually smoother than with the factory parts, and the one-piece shaft was lighter than the factory two-piece.

This made me wonder why I don't see people switching to a one-piece driveshaft on the E36. What makes this car different, that a one-piece or solid guibo makes things so rough?

[NeilM]

I have never heard of a sudden catastrophic guibo failure.

Really? Hey, I thought you got out more! I've seen lots of pictures of them over the years. Google it and you'll get plenty of hits. Here's one to you get you started:

http://cache.gawker.com/assets/images/12/2009/08/500x_UKF-Guibo-Kaboom.jpg

(From http://jalopnik.com/5338355/guibo-failure-sidelines-mad-sciences-6-series-but-not-for-long)

I'd suggest inspecting the giubo annually or roughly every 10K miles starting at 50K part miles, or sooner on cars that are tracked or otherwise driven hard. Every couple of years might suffice otherwise. It's not as if the giubo is hard to inspect.

The principle here, for those still following along, is that if some part has a mean time before failure of say 50K miles, that doesn't mean you inspect it at 50K, then again at 100K, etc. Instead you take into account that some proportion of them will fail early, and that after the MTBF point you'd expect the failure rate to pick up.

(Note: I'm not suggesting that the giubo MTBF is only 50K miles—that's for example purposes only. If I had to make a guess it would be that you'd expect maybe double that in ordinary driving.)

Neil

[scooper]

wow that's nasty! Thanks for the pic! I have 142k+ and now I'm starting to see cracks. I guess either my car was driven gently or the flex disc has already been replaced once. Is new hardware necessary with the install? I think I should get some. When I drop the exhaust do I need to get new hardware too or can I re-use everything? Thanks all!

[BMWManiac]

So, I didn't see it, but is that aftermarket guibo supposed to never need replacement? If it does the same job, without additional noise or vibration, I would say that is a pretty good deal.

[NHbmw325I]

scooper I would replace the exhaust gaskets.

[NeilM]

Is new hardware necessary with the install? I think I should get some.

I'd use new locknuts at least. The BMW locknuts don't use a nylon insert and are good for only one or two assembly cycles.


When I drop the exhaust do I need to get new hardware too or can I re-use everything?

You'll probably be forced to use new hardware, at least in part. The exhaust system fasteners tend to corrode and then break when you try to remove them. I routinely replace them with hardware store stainless steel fasteners.

Neil

[scooper]

Thanks Neil. What are the fasteners size/length/hardness?

[NeilM]

Thanks Neil. What are the fasteners size/length/hardness?

The ones that nearly always break are on the flanges joining the cat and muffler sections. The originals are M8x55. The SS replacements you'll commonly find will be a bit longer, M8x60.

The nuts on the studs studs joining the exhaust manifolds to the forward end of the cat section can be problematic to remove, and these studs are more difficult to replace. Use some good quality penetrating oil (Kroil, Würth or PB Blaster) there and let it seep in for several hours if possible.

Neil

[scooper]

can I find those M8x60s at the hardware store? Sounds like I should use an impact gun which I still need to buy...

I'll need new gaskets too? Is it the case that whenever I unbolt the exhaust I should use new gaskets and bolts (if duration is greater than a few months)?

Also, I've read that using long tubes give no gain if not using cams. This true? Sure like the sound of long tubes though.

I've installed a TRM chip though I need to re-do the CAI to make it fit better, but I can see myself wanting more power (which is bad)....next step would be FI I guess? I've got a 3.46 on there now. maybe I'll just roll like this for awhile...

[Mad Dog 20/20]

Really? Hey, I thought you got out more! I've seen lots of pictures of them over the years. Google it and you'll get plenty of hits.

No, I said I've never heard of a "sudden catastrophic failure" of a guibo.



I have never heard of a sudden catastrophic guibo failure. Guibo's, usually very gradually fail over the course of about 10-20k miles (ie, @ 50k+ miles, they begin to gradually degrade and may become disfunctional at 70k+ miles). First they develop tiny stress cracks in the rubber, then, much later, chunks of rubber begin to come free from the Guibo, then much later, the threads in the rubber are exposed and then later still, the threads begin to fray. At some point along this failure process, the driveshaft will begin to vibrate badly, and then finally it will begin to contact the shaft tunnel in rather dramatic fashion under acceleration.

I've obviously seen failed guibos before, as I already described the failure process, including the fraying and rubber cracking/chunking, etc. that is depicted in the photo you posted. A picture of a failed guibo does nothing to suggest that it was "sudden".

My point was that I have never heard of somebody's guibo suddenly failing and leaving them stranded (which can happen w/ a hose, belt, etc.) Now if somebody takes a 25 yo car to the race track and tries to race w/ a 25 yo dry-rotted guibo, it may very well fail on lap 1 (along w/ god knows what other rubber parts). But I dont think that's what we are talking about here.

A failing guibo will give the driver plenty of warning (via serious vibration and/or a knocking noise) long before it reaches the catastrophic failure point.

Assuming it has a 100k+ mile lifespan with normal street use, and given its gradual and highly symptomatic failure mode, a general 10k inspection interval for the part would border on the absurd.




To the OP, the reason there have been few, if any, aftermarket guibos for the e36 is that the OE part is generally very robust and typically performs its function quite well for 100k+ miles of normal use, is not prone to sudden catastrophic failure, and is very easy to inspect/replace. If guibo's were leaving people stranded every 10k miles, obviously there would be a very strong market for something much more durable.

[NeilM]

can I find those M8x60s at the hardware store?

Well, not knowing either your local hardware store or your finding ability I can't answer that one!
I can tell you only that I'm able to find them at my local hardware store.


Sounds like I should use an impact gun which I still need to buy...

No, that's just what you don't want to use on small diameter bolts.


I'll need new gaskets too? Is it the case that whenever I unbolt the exhaust I should use new gaskets and bolts (if duration is greater than a few months)?

You should use new gaskets on the header to cat section flanges unless they've already been replaced relatively recently. If you use SS bolts on the exhaust system you'll likely never need to replace them again—that's the point.


No, I said I've never heard of a "sudden catastrophic failure" of a guibo.

I've obviously seen failed guibos before, as I already described the failure process, including the fraying and rubber cracking/chunking, etc. that is depicted in the photo you posted. A picture of a failed guibo does nothing to suggest that it was "sudden".

Giubo failure is sudden by definition. That 6er giubo failure wasn't sudden?

It's the degradation that isn't sudden, hence the need to inspect at some rational interval to allow replacement before failure. Those of us with track cars tend to spend enough time underneath them that we're going to pay attention to stuff like this, but that may well not be the case for the average owner.

Neil

[NeilM]

can I find those M8x60s at the hardware store?

Well, not knowing either your local hardware store or your finding ability I can't answer that one! I can tell you only that I'm able to find them at my local hardware store.


Sounds like I should use an impact gun which I still need to buy...

No, that's just what you don't want to use on small diameter bolts.


I'll need new gaskets too? Is it the case that whenever I unbolt the exhaust I should use new gaskets and bolts (if duration is greater than a few months)?

You should use new gaskets on the header to cat section flanges unless they've already been replaced relatively recently. If you use SS bolts on the exhaust system you'll likely never need to replace them again—that's the point.

Neil

[kenndoggy]

Because you'll twist the driveshaft first before you tear the guibo.

[Mad Dog 20/20]

Giubo failure is sudden by definition.

Dont wanna play semantics with you. But a cracked bushing is a "failed" bushing. A cracked guibo is a failed guibo. Both parts can remain in service for perhaps another 20k+ miles before they become symptomatic. Then the vibrations, then the loud sound of the driveshaft hitting the trans tunnel - all over the course of many many more miles. This is a long progressive failure mode with a lot of warning. The driveshaft coming completely free from the tranny RARELY if ever happens, and when/if it does, the guibo failed a LONG LONG time ago and somebody just ignored the symptoms and kept driving. This is the antithesis of "sudden".

Sudden is whe you are driving down the road and a hose blows or a belt goes without warning.

[scooper]

ok thanks guys!