Revshift Guibo / Flex Disk Resource & Review

[pbonsalb]

Try it out and report back.

[Inflame]

Everything posted in this thread is speculation. All assumptions. Not a single source of data has been posted. I haven't seen a graph, an official document, nothing posted by a creditable source. "But but but, RACE CARS use it" - Great, that's fantastic, home-brewed garage car's don't have much data either. I understand that "if it ain't broke don't' fix it" kinda holds water, but that doesn't mean that upgrading the guibo is a fallacy. So, until someone decides to take some time out of their day to prove everyone and myself wrong about upgrading the guibo, upgrading it cannot be thrown out the window.

[jeremy5000]

Everything posted in this thread is speculation. All assumptions. Not a single source of data has been posted. I haven't seen a graph, an official document, nothing posted by a creditable source. "But but but, RACE CARS use it" - Great, that's fantastic, home-brewed garage car's don't have much data either. I understand that "if it ain't broke don't' fix it" kinda holds water, but that doesn't mean that upgrading the guibo is a fallacy. So, until someone decides to take some time out of their day to prove everyone and myself wrong about upgrading the guibo, upgrading it cannot be thrown out the window.

99mpower HAS used this before om a customer's car though. That's enough data for me to not use this.

[hsvturbo]

Here is my experience running rev shift coupling on my turbo e30. It too vibrated at 20-25 mph, but could hold the torque when drag racing. I never tried the shimming that the OP indicated, or replacing worn parts.

Eventually, the dislike of the vibration as a DD was so annoying, I replace it back to OEM rubber, but would switch it back when going to the drags.

[pbonsalb]

My turbo 99M3 has 550 rwhp and 500 lbs rwtq. Launching on drag radials at the strip, I have fused two clutches, broken two driveshafts, and broken one axle. However, I have had no problems with the stock guibo. I don't really see any need to replace it.

That said, I just installed a DSS driveshaft that does away with the guibo. The car is not yet on the road, so I do not know the price in NVH that I will pay for the one piece driveshaft with no guibo.

[Bimmerman4ever]

I'm glad I didn't go through the trouble of reading every response and went directly to the last page.
Thank you for the input.
I recently just replace mine with a stock guibo but unfortunately found out later about the center bushing (mine didnt have one).
That bites. Will have to take all back apart again to put one in.
I understand it will cause premature failure. Although I've had many BMWs and never notice the center bushing when replacing them, and they lasted fine.
But this is my first M3 so it will have a bit more torque then a regular 3 series.

Anyone have experience with running a flex disc with and without the center bushing on an M3?

[Genes1s]

I have never tried solid "Guibo" in my car but from understanding what "Guibo" on AC/DC Servo/Stepper Motor on Linear actuator (high speed CNC or automation) is, I would never put a solid guibo in my e36 M3 car, even if I track it.

A "Guibo" is a type of Flexible Coupler. A coupler is a way to transmit the power from the motor to the drive shaft. Some couplers use metal/alloy, which is called solid coupling. Some use rubber, which is called flexible coupling, like Guibo in E36.

A drive shaft that has solid guibo connected to the motor will have several natural frequencies. This can be remedy by balancing the drive shaft, the motor shaft, and the coupler as a system BUT as soon as there is a slight mis-allignment due to wear or assembly error, you will have another mode of frequency which will cause vibration. This is why the rubber Guibo have the advantage over Solid one, the rubber, due to its durometer rating, needs to be hard enough to transmit the torque efficiently but yet soft enough to absorb any vibration from modes of natural frequencies or any mis-allignments. A 95A Durometer is pretty hard, this would transmit more torque than, say, 60A durometer. Consequently, 60A Durometer will absorb more vibration than the 90A could.

On the new BMW that has solid guibo, the designer must have tested the drive train as a complete unit that they see very minimal vibration produced from modes of frequencies, any mis-allignment, or any mechanical wear. How do they do that, well.....better manufacturing, tigther quality control, more tools to design/predict failures up front, in other word they did their homework!

Back then when the precission and mass produced quantities were not hand in hand, the BMW engineers knew that it would be a mistake to put solid guibo on their E36/E30. They had too much tolerance to deal with, quality control wasn't as good as today, and they couldn't reliably predict failure up front. As a result, they went with flexible guibo which will minimize any vibrations at the cost of small power loss to the wheel.

My take on solid guibo design is when it is designed properly with the correct material and dynamic damping ability, it is defenetly the way to go since you can transmit that engine power to the drive shaft efficiently AS LONG AS your drive shaft or other drive train components are able to keep up with it. If you have solid guibo, but your axle is clunking and old age, your just going to kill the rest of the components sooner than later.

my 2 cents.

[projekt h]

"well X had it and this happened" "this guy had it and it made noise"

Lots of people die from alcohol poisoning, does that stop you from having a beer? People blow off their hands with fireworks, does that stop others from buying them? Thousands die in car crashes every year, but here we are as car enthusiasts.

"well that's different, those people did something wrong"

Yes and no. It IS the same because someone did something wrong.

The common misconception with this part is that people think it's a just an OEM replacement made to seem stronger. It isn't. It's a precision-machined part intended for high-performance applications in which the stock rubber unit is more prone to failure. Yes, this guibo will make noise like hell.... IF you don't properly align your drivetrain. No, in no way shape or form will that specific part be the cause of your blown your transmission or differential.

If you're extremely hard on your vehicle and don't mind taking the extra bit of time and care it takes to make sure the engine and transmission mounts are not over-compressed or split, the rear subframe and differential are where they should be, the center support bearing is in good health and taking the measurements and making necessary adjustments then yes it could be a great solution that will show no adverse effects. Think of it like you're making your driveshaft into a 1-piece unit, you have to have everything aligned right. If you don't really care, have mounts that may be blown out, can't spare the 30 minutes (tops) it takes to align things or are just plain lazy then buy the rubber one.

It's held up for 800+ whp street cars, designated track rats, and daily-driven toys that get beaten like rental cars with no failures of it or other components induced by the part in question. For 99% of the problems out there with these, it's not the guibo, it's the installer.

FWIW, I do have hands-on experience with the part in question here, I have had it on a previous vehicle with no issue.

[RatedM3]

Giubo*.........

[projekt h]

-_-

Turner* (link in your sig)

[mcstahl]

God I hate this place sometimes. Guy asks some questions and tries to do some testing for everyone else free of charge and he gets crucified. And this is a place for people to meet with the same interests.

Do you people realize that the majority of cars don't have a flex disk or an equivalent? As a matter of fact I had never seen one before owning a BMW. How did these cars get by without a driveshaft that didn't have a rubber component that reduced vibration? Oh yeah, it's because it isn't necessary. Plenty of cars have a solid connection between the engine and the rear axle.

[pbonsalb]

No, they all have some sort of give. Two piece drive shafts, CV joints, soft bushings, etc. I agree you don't need all that AND a flex disk even if BMW used it all for ride quality purposes. But the idea that the solid flex disk is necessary is questionable given that you won't destroy a stock M3 flex disk with 500 rwhp. If you want to make the driveline snappier, try a one piece carbon fiber driveshaft like BMW is using on the new M3/4.

[Bimmerman4ever]

God I hate this place sometimes. Guy asks some questions and tries to do some testing for everyone else free of charge and he gets crucified. And this is a place for people to meet with the same interests.

Do you people realize that the majority of cars don't have a flex disk or an equivalent? As a matter of fact I had never seen one before owning a BMW. How did these cars get by without a driveshaft that didn't have a rubber component that reduced vibration? Oh yeah, it's because it isn't necessary. Plenty of cars have a solid connection between the engine and the rear axle.

I think they just designed it with "extra" rubber bushings, mounts, resonators, muffler, etc, etc... for the daily driver that wants something smooth and quiet. Yea sure you can take all that off for the track, performance, more noise, whatever...
Yea some cars dont' have flex disc though maybe that's why I see some old Fords and Chevys broke down on the side of the road with their drive lines laying on the ground.
But I know what you mean about some comments going overboard. Just filter what is useful info for you and ignore the rest.

Sold my M3 to get my 500SL back
an auto but still fun to drive

[dohcdoh]

I think they just designed it with "extra" rubber bushings, mounts, resonators, muffler, etc, etc... for the daily driver that wants something smooth and quiet. Yea sure you can take all that off for the track, performance, more noise, whatever... But I know what you mean about some comments going overboard. Just filter what is useful info for you and ignore the rest. Sold my M3 to get my 500SL back an auto but still fun to drive

Your username is now a lie. But having never ridden in an sl I can't say whether I blame you or not. Judgement reserved.

[Butters Stoch]

Your username is now a lie. But having never ridden in an sl I can't say whether I blame you or not. Judgement reserved.

+1 on the liar. The merc is a very nice ride. But not as fun. With mucho driving I would pick the Merc as well. Working on them, not so fun.

[Bimmerman4ever]

+1 on the liar. The merc is a very nice ride. But not as fun. With mucho driving I would pick the Merc as well. Working on them, not so fun.

Wasn't too difficult to learn how to fix what was needed. Never dealt with the old school KE Jetronic fuel system so I had to learn how to dial it in.
With the suspension, wheel upgrades, new tranny, and the fuel system dialed in it is very fun to drive even though having the old 4 speed auto

But still... I have owned over twice as many BMWs vs Mercedes
so I'd say my username holds true

[e36 caveman]

Should i try it if i don't care about the ride quality over me getting back and forth to work? I keep losing my flex disc to the point that there is nothing left but the bolts. i've gone a 1000 miles on just the bolts without a vibration( well till the bolts really wore out). I replaced flex disc, center supports, sent driveshaft out to balance it, motor mounts, trans mounts, cross member. Can a guy get a break! i'm going to do all the bushings in the rear and see if it does the trick. I'm getting 6 months out of a Giubo, and doing everything the Pros say to do. Just don't want to give up the 30mpg.

[pbonsalb]

Are you using a real one or a possibly junky aftermarket one?

[Bimmerman4ever]

Wasn't too difficult to learn how to fix what was needed. Never dealt with the old school KE Jetronic fuel system so I had to learn how to dial it in.
With the suspension, wheel upgrades, new tranny, and the fuel system dialed in it is very fun to drive even though having the old 4 speed auto

But still... I have owned over twice as many BMWs vs Mercedes
so I'd say my username holds true

Just recently traded my 92 MBZ 500SL for a 98 540i w/M5 front bumper. So I'm back in a bimmer again

[hide1]

Thanks for the update. The Benz didn't have the magic to keep you away for long I see..

[Blue555]

Anyone have any more experience with this? Considering it for our e30 ChumpCar build. I have read the OEM style ones fail frequently in race conditions.

[ScotcH]

Anyone have any more experience with this? Considering it for our e30 ChumpCar build. I have read the OEM style ones fail frequently in race conditions.

Not really. We replace ours every 2 years or so ... Never had one actually fail. OE is cheap, so just call it maintenance for a race car. Buy a new one to start with. If you're running a ZF, use the M3 version. It's beefier.

[jazigk]

Hi guys... Kicking off the fight again... What happened tot he OP, Themes? Did I skip past his final review of what happened or if he actually sorted out the vibration? Did he switch back to the rubber?



Now for my reason into actually posting here...
From the Alfa scene... No answers or silver bullets here, just more problems haha. Optional reading...

Our cars run 3 guibos. Regularly a discussion of failure, because we run transaxles that brings other problems [Tail shaft rpm = engine rpm. Factor in engine/transaxle alignment and movement at high RPM].
OEM is fading. No longer made so stock at suppliers is fading. Some guys, as I understand, are even selling the guibo BMW deceptively for the centre because they can't find the Alfa part [BMW is 5mm thicker, so needs machining down somehow].

People are searching for alternatives because the aftermarket guibo's are awful. Poorly made and dangerous in some cases.
People often enough bring up these bushed type discs. No one has tried one. Maybe it would work better since we have 3 guibo's [3 times the bush flex Vs. 1 in the BMW here]. Rhetorical question.
There are threads where people have made the tail shaft up to accept CV joints front and rear but they died pretty quickly [If I find the thread and it interests someone I'll post pictures... very interesting and seemingly a harmonic issue that showed up fast, even on a shop made, balanced shaft it still failed within days/weeks of daily street driving].
Uni-joints and single piece tailshafts are another option some people use.
But ultimately, there is no set, tried and proven method in the Alfa circle that everyone uses.

I plan to have a shaft made up using 3 current model local guibos. Should have easy access for OEM grade replacements for decades. Modern ones should handle much higher power too.

There are people who use cages for strength AND safety [7K plus RPM tailshaft failure can create miniature supernova events under your legs haha]. If the official race team used it, it must work. But it doesn't replace old, NLA guibos... A whole discussion that might apply to you guys could be had about this, but not with me haha. Good info here, with pictures of the cages and shim options. It does not stiffen the guibo! Only reinforces the bolt position to stop the bolts flexing and PCD moving around under force.
http://www.paulspruell.com/gearbox_instructions.html
http://www.ebspares.co.uk/new22.htm

Cage/plate stops the bolts doing this...


Image from this thread...
http://www.alfabb.com/bb/forums/gear...ibo-donut.html

[henryki]

OK its time to bump an old thread with a lot of controversy. After reading through this entire thread I have learned a lot about flex discs and also some of the physics behind them (which btw to the engineers who posted on this thread, I'm going through an intro physics class required by major and used your posts to help me practice some more physics problems and I thank you.)

More importantly, I am genuinely curious to what OP overall thoughts are of this product.

But to anyone reading this and wants to comment, even if you disagree and think its a horrible idea please for the love of God be civil and respectful with your replies. The poor guy who started this thread was just trying to give his $.02 by trying out a controversial product. TBH from what I've read from other users real world applications and educated responses explaining what components would be stressed and fail prematurely, I would not run this product in my own car. The only reason I even ended up on this thread in the first place was due to my flex disc looking questionable, and I was planning on replacing it as preventative maintenance since I'll already be in there replacing trans mounts and shifter components next week.

My closing thoughts/pieces of advice to anyone who actually reads this. After owning and working on BMW's for a few years there is one thing that I learned. You get what you pay for and you'll see this same theme again and again, its applicable to more than just driveline components. For example, when the clutch went out in my (now sold) E30 325i sedan I opted to replace the flex disc when I replaced the clutch. I was a broke college kid so I bought some cheap aftermarket unit and it failed less than a year later with the new owner.

sorry if i ranted a little, Henryki

[Bimmerman4ever]

Thanks for the update. The Benz didn't have the magic to keep you away for long I see..

540i is gone now have a 740iL lol