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Discussion Starter #1
I have been reading the threads here for some time and I must say WOW! You guys know more about these cars than I do my personal life. Your knowledge made me armed when making my purhcase - thank you all! As background, I had a 1997 540 with 135k that I sold to acquire the M5. The M5 is truly a beast.

About 2 months ago, I bought a 2002 M5 with 66k on the clock. It needed rear tires, a clutch, control arms and is throwing some codes - no SES, but my local indy that did the work said I will need to spend some $ soon to make it "perfect." Anyway, to my problem and reason for writing.

Just after shifting into 5th and 6th gear, there is slack in the driveline. I press the accelerator and there is a hesitation lsimilar to a bad u joint. I have not noticed any posts on bad u joints - is this uncommon? This only happens (or is noticeable) in the 5 and 6 gear, but might be occurring elsewhere-I do not notice it though. After the initial "slack" is realized in the specific gear, it will not reproduce the slack after releasing throttle and depressing again while in the same gear...it only occurs as the initial load is placed on the drivetrain in that gear. Any thoughts? I love the car, but need to know what to expect. Anyone else had these issues?
 

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MAFs...?

Not sure if that would cause this without other symptoms, but it seems the right mileage to start thinking Mass Air Flow sensors?

Just my inexperienced $.02
 

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Discussion Starter #4
Are you suggesting the problem is the guibo or that a u joint is known as a guibo on this website?- I'm still a rookie here. Also, is replacing the guibo comparable to replacing a u joint in a common vehicle or is the process more involved...I am relatively mechanically inclined and have access to a car lift that will make mechanicing easier than working on my back. Is this a DIY or mechanic fix?
 

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Discussion Starter #6
chowdah - thank you for the reply and link. It will be very useful if I need to replace my guibo. Are you familiar with the guibo - common problem? Is this something that needs to be replaced immediately or can it wait until I need brake in a month or so?
 

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I'm saying that what you call a "u joint" is better known as a "guibo" or "flex disc" here (to aid your searches). I'm also saying it's an easy inspection to quickly rule in/out as a problem. Worn guibos are not uncommon.
 

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So are you saying the clutch was replaced or still needs replacing? A slipping clutch will be more noticeable in the higher gears at first. May be reason for your hesitation? Congrats on the car and welcome!
 

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Discussion Starter #11 (Edited)
New clutch was installed 2k miles ago. I did not push the car until about 250 miles ago so it was broken in correctly and I still have not gone crazy with it. I would like to think that my indy would have noticed a bad guibo when the tranny was out to replace the clutch. I need to check my receipt and see if he billed me for a guibo replacement. My indy is a BMW only mechanic. I am not saying he is perfect, but he knows his stuff. He maintained my 540 and was very familiar with the M prior to my purchase...and he is a friend, so I trust his input. The car had the Inspection 2 service performed at 60k and should be up to date except for the thrust arms...those do need replacing soon. What about clutch adjustment? Could it possibly be the clutch needs to be adjusted out? It shifts well throughout the other gears...only 5th and 6th show the slack. The slack only happens when initially placed in gear, released clutch and accelerator applied. Once the initial slack is realized, it will not replicate the slack while in the same gear, but it will replicate the slack if I shift between the gears and accelerate again (5th and 6th).
 

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I'd say clutch or guibo.

Guibo is easy to check, as Chowdah said just put it on a lift and look. If you see cracks you need to replace it.

I'll give you 2 methods for checking your clutch:
1. (this is the method I learned long ago on low horsepower vehicles - not sure if it applies) With the car idling and foot firmly planted on the brake, put the car in 5th gear. Slowly and steadily release the clutch. The vehicle should just die. Any slipping or additional revving while releasing means new clutch.
2. The recommended test I've read on this board is to get your car in 3rd car at about 2500-3000 rpm under steady throttle and then floor it. If you get revving without acceleration = new clutch.

Good luck!

d-
 

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Discussion Starter #13 (Edited)
Let me give a bit more data - I have had the car in 1st, 2nd and 3rd recently and was able to "test" out the clutch. I can hold the throttle down and no revving. The car had a bad clutch when I got it, so I am familiar with a bad clutch rev - it is not doing that. Clutch was fully released when I was "testing" the car...no throttle with foot on clutch pedal.

Further clutch testing scenario - put the parking brake on and release the clutch with some throttle...it should die and show a good clutch or rev and show slip.

Thanks folks!
 

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Discussion Starter #15
Not yet - it has been raining here and I have not had the desire to crawl underneath the car yet. I am driving my truck until I can inspect. I will check it out when the rain quits and repost accordingly. Thanks again!
 

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Discussion Starter #16
guibo is cracked - evidently a result of the new clutch and my desire to "test" it out to make sure it works. I need brakes and lower control arms anyway, so I guess it is off to the mechanic for some repairs. Oh well, I can't think of any other way I'd rather spend a couple thousand $.
 
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