That gearchange clunk

Sajk

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I have searched this and I know "they all do it" but mine never used too. Have had it checked out twice and get told nothing wrong. My wife just picked it up for me after the vanos seals were replaced and the first thing she said is "why does it clunk when you change gears"

It does have poly sub frame bushes so i expect more noise but it did it before that.

Has anyone gotten to the bottom of this.

Model year 1999 z3 2.8 roadster

Cheers
 
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Dunkelgrun

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More knowledgeable minds than mine might chime in but I would guess there is play somewhere in the the driveline. Need to put it on a lift and slowly go around looking for the play in the guibo, driveshaft bearing, differential, axles, etc. till you find it. Is the differential full? Is the slave cylinder bled? I think mine clunks a little too but I’ve never had the radio on low enough to hear it 😎
 

Sajk

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Mostly without the roof I can't hear it but roof on it's very noticeable. I trust my shop guy who has worked on my Z a lot. Cams vanos etc but I don't believe bmw designed it to go clunk gd gd gd when you change years or press the clutch in. I can drive so it's less but...
 

Lee

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Hi @Sajk the clunk is becoming more common as these cars age now and when they start to clunk all depends on how they’ve been treated. We’ve fixed a few zeds with clonks here and it’s the Diff every time. The most common part in the diff is the crush sleeve loosing its preload allowing backlash in the gears, the second issue is a bearing beginning to fail allowing play in the gears. They’re very robust diffs so don’t tend to show any damage inside regardless of how bad the clonking is.

You should hear how much it clonks on my Zed, I believe this is the track days causing accelerated wear, bare in mind though most of these diffs now are over 20 years old.

We have a local diff guy, I supply the parts and oil and he charges us £300 for a rebuild, he supply’s bearings.

Hope this gives you clarity.
 

Sajk

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Hi @Sajk the clunk is becoming more common as these cars age now and when they start to clunk all depends on how they’ve been treated. We’ve fixed a few zeds with clonks here and it’s the Diff every time. The most common part in the diff is the crush sleeve loosing its preload allowing backlash in the gears, the second issue is a bearing beginning to fail allowing play in the gears. They’re very robust diffs so don’t tend to show any damage inside regardless of how bad the clonking is.

You should hear how much it clonks on my Zed, I believe this is the track days causing accelerated wear, bare in mind though most of these diffs now are over 20 years old.

We have a local diff guy, I supply the parts and oil and he charges us £300 for a rebuild, he supply’s bearings.

Hope this gives you clarity.
Thanks. This is a low mileage car. About 70k Kilos. But it did stand for a long time. I assume this requires taking the diff out completely?

Is it safe to leave alone?

EDIT

It also seems much worse when its cold. Once it warms up it lessens but that could be an illusion as I adapt my style to avoid the clunk.
 

Lee

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Thanks. This is a low mileage car. About 70k Kilos. But it did stand for a long time. I assume this requires taking the diff out completely?

Is it safe to leave alone?

EDIT

It also seems much worse when its cold. Once it warms up it lessens but that could be an illusion as I adapt my style to avoid the clunk.
Yeah this requires diff removal, a good hours work with experienced hands. I've driven for years compensating for it with no issues.

This comes back to what most owners say, they all do it...
 

motco

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I did a track day in my (then) 40k mile 2.2 Sport which has a Torsen diff. Mine always gives the impression that I haven't depressed the clutch pedal adequately and the synchro is struggling to prevent gear grinding. This is not the reason though, I'm sure of that because even when I press the pedal to the floor - way past the bite point - it will still clunk. It almost seems that the more care you take in the change to make it smooth, the more it clunks! However, back to the track day. My gear changes when 'pressing on' are as fast as the speed of my foot and hand plus the synchro baulking. There were NO clunks at full throttle maximum revs fast as possible changes! Make of that what you will, it baffles me. It has clunked ever since I bought it at 30,000 miles in 2009.
 

Lee

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I did a track day in my (then) 40k mile 2.2 Sport which has a Torsen diff. Mine always gives the impression that I haven't depressed the clutch pedal adequately and the synchro is struggling to prevent gear grinding. This is not the reason though, I'm sure of that because even when I press the pedal to the floor - way past the bite point - it will still clunk. It almost seems that the more care you take in the change to make it smooth, the more it clunks! However, back to the track day. My gear changes when 'pressing on' are as fast as the speed of my foot and hand plus the synchro baulking. There were NO clunks at full throttle maximum revs fast as possible changes! Make of that what you will, it baffles me. It has clunked ever since I bought it at 30,000 miles in 2009.
There are other various reasons that cause the clunk engaging gears, Guidbo, clutch hose.

But your no clonking under load is due to the drive train being loaded, if you were to back off the throttle and pause for a second you'll then notice a clunk re engaging.
 

Nodzed

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Have you checked the Guibo? It can be difficult to see if its failing but worth a check
 
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Sajk

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I am told that all the external components have been checked but I cannot say for sure its not the Guibo...

Thanks for the replies all...
 

t-tony

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Have the gearbox and Diff. oils ever been changed? Many won’t have at that mileage as BMW call them “filled for life” but it can make a difference. If you’re not sure if they have been changed it’s a relatively inexspensive way see if it would help.

Tony.
 

motco

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There are other various reasons that cause the clunk engaging gears, Guidbo, clutch hose.

But your no clonking under load is due to the drive train being loaded, if you were to back off the throttle and pause for a second you'll then notice a clunk re engaging.
Lee, I have removed the CDV long since and that made manoeuvring so much easier - less like a learner with the fly-by-wire throttle wavering the revs about to boot! I was out today in my 2.2i and came to the conclusion that I am at cross purposes with Sajk (OP) and that mine is not 'clonking' but it is a notchy gear change mechanism. His problem may well be one of the items you list or others suggest, but mine is local to the gear lever and is probably a feature of the marque.
 

Lee

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Lee, I have removed the CDV long since and that made manoeuvring so much easier - less like a learner with the fly-by-wire throttle wavering the revs about to boot! I was out today in my 2.2i and came to the conclusion that I am at cross purposes with Sajk (OP) and that mine is not 'clonking' but it is a notchy gear change mechanism. His problem may well be one of the items you list or others suggest, but mine is local to the gear lever and is probably a feature of the marque.
This is another issue altogether, give the gearbox oil a change and see if it gets better also swap out the clutch hose for a braided equivalent. Failing that it will be the shift pins or Indent pins others call them in the gearbox itself.
 

mwpe

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When I bought my Z it had 21,000 miles on the clock and I noticed a slight clunk which appeared to come from the diff area. It now has 151,00 and the clunk is still the same. I think the diff crush sleeve compresses to a degree in early life and then settles down.
 
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colb

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Life of the BMW Warranty period on a new car, when that expires they don't want to know, just pick your pockets
 

motco

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@Tony

No gearbox and diff oil as from factory. Will give that a go before surgery. Filled for life. Whose life?
That's the same as 'guaranteed for life'. When it fails that's the end of its life! It's a bare-faced con!
 
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