Diff mounting bush replacement advice.....

[dva99999]

Thanks to Antm72 for confirming the problem I have with the clunking noise.
I took a picture of the offending part but having looked at what's required, I'm not sure I'm in a position to tackle it. The exhaust needs to be dropped down to gain access but it also seems that I need to loosen some bolts on the drive in order to 'drop' it slightly to gain access.

I've had a quote from a Demon Tweeks for 3 hours @£60 per hour as I bought the Powerflex diff bush from them.

Any thoughts on this. I'd like to have a go especially if I'm currently looking at it in the wrong way.

Are there any guides as I couldn't find anything.

Thanks

 

[andyglym]

Thanks to Antm72 for confirming the problem I have with the clunking noise.
I took a picture of the offending part but having looked at what's required, I'm not sure I'm in a position to tackle it. The exhaust needs to be dropped down to gain access but it also seems that I need to loosen some bolts on the drive in order to 'drop' it slightly to gain access.

I've had a quote from a Demon Tweeks for 3 hours @£60 per hour as I bought the Powerflex diff bush from them.

Any thoughts on this. I'd like to have a go especially if I'm currently looking at it in the wrong way.

Are there any guides as I couldn't find anything.

Thanks

Hello mate, you could try Pelican Parts, it has a full Tec guide with pics on most things. Just Google Pelican Parts and follow the Tec Guide links.

 

[Low Rider]

Now i know someone posted on here recently about how they did their's

 

[GazHyde]

It's relatively straight forward to replace without dropping the back end of the car, been done by a few peeps on here. You should be able to see it from this picture.

The rubber core will just prise out with little effort but the worst bit is cutting the metal ring that surrounds the rubber in the bush - but with a sharp enough hacksaw it's OK.

The PowerFlex diff bush comes in three parts and can be pushed in by hand unlike the OEM style. Pics below shows one half of the bush inserted, and the second shows both sides and the central metal core.

 

[Low Rider]

It's relatively straight forward to replace without dropping the back end of the car, been done by a few peeps on here. You should be able to see it from this picture.

The rubber core will just prise out with little effort but the worst bit is cutting the metal ring that surrounds the rubber in the bush - but with a sharp enough hacksaw it's OK.
View attachment 30544

The PowerFlex diff bush comes in three parts and can be pushed in by hand unlike the OEM style. Pics below shows one half of the bush inserted, and the second shows both sides and the central metal core.
View attachment 30545

View attachment 30546

Excellent photos Gaz and info

 

[dva99999]

That's brilliant.....I've just been reading elsewhere on the forum that the powerflex bush is not the way to go in this instance. As it stiffens up that area it also transfers stress to other parts. (Why do I find bad things out after I've made a purchase...!)

Is this warning warranted?

 

[Antm72]

The powerflex will be fine , its more that you can fit it by hand rather than having to get the oem one pressed into the diff casing and then you have to remove it to fit it.
The zed shed has done multiple fittings without issue.
I would say the fact that the bush is solid means the give is far less than oem and the clunking of the diff moving sharply is likely to be of more detriment to the mount than any new bush

 

[dva99999]

Seems pretty clear cut then....will give a go tonight!

 

[GazHyde]

The PowerFlex was the only concession to poly bushes when we rebuilt the rear sub frame on my 2.2, just purely for ease of fitting.

 

[dva99999]

Having dropped the diff down ever so slightly I found the bush was fine, in fact it looked like it had been put on recently. My phone camera didn't pick out the full picture. This picture shows exactly what it looked like with a manufactured gap at the top and bottom. I didn't take a pic because I didn't have my camera but suffice to say I'm pleased that; a. It's not the mount and, b. I saved some money.
While the wheels were up I tried moving the drive shaft (?) backwards and forwards, left and right and there was slight movement, possibly around half an inch left and right at the most. Following the shaft in towards the diff, there was ever so slight movement of the joint that's (6) bolted to the diff. Each side turned about 1cm.
From looking at all the bushes I could find, none had deteriorated, all seemed to have been replaced recently and the rear left brake cable has a small split in it......

So what the hell is that clunk? Back to the drawing board!!

 

[Brian H]

Having dropped the diff down ever so slightly I found the bush was fine, in fact it looked like it had been put on recently. My phone camera didn't pick out the full picture. This picture shows exactly what it looked like with a manufactured gap at the top and bottom. I didn't take a pic because I didn't have my camera but suffice to say I'm pleased that; a. It's not the mount and, b. I saved some money.
While the wheels were up I tried moving the drive shaft (?) backwards and forwards, left and right and there was slight movement, possibly around half an inch left and right at the most. Following the shaft in towards the diff, there was ever so slight movement of the joint that's (6) bolted to the diff. Each side turned about 1cm.
From looking at all the bushes I could find, none had deteriorated, all seemed to have been replaced recently and the rear left brake cable has a small split in it......

So what the hell is that clunk? Back to the drawing board!!

If that is your bush in the first pick? If so this does not look too recent to me, you can see where the rubber is delaminating from the metal outer ring.

Many people have sought to get rid of the clunk when engaging gear, I personally think this is a trait of the car, albeit some worse than others, the movement in the prop and half shafts you mention will contribute to that noise, as they are put under load when you select first gear.

 

[Grumps]

I too have a "clunk" It seems very common on the old zeds. I have not investigated as yet as it tends to settle once I been running for a bit. Always at its worst when I first set off on a journey. It's definitely around the diff area tho. Reading this has spurred me into looking into it further but in the four odd years I've owned the car it's never gotten any worse.

 

[Lee]

I had the same clunk in my old 2.8 which still clunks, I also had it in my M which drove me mad trying to find it, I don't do noises. Eventually found it to be the backlash in the diff causing the clunk. I dropped the oil and removed the back cover so its easier to hear.

(Obviously sounds different with the oil removed and case off)

View: https://youtu.be/MR83kb5ME3c

 

[Antm72]

I thought mine looked ok and the play in the drive shafts is just back lash in the diff its there to allow the diff to expand when hot or it would seize.
When i looked for the problem it was odd.
I had test drove the car before purchase and not found any clunk present when i picked it up and drove it home it became apparent.
I too jacked the car up looked at the bush thought it looked ok and thought nothing of it when i drove the car after it had gone !
It reappeared when i swapped the wheels i can onky surmise that jacking the car altered the way the diff sat giving it repease.
Can you look at the diff mount with the car sat on the tarmac does it look to be held central in the mount or does it appear to sag? When i did mine it was sagging alittle the clunk when you read up on it is fairly common to a 2.8 by nature the bush is designed with the holes top and bottom the ///M version is solid.
As the rubber deteriorates it allows more free movement so the bolted pivit pont moves more in its free space creating the clunk.
Its a first and second gear trait normally and the faster your clutch action the louder it is.
If it looks ok then in your case maybe it is something else but with mine its totally removed any clunk at all.

 

[Grumps]

Mine seems worse when cold and like @Antm72 says in 1st and 2nd gears. Don't tend to here it after that. Certainly listening to @Lee video I'd say it was the same thing.

 

[Antm72]

Mine seems worse when cold and like @Antm72 says in 1st and 2nd gears. Don't tend to here it after that. Certainly listening to @Lee video I'd say it was the same thing.

When the diff heats up it expands which is probably why its a there when cold and improves

 

[Antm72]

Looking back at your first picture the diff does look like its sagging in the mount as mentioned by @Brian H it looks like its delaminating from the outer ring.
If may look fine when you drop it out as its not under load from the diff weight add the torque kick to worn bush and its gonna move more than you think.

 

[dva99999]

What made me think further was that when I'd unscrewed the bolt through the centre I had expected the rubber to fall out. When it didn't I tried easing, then pushing and finally wedging it out and it moved about 2mm.

I realised that the only way to get it out was to remove the rear casing off the diff via the bolts which I hadn't accounted for. If the bush wasn't going to budge then something was right.

I just screwed the bolt back up as tight as I could and took it out for a spin. I also changed my driving style by easing off the clutch more smoothly and this seemed to reduce the clunk somewhat. I think for the moment I won't change it, but will inspect it periodically.

I've ordered a new gasket from BMW and some more diff oil in case I do change it.

Thanks for your help though.....

 

[pgunter]

Also just a thought, have you considered getting your diff oil changed as well as the gearbox oil ?

 

[Grumps]

Also just a thought, have you considered getting your diff oil changed as well as the gearbox oil ?

I did mine Paul last service. 8t did improve slightly but still there.