M635 Diff mount

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BenM635i
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M635 Diff mount

Post by BenM635i »

Hello again gentlmen, been away from forum for a few months now so hope you are all keeping well. Seems the usual names are still about :lol:

Car has been in the garage for the last 7 months having a lot of bodywork done, she is back and i am well chuffed.. the guy who did the work has done me proud. Had rot chopped out of back arches inner and outer, work done on boot and wings and much new paint - she looks beautiful now. Will post up some photos once the sun comes out and i have proper camera.

For now though immediate question / concern is around diff and the mounting, know they can be weak and i asked the guy to check before he gave it back and the mouting seems very loose.

Photo here (if it works):

Image

Question is what part do i need to order, any idea if main stealer do it and any advice for swapping it out? Plan to do next week as scared to drive her 'properly' lest i see the diff in the road behind me!

Glad to be back, glad to have her back.. feel reunited
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tschultz
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Re: M635 Diff mount

Post by tschultz »

You want the 528e diff mount! Stronger and cheaper. Quite easy to replace too!
http://www.Drive4Corners.com
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BenM635i
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Re: M635 Diff mount

Post by BenM635i »

Cheers for the quick response, would the 528e mount be ok and interchangable on M635?
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tschultz
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Re: M635 Diff mount

Post by tschultz »

Worked on my 1988 M5 which looks to be the same mount as what you have pictured...
http://www.Drive4Corners.com
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BenM635i
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Re: M635 Diff mount

Post by BenM635i »

Legend, thank ye sir :)
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Ralph in Socal
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Re: M635 Diff mount

Post by Ralph in Socal »

tschultz wrote:You want the 528e diff mount! Stronger and cheaper. Quite easy to replace too!
The perfect answer!!

Ralph
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BenM635i
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Re: M635 Diff mount

Post by BenM635i »

So have the part number as 33171129786 - eBay sells a generic mount (Meyle) for about £32 but the only proper OEM part with that number as far (as i can tell) is available across the pond.

Will call the Stealer tomorrow and see if they can get the right part number.. failing that anyone know where to pick one up in good old UK?
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BenM635i
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Re: M635 Diff mount

Post by BenM635i »

QUick update - 33171129786 is available at Dealers for a princely price of £42+VAT (part is same but last 2 digits have changed.. fits M535i so happy days)

Picking it up tomorrow. Cant be bad.

Thanks gents.
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ron
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Re: M635 Diff mount

Post by ron »

BenM635i wrote:QUick update - 33171129786 is available at Dealers for a princely price of £42+VAT (part is same but last 2 digits have changed.. fits M535i so happy days)

Picking it up tomorrow. Cant be bad.

Thanks gents.
RealOEM gives a different part number for the M635 only.

http://www.realoem.com/bmw/enUS/showpar ... 3171130900

The part number you've got shows 635 only.

http://www.realoem.com/bmw/enUS/partxre ... series=E24
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BenM635i
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Re: M635 Diff mount

Post by BenM635i »

ron wrote: RealOEM gives a different part number for the M635 only.

http://www.realoem.com/bmw/enUS/showpar ... 3171130900

The part number you've got shows 635 only.

http://www.realoem.com/bmw/enUS/partxre ... series=E24
Hello Ron, seems that there are a multitude of mounts that are pretty much interchangable?

Read through this: http://www.mye28.com/viewtopic.php?t=63605

Opinion seemed to be that the part 33171125290 is the strongest one.. and also a quarter the price of the correct M6 one.

Ill pick the part up tomorrow and have a look.. has anyone definitively replaced their diff mount on a M635csi and if so whats the feedback? :-?
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BenM635i
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Re: M635 Diff mount

Post by BenM635i »

Ron nailed it.

Back in from the garden, chased inside by the rain / sleet in need of a cup of tea and warmth.

The M635CSI differential mount is different than the mount for M535 / 635.. so if anyone is thinking of buying a £42 instead of a £226 mount for their M635 then dont :wink:

The mount that many 'internets' say works ok and is interchangeable looks like this:
IMAG1944.jpg
IMAG1944.jpg (121.36 KiB) Viewed 9714 times
The M6 mount looks like this:
IMAG1945.jpg
IMAG1945.jpg (136.88 KiB) Viewed 9714 times
The M6 is a lot more substantial, larger and the total depth from chassis to diff mount point is approx 3cm greater.

Have just ordered one of the M6 mounts from BMW (Germany back order) which is annoying as it will take till end of the week to arrive.. so i put the old mount back in in case the jack slips. The old mount is very ruined and floppy for want of a better word, one side has completely detached so i reckon only a matter of time until it would have destructed making for an expensive repair.

Will try to return the £42 mount however its possible that ill have it up for sale end of next week for the cost of a few beers if anyone is interested.

Now if the snow will only stop i can get back out there and do the oil / filter and power steering fluid change.
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wattsmonkey
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Re: M635 Diff mount

Post by wattsmonkey »

That is very interesting.

The mount fitted to my diff was the "same as the others" type in initial appearance, but I'm sure there was some additional strengthening.

I cannot get my head round the added 3cm depth: the diff is a large case, same as the cooking 635. The greater depth would tilt the whole rear beam, wouldn't it? I'm trying to work out what the effect of this might be.

I'm really interested to see the new mount when you get it, if you don't mind taking pictures.

Many thanks for posting,

Rob
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BenM635i
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Re: M635 Diff mount

Post by BenM635i »

Rob, ill take a photo of all 3 side by side later this week once the new one arrives (new one is part number 33171130900).

The photos i stuck on above show the difference in the mount shape, the M635 is a lot more substantial than the one recommended for M535i which is part number 33171129784.

Key difference is also that the non M-mount thread is set much nearer the car chassis than the M635 mount. So the bolt that goes up through the diff into the mount will not reach the thread on the non M-mount ...

It might be possible to use the non M-mount however would need to find a longer bolt to go from diff to mount, also the diff would sit higher due to the lower profile of the non M-mount in comparison to the right part.

Hope above makes sense, ill post pictures Thursday / Friday and 'a picture is worth a thousand words' - especially mine :lol:
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BenM635i
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Re: M635 Diff mount

Post by BenM635i »

So, the saga continues.

On the left we have part number 33171129784 at around £50 inc VAT

On the right we have part number 33171130900 at around £270 inc VAT (yep, eye watering).
IMAG1949.jpg
IMAG1949.jpg (1.4 MiB) Viewed 9627 times
As you can see, they would 100% be interchangeable and i cant see how the £270 is superior apart from a fake golden colour - but it isnt gold despite the price as i bit it pirate style and it wasnt soft.

However they are not the right part for my M635... so have ordered 33171125290 which is £139 inc VAT - so mid range. This part # is what the BMW parts system has as an updated version of the £270 one (33171130900). The parts dealership missed the note saying to order this updated version when they ordered the gold / platinum / diamond crusted version.

So ill be back there in a few days to pick up one which i hope will look something like this :D
IMAG1945.jpg
IMAG1945.jpg (465.06 KiB) Viewed 9627 times
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Re: M635 Diff mount

Post by wattsmonkey »

This made me laugh: "it isnt gold despite the price as i bit it pirate style and it wasnt soft"

The part you got from BMW is the same as that fitted on my M: it is different from the standard one, but you have to look for the difference.

Thanks again for the pics: I'm embarrassed (no, I'm not really!) at how interesting I'm finding this.

Cheers,

Rob
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BenM635i
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Re: M635 Diff mount

Post by BenM635i »

Rob, nothing better than getting to the bottom of mystery part numbers and what fits 8)

So the saga concludes - part number 33171125290 is as below, costs £139 inc VAT and is the same as is fitted to my M6:
IMAG1955.jpg
IMAG1955.jpg (222.69 KiB) Viewed 9578 times
So now all i need is a dry day without ice on the ground then it can be fitted.
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Re: M635 Diff mount

Post by olympia57 »

Interesting as it looks very similar to the one fitted to my stock series one .
IMGP0467 - Copy (Medium).JPG
IMGP0467 - Copy (Medium).JPG (163.74 KiB) Viewed 9569 times
Can I ask you to confirm what the difference is between the two ?
Thanks
Don
m6 diff mount (Small).jpg
m6 diff mount (Small).jpg (86.29 KiB) Viewed 9569 times
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Re: M635 Diff mount

Post by BenM635i »

Hi Don,

Yes design looks similiar i.e. metal plate bonded to the rubber.

2 main reasons i needed this rather than the 'normal' part.

1) was the height as you have asked about, this part has 51mm where as the height of the 'usual' part numbers was about 10-15mm less, so the diff would have been nearer the chassis once bolted up on the other 2

2) the thread where the bolt goes into though the diff casing. The other part numbers had the thread set nearer the chassis, whereas this one has the thread starting near the face of the mount nearest the floor. Not sure that this is the best explanation. Another way to say it is that the other mounts need a longer bolt to go through the diff into mount, where as this mount needs only around 35mm of thread on the bolt.

Photo here:
IMAG1959.jpg
IMAG1959.jpg (1.03 MiB) Viewed 9551 times
This one actually seems good value at £139, its very substantial in comparison to the other versions and has extra rubber bumpers that damp against the large metal plate.
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wattsmonkey
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Re: M635 Diff mount

Post by wattsmonkey »

That is really interesting now.

Don: I'm guessing yours is the centre mount type for the early medium case dif.
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Re: M635 Diff mount

Post by olympia57 »

wattsmonkey wrote:That is really interesting now.

Don: I'm guessing yours is the centre mount type for the early medium case dif.
I " think " so Rob. Mine has the oil cooler fitted, but is an open diff.
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Re: M635 Diff mount

Post by wattsmonkey »

The bit I'm struggling with is the extra height of this supermount.

I'm absolutely certain that my 9/86 build M635 did not have this type fitted as the witness marks on the mount support beam show only the "other" sort, where the centre section of the mount is not in contact with the body.

I can't believe your diff is any different from mine - it will be the 3.73:1 large case LSD, with the same offset lug on the backplate. The extra depth will cock the front of the diff at a more acute angle, pushing the rear of the prop up towards the body of the car.

I dare say the change in angle isn't significant: the whole rear beam must move up and down on the bushings by more than this.

Yes, brain in musing mode!

Cheers,

Rob
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Re: M635 Diff mount

Post by wattsmonkey »

olympia57 wrote:
I " think " so Rob. Mine has the oil cooler fitted, but is an open diff.
Now I've got oil cooler AND super diffmount envy!
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Re: M635 Diff mount

Post by olympia57 »

Ben , my apologies if I'm being dumb here but when you say that the first one is 3cm lower than the second does that mean that the first is 21mm from chassis to diff mount face ?
IMAG1944 (Small).jpg
IMAG1944 (Small).jpg (89.48 KiB) Viewed 9530 times
IMAG1959 (Small).jpg
IMAG1959 (Small).jpg (102.21 KiB) Viewed 9530 times
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BenM635i
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Re: M635 Diff mount

Post by BenM635i »

olympia57 wrote:Ben , my apologies if I'm being dumb here but when you say that the first one is 3cm lower than the second does that mean that the first is 21mm from chassis to diff mount face ?
Hey no way sir, my explanations are not always the best :wink: Unfortunately i didnt measure the original one, however i would say the original are ~10-15mm less in height from chassis to diff mount face than this last one.

Rob, yes my diff must be at a slightly different angle than yours if we are on the different mounts. I could likely have used the original mount i ordered (that you have) however on mine the diff would then have been higher by 10-15mm and have less angle. Also, i would have needed a longer single bolt as the thread on your mount is set nearer the chassis than on whats now termed 'the man supermount' :D

Not had a chance to fit this yet but its definitely whats on there now.

Also, this is the part that BMW's system comes up with ... however this part is ordered only if the dealer reads the additional comment on the system advising of an update. If they dont, they order the fake gold mount for £250+... then they have to send it back to Germany and reorder the supermanmount for £139.
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