Rebuilding M635 Bilsteins

Post in this forum for topics relating to suspension, steering, and brakes

Moderators: GRNSHRK, ron, bfons

User avatar
Brucey
6 Series Guru
6 Series Guru
Posts: 10077
Joined: Fri Apr 09, 2004 7:17 am
Location: Cambridge, UK

Post by Brucey »

bpoliakoff wrote:Anyone thinking Bilstine will honor the life time warranty may be in for some bad news. Bilstine will only warranty the shocks if you have the original bill of sale showing they came from a retailer. Reason being they don’t want to honor the warranty if ther shocks were bought on Ebay etc, but if it is a parts place they will then honor the warranty. Again a purchase receipt is required.
I think it is important to stress that (as I understand it) this warranty is offered by Bilstein's US distributor. Elsewhere Bilstein shocks (sold in the UK, Germany etc) do not carry the same warranty at all.

cheers
~~~~~~~~~~~~Brucey~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
User avatar
Brucey
6 Series Guru
6 Series Guru
Posts: 10077
Joined: Fri Apr 09, 2004 7:17 am
Location: Cambridge, UK

Post by Brucey »

DRPM635CSi wrote: From RealOEM, I've got my rear shocks coming out as being BMW part number 33522225150. Does that mean they're not these B46-0725 model?.....
I don't know. Like the front insert BMW part number mentioned above, I can't find a X-ref anywhere

If you have the original shocks to this PN they will have a load of numbers on them including the Bilstein number which should be meaningful.

*** Reminder*** I have long anticipated this kind of problem hence I started a thread called 'an appeal for Bilstein information' or somesuch; contributions to this thread have thus far been conspicuous by their absence... So anyone who has original shocks (to obscure BMW PNs) we could do with all the numbers on them so that we can find the correct X-refs in the future.

cheers
~~~~~~~~~~~~Brucey~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
User avatar
DRPM635CSi
Posts: 280
Joined: Thu Jul 09, 2015 6:50 am
Location: Perth, Australia
Contact:

Post by DRPM635CSi »

Brucey wrote:
DRPM635CSi wrote: From RealOEM, I've got my rear shocks coming out as being BMW part number 33522225150. Does that mean they're not these B46-0725 model?.....
If you have the original shocks to this PN they will have a load of numbers on them including the Bilstein number which should be meaningful.
Okay, I've jacked up the rear of the car and taken photos of all the numbers I can find on these rear shocks while still mounted in the car. On one side is clearly stamped "Bilstein BMW Made in Western Germany and then below that the number 33.52-2225 020.9

Opposite that on the other side is the number 5150725W00. See photos. I can't find any other identifying marks on them other than a strip of green paint which may well be completely meaningless. The shafts measure on my very dodgy plastic verniers Ø10.44mm

Image Image Image

Gallery
User avatar
Brucey
6 Series Guru
6 Series Guru
Posts: 10077
Joined: Fri Apr 09, 2004 7:17 am
Location: Cambridge, UK

Post by Brucey »

OK, from those numbers I am 99% sure that those shocks are B46-0725 Bilsteins, as you would find on all other M635 models. The chances are excellent that the fronts are the matching PN too; you'll find that out when you strip the suspension down and you can get a look at the PNs.

The lack of X-ref data to the Japanese spec BMW part numbers may well be just because the number of cars made with those PNs was very small. Possibly BMW issued a separate PN in expectation of using different damping rates, but then either didn't, or made changes that were so small that they were covered within one Bilstein part# anyway.

Thought; what diameter are those springs? M635 normally uses a larger dia rear coil but those are not obviously like that to me. If they are the standard diameter for other E24 then this would make the shock body the same bilstein PN as normal (for an M635), but a different BMW part number because the (detachable) spring perch is different, and BMW supply the whole thing as one. Similarly the fronts may use a different (rate) spring to other M635s and this may mean a different internal bump stop is fitted to the damper insert. Again this could be a single Bilstein PN (I think they may have issued suffix numbers for small variations like this) but again a different BMW PN.

cheers
~~~~~~~~~~~~Brucey~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
User avatar
DRPM635CSi
Posts: 280
Joined: Thu Jul 09, 2015 6:50 am
Location: Perth, Australia
Contact:

Post by DRPM635CSi »

Brucey wrote:Thought; what diameter are those springs?
I didn't measure that while I was in there but I could do this tomorrow is it's important. Are you querying the steel rod diameter or the coil diameter, or both? I can get the rod dia pretty easily with my plastic verniers, but for the coil with them in the car I'll have to tape measure them and apply some basic mathematics for an outside Ø only, not a PCD of course.
Brucey wrote:M635 normally uses a larger dia rear coil but those are not obviously like that to me.
These are the springs it came with from BMW. Nothing's been toyed with in the suspension of this car since it was built other than me adding front and rear strut braces across the tops of the towers. Front by Mason Engineering in the US and the rear one is the standard BMW-issue reinforcement one from the E28 towing pack, but aside from that, it's completely bog-standard complete with big lean down on the (RHD) driver side to compensate for a (non-existant) LHD driver's weight.
User avatar
Brucey
6 Series Guru
6 Series Guru
Posts: 10077
Joined: Fri Apr 09, 2004 7:17 am
Location: Cambridge, UK

Post by Brucey »

standard (non-M) E24 rear springs are about 96-97mm outside diameter, and M635/M6 springs are normally a larger size than that.

Actually now I look at your pictures again they do look like the larger springs...

cheers
~~~~~~~~~~~~Brucey~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
User avatar
DRPM635CSi
Posts: 280
Joined: Thu Jul 09, 2015 6:50 am
Location: Perth, Australia
Contact:

Post by DRPM635CSi »

Brucey wrote:Actually now I look at your pictures again they do look like the larger springs...
Yeah they should be. Raining here today so I can't easily jack the car back up and measure them, but I would not expect anything unusual.

Seem to be making some progress here now with the local Bilstein agency. Appear to be slowly winning the battle against the throwaway attitude steering me toward just buying new ones. They're still pushing me to accept a rebuild using new (larger dia) shafts simply because the seals for the Ø10.5mm shafts are officially NLA. However I have had an admission that they know Germany do unofficially hold a 'secret stash' of old size seals not officially recorded in their stock control computers for just such occasions as when one of the car manufacturers want to restore one of their personal museum vehicles to original spec. It is this 'secret stash' of obsolete perishables that needs to be accessed now for these shock to be rebuilt.
User avatar
Brucey
6 Series Guru
6 Series Guru
Posts: 10077
Joined: Fri Apr 09, 2004 7:17 am
Location: Cambridge, UK

Post by Brucey »

DRPM635CSi wrote:
Seem to be making some progress here now with the local Bilstein agency. Appear to be slowly winning the battle against the throwaway attitude steering me toward just buying new ones. They're still pushing me to accept a rebuild using new (larger dia) shafts simply because the seals for the Ø10.5mm shafts are officially NLA. However I have had an admission that they know Germany do unofficially hold a 'secret stash' of old size seals not officially recorded in their stock control computers for just such occasions as when one of the car manufacturers want to restore one of their personal museum vehicles to original spec. It is this 'secret stash' of obsolete perishables that needs to be accessed now for these shock to be rebuilt.
eh? You can still buy new ones to this PN can't you? Don't these have the same size shafts as ever they did?

cheers
~~~~~~~~~~~~Brucey~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
User avatar
DRPM635CSi
Posts: 280
Joined: Thu Jul 09, 2015 6:50 am
Location: Perth, Australia
Contact:

Post by DRPM635CSi »

Brucey wrote:You can still buy new ones to this PN can't you? Don't these have the same size shafts as ever they did?
Well, no, I don't think you can. RealOEM doesn't recognise the part number on my OE shocks anymore at all. Part number 33.52-2225 020.9 (even without the .9 on the end), simply doesn't exist anymore according to the latest ETK. It's now part number 33 52 2 225 150. So the 020 shock has been replaced with a 150.

Now I don't know what that means from an actual practical stand point, but maybe it means the BMW shock (if you purchased one new from your local BMW (st)ealer's parts dept.) now comes with an Ø11mm or Ø14mm shaft, which are the two sizes Bilstein Australia are threatening to rebuild my shocks to if they can't get the Ø10.5mm shaft seals they claim are officially NLA.

BTW: I did get confirmed agreement from Bilstein Australia that my rear shocks with their 5150725W00 part number are indeed better known as Bilstein B46-0725, so that much is confirmed correct. They also advised that to Bilstein 'W' numbers mean Original Equipment which means that typically their service departments do not have access to them to sell as replacement units and following on from that, that replacement parts for them will not be easy to obtain either due to the life-long contractual supply agreements entered into with the car manufacturers.
User avatar
Brucey
6 Series Guru
6 Series Guru
Posts: 10077
Joined: Fri Apr 09, 2004 7:17 am
Location: Cambridge, UK

Post by Brucey »

the only different between B46-0725 and countless other Bilstein rear shocks (all still made AFAICT) is the shim pack inside the shock. All the other parts are common Bilstein parts.

You can still buy the other E24-fit shocks and AFAIK they all have the same shock shaft diameter (can someone check a recently purchased set?); they are basically identical to BMW OEM Bilsteins, with perhaps slightly different valving and in some cases different grooves in the outer body, or a different stroke (which sometimes means a shorter or longer shaft but can equally mean different spacers inside the shock).

In the US and the UK they can be rebuilt and in the US they are sold with a lifetime warranty; this wouldn't be worth the paper it is written on if the spare parts were not available.

So I am wondering what they are on about; You can buy B46-0725 as a Bilstein spare or the same thing (for more money I expect) via BMW. It'll be the same story about your front insert too I expect.

BTW unless your shocks have leaked the seals will likely be fine anyway. People tear apart similar shocks every weekend if necessary and they don't always replace the seals. The main benefit of stripping the shocks is to change the oil for clean fresh stuff that is still in grade and isn't loaded up with wear debris.

BTW if you are trying to read a BMW part number off an old BMW part, forget it; they appear to have used 'in production' numbers (or something) that mean nothing later on when you type them into the ETK. This goes for shocks, head castings, a whole bunch of stuff. In most ETK versions you can look up the history of a current BMW part number and it will list all previous part numbers that were used for the same job. If the part number has never been superseded, the part should be identical in every respect.

IME the Bilstein part number (which has a W in it on OEM shocks) is meaningful if the shock existed prior to a certain date i.e. when rear shocks for E24 were listed as B46-XXXX and fronts as P36-XXXX . In each case the XXXX number appears in the Bilstein mark.

cheers
~~~~~~~~~~~~Brucey~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
User avatar
DRPM635CSi
Posts: 280
Joined: Thu Jul 09, 2015 6:50 am
Location: Perth, Australia
Contact:

Post by DRPM635CSi »

Brucey wrote:So I am wondering what they are on about; You can buy B46-0725 as a Bilstein spare or the same thing (for more money I expect) via BMW. It'll be the same story about your front insert too I expect.
I agree completely. It's just a case down here of them wanting to stick steadfastly to their throwaway society mantra as hard as possible. They've got stock sitting on their shelves in boxes ready to go, and they would MUCH rather sell me that than mess about rebuilding a set of 30 y.o. shocks. That's the simple truth. They make a tonne more profit from selling me something in a box they don't even have to open and best of all they carry no responsibility if it fails or is otherwise knackered in the warranty period. That responsibility just goes back on the factory and they're no more disadvantaged by it. All profit and no care. That's the modern way of doing business and they will come up with whatever excuse or story they have to to steer you into making that decision. New is always better than old. Old things should be thrown away into landfill. They're too much trouble. Not worth repairing.

You should just throw your bunky old clapped out M635 away to the crushers and get a modern up to date car like an idecream container white Toyota Camry with bluetooth and Facebook & Twitter and built-in Instagram and Pinterest & Snapchat and more bollocks than you can poke a stick at so it beeps at you constantly. Your M635 is shit and hopelessly outclassed by modern, safer plastic cars. This is the overriding mantra that exists down here. We don't get shows like Car SOS or The Classic Car Show or For The Love of Cars down here. We get endless shyte about cooking, dancing, singing, gardening, home renovation DIY, dating, shaming & weird American so-called celebrity self-centred 'reality' shows usually about someone named Kardashian. People down here have no idea what a classic car even is. There is no classic car culture in Australia.

I have been told everything you can imagine so far. The seals are NLA, your shafts are bent, they're corroded. The seal running surfaces are worn. It'll cost much more to rebuild these than it will to just buy new ones. We won't warranty anything rebuilt, whereas you'll get a 5 year warranty on new ones. Just the postage cost across the country to the rebuilders in Sydney will be more than new shocks from the local suspension shop. They're old technology that even if rebuilt will be hopelessly unsafe and uncomfortable on modern roads in modern traffic conditions than newer shocks... you name it, I've already been told it. Anything to convince me to just throw them away and buy new ones.

You have to be REALLY determined, willing and able to take on a lot of the running around yourself down here to get what you want done rather than what someone else wants to do.
wattsmonkey
Platinum Member
Platinum Member
Posts: 1649
Joined: Mon Jul 16, 2007 2:58 pm
Location: Cheltenham, U.K.

Post by wattsmonkey »

Well, I've just given up on getting the parts I need from Bilstein. I have just fitted new shocks to my M635, bought from Walloth and Nesch for just over £300 delivered.

Cheers,

Rob
"Most of it necessary; all of it enjoyable." LJKS
'84 635CSi, dogleg...itbs and supercharger????? Eaton Mess
User avatar
DRPM635CSi
Posts: 280
Joined: Thu Jul 09, 2015 6:50 am
Location: Perth, Australia
Contact:

Post by DRPM635CSi »

wattsmonkey wrote:Well, I've just given up on getting the parts I need from Bilstein. I have just fitted new shocks to my M635, bought from Walloth and Nesch for just over £300 delivered.

Cheers,

Rob
I for one woud dearly like to know what Ø shafts those new shocks come with. There's nothing on the Walloth & Nesch website to say these are anything other than bog standard straight Bilstein Sport shocks (which are available anywhere from Bilstein dealers. They certainly don't go out of their way to demonstrate to any degree that these are the identical units as fitted OE to the M635. I rather suspect they're not.
wattsmonkey
Platinum Member
Platinum Member
Posts: 1649
Joined: Mon Jul 16, 2007 2:58 pm
Location: Cheltenham, U.K.

Post by wattsmonkey »

Fitted to the car now, sorry. Diameter appears identical to original shocks, but I understand you're after precise dimensions.

They are certainly much firmer than the originals!

Rob
"Most of it necessary; all of it enjoyable." LJKS
'84 635CSi, dogleg...itbs and supercharger????? Eaton Mess
User avatar
DRPM635CSi
Posts: 280
Joined: Thu Jul 09, 2015 6:50 am
Location: Perth, Australia
Contact:

Post by DRPM635CSi »

Thought it was about time for an update on proceedings down here. Suspension is now all out of the car which is looking a bit sad sitting up on chassis stands.

Shocks are all over in Sydney at Bilstein Australia and I can confirm without doubt a few things:
Front inserts are indeed Bilstein part number P36-0242 as advised
Rear tubes are Bilstein part number B46-0725 as advised
Front inserts do definitely have internal rebound springs which is complicating their reassembly somewhat, however it doesn't appear to be a show-stopper.

All have Ø10.5mm shafts and the seals for them are hard to come by, however they have found a set for mine and are rebuilding them back as per original spec.

New rear bump stops, top bushes & top mount gaskets have arrived today from the US for the refitment. Springs are all out and marked for refitment. They all look fine to me. Haven't looked at their standing height just yet to see if they could use some swapping around to take out the LHD lean chassis bias, but will check that out.

That's about all for now, will take some photos when I next go back down to the workshop before the shocks come back. Hopefully car will be a runner again in about another week & a half.

Edit: Here's the shock dyno trace of the before & after rebuilt stock shocks. Anyone care to interpret for me?
https://dl.dropbox.com/s/6y5oiny8xqhadq ... traces.pdf
User avatar
DRPM635CSi
Posts: 280
Joined: Thu Jul 09, 2015 6:50 am
Location: Perth, Australia
Contact:

Post by DRPM635CSi »

Suspension is all back together now and low-speed damping has been restored to the car. Rides nice again without needing dentistry work after every drive.

Couple of annoying aspects from doing this work though. The replacement front top strut mounts by Lemforder/ZF have a larger opening in them such that the sealing caps no longer fit to stop dirt & moisture getting in and polluting the ball bearing. I am having to try and source some O-rings to use as packers to get them to fit and seal the opening.

Secondly, removal of all the struts obviously necessitated all the ABS proximity sensors having to be removed, which of course cracked away all the brittle insulation from around the wires. Upon refitment, this has resulted in the signal strength from all of them being way too low now, such that the ABS pump operates at very slow speeds because obviously some flags on the trigger wheel are being missed by the prox & this is interpreted as a locked wheel. So as you pull up to a slow controlled stop, you suddenly lose all brake pressure when the ABS pump releases it to stop what it thinks is a locking wheel. Most unnerving. So now I have to replace all the wheel ABS sensors too. Not planned for :-(
m6dave
Posts: 376
Joined: Sun Oct 04, 2009 10:50 am
Location: New South Wales Australia

Post by m6dave »

DRPM635CSi wrote:Suspension is all back together now and low-speed damping has been restored to the car. Rides nice again without needing dentistry work after every drive.

Couple of annoying aspects from doing this work though. The replacement front top strut mounts by Lemforder/ZF have a larger opening in them such that the sealing caps no longer fit to stop dirt & moisture getting in and polluting the ball bearing. I am having to try and source some O-rings to use as packers to get them to fit and seal the opening.

Secondly, removal of all the struts obviously necessitated all the ABS proximity sensors having to be removed, which of course cracked away all the brittle insulation from around the wires. Upon refitment, this has resulted in the signal strength from all of them being way too low now, such that the ABS pump operates at very slow speeds because obviously some flags on the trigger wheel are being missed by the prox & this is interpreted as a locked wheel. So as you pull up to a slow controlled stop, you suddenly lose all brake pressure when the ABS pump releases it to stop what it thinks is a locking wheel. Most unnerving. So now I have to replace all the wheel ABS sensors too. Not planned for :-(
Hi Dean
Measure the new cap size you need, it is probably 32mm, check here the part number is listed, Pelican parts have them for $3 each.
http://www.realoem.com/bmw/enUS/showpar ... Id=31_0082
http://www.pelicanparts.com/catalog/Sup ... .htm#item6
cheers
Dave
User avatar
Brucey
6 Series Guru
6 Series Guru
Posts: 10077
Joined: Fri Apr 09, 2004 7:17 am
Location: Cambridge, UK

Post by Brucey »

DRPM635CSi wrote: ......removal of all the struts obviously necessitated all the ABS proximity sensors having to be removed, which of course cracked away all the brittle insulation from around the wires. ...... So now I have to replace all the wheel ABS sensors too. Not planned for :-(
you don't have to remove the ABS sensors; if they come out very easily, fine, but it is usually best to leave them in the strut, and to disconnect the wiring harness on the yellow plugs, one for each sensor, eg just through the inner wing on the fronts.

If I had a quid for every time someone wrecked an ABS sensor quite needlessly, I'd be considerably wealthier than I am; as it is, the correct new ABS sensors are pricey little blighters....

Glad your suspension is in good shape now.

BTW a cheap fix is to use insulation tape round the strut top plug...

cheers
~~~~~~~~~~~~Brucey~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
User avatar
DRPM635CSi
Posts: 280
Joined: Thu Jul 09, 2015 6:50 am
Location: Perth, Australia
Contact:

Post by DRPM635CSi »

m6dave wrote:Measure the new cap size you need, it is probably 32mm, check here the part number is listed, Pelican parts have them for $3 each.
http://www.realoem.com/bmw/enUS/showpar ... Id=31_0082
http://www.pelicanparts.com/catalog/Sup ... .htm#item6
cheers
Dave
Thanks Dave, you're dead right... Ø32mm is correct. I bought some Ø28x2mm o-rings today to use as packers around the old caps, but it doesn't work. Oh well, I have to buy three new ABS wheel sensors now anyway to get the ABS working again, so I'll just add these on that order. It'll all be coming from OS of course because it's utterly pointless even asking the question of parts for these cars from anyone actually within Australia now.

Can't even get windscreen wiper blades for BMWs this old over here anymore. Windscreen wiper blades!! No kidding. I just add a couple of wiper blades now to every order I place overseas whether they need replacing right now or not. I'm not paying separate international postage on wiper blades on their own! Support for these old cars now has almost complete evaporated over here. Getting really hard.
User avatar
DRPM635CSi
Posts: 280
Joined: Thu Jul 09, 2015 6:50 am
Location: Perth, Australia
Contact:

Post by DRPM635CSi »

Brucey wrote:you don't have to remove the ABS sensors; if they come out very easily, fine, but it is usually best to leave them in the strut, and to disconnect the wiring harness on the yellow plugs, one for each sensor, eg just through the inner wing on the fronts.
To be fair, they were well & truly rooted anyway before anyone laid a spanner on the suspension at all. All the thick rubber insulation/shielding encasing the two wires to the prox switch was all hard, brittle & cracking. All you had to do was barely look at them the wrong way and big chunks of insulation would fall off. I don't know if that insulation is only there for impact damage protection from road schrapnel being so close to the revolving wheel or whether it also provides EM interference shielding as well in a cheap and nasty alternative to proper co-ax type cabling, but I do know that my signal strength from my old sensors now with the insulation all cracked off them varies between 60-150mA, whereas the one brand new one just fitted to replace the dead one on left rear wheel is outputting over 200mA.
the correct new ABS sensors are pricey little blighters....
Yes they are, I'm finding this out right now.
BTW a cheap fix is to use insulation tape round the strut top plug...
Thought of it already, but a little bit too dodgy for me. I'll do that as the temporary fix though until I can get the larger ones seeing as how my O-ring solution was a massive FAIL.
rhanley 635csi89
Bigcoupe Contributor
Bigcoupe Contributor
Posts: 323
Joined: Wed Sep 10, 2014 12:08 am
Location: Arden, NC 28704

Strut Caps

Post by rhanley 635csi89 »

I had the same issue with the smaller strut cover cap, used Permatex, Ultra Black Gasket Maker around the edge to hold them in place, holding well for nine months . I'll order the 32mm, didn't enter my mine they were even available.
I'm still running the ABS cables with the a lot of the insulation broken off, so far, so go.
89 635CSiA (11/88 build)
AlpineWeiss II (218)/Natur(0200)
87 L6 635CSI Sold
87 MB 560SL Sold
User avatar
Brucey
6 Series Guru
6 Series Guru
Posts: 10077
Joined: Fri Apr 09, 2004 7:17 am
Location: Cambridge, UK

Re:

Post by Brucey »

DRPM635CSi wrote: Wed Sep 09, 2015 4:46 am Shocks are all over in Sydney at Bilstein Australia and I can confirm without doubt a few things:
Front inserts are indeed Bilstein part number P36-0242 as advised
Rear tubes are Bilstein part number B46-0725 as advised
Front inserts do definitely have internal rebound springs which is complicating their reassembly somewhat, however it doesn't appear to be a show-stopper.

Edit: Here's the shock dyno trace of the before & after rebuilt stock shocks. Anyone care to interpret for me?
https://dl.dropbox.com/s/6y5oiny8xqhadq ... traces.pdf
a long time ago now but I missed the shock traces first time round and now I can't access them, the link doesn't work.

Anyone able to see them, then or now?

cheers
~~~~~~~~~~~~Brucey~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
User avatar
hornhospital
Platinum Member
Platinum Member
Posts: 2931
Joined: Sun Jul 11, 2010 6:46 pm
Location: Silverhill, AL
Contact:

Re: Re:

Post by hornhospital »

Brucey wrote: Wed Feb 14, 2018 11:31 am Anyone able to see them, then or now?

cheers
Nope. "Failed-forbidden" is what comes back when you attempt to download and open the .pdf.
Ken Kanne
'84 633CSi "Sylvia"; '85 635CSi "Katja";'85 325e "Hazel Ann"; '95 M3 "Ashlyn"
Post Reply