Servo ABS Unit Parts?

Hunda67

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Since the dreaded brake failure last year I have finally got round to investigating the ABS/Servo module itself.

First I tried all the usual:

Check brake lever switches - both OK.
Check wheel sensors - all OK.
Check wiring - all OK.
Flushed system through with new brake fluid - no difference still getting brake failure.

So before going with the servosectomy decided to remove the ABS/Servo module and take a look to see if anything was fixable.

Once out I checked the pressure relief valves as instructed here: http://forum.hexcode.co.za/forum/index.php?topic=4.0 - these seemed OK to me. I then checked the filters as described here: http://www.ukgser.com/forums/showthread.php/254381-A-simple-fix-for-some-brake-servo-problems?p=2601718#post2601718

I took the unit apart as far as I could. At the back of the unit there is a plate with two pressure switches inside bolted on:


It looked fairly grubby in there so I cleaned it up and noticed one of the switches had a hairline crack which then came apart when it was touched so I'm guessing this is my problem:


I have had a good Google around and can't find anywhere to get these switches.

I don't suppose anyone on here knows where to get some from?

If not I'm guessing next step is Servosectomy or get another complete unit from somewhere and hope it's switches are good.
 
I have a removed unit here If you want I can have a look and see what they are like in it?

Electronics box was retained on the bike

Its just lying on the shelf

P.S. can you see how to unplug them?
 
That would be great if you could - would be happy to buy from you.

I removed the electronics unit and just unplugged them from there (there are two little multipin connectors on the PCB - one for each pair of switches). My broken one is on the back of the unit - the cable just runs through a sort of tunnel through to the electronics unit. There is also an identical plate with switches on mounted on the inside behind the electronics unit.

I can take some pictures tomorrow of the disassembled unit if it helps.

Thanks.
 
I have on in the workshop, it may be good i dont know. You can have it if you stump up for the postage.
 
I'd hazard a guess its some sort of Piezo or similar pressure switch

Mart
 
It seems to be a small circuit board with an IC on it some other surface mount components - I guess it's more than an on/off pressure switch.

DrFarkoff - I'll happily have both sets of switches out of your unit - I'm guessing maybe at least one of your sets has gone too maybe. It's up to you if you want to get them out yourself or sell the whole remaining unit. I'll certainly give you postage costs and a bit extra for your trouble. I'll send you a PM with my e-mail etc. Do you want me to take some pictures of how to get the switches out etc. and post them on here?

Thanks.
 
patzx12 - sorry I've just noticed your offering switches as well. Much appreciated.

Thanks to you all.

I'll post some pictures tomorrow of getting the switches out of the unit.
 
This company in Germany repairs ABS units for BMW motorcycles (inclusive the servo ABS) and other vehicles:
https://rhelectronics.de/
I do not know if they would sell parts, but you could ask I guess.

Good luck with your repair anyway.
 
So here's how I got out the switches:

First I undid the electronics unit by undoing the silly 5 pointed security torx things and folded down the electronics unit:


I then removed the two multipole connectors for the pressure switches (white connector is for the switches on the back of the unit and black connector is for the internal pressure switches). The connectors just pulled straight up (a small flat bladed screwdriver can help with leaverage):




Next to remove electronics unit completely I had to disconnect the cables going to the servo motors and abs coils. I removed these by grabbing the plastic connectors with a pair of long nosed pliers and pulling gently with a little bit of wiggle to get the connectors moving:




The electonics unit is now completely free:


Next the next assembly was removed by undoing the 4 T25 bolts shown (once the bolts were undone a bit of pulling is required as there is some instant gasket holding the assembly in place):




That leaves view of the tunnel through the unit that the cable the rear mounted switches runs through:


The rear switch assembly can be removed by undoing the 4 security bolts and levering off with a knife blade (instant gaskety sticky stuff again) and pulling the cable and connector carefully through the tunnel:




The front switches are attached to the assembly removed after removing the electronics unit by undoing the 4 security bolts and lifting out:


In my unit the rear switches (along with being broken) were very gummed up with dirt etc. whereas the front ones were much cleaner and looked like new so I'm guessing these front ones are more likely to be working properly. The cable is shorter on the front ones but I reckon extending the cable to use these at the rear of the unit would be doable with some ribbon cable, careful use of a soldering iron and some bits of heatshrink. I'll give it all a go if the generous folks on here are going to help with suppying me their switches.

Thanks guys.
 
You have done a really top job here and I will be interested to find out just how this ends. If these switches are the problem how are owners going to be able to get their hands on replacements though? I fear that the manufacturers have us by the short ones even if you do find out that the fix works.

edit
Looking at the actual unit and the workings of it ... is it really surprising that there are problems with the function of this unit? It looks like a piece of shoite that is made in someone's shed rather than a part that is going to cost £1500 to replace. I mean from the point of view of some very complicated electrics coupled to a heap of shite engineering which looks to be reliant on absolutely gunge free operation... you can understand why the brake fluid has to be changed every third lamppost or 250 m which every comes sooner. There looks to me at least to be a concern whether this is a reliable system to fit to a machine that is going to be subject to immense levels of humidity!!!!!!!!!!!!!!!
 
I was surprised how much gunge was around the rear switches - wether or not that had anything to do with mine breaking I have no idea. Now I am no expert on braking systems (or hydraulics for that matter which is what a lot of it looks like to me) but there are some very narrow pipes that the fluid flows through - I am sure these could gum up very easily.

I tried https://rhelectronics.de/ for some spare parts but their only wanted me to send them the unit and they'll try to repair it - that option was going to cost €900 plus postage of the whole unit to Germany and back with no guarantee of repair (they were going to charge €200 if they couldn't fix it) - I can't justify spending that sort of money on the bike. I was just going to go for a sevosectomy but thought I might as well try - nothing to lose except some of my time trying. I will keep this post updated with how I get on.
 
I was surprised how much gunge was around the rear switches - wether or not that had anything to do with mine breaking I have no idea. Now I am no expert on braking systems (or hydraulics for that matter which is what a lot of it looks like to me) but there are some very narrow pipes that the fluid flows through - I am sure these could gum up very easily.



For me this is the essence of the matter. It is a unit that relies on very precise electrical impulses ... but the whole show is doomed to failure because of the problems of the brake fluid reacting with water vapour and the effect this has with the alloy of the unit itself and gumming up of very fine passaging for the fluids in short its shite! I have a crappy Renault Laguna II it is more than 14 years old and has it had any problems with its ABS .... not a bit of it and the brake fluid has never been changed in that time and 80k miles since new!
 
BMW always seem to re-engineer stuff for the sake of it and usually not for the better.
The clutch is another example back to front design with over-hung gearbox shaft. An ordinary car clutch with toroidal slave cylinder would just as well. And be more reliable.

Even the heated grips are bespoke so cost silly money to replace - apart from BMWs wasted development efforts.
 
Well the incredibly helpful and all round nice guy Dr Farkoff has sent me a couple of ABS units :thumby:

I'll get started at the weekend with stripping the down, get the suspect parts from mine replaced, clean it all and see if I can get it all working again.

I'll start another thread of how I get on in case it is of help to anyone else out there again.
 
Hunda67 said:
Well the incredibly helpful and all round nice guy Dr Farkoff has sent me a couple of ABS units :thumby:

I'll get started at the weekend with stripping the down, get the suspect parts from mine replaced, clean it all and see if I can get it all working again.

I'll start another thread of how I get on in case it is of help to anyone else out there again.
Click to expand...

Top man, good luck with it :thumb2
 
Hi,

I realise this is a long long long shot 'cos the electronics bit is the useful part, but does anybody have the electronics part I can hack?

I'm trying to make an open version of this replacement unit that 'fakes' the CAN messages: http://www.ebay.es/itm/EMULATOR-ABS-POMPA-MODULATOR-PUMP-BMW-R-1150-K-1200-LT-GT-GS-RS-S-RT-ST-C-CL-/262895740608?var=&hash=item3d35cea6c0:m:mJZSPZIr59GjaYVF7UnXcmg

I've got my laptop sending CAN messages OK and I've hacked a couple of wires onto the CAN bus but don't really want to chop it about much more as I need the bike to get around. I've also got an Atmel dev board sending the CAN messages (must find code again) so I'm making some progress.

I also need to test out interfacing to either of the speed senors and I'm toying with a Maxim chip. However I either need to hack the loom about more to try it or get the proper connector hence the desire for an old unwanted electronics unit.

S
 
For your next project, a Canbus hack to make the indicators start and stop with the ON paddles would be nice. That off paddle is a PITA.
 
Hi,
That *might* just be possible. The ABS unit 'sees' message 130 which contains the state of the indicators. I'd need to see if this is just used to get the mimic lights on clocks to flash with the actual indicators or whether sending the appropriate 130 message will actually trigger the indicators. It has been a while but my very very poor memory thinks it might work.

So assuming the 130 message does control the indicators then a widget on seeing the second left or right message from the left or right paddle could wait say 50mS then send the cancel message. It's a hack and it would have to watch for a cancel message in case that was presses but it *might just* be possible.

I need to sort the connection out reliably 'cos I don't have a car so the GS has to work. Going to the garage to think about it :)
 
simonisahome said:
Hi,
That *might* just be possible. The ABS unit 'sees' message 130 which contains the state of the indicators. I'd need to see if this is just used to get the mimic lights on clocks to flash with the actual indicators or whether sending the appropriate 130 message will actually trigger the indicators. It has been a while but my very very poor memory thinks it might work.

So assuming the 130 message does control the indicators then a widget on seeing the second left or right message from the left or right paddle could wait say 50mS then send the cancel message. It's a hack and it would have to watch for a cancel message in case that was presses but it *might just* be possible.

I need to sort the connection out reliably 'cos I don't have a car so the GS has to work. Going to the garage to think about it :)
Click to expand...

You could also look at a low cost widget to convert a float fuel gauge to work on a fuel strip bike. A Dutch guy sells a device that works but about £100 isn't cheap.
 
Nippy Normans supply Touratech, Wunderlich, Desert Fox and many other makes of accessories.
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