ABS pump stripped today

[SBeachill]

Anybody know the sizes of the O rings on the solenoid pistons? 1 of mine has a nick in it and the others seem a little sloppy??

Also anyway of testing the solenoids before re-assembly?

Steve

[Trev]

Best i can tell u to help, its to read Mike lovely post/cronic about ABS.
And wait for hes reply, he may know the correct size.

http://www.mjscrane.com/GTS1000/files/4d0dccdd62ce5a600ad2387a2ae4963c-9.html

Regards

[Devonian]

I am also about to embark on an ABS strip and clean. I have access to a reasonable collection of buna (rubber) O-rings but not certain of their duro ratings. Anyhow, according to this reference: http://www.marcorubber.com/material_chart.htm, buna is not a suitable material. Preferred O-rings would be made from Viton (ETP), EPDM (PC), Kalrez, Markez, Simriz, or Chemraz (Trade names I am not familiar with). One would also need to know the hardness (durometer) of each O-ring.

Hopefully I will not need anything, but if I do, I will first try one of the local industrial supply houses to see if they are willing to measure my existing O-rings and if that fails I will buy a sizing tool, measure them myself and mail order enough to make a few sets, guessing at the hardness requirement.

If someone else beats me to it, I would gladly pay for a kit containing the appropriate parts.

[24c]

There was a kit of O rings available on a German website, but you can reverse engineer the sizes by looking at the application type & groove diameters.

Material selection is easy, as you just look for brake applications, and I would think a PTFE/Viton might be the way to go, but the OEM looks like Nitrile.

PS SBeachill I saw your post, and have a box of ABS stuff somewhere, all wrapped up, and I was going to measure them. I have written this stuff down previously, just never added it to the blog. So to answer your question, 16x2.

PS Found it ...enjoy it's in German, but there are the other sizes on there too.

PPS Do not use WD40 as it swells the O rings, please use brake cleaner.

[Devonian]

I had hoped that I might find the ABS on my bike just lightly gummed up and that repairing it would be easy. No such luck it appears. Things don't look as bad as Mike Crane's photos. There's no congealed brake fluid in the filter screens. However I'm seeings the same stubborn stains in the piston bores, everything is stuck together just as Mike showed, and most significantly, those pump pistons just don't seem to want to budge.

All the O-rings look to be in fine shape, so I probably won't need any new ones. The only seal I'm concerned about is the unique little one on the pump piston - I haven't seen either of them yet because I can't get the buggers out. Currently soaking them in warm penetrating oil (PB Blaster) in an ultrasonic cleaner. They are getting very clean but the piston can not be persuaded to move. If I leave them to soak for a few days will the seal be damaged?

Hoping if I get the aluminium cap off I might then be able to drift the piston out from that side but having no luck there either. Is there a particular trick? Do I heat it or cool it to help get it off the pump assembly? Have so far tried both approaches but not to extreme yet. Do not have access to a dual-chuck lathe at present either.

[24c]

Hoping if I get the aluminium cap off I might then be able to drift the piston out from that side but having no luck there either.

Place the aluminium cup on a hot plate with a Pyrex glass bowl covering it. The aluminium will warm up faster than the steel, and the spring inside will push it off. Don't be silly with the heat, because you might damage the spring temper, but I would reckon 150-220 ºC should pop it.

Stubborn stains, I used an old toothbrush and mild truck wash.

There is a possibility that the seal might be damaged by soaking in penetrating oil, but chain lube suitable for O rings etc would be OK. I would still use heat, and possibly use a DIY oil bath and warm the sucker up. I did drift mine out, but you might be able to tease a little movement, and re soak, tap again etc. Again silicon type lubes should be OK, if you clean off traces after.

[Devonian]

I read the hot-plate trick but it was described as a way just to get the valve seat out of the cap. I also read about freezing some parts and wondered what that was about.

Does the cap fit onto the body of the pump or does it fit over the valve seat which in turn fits into the pump? Reason I ask is that if I use heat I imagine it would just remove the cap, still leaving the valve seat in place - so I would then be trying to remove that.

[Devonian]

Still haven't been able to get the pistons out of the pump assys, nor get the aluminium caps off. Have had them soaking in an ultrasonic bath with penetrating oil and brake cleaner. They are very clean now but the piston still won't move. Any suggestions?

[24c]

I am slightly confused, but I assume the aluminium caps are the same ones I put on a hotplate. If so, they should separate if you put them aluminium side down, just put a Pyrex bowl over them otherwise you'll loose the ball & spring.

To get the piston to move, try using a Snap On pick tool through the hole. Yes, I know it sounds dodgy, but used carefully no damage will occur, and you can tease a little movement out of the piston. Once you do this lube again, and tap it back and repeat.

[Devonian]

I tried the hotplate and tried removing the assy from the freezer and hitting the aluminium cap with a micro blowtorch. Have also been prying away with jeweler's screwdrivers through the holes. The pistons are not moving at all. Trying to be gentle with the heat so as not to damage the screen or seal, neither of which can be removed until the whole thing is dismantled.

The units themselves do not look as bad as your photos so either the appearance is misleading or I am not being aggressive enough.

[Devonian]

Still fighting with these pump assemblies. Latest effort involves a weak vinegar solution in the ultrasonic bath. As you can see, they are now very clean on the outside but have yet to show any signs of the piston freeing up. Have yet to find someone with the requisite tools to pull/twist the aluminium end cap off and repeated heating/cooling cycles have not budged anything either. I'm keeping at it.

[24c]

They look really clean enough now.

Have you tried tapping the pistons back in, either in a soft vice or using a small copper/nylon hammer. If you do this it will free the small piston, and you should be able to pry (through the holes) using a pick tool and move them back to the position seen in the photos. By wiggling back and forwards, you'll achieve the result you want.

It has been a while since I played with these rascals, but once you get the pistons out, you can drift out the aluminium cap part. The hot plate trick is just to separate the components within the aluminium cap.

[Devonian]

Finally got the little buggers apart.

I had already tried tapping the piston inward with no luck. However, after several rounds of ultrasonic cleaning in a weak vinegar solution, freezing/thawing and a final time back in the ultrasonic bath with penetrating oil, both pistons started to move. Now both apart and being cleaned. Hopefully will have them reassembled and be back on the road within a day or so.

I note that the metal of the pistons and bodies is VERY hard. I was able to (carefully) use a cheap pair of pliers to twist the pistons out without marring their surface whatsoever.


Off to find some brake grease that might keep moisture out of the O-rings around the solenoids

[24c]

TFFT...doesn't need translation

Finally you've got there, plain sailing from now on. Well done, I am going to get an ultrasonic bath now too. I was already looking at one on fleaBay, but they look like a really useful bit of kit.

Well done again.

PS Yep, the metal is well hardened.

[Devonian]

So near but yet so far...

Not sure if the damage was started during disassembly but anyway, I managed to nip one of the seals putting the pump piston back in place. Now I've got to go off hunting around the various local industrial/hydraulic suppliers to see if any such thing is available as a replacement.
Yes that is sitting on a penny - The damage is hard to spot with the naked eye but I'm not going to chance it with such a critical item.

Hopefully nothing else will seize up again while I'm looking. Dammit!