ABC valve block rebuild pics? Is this right?

[cfoster]

Hi Nic,

I will indeed sell the bits seperately yes, I also have one spare pack of green O rings that I got from the states which I can sell to you to save you the hassle of shipping? PM me if you are interested!

Cheers

 

[NicBowman]

interested

Hi Chris,

have pm'ed (I hope, not so good at IT!).

Nic

 

[Lowe712131]

ABC Valve Blocks - O Rings Sizes and Materials

Hi Guys,
I am in the process of rebuilding my whole ABC system, I have the front and rear valve blocks on the bench and have been doing some research on the O rings / materials etc.
Pentosin CHF11S is a synthetic-base Hydraulic Fluid, which is bad news for most rubbers (NBR, Nitrile, EPDM etc..), so looking in some decent reference material (e.g. Parkers or James Walker), the best materials are listed as :-

Flourosilicone (FMVQ) - good for static applications, but only listed as '2' for material compatibility (with 1 being the best ... etc.)

FKM - Fluorocarbon Rubber, Listed as '1' for material compatibility against all Hydraulic Fluids - mineral or synthetic base. Viton is the Dupont trade name for FKM and is readily available, albeit a little more expensive than standard (but still cheap in the grand scheme of things!).

FFKM - Perflouroelastomer - Trade name Kalrez, these are chemically compatible with just about anything, although they are not as widely available and are expensive.

Standard O rings in EPDM or Nitrile are readily available in 70 - 90 Shore hardness, which is directly related to the sealing force. I don't know the hardness of the standard O Rings in the ABC system, however I would estimate them to be in the 70 range, judging by the 'give' in them, compared to some 70 Shore rubber I have used in other applications.

From this information, I am going to use 75 Shore Viton/FKM O rings in the blocks on my car.
The sizes for the O rings on the solenoid valves are as follows :-

Control Solenoid
Bottom O Ring (Smallest) - BS013 : 10.82mm I/D x 1.78mm Section
2nd O Ring - BS014 : 12.42mm I/D x 1.78mm Section
3rd O Ring - BS016 : 15.60mm I/D x 1.78mm Section
4th O Ring - BS018 : 18.77mm I/D x 1.78mm Section

Lock Solenoid
Bottom O Ring (Smallest) - BS015 : 14.00mm I/D x 1.78mm Section
Top O Ring (Largest) - BS016 : 15.60mm I/D x 1.78mm Section

Don't worry too much about the PTFE (white) spacer rings either side of the O rings - they don't actually seal anything, they just let the O Rings do their job - if they are in good condition, there is no need to replace them. I have seen people remove them and put 3 O rings in there instead, but I prefer to stick to the standard design and engineering principle.

There are many O Ring suppliers on the net, I used www.polymax.co.uk here in the UK, they have a good online ordering system and the prices/deliveries are good.

This covers all the external O rings on the Valve Shafts - the rings on the internal shafts are another matter. These are the dynamic part of the system (i.e. the part that moves). I don't doubt FKM is OK for this part of the valve, however I haven't got as far as dismantling the Control solenoid to get at the internal shaft to replace them. The lock solenoid shaft is easy, as it just comes straight out, with the spring on the end of the shaft (Incidentally, when dismantling the rear block on mine, I found the spring was not attached to the shaft on one of the lock solenoids, it was just sitting in the bottom of the block - this MAY have been the cause of the slow leak-down I was experiencing), but I still don't know how to remove the shaft from the control valve (any help would be appreciated??)

I've just got to get it all back together now, had a few 'adventures' with seized quick-release connectors and worn bottom ball joints (thanks to the 4wheel alignment place in Liverpool for the great refurb service!) but have enjoyed the challenges!

Now the legal disclaimer! I have carefully measured and selected these O ring sizes and materials and I will be using them on my own car, however I offer NO guarantee they are correct and anyone choosing to follow the above information must independently check and verify their suitability before using them on their own car. I shouldn't have to say it, but them's the times we live in!

 

[Philedge]

I contacted Powerenhancer, the UK distributor of Pentosin, about compatible materials with CHF11S and they advised HNBR or NBR, which is different to what you are saying about NBR being incompatible!! All the seals you have listed are static and just seal between the chambers of the solenoid but never move so are unlikely to wear out.

HNBR seem to be the seals most people use.

I wouldnt waste your time sourcing O rings for the solenoid shaft on the lock solenoid as it opens when you start the car and closes when you stop so gets very little use, unlike the control solenoid which is chattering away constantly. If your car is dropping just lap the metal to metal faces on the lock solenoid and that should sort the dropping out. Mine dropped noticebly overnight yet the lock solenoid sealing faces looked pristine. All I did was lap them and the strut holds up for weeks now.

I've not stripped a control solenoid but on the lock solenoid the dark plastic encased coil unscrews off the steel solenoid body. This gives you access to the topf the solenoid shaft housing and the shim that controls its travel. I think the control solenoid will come apart in a similar way but as its a 3 postion solenoid its going to be configured differently to the 2 position lock solenoid.

If you get the control solenoid apart post up some piccies please.

 

[Lowe712131]

ABC O Ring Selecetion

Hi Phil - thanks for the reply. Yes, I am happy with the lock solenoid shaft seal now, but will lap in the metal to metal face, thanks for that.

With regard to the material selection for the O rings, it has been a while, but I used to carry out material selection as a small part of my job, and I always used to refer to the Parkers manual as my main source, as it is a wealth of info on all aspects of O ring sealing - you can download a copy here.
Page 187 has the Hydraulic Oils and you are right, NBR and HNBR are listed as 'Fair' (grade 2) for Synthetic Base Hydraulic Oils, so they will probably be OK, especially for static seals.
Apologies if my previous post made it sound like NBR or HNBR were no good at all, I should perhaps have just said Viton/FKM are better. It is good practice to install the best seals possible (if the cost is not prohibitive) and, as the Viton seals are really cheap (10p each - ish), I decided to go with them.
Cheers
Simon

 

[Philedge]

Great. If you manage to source the moving seals for the control solenoid spool then post up the details as that seems to be an unknown.

 

[JettaRed]

I might have missed it, but didn't someone point out the obvious that maybe the shop didn't know what it was doing? It looks like they stacked all the green o-rings on one valve. With each o-ring there is either one or two square spacers (versus round o-ring). While you can use a round o-ring as a spacer, that's not normally how it's done. I bet the shop had one green ring left over that they thought was a spare. Or came up short. In any event, it looks like they replaced all of the spacers with round o-rings.

Hi all, bit of a question really. Recently I had my SL55 serviced (B service), alongside the service I had issues with my ABC valve block, the front wasn't playing ball and I was getting errors on the dash...






Thanks
Chris

 

[Craiglxviii]

Holy thread resurrection Batman!