240DKW Dan & Namerow,

Thanks guys.  I believe that between your two suggestions, you may have identified the problem.  While I' pretty sure we installed the upper seal the only way it could logically fit, that particular area is apparently where the problem originates.  The two seals in the kit (the third piece is just an o-ring that fits on the screw-on cap) appear identical, whereas in the FSM drawing, they are not.  Hence the blockage.  

I'm sure I can't be the only one who has had this issue - 47 year old rubber on any car will fail at some point.   Motorsport and others have a rebuild-exchange opportunity available to them.  

Again, many thanks All    

I have a rebuild kit on order from MSA.  When I get the chance to have a look at it, I'll let you know whether the two seals are identical vs. different.

Good to hear you solved it, all be it with another unit. It's a pitty the kit is so challenging to fit and get working right.

Namerow,

Please let us know how you make out.  Good luck.

I've now received my rebuild kit from MSA and I've taken a few pictures for reference.  As you'll see, the three seals in my kit are all different -- two are lip seals, the third is an O-ring. One of the lip seals (the one on the left in my pix) is lipped on both the inner and outer circumference.  The other (in the centre) is lipped on the outer circumference only.  Both are about the same in height. 

The seal on the left with the inner & outer lips is pretty clearly Item 5 in FSM diagram BR-8.  By default, that means that the single-lip seal in the centre has to be Item 3.  Obviously, placing them in the right locations and getting each one correctly oriented (lips face inboard, flat sides face outboard) is going to be critical to making the valve work properly.

I continue to be confused by the way the upper seal (Item 3) is depicted in FSM diagram BR-9.  The shape of the seal's section on the left makes sense.  However, the sectional shape on the right looks like a completely different seal!  Am I missing something here?

Edited July 20, 20177 yr by Namerow
re-position pix

Namerow,

You and I have been sold different kits.  

The O-ring is fine, but the other seals in my kit differ from yours.  I hope the attached photo is clear in showing the the seal that I - rightly or wrongly - mounted at the bottom (inner) end of the  stem has notches around the perimeter.  Neither of yours appears to have these.  Their purpose?

While it is always a source of great satisfaction to solve a difficult problem such as presented by the brake proportioning valve, I am grateful to Grannyknot for selling me a workable used unit.  I am now able to get on to the thousand and one other little items that have my restoration project many moons behind what I originally envisioned.  Perhaps a plea to the overall membership of this forum for a good, used unit?

Best wishes,

 

5 hours ago, Richard McDonel said:

I am grateful to Grannyknot for selling me a workable used unit.

Selling? Pretty sure I gave it to you, but you can send money if you like

7 hours ago, Richard McDonel said:

The O-ring is fine, but the other seals in my kit differ from yours.  I hope the attached photo is clear in showing the the seal that I - rightly or wrongly - mounted at the bottom (inner) end of the  stem has notches around the perimeter.  Neither of yours appears to have these.  Their purpose?

I have never seen a rippled seal like that in a hydraulic system before.  Maybe someone else has, but not me.  It looks more like a washer than a lip seal. Without seeing the other side (of both items), though, I won't speculate any further.

grannyknot,

Mea culpa!

I forgot the great price (free) that you offered.  Again, my thanks.

Best regards,

Richard McDonell

 

On 25-7-2017 at 2:59 AM, Namerow said:

I have never seen a rippled seal like that in a hydraulic system before.  Maybe someone else has, but not me.  It looks more like a washer than a lip seal. Without seeing the other side (of both items), though, I won't speculate any further.

The later proportionjng valve has one too. Im not sure why the made them like that.

 

Namerow,

Here is the reverse side view of the two seals.  Don't know if it will solve anything for you.

There is a market opportunity out there that someone is missing out on.  Certainly the need is there; a part that the fsm says cannot be repaired, with the only option being to buy a new one, but the factory doesn't make new ones.  Someone must have the tools and the knowledge to rebuild these these things.

For myself, I'm just grateful that Grannyknot was able to come through for me with a workable used unit.  I'm one step closer to putting my many-year project on the road.  

I rebuilt two proportioning valves this weekend. I used the seal kit from MSA. I paid close attention to the orientation of the seals during disassembly. Both valves had the exact same seals in them and they were identical to the photos above where seal (3) in BR-8 is fluted / grooved on the flat outside edge and dotted on the cupped inside edge. Seal (5) in BR-8 is exactly like the photos above where it is a little thicker than seal (3) and not dotted or fluted / grooved on the outside or inside surface. For clarity, in the case of both seals, the cupped side is oriented to face the middle of the valve.

I personally was easily able to match up the MSA seals with the equal (but not identical) original seals.

I found disassembly and re-assembly to be fairly quick and easy. I used a small c-clip squeezer (not spreader) (OTC brand, 1120) to squeeze the c-clip and remove from valve. Re-installation is a little more tricky. I use the same c-clip squeezer to squeeze the c-clip and insert it partially into the valve. Then I used a 5/16 deep socket to push / press (gently) the c-clip down until it clicked into position.

To be clear, I don't yet know whether the proportioning valve works as I am still rebuilding the brakes on my 240z. I should know in a week or so. 

The valve from my low mile car was very clean. The valve from the car I am rebuilding the brakes for was very full of dirt and sediment....but not corrosion. So, I feel like I accomplished something....assuming the valve works. And, I enjoy rebuilding little parts.

I should also mention that I cleaned up all original seals and, to me, they look new....like they could be reused without concern. Again, I think the key thing I accomplished is cleaning out the valve.