Rear proportioning valve (105) - Page 4

**Farace** · #46 (**permalink**) 08-06-2009, 10:10 PM

I could use one or two, but before I commit, let me check over the weekend and make sure that the unit I have in my tool box is worth rebuilding. I've yet to open it . . .

**Farace** · #47 (**permalink**) 08-07-2009, 11:57 PM

Quote:

Originally Posted by Farace

I could use one or two, but before I commit, let me check over the weekend and make sure that the unit I have in my tool box is worth rebuilding. I've yet to open it . . .

**Anfanuts** · #48 (**permalink**) 08-08-2009, 06:43 AM

I'd take a couple of sets. I have two old ones now one leaking, one holding, I think, on the car.

**Farace** · #49 (**permalink**) 08-08-2009, 03:20 PM

Quote:

Originally Posted by Farace

Re: the O-rings, will any old hardware/plumbing store O-ring work, or do I need something meant to be used with brake fluid?

rockiemosley · #50 (**permalink**) 08-09-2009, 06:40 PM

Hey I would like 2 of those seals. Let us know. Many thanks.

**Chris1750** · #51 (**permalink**) 08-09-2009, 07:32 PM

I've just mailed 3 of these cup seals to Rossano in Canada (he was one of the first to show interest and the first to PM me with his postal details). If he gives them the thumbs up, I'll source some more and start taking names and addresses.

I imagine it will take about a week for the small parcel to get to Ontario and a couple of days for him to try them out and post his comments here. A fortnight maybe and we'll know whether they are any good or not. FWIW, my brakes are now terrific and the PV seems to be working as well as would have when new.

I'd like to get this sorted before the 21st September as I head off overseas for a couple of months after that date.

Regards,
Chris

**1750GT** · #52 (**permalink**) 08-09-2009, 08:48 PM

Chris it seems based on your initial findings that the seal is working as one would hope. My only caveat is that the seal material and it's manufacturer is unknown and as such it's compatibility with brake fluid is also unknown. I would suggest that a series of regular visual inspections of the seal be performed over the next year or so to ensure that no swelling or deterioration is occuring.

Other than this I say thank you for pursuing this to the extent that you have...good on you!

Regards

**Chris1750** · #53 (**permalink**) 08-10-2009, 12:02 AM

Quote:

Originally Posted by 1750GT

My only caveat is that the seal material and it's manufacturer is unknown and as such it's compatibility with brake fluid is also unknown. I would suggest that a series of regular visual inspections of the seal be performed over the next year or so to ensure that no swelling or deterioration is occuring.

**Farace** · #54 (**permalink**) 08-10-2009, 06:08 AM

I think more important than who makes it is what it is made of. Maybe this is something they can let you know. In my search for compatible O-rings, I found the following table, which I'm sure applies to cup seals as well; it seems brake fluid is incompatible with compounds that are quite happy with other hydraulic fluids:

eFunda: O-Ring Materials Compatibile with Chemical Brake Fluid

Quote:

Originally Posted by Chris1750

I'll try to find out who actually manufactures these seals, but no doubt it will turn out to be one of the major rubber extruders in Australia. It is a similar story with many of the generic hydraulic o-rings.

What I could do is soak one in a sealed clear glass container of brake fluid and have a look at it now and again. Otherwise, I'll let you know if the one fitted to my car starts pissing brake fluid or if the rear tries to overtake the front during a 'panic' stop.

Chris

**Chris1750** · #55 (**permalink**) 08-10-2009, 03:57 PM

Quote:

Originally Posted by Farace

I think more important than who makes it is what it is made of.

**Chris1750** · #56 (**permalink**) 08-10-2009, 08:15 PM

For anyone wanting these seals, I suggest the following -

1) PM me with your requirements and address.
2) Using the current exchange rate, the seals are costing me about $US7.50 each and total postage for up to four seals costs around $US2.50. So one seal = $US10.00, two seals = $US17.50 etc.
3) I have an active PayPal account - this is probably the easiest way to transfer money internationally. I'll let you know my email address when you contact me.
4) I can't handle orders larger than about 4 seals.
5) It will take me about a week or so to get a supply.
6) These seals come with no warranty. I've rebuilt 2 PVs using them with no problems thus far. I believe, to the best of my knowledge, that the seals are manufactured from a good quality, hydraulic fluid compatable compound. I will endeavour to find out what that compound is and let you all know.
7) If you rebuild the PV in your car then go tearing down the road and have an accident, please don't try to sue me - I'm descended from poverty stricken convict stock so I have no vast reserves of either congenital or acquired wealth and, apart from you guys, I have no important worldy connections so I'm not even worth kidnapping

8) When you receive your seals and fit them, please let the forum know the good, the bad and the ugly. For example, I split the first one I tried to put one. The seal was well lubricated but it still split. I found that if I went slowly and warmed the seal so it was a bit more pliable, it went on without any drama.

Over the next 2 weeks or so, I'll let you know what stock I have and an idea of what extra stock exists.

Finally, I'd encourage you to find local suppliers if possible. I don't at all mind doing this, but I do have a fulltime job and a family whom I like to see now and again

My motives in this are altruistic. I'm just a quiet soul with a love of old cars. If I can help my mates, then, within reason, I'll help.

Regards, as usual,
Chris

**Chris1750** · #57 (**permalink**) 08-13-2009, 11:03 PM

I now have a number of these cup seals.
Anyone wanting up to 3 or 4, please PM me with your name, address and requirements. I'll put them in the mail next week.
Chris

cuorealfa · #58 (**permalink**) 10-10-2009, 10:29 PM

Hello chris i would like 2 seals if still available

**PMB_Performance** · #59 (**permalink**) 10-26-2009, 04:54 PM

Chris,

Awesome that you are making these available and helping people with this valve.

I was concerned when I first started reading as, the common misconceptions about this valve were rearing their ugly head.

This is not a proportioning valve. It proportions Nada. It is better described as a "Saftey Shut-Off Valve". Once 535lbs of pressure (variable buy the 5mm hex and the 15mm lock nut) is reached within the valve body that micro switch on the end is pressed against the large nut on the end effectively shutting off the rear calipers in a panic stop. Read Vic Elford on "Polar Moment Inertia". Pete was spot on in a very early post.

Do not remove these and replace them with a "T" fitting. Again, good work on the restoration thread. The rusty ones have seen lots of water in the system. These things rarely fail. The clean ones are a testimonial to change your fluid after every race or once a year for a street car. I've torn apart thousands of calipers and it's AMAZING what regular fluid changes can do.

How can you tell if they're working? If your rear calipers are working and do NOT lock up in a panic stop. If they're gummed up, your rear calipers may not be getting fluid at all.

**papajam** · #60 (**permalink**) 10-26-2009, 06:17 PM

For Alfas explanation on how the brake pressure regulator works, please click below.