69 GTV Brake Pressure Sensor Manifold - Piston Seals

[1750GT]

Daveydog..I do have an air compressor and tried the air method at first as well...but to no avail (probably the piston area is too small and does not generate a force large enough to overcome the friction caused by some of the corrosion and crud inside). The heat I applied was via a propane torch and not an acetylene torch and so I was not concerned about damaging the housing by overheating. I really had to slam the unit down hard for about 15 minutes and with repeated heating cycles before the pistons finally moved out. Now had this failed I would have tried to use the compressed grease into the cavity approach which I recall someone on this BB suggested using instead of air.

[papajam]

Quote:

Originally Posted by 1750GT ...a loss of fluid on side (one half of the system) will cause this valve to shut the flow through it thereby preventing a total loss of fluid from the reservoir.

[bjfrantz@charte]

I once had the brake-balance device on my Peugeot 504 wagon fail. I tried bypassing it but got instant rear lock up. A family friend who built hydraulic agricultural equipment fixed me up with a simple "o" ring of the correct dimensions. He said it was as good as the square cut seal it replaced. He lso said, if he had no ring the right size, it would be no problem to cut a new groove for a seal of an available size. I was skeptical, but I never replaced that "o" ring for the next several years I drove the car all over the western states. I'll bet any good hydraulics technician could redo one of these goofy devices on 69 GTVs. I did not even know I had one until now, so I will also have to decide how to go. Repair or eliminate? I look forward to further feed back.

[1750GT]

Thanks for the clarification Jim. BTW, I took measurements of the piston (which are in metric mm)...perhaps someone can assist to find a "lip seal " from some other application that is compatible with the groove configuration of the ATE piston.

ate valve piston.pdf

[Alfajay]

1750GT had written the stuff in quotes:

"I don't believe that a warning light should be termed an "idiot light" either."

Well, OK, that is an emotionally-charged term. But, how would you characterize someone who needs a light to figure out that they've lost half of their braking system?

"As Osso explained, a loss of fluid on side (one half of the system) will cause this valve to shut the flow through it thereby preventing a total loss of fluid from the reservoir. If you simply introduce a dam in the unit you could potentially lose all of the fluid....not a scenario that I'd want to be caught in."

Two points: 1) Papajam tells us that the BPDV does not shut off flow. 2) most master cylinder reservoirs have a warning light that indicates when the fluid level has dropped. Now that function I agree is critical - you aren't going to know that the brake system has begun to leak by the "seat of your pants".

"Lastly, don't underestimate the liability situation that one might be trapped in should a "modified" vehicle be involved in a traffic accident.....or god forbid a traffic fatality!"

You know, that is a very good point. Still, I worry that if someone gets injured by my 40 year old car, I'm going to get crucified even if it is 100% original.

[daveydog]

Please feel free to correct me if I'm wrong, but I seem to remember that the term "idiot light" came into our vernacular from those lights on the instrument cluster, (if you can call it that), in the lead sleds of the Sixties. You know the ones I'm talking about. The Big Three decided collectively to replace all those pesky and expensive gauges with little lights that would tell the operator of the car that the coolant temperature was too high, the generator was not working, the oil pressure was down below a pre-set level etc. (Like an old girlfriend of mine who drove her early The only gauges left were the speedometer and of course the gas gauge.
But then if one were to leave one's foot operated parking brake on when driving, like us in our Alfas with our handbrake on, then maybe we DO need those idiot lights

But back to 1750's question, I think that ATE must have had other buyers of their products and "somewhere" there must be a cross reference to another car manufacturer that uses those seals. I mean, people have been rebuilding Alfa brake systems for years and you mean there's no parts available for the BPDV? I wish I could help.

[daveydog]

Sorry guys, the pizza man showed up at my door while I was typing What I meant to say was an old girlfriend of mine was driving around in her early Seventies Plymouth Valiant with this little red light on the dashboard on and when she got back to my place and she told me, I looked under the hood and as the motor was making these weird cracking, snapping, creaking sounds, I pulled out the dipstick only to find NO OIL. She'd burned through about 4 quarts in a month or so since I'd last checked it. I couldn't call her an idiot because actually she was really smart but WTF,... oh well... I guess I should have checked it

[1750GT]

And daveydog wrote:....""somewhere" there must be a cross reference to another car manufacturer that uses those seals".

I was thinking the same thing, and I'm still hoping someone has been able to find such a cross reference for these parts.

[ossodiseppia]

Posceh master cylinders from that vintage had the valve integrated into the master cylinder. Here's a couple of picture I nabbed off the internet. I know that VWs from late sixties also had the warning light, but I am not certain if they had this same valve. During my quest for new seals, I remeber reading on one of the Porsche sites that the seals for the valves are not included in the rebuild kits. Interestingly, the instructions that come with the Ate kits have directions for assembling the valve. Now, it could be that rebuild kits for the valves included pistons and seals.

[1750GT]

Great find Osso! Your internet search skills are definitely better than mine, I looked and searched for a while and did not find those exploded diagrams and boy they definitely look like a match don't they? Next step is to find these rebuild kits....hopefully they'll be cheaper than the rebuild units themselves.

[1750GT]

Osso, I now recall that I did look at Ate's website...

ATE -Login to the European ATE Web Catalog

but after spending quite a bit of time....I couldn't figure out how to download any literature from it. Well it may be moot point anyway since they probably don't support any of these older cars any more other than through the auto manufacturers themselves.

[bjfrantz@charte]

Rossano, You might call Goldline Brakes in Seattle, 1 877 347 2225. I forget the gentleman's name, but he is very knowledgeable and experienced. He rebuilds ATE calipers all the time and should know about the pressure differential valves. He is very helpful over the phone. Did a great job on my calipers.

Barry

[1750GT]

Barry, I'll keep these guys in mind should my search come to an end.

[karmat]

I'd say if you can find a rebuild kit for the Porsche one you're likely in luck. ATE made a lot of different housing designs for lots of manufacturers, but the piston designs were not all that unique. For a typical thickness of piston they tended to use the same seal. I have an ATE rebuild kit for some model year of VW bus that has all the right seals in it for my '69 GTV's master cylinder, for example. Surely ATE built pistons of the same diameter for another manufacturer. If you can find a VW part that had these you're likely to find OEM rebuild kits on eBay for cheap. It's amazing how many beetles and buses were produced and how many people bought parts for them they never used.

Hope that helps.

Karl

[1750GT]

Lots of maybes.....each will require investigation and will take some time. The closest (from photo's and drawings) seems to be the 914 MC and am looking int this. I'll need to get either a rebuild kit or used MC and then measure the seals...no one said it was going to be easy.