69 GTV Brake Pressure Sensor Manifold - Piston Seals

[1750GT]

Rich, I've seen the brake switches for sale on overseas suppliers' sites....not sure about the ones in the States though. Also, I could produce a drawing of a seal except that I don't have a new one to go by and so would have to do some investigation on tolerances and clearances. Now it sure would be sweet if we could a obtain a copy of an original seal drawing...but who would have that available?

Another lead I have is with a local "Jobber" or remanufacturer of brake systems. I have a meeting set up tomorrow with a shop locally...I'm going to bring a Bonaldi booster as well to see if the rarity/uniqueness of these ALFA units might be of interest to him to rebuild.

[1750GT]

Well the lead I had turned out to be a dead end. The shop primarily does American car stuff...doesn't do plating nor coatings other than paint. I'll have to try some of the other suggested shops.

[ossodiseppia]

Ok, I hear back from my contact at Ate. Here's what he had to say:

Unfortunately we do not have the possibility to supply you with the internal seals only. I have no idea if the internal seals were ever offered as a replacement part in the market. At least not by ATE, this is what I know for sure. Offering the internal seals only brings along a lot of trouble with handling and the expiration date of the rubber.

So, that should be the final word on replacement parts availability.

[1750GT]

So that makes two items in the brake systems components for these cars that are NLA as replacement parts...the other being the little plastic (almost spherical) seal backing found in the Bonaldi brake boosters.

[papajam]

Have an industrial supplier working on the piston seals right now. Should know in about a week.
Can you post a pic and the size of the plastic seal in the booster?

[1750GT]

I see it's been a while since my last post in this thread.....and not much progress has taken place to date. However (and I post this up out of curiosity) but I stumbled upon another possible lead for spares.....see link below.

http://members.aol.com/danmas6/

...the PDWA on the TR250 sure looks very similar to our ATE PDWA. Of particular interest is that the exploded view of the unit shows the use of "O" rings in place of our lip seals. Also, the pistons seem to be installed in reverse direction w.r.t. to the ramp up or sloping end as compared to our units.

....more sleuthing required here on my part.

[1750GT]

Further surfing got me to this link showing a detailed rebuild of a TR250 m/c and DPWA...

http://lotus-europa.com/files/mc%20rebuild.pdf

And it looks like the same problem of sourcing replacement lip seals on the DPWA exists on the TR's (at least that is what the author of that article is lamenting about).

[1750GT]

I stumbled upon another possible solution to the seal dilemma. I noticed that the seal for the Bonaldi Booster pentagonal valve actuator piston (on the right) seemed similar in size to the DPWA seal (on the left). There are visibly distinct differences between the two and my limited (and admittedly) basic knowledge of piston seal design tells me that the two probably could be used interchangeably provided all other installation parameters are the same. The DPWA seal under normal conditions does not move a whole heck of a lot (if at all) and so any dynamic performance benefit that the original Booster seal had may not be such a huge factor.

...see pics in post #54....

I measured both housing bores at .375 inch. However, the seal I.D.'s differ slightly .005 in (.162in vs .167in) and the lengths differ by .030in (.166 vs .136). I also made drawings of the two seals...

bonaldi pentagonal valve piston seal.pdf

ATE DPWA piston seal.pdf

Since the booster seals are available in booster rebuild kits from various suppliers, it seems that one possible solution is to have new DPWA pistons machined with a seal groove geometry that will accomodate the narrower booster seal. However, this is not cheap either since 2 kits would be required for the 2 seals...(I bought a pair of rebuild kits for around $45 each last year)....and I'm sure they're more expensive than that now.

I'm going to follow up the Booster seal availability with a UK rebuilder. I'll keep you all posted.

[1750GT]

...not sure why the pics didn't come through in the previous post...so here they are...DPWA seal on left ....booster penta valve seal on the right...