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Opeler
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Discussion Starter · #1 · (Edited)
Just dropped by Tim's Opel Gt page to check some interchange info and all that is there is a spam search engine. Anyone know what happed? Fortunatly I saved allot of his pages, but certianly not all.
jb
 

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jb, what exactly are you looking for? I have a Excel crossover list that I saved from somewhere? If that would be of any help. Jarrell
 

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Opeler
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Discussion Starter · #3 ·
Thanks Tazer, Was looking for calipers this round. The bolts to split mine in half are stuck, T30 slips, T35 fits great but can't find it localy in other than a screwdriver. Thought of cutting the bolts, but can often buy another part from junk yards cheeper than specialty bolts. Mine's a 71 which I understand there was a mid year change, on top of wich the front of this car has been replaced twice, so no telling what is original or not.

Tim's page was great for browsing through and figuring things like this out.
 

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Opel-ing since '74
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You don't really want to do that, do you ?

The seals required to rebuild your brake calipers are made of "unobtainium" (that is, impossible to find). You'd make out better by getting rebuilt units from OGTS or possibly an equivalent replacement part.
Rick
 

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I'm not aware of a cross reference resource that I trust. However, several of us have original Opel parts books. It only takes a couple of minutes to check for common part numbers between the GT, Kadett, and 50 series Opels. I'd be glad to check out individual parts for you?
 

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Rick;
The seals you're referring to, do you mean the ones that go on the piston in the caliper, or the ones that seal the two halves of the caliper housing?
Gene
 

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Rick;
Dave is right, I have found a place for the seals and I have them on my on Wagon. I rebuilt mine about two years ago and still no problems.
Gene
 

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Opeler
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Discussion Starter · #10 ·
Wow, had no ideal that was a special seal, I have always just used rubber o-rings. I know I have and drive allot of different cars, but I probably have more time behind the wheel of a GT than I have of any other single model. Lamborghini, Jaguar, Corvette, etc; I own them, but here I am, putting together another GT. Just like the car, sporty, fun to drive, and economical. But back to the point, I have owned maybe five of them over the last twenty or so years, and had to redo the brakes on maybe three of them. I have never had a problem... yet. But I would like to know what I am risking, if anyone knows why it needs to be a special material.

Not rebuilding the calipers at the moment, just changing the pads, I've always broke the calipers in half to change the shoes, and honestly would not know how to do it otherwise with thoes pins?

Will get the numbers off of them though, thanks.
 

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NudeAutoMall said:
But I would like to know what I am risking, if anyone knows why it needs to be a special material.
Risk? Complete brake failure. Those seals have to deal with 1500-2000 psi, and also they have to tolerate contact with brake fluid (non-compatible materials will fail).

Changing pads is simply a matter of driving out those pins you spoke of, slipping the pads out, and driving the pins back in. In fact, in an endurance-racing application, I've swapped front pads (hot pads BTW!) in under a minute per side.

Opel warns never to split the caliper halves because the proper seals quite simply are not available. I know people have found alternatives, but unless you know the o-ring is the correct size and material type, the consequences could be fatal.

Bob
 

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Opeler
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Discussion Starter · #14 ·
Brake Fluid eats through everything, including the Cast Iron of the Caliper itself, anyone that restores Corvettes knows that problem all to well. If the only risk is of desulving of the rubber, that's fine, breaks get sluggish first long before a seal can fail. Sounds like I might soak a seal on brake fluid for a few days this time first, just to make sure I just didn't just get lucky and find some resistant rubber the times before.
As for the pressure, I'm sure that is the reason the O-ting is counter sunk, so the cast iron takes the bulk of the pressure, not the seal.
Cars loose brakes all the time, and with all the junkers I have driven over the years, I can not honestly count the times I have lost brakes (never from anything I have rebuilt). But los of life, I would bet, is more often due to panic of the falure, than the actual falure. Most cars can be stopped safely enough by simply down shifting, and the use of the cable brakes. In more urgent situations, reverse works well, especialy in a manual where you can rev the engine and play with the clutch. A little rough on the trans, but the trans is much easer to replace than your life.
 

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Also, keep in mind the heat handling requirement of the seal material.....brakes get hottttt!
 

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Lotsa info there about O-Rings. Lemme give you an example of what and why it is critical to have the correct O-Ring in the application. Most know I've spent a day or two in the USAF as an aircraft mech working on low and slow to the world's fastest and highest, but that's another topic. When the requirement for higher and faster became evident new fluids were being developed that could survive in the environment the aircraft was in. It became apparent quickly, the new fluids were not compatible with the O-Rings currently in use, so new synthetic seals were developed, problem was, some worked o.k with some fluids others disintegrated or expanded in other fluids. So, until all seal were compatible with all fluids, which eventually happened, almost, seals were color-coded with dots of color on them. That worked pretty good, dots of red, yellow, and blue on a seal worked in most environments. The one thing the chemists could not do was find a seal that would work with brake fluid and any other aircraft fluid, until the last 30 years or so. What we did to educate the newbies on how important the right seal in the right system was, we put various seals in containers with the fluids used on the aircraft and the next day looked at them. Most would be disintegrated, or swollen to 3-5 times normal shape, the correct one for the system was not changed at all. It was very graphic. Here's a personal note, on the Blackbirds (SR-71) there are no o-ring seals anywhere on the aircraft, they would melt during the first flight. Sorry for being so long winded on this. Brakes are critical on cars, wrong seals installed will have deadly results.
 

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Opeler
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Discussion Starter · #17 ·
Ok, a little thought, a little research, and a little help.
Thought: Hydraulic Cylinders on my Bulldozer and End Loader both sustain much more pressure with allot more exposed surface, yet those are readily available. Carosiveness of Brake Fluid, well resistant materials are made for most any carosive, and o-rings are readily available for most any other car, and where there is allot more exposed surface area. Heat is another consideration (thanks) but I have also rebuilt cylinders in injection moulding machines, and considering I have seen those things get hot enough to warp a mold over a foot thick, I think we can exceed breaking tempatures under most cercimstances, yet again those o-rings are readily available.

Research: A little diging around on Google produced a wealth of info about O-rings. I like the OringUSA page was the best so I dropped them a line.

Help: OringUSA dropped a simple chart that lead to this link:
http://www.oringsusa.com/my_html/buy_e70.html

Now, anybody know the exact size, since we have now surpased all other deamons :)
 

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NudeAutoMall,

I have no doubt that an o-ring can be sourced to work between the two halves of the brake caliper. The problem is that most people (myself included) who are qualified to select the o-ring fear the liability issues.

This should help you out with the material selection.

http://www.efunda.com/designstandards/oring/oring_chemical.cfm?SM=none&SC=Automotive Brake Fluid#mat

Now you just need to measure the gland size and figure out where to go from there. As the stock o-ring has a rectangular cross section, you'll need to start from scratch in your selection....

The info is all on the net BTW.

-Travis
 

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To start at the beginning it's not an O ring. It's a square shouldered seal. It measures 10mm od 5.5 id and 2mm thick. Viton will hold up to break fluid and the temperatures. Given that info go get a sheet of Garlock and a couple of gasket punches.
 
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