Brake Master Cylinder Swap.

[wnagel]

Well today I put the new Master and the pipes between the master and the proportionig valve are not the same, the front pipe are more reduce and the rear are more big......sorry for my english. ...

 

[Monte Cristo]

he is not redesigning the brakes, the master was superseded by the master he wants and if you look up the calipers the same caliper was used from 78 up to 87.

From this 1994 alert from Bendix, the low drag caliper was not released by GM until 1980:
http://www.remaninc.com/pdfs/lowdragcalipers.pdf
There can be problems from cross use of traditional vs. low drag calipers, and the remanufacturers and vendors don't distinguish this FACT. They reman the cores indiscriminately, and its difficult to check without taking the seals out. So, yes, this can be a kind of modification, but most people don't realize it. For this reason, some people won't buy reman calipers.

 

[Monte Cristo]

Well today I put the new Master and the pipes between the master and the proportionig valve are not the same, the front pipe are more reduce and the rear are more big......sorry for my english. ...

I'm not sure exactly what you mean by "pipes". The brake lines should all be the same 3/16 inch diameter. Otherwise, someone has changed the stock hydraulics and modified your brake system. (Maybe it is easier to find metric brake lines in Chile?) However, the fitting nuts can be different sizes. That was probably done on the assembly line so the workers didn't put the wrong brake line in the wrong place. Changing the fittings and reflaring the lines is no big deal, but if the brake lines are different diameters, you may have a problem.

 

[pontiacgp]

From this 1994 alert from Bendix, the low drag caliper was not released by GM until 1980:
http://www.remaninc.com/pdfs/lowdragcalipers.pdf
There can be problems from cross use of traditional vs. low drag calipers, and the remanufacturers and vendors don't distinguish this FACT. They reman the cores indiscriminately, and its difficult to check without taking the seals out. So, yes, this can be a kind of modification, but most people don't realize it. For this reason, some people won't buy reman calipers.

The difference between the two calipers is very minor and has little effect. I doubt the standard caliper has been on the shelf for decades. His car most likely has had the calipers changed and they are probably the low drag style. I'm not sure where you buy your calipers but for years the only ones sold are the remans,

 

[pontiacgp]

Well today I put the new Master and the pipes between the master and the proportionig valve are not the same, the front pipe are more reduce and the rear are more big......sorry for my english. ...

Don't worry about your English....If the fittings are not the same for both masters you will have to change the fittings on the brake lines....

 

[malibudave]

In the states, from 1978-1981 g-body cars came with strait bore master cylinders. 1982 to 1988, gbody cars came with step bore master cylinders. Step bore master cylinders where used because almost all GM rear wheel drive, vacuum boosted cars and S10 pickups came with LOW drag calipers to help save on fuel. In 1998, GM stopped using step bore master cylinders and LOW drag calipers in the S10 pickups and I believe they were eventually phased out of the other car lines.

Long story shortened, you want the newest master cylinder that will work with your booster. Stock size bore for 1978-1981 gbodies is 24mm. There is a newer S10 master cylinder that can be used and it is a bolt on. It has a 1.0" bore and should work fine with your stock brakes if your booster is working well. Go to this link to read about it. It is made for right hand drive S10s and has the outlets you need to be a bolt in. This master cylinder is NEW, its aluminum, and has a larger reservoir so it can be used with rear disk brakes with stock type rear calipers.

http://www.maliburacing.com/forum/viewtopic.php?f=25&t=124945

Front brake line coming out the master cylinder is 3/16 inch in diameter and have a 1/2-20 inverted flare brake line fitting. They install on the rear port of the master cylinder and go to the front brakes.

Rear brake line coming out the master cylinder is 1/4 inch in diameter and have a 9/16-18 inverted flare brake line fitting. They install on the front port of the master cylinder and go to the rear brakes.

All reman calipers sold from 1978-2003 have the same part number regardless of year, car, or truck they came on. 1978 g-body caliper part number is the same for a 1988 S10, F-body, or G-body car and is the same part number as a 2003 single piston front caliper 2 wheel drive S10.

I CANNOT verify my statements below as fact, but it is my OPINION, but most of the calipers are rebuilt to NON low drag (normal) specifications. This is so they will work with both the strait bore master cylinders that were used from 1978-1981 and 1998-2003, and also the step bore master cylinders used from 1982-1997. This saves money as they don't have to built them for specific years and they do not have to worry about returns because someone put a LOW drag caliper on a car with a strait bore master cylinder.

It is MY OPINION that all the calipers built from 1978-2003 have a square grove machined in the caliper housing bore and it is NOT beveled as the link given in a previous post. It is my OPINION that the only difference between a LOW drag caliper that was used from 1982-1997 is the seal. I know what the previous link has said about the design, but from the calipers that I have taken apart I have not seen it. That being said, I have NOT taken apart a lot of calipers. The only real way to verify this is to pull apart an original 1982-1997 caliper from a G-body (1982-1988), F-body (1982-1992), or S10 (1982-1997) which I do not have access to.

 

[Clutch]

Guys I did this on my 78 Cutlass the g-body of the month. I used a used master and the 2 lines to the porp valve from my 79 parts car and it works great

 

[Monte Cristo]

Rear brake line coming out the master cylinder is 1/4 inch in diameter and have a 9/16-18 inverted flare brake line fitting. They install on the front port of the master cylinder and go to the rear brakes.

Malibudave, thanks for joining the discussion. To be positive, you had some good information. However, I disagree that 1/4" brake lines were stock in a late 70's car. Fred Puhn, a professional engineer wrote in my 1985 edition of his Brake Handbook that 3/16" tubing was used in "most" modern cars because it "stiffer, lighter, and easier to bend". (I would add that it is also cheaper for the auto makers to buy, and for a collector/restorer, it has less internal surface area to rust and damage the cups and seals.) Puhn noted that the 1/4" tubing is less restrictive of fluid flow, and less likely to get damaged in handling, but were only found on older vehicles. So the 1/4 lines might be useful for off-road vehicles where the lines might get kinked from rocks and debris, or they might be considered as a way to get more fluid to disk caliper cylinder in a modified system that needs more fluid than stock. Why would that be the case for rear drum wheel cylinders? That just doesn't make any sense. The one explanation that I can give is that the fitting nuts from the 1/4 tubing sold for fuel lines fit in the m/c port, so some DIYers saw a way to avoid reflaring a line. I redid all of the lines in a 75 Ford and they were all 3/16", as is every car I can remember. Puhn recommends 3/16" for the entire brake system, and I can see no good reason to change that.

All reman calipers sold from 1978-2003 have the same part number regardless of year, car, or truck they came on. 1978 g-body caliper part number is the same for a 1988 S10, F-body, or G-body car and is the same part number as a 2003 single piston front caliper 2 wheel drive S10.

Yes, well why is that since these were originally two different parts? Maybe a guy who has a website about brakes could get an answer from the reman companies and tell us what they are actually selling people, and what they do with the cores that are non-conforming to their intended design?

I CANNOT verify my statements below as fact, but it is my OPINION, but most of the calipers are rebuilt to NON low drag (normal) specifications. This is so they will work with both the strait bore master cylinders that were used from 1978-1981 and 1998-2003, and also the step bore master cylinders used from 1982-1997. This saves money as they don't have to built them for specific years and they do not have to worry about returns because someone put a LOW drag caliper on a car with a strait bore master cylinder..

An opinion is like a belly-button. Everyone has one. A bigger problem is getting one reman caliper that is standard, and a second that is low drag. Most certainly, the traditional will grab first and the car will pull to that side in a hard brake. I had an experience around the time of that Bendix letter I gave the link for when the car did a 180 into the incoming lane avoiding a deer in the wee hours of the morning. Fortunately, there was no one else on the road, but I don't doubt that kind of thing was happening. Not checking the grooves might save money short term, but it would open them up to a nasty product liability class action lawsuit.

It is MY OPINION that all the calipers built from 1978-2003 have a square grove machined in the caliper housing bore and it is NOT beveled as the link given in a previous post. It is my OPINION that the only difference between a LOW drag caliper that was used from 1982-1997 is the seal. I know what the previous link has said about the design, but from the calipers that I have taken apart I have not seen it. That being said, I have NOT taken apart a lot of calipers. The only real way to verify this is to pull apart an original 1982-1997 caliper from a G-body (1982-1988), F-body (1982-1992), or S10 (1982-1997) which I do not have access to.

So, do you link the link with the Bendix letter is a fraud, or was Bendix wrong? What's your opinion on that? Here's that link again:
http://www.remaninc.com/pdfs/lowdragcalipers.pdf
Here's another link stating that the difference is between a 15 degree grove on the standard calipers and a 30 degree grove on the low drag calipers with diagrams for those who need a better visual:
http://www.idmsvcs.com/2vmod/brakesystem/hydraulic/disassembly/calipers/pdfs/mpbrakes_lowdrag.pdf
For your opinion to be correct, both of these links need to be wrong.

The difference between the two calipers is very minor and has little effect. I doubt the standard caliper has been on the shelf for decades. His car most likely has had the calipers changed and they are probably the low drag style. I'm not sure where you buy your calipers but for years the only ones sold are the remans,

Well, since the reman companies and the vendors won't tell us, we really don't know what's inside the calipers. Since its possible to get the wrong ones for the m/c, or worse yet, a mismatched pair, it makes more sense to buy a new set. Raybestos still makes them new, no core needed, and listed as having "residual drag torque", which I assume is the original standard version:
http://www.rockauto.com/en/moreinfo.php?pk=8467976&cc=2002800&jsn=455
If not, they should be at least a matching pair.
[Edit to note that a series of small changes to a hydraulic system can have a negative sum result, or could multiply small problems created by each.]

Guys I did this on my 78 Cutlass the g-body of the month. I used a used master and the 2 lines to the porp valve from my 79 parts car and it works great

Thanks for stopping by Clutch. When you get a chance, how about peeking under the hood and tell us what size the brake lines are coming out of the m/c?

 

[Clutch]

Malibudave, thanks for joining the discussion. I disagree with that. Fred Puhn, a professional engineer wrote in my 1985 edition of his Brake Handbook that 3/16" tubing was used in "most" modern cars because it "stiffer, lighter, and easier to bend". (I would add that it is also cheaper for the auto makers to buy, and for a collector/restorer, it has less internal surface area to rust and damage the cups and seals.) Puhn noted that the 1/4" tubing is less restrictive of fluid flow, and less likely to get damaged in handling, but were only found on older vehicles. So the 1/4 lines might be useful for off-road vehicles where the lines might get kinked from rocks and debris, or they might be considered as a way to get more fluid to disk caliper cylinder in a modified system that needs more fluid than stock. Why would that be the case for rear drum wheel cylinders? That just doesn't make any sense. The one explanation that I can give is that the fitting nuts from the 1/4 tubing sold for fuel lines fit in the m/c port, so some DIYers saw a way to avoid reflaring a line. I redid all of the lines in a 75 Ford and they were all 3/16", as is every car I can remember. Puhn recommends 3/16" for the entire brake system, and I can see no good reason to change that.



Yes, well why is that since these were originally two different parts? Maybe a guy who has a website about brakes could get an answer from the reman companies and tell us what they are actually selling people, and what they do with the cores that are non-conforming to their intended design?



An opinion is like a belly-button. Everyone has one. A bigger problem is getting one reman caliper that is standard, and a second that is low drag. Most certainly, the traditional will grab first and the car will pull to that side in a hard brake. I had an experience around the time of that Bendix letter I gave the link for when the car did a 180 into the incoming lane avoiding a deer in the wee hours of the morning. Fortunately, there was no one else on the road, but I don't doubt that kind of thing was happening. Not checking the grooves might save money short term, but it would open them up to a nasty product liability class action lawsuit.



So, do you link the link with the Bendix letter is a fraud, or was Bendix wrong? What's your opinion on that? Here's that link again:
http://www.remaninc.com/pdfs/lowdragcalipers.pdf
Here's another link stating that the difference is between a 15 degree grove on the standard calipers and a 30 degree grove on the low drag calipers with diagrams for those who need a better visual:
http://www.idmsvcs.com/2vmod/brakesystem/hydraulic/disassembly/calipers/pdfs/mpbrakes_lowdrag.pdf
For your opinion to be correct, both of these links need to be wrong.



Well, since the reman companies and the vendors won't tell us, we really don't know what's inside the calipers. Since its possible to get the wrong ones for the m/c, or worse yet, a mismatched pair, it makes more sense to buy a new set. Raybestos still makes them new, no core needed, and listed as having "residual drag torque", which I assume is the original standard version:
http://www.rockauto.com/en/moreinfo.php?pk=8467976&cc=2002800&jsn=455
If not, they should be at least a matching pair.
[Edit to note that a series of small changes to a hydraulic system can have a negative sum result, or could multiply small problems created by each.]



Thanks for stopping by Clutch. When you get a chance, how about peeking under the hood and tell us what size the brake lines are coming out of the m/c?

so that's the 79 in the 78

there's a reference for size and here's a 79 H/o

does that work for you?

 

[Clutch]

View attachment 73596 so that's the 79 in the 78View attachment 73597 there's a reference for size and here's a 79 H/oView attachment 73598 does that work for you?

And no I won't go back out in the mosquitoes with a digital micrometer and get more pictures I'm tired from fixing cars all day hope the pictures help that Hurst Olds has never been apart it has 73k on it