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Author Topic: Finding Rear Disk Brake Calipers  (Read 10999 times)
MalteseFalcon
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« on: February 02, 2007, 11:29:35 PM »

I'm putting together a 1979-81 WS6 rear disk brake set up for my 1978 WS6 Trans Am. I elected to buy the backing plates and power booster used, and complete the system with new or rebuilt parts.

You can buy calipers at NAPA. Get the ones with hardware (caliper mounting pins and dampening springs) you need this anyway.

Emergency brake cables can also be bought at NAPA. They cost about a third what they did from GM before they were discontinued, and a lot less than NOS (I paid $14 for one side and $18 for the other).

Scarebird Mechanical makes an emergency brake bracket and lever kit that uses Cadillac springs that are still available - about $75 - $100.

If you are buying rebuilt calipers, check them before you leave the store. The casting number of both sides is "451" and both sides have an "R" cast into them. Neither has an "L". The castings appear to be the same on both sides, but the difference is in the piston and / or ratchet mechanism for the emergency brake. There is an "L" stamped into the end of the bolt that the emergency brake lever attaches to on the left side, and an "R" stamped in the same place on the other. The "L" is located in the spot that is painted yellow in the first picture.





I was given a caliper that had "450" and "L" on it by NAPA. It was wrong - it couldn't have worked because it was backwards (the bleeder valve would have been on the bottom, and there wasn't room for the spring for the emergency brake). After a bunch of research, I found that it was from a 1979 Cadillac Fleetwood. I took it back and got one with the "451" cast into it.



So: always look for casting 451 for both sides, don't be confused by the "R" on the left caliper casting, and look for the little "L" or "R" stamped into the bolt
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Steve

1978 WS6 - W72 4 Speed, Martinique Blue on Light Blue - Fire Am Restification Project

2000 WS6 6-Speed Trans Am, Black on Ebony

2009 VW Jetta 2.0 TDI Clean Diesel, Platinum Grey on Grey leather -  50 MPG daily driver!

2005 BMW 645Ci Convertible, 4.4 V8, 6-speed Auto triple black German Pony Car
78thumper
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« Reply #1 on: February 03, 2007, 01:15:25 PM »

Nice tips, especially about the "R"

Thanks Steve
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Later
Steve R.
IFLYBY
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« Reply #2 on: February 03, 2007, 09:19:02 PM »

Thanks , dude ! Several years ago I worked on this setup on  my 79 W/72 car and it was a bitch ! I would bleed the brakes till it had outstanding pedal , bolt on the wheels , and by the end of the driveway the brakes were gone . Even the brake shop had to do it twice .  Sad
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Everything is a car , was a car , or will be a car . 79 W 72 T/A--05 GTO--69 GTO Judge ( very , very sick )
Grand73Am
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« Reply #3 on: February 17, 2007, 05:35:20 PM »

That's a great write-up about the rear discs. I'm glad to hear about the NAPA cables, since I'm gonna need some.
I have had some trouble with bad sealing surfaces where the hose connects, causing leaks. Had to get 3 of them to get one that was in good enough condition and even then, I had to do a little Dremel tool work on the surface around the hole to smooth it out so the copper washer would seal. Something else to watch out for Smile .
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Steve F.
Hugh Jass
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« Reply #4 on: February 17, 2007, 08:07:28 PM »

Thanks for the info Steve.
Where did you get those rotors?
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79 W72 WS6,  work in progress - nicknamed Lucy
Rick
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« Reply #5 on: February 17, 2007, 10:39:45 PM »

(Don't forget to ask about his experience in getting the lugs pressed in while you're at it... Shocked  Shocked )
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MalteseFalcon
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« Reply #6 on: March 01, 2007, 11:35:17 PM »

I got the rotors off of a vendor on eBay. They'll do for a start, but they were a good deal and I'm not sure how high performance they are yet.

I think Rick is referring to the fact that when I installed SAE studs in the front rotors, the surface cracked - basically, a chip came out. I'm not sure that was the rotors' fault, but the machine shop was able to fix it.

If I replace these, I'll go with high-end rotors from Baer or Brembo.
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Steve

1978 WS6 - W72 4 Speed, Martinique Blue on Light Blue - Fire Am Restification Project

2000 WS6 6-Speed Trans Am, Black on Ebony

2009 VW Jetta 2.0 TDI Clean Diesel, Platinum Grey on Grey leather -  50 MPG daily driver!

2005 BMW 645Ci Convertible, 4.4 V8, 6-speed Auto triple black German Pony Car
TACZippy
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« Reply #7 on: March 05, 2007, 03:01:24 PM »

Are those rotors from a ebay user named R1 Motorsports or something like that?  I got a set of rotors that look exactly like that, except they aere colored Black.  They seem to work alright, stop better than the stock rotors, for sure.
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If it aint broke, modify something till it is.
harristw
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« Reply #8 on: March 05, 2007, 10:36:59 PM »

im getting my rear calipers blasted.  I've sourced the 2 seals in it and my total per caliper is going to be less than 20 bucks each in the complete rebuild.  Not much to them.
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MalteseFalcon
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« Reply #9 on: March 10, 2007, 10:44:17 AM »

Quote from: "harristw"
im getting my rear calipers blasted.  I've sourced the 2 seals in it and my total per caliper is going to be less than 20 bucks each in the complete rebuild.  Not much to them.


That's great if you have them already. This is kind of directed at those who are converting to rear disks from drums or are buying rebuilt calipers. Let us know how the rebuild goes.
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Steve

1978 WS6 - W72 4 Speed, Martinique Blue on Light Blue - Fire Am Restification Project

2000 WS6 6-Speed Trans Am, Black on Ebony

2009 VW Jetta 2.0 TDI Clean Diesel, Platinum Grey on Grey leather -  50 MPG daily driver!

2005 BMW 645Ci Convertible, 4.4 V8, 6-speed Auto triple black German Pony Car
MalteseFalcon
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« Reply #10 on: April 01, 2007, 09:34:18 PM »

Here's another "tip" - If you buy rebuilt calipers, your best bet may still be to start with a set of calipers off of a 1979-81 Firebird. You can buy the calipers and hard lines, and you can get the e-brake levers from Scarebird, but (at the moment) you can only get the brass block / fitting that goes from the hard line to the caliper off of a car that originally had them.

The blocks do not appear to have a part number of their own, at least not in my 1981 AIM.

I have been told that 1979-85 Cadillac Eldorados with rear disks used a similar block that can be adapted by drilling out the 10 mm hole to 7/16, but have yet to test it out. I have asked Inline Tube if they can make them (they make other banjo fittings, so they should be able to make these) but they may need a sample. I'll update this with any progress. If you have a solution, please add it.
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Steve

1978 WS6 - W72 4 Speed, Martinique Blue on Light Blue - Fire Am Restification Project

2000 WS6 6-Speed Trans Am, Black on Ebony

2009 VW Jetta 2.0 TDI Clean Diesel, Platinum Grey on Grey leather -  50 MPG daily driver!

2005 BMW 645Ci Convertible, 4.4 V8, 6-speed Auto triple black German Pony Car
dopey454res
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« Reply #11 on: April 16, 2007, 10:33:51 PM »

would the calipers from a RWD late 70's CAD Seville work, also the backing plates/brackets from the same
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Joker (§ir£Ðragon)
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« Reply #12 on: April 25, 2007, 06:17:47 PM »

Quote from: "dopey454res"
would the calipers from a RWD late 70's CAD Seville work, also the backing plates/brackets from the same


That's a good Q. Hey Steve! Laughing
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Larry

MalteseFalcon
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« Reply #13 on: April 25, 2007, 07:27:50 PM »

Quote from: "SirLDragon"
Quote from: "dopey454res"
would the calipers from a RWD late 70's CAD Seville work, also the backing plates/brackets from the same


That's a good Q. Hey Steve! Laughing


I have read that they are, but can't confirm from personal experience. I think its only the '78-'79, though.
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Steve

1978 WS6 - W72 4 Speed, Martinique Blue on Light Blue - Fire Am Restification Project

2000 WS6 6-Speed Trans Am, Black on Ebony

2009 VW Jetta 2.0 TDI Clean Diesel, Platinum Grey on Grey leather -  50 MPG daily driver!

2005 BMW 645Ci Convertible, 4.4 V8, 6-speed Auto triple black German Pony Car
Grand73Am
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« Reply #14 on: April 25, 2007, 10:39:41 PM »

I know the 79 Cadillac Seville rear disc brake parts are the same since I pulled some rear brackets, calipers, and park brake pieces from one a few years ago.

Looking in my interchange manual, I see there are some other Cadillacs and other big cars that used the same rear disc brakes too. Try looking at 77-79 Cadillac, 77-79 Seville, 79-82 Cadillac Fleetwood, 77-78 Riviera, 78-80 Buick.

    I think it's just that the rotors are different, since the TA's use the 4 3/4" lug pattern and the others use a 5" lug pattern. So, just buy some new TA rotors and you're good.
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Steve F.
MalteseFalcon
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« Reply #15 on: April 26, 2007, 08:41:08 AM »

Quote from: "Grand73Am"
I know the 79 Cadillac Seville rear disc brake parts are the same since I pulled some rear brackets, calipers, and park brake pieces from one a few years ago.

Looking in my interchange manual, I see there are some other Cadillacs and other big cars that used the same rear disc brakes too. Try looking at 77-79 Cadillac, 77-79 Seville, 79-82 Cadillac Fleetwood, 77-78 Riviera, 78-80 Buick.

    I think it's just that the rotors are different, since the TA's use the 4 3/4" lug pattern and the others use a 5" lug pattern. So, just buy some new TA rotors and you're good.


Careful, though - have a read though my post above. The 1979 "450" Fleetwood calipers definitely don't fit - they're backwards, because I'm pretty sure on those cars, they are not staggered one in front and one behind the axle, like they are on the leaf spring Trans Am and Nova-based 1977-79 Seville. If the calipers aren't staggered, the backing plates won't be either, and the backing plates have a left and right side on our cars.
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Steve

1978 WS6 - W72 4 Speed, Martinique Blue on Light Blue - Fire Am Restification Project

2000 WS6 6-Speed Trans Am, Black on Ebony

2009 VW Jetta 2.0 TDI Clean Diesel, Platinum Grey on Grey leather -  50 MPG daily driver!

2005 BMW 645Ci Convertible, 4.4 V8, 6-speed Auto triple black German Pony Car
harristw
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« Reply #16 on: June 17, 2007, 10:42:56 AM »

hey guys...I've got rear disc's that I just rebuilt.  Unless your cores are really bad, ie broken, cracked, missing parts I would rebuild them.  Cost me 18bucks to have the pair blasted, Autozone sells a seal kit for them ($6ea side) and I painted them up.  so for $30bucks i rebuilt my pair!!  I didnt realize anyone sold the oring/seal kit until early last week. dissassembly is cake so i would think that even a first timer could figure it out.
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NSAN1T
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« Reply #17 on: July 23, 2007, 12:30:44 PM »

Do you need a proportioning valve or something to switch over to 4wheel disc???
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1978 Firebird Formula ~ 1977 F150 Custom ~ 1984 Fiero Indy Pace Car ~ 1987 Fiero SC ~ 2000 Protege ES
harristw
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« Reply #18 on: July 23, 2007, 02:42:01 PM »

I'd recommend it.
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MalteseFalcon
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« Reply #19 on: July 23, 2007, 10:59:13 PM »

Quote from: "NSAN1T"
Do you need a proportioning valve or something to switch over to 4wheel disc???


Technically, you have a prop valve if you have front disks and rear drums, but the problem is that its not calibrated for rear disks, and its not adjustable, so you need either:

(a) a prop valve from a 4 wheel disk car; or

(b) if its not stock down to the tires, you'll likely need an adjustable prop valve. You can add one to the rear brake line and continue to use your existing prop valve as a distribution block. I would assume that you could do that with the original drum brake prop valve. You can also get a distribution block with an adjustable prop valve in it from SSBC, Jegs, Summit, etc.
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Steve

1978 WS6 - W72 4 Speed, Martinique Blue on Light Blue - Fire Am Restification Project

2000 WS6 6-Speed Trans Am, Black on Ebony

2009 VW Jetta 2.0 TDI Clean Diesel, Platinum Grey on Grey leather -  50 MPG daily driver!

2005 BMW 645Ci Convertible, 4.4 V8, 6-speed Auto triple black German Pony Car
cheapta
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« Reply #20 on: August 04, 2007, 09:28:16 PM »

I put this setup on my 69 Z/28 before I bought my TA. One other thing to watch for with the NAPA calipers: They offer a few different ones and,of course,I got the cheapest they offered. I found they media blast the whole caliper,including the stud for the e-brake mounting.This made junk of the threads on the studs and made installing the e-brake lever a monumental pain. When I get a rebuilt set for the TA I'll certainly take a nut with me and make sure it threads onto that stud.
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79 WS6
69 Z/28
65 Nova
66 Buick Special Ragtop
67 Buick Special sedan,
80 Harley FLT,it may be ugly but it sure is slow!
98 Harley 883 Hugger
The Buicks and Hugger belong to my Fiance.
pontiacfreak
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« Reply #21 on: July 19, 2011, 09:27:00 PM »

i know this old post but very good info. anyone have where 3 brake cables connect for emergency brake?  Im converting and something seems missing or wrong
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Grand73Am
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« Reply #22 on: July 23, 2011, 07:29:39 PM »

You need the equalizer at #1 and the connector at #3.

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Steve F.
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