69 rear disc conversion, weak emergency brake. - Impala Tech
Brakes & Suspension Conversion Questions & more

 
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post #1 of 7 (permalink) Old 07-21-2014, 05:45 AM Thread Starter
 
 
Join Date: Sep 2012
Location: Sweden
Posts: 10
 
69 rear disc conversion, weak emergency brake.

I have converted my 69 with a 11" rear disc kit from "the right stuff".
The calipers are adjusted after the descripions, and the e-brake pedal are not going all the way to the floor, but i still have very weak e-brake. Way to weak to pass the Swedish car inspection..
It feels like the gearing between pedal and caliper is wrong, but i have even tried to extend the levers on the calipers ½" for more power without any better result.
Right now it feels like "the right stuff" are the wrong stuff to buy..
Please help me with ideas, the time is running out. I am going in for re-inspection again tomorrow..
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post #2 of 7 (permalink) Old 07-21-2014, 10:54 AM
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Welcome to the Team Mattias!

Usually the brakes are out of adjustment, which is why they do not hold on a hill or slow the car down when looking for an emergency brake. They are supposed to be self adjusting, but that requires that you actually tap the brake pedal when traveling in reverse to tighten up the adjustment. Most people coast to a stop or worse slam the tranny into forward whiled still traveling backwards.

If after the shoes are adjusted you have issues look to removing slack in the e-brake line by tightening the turnbuckle or where the cable pulls on the rear brake loop cable up under the drivers side of the car.

Big Dave
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post #3 of 7 (permalink) Old 07-22-2014, 03:44 AM Thread Starter
 
 
Join Date: Sep 2012
Location: Sweden
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Thank you for your answer, but what is happening when you run backwards and brake, that is different from forward?. I guess you can not get the piston to rotate or something like that?. I am a mechanic and have worked with european cars for many years, but have never had this kind of problem before.
The instruction says that you should take off the lever on the caliper, and adjust by turning the axle as much as possible. That i have done, and the lever is moving less than half its way before it starts to stop the wheel. I can get it to brake so you can not turn the wheel by hand, but when trying it in slow speed it brakes almost nothing.
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post #4 of 7 (permalink) Old 07-22-2014, 09:17 AM
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The engineers figured you where not going to jack up the car and adjust the brakes every weekend so they incorporated self adjusters in the design that is activated by the brake being used in reverse. If your car has early Cadillac rear disc brakes the situation is even more difficult as the rear brakes will not work at all unless kept adjusted. It is this lack of adjustment that had the brakes replaced by the PBR brakes first used on F-body cars (Camaro-Firebird).

Have you shimmed the caliper so they are centered on the rotor and deglazed the rotors and shoes to bed them in?

Big Dave
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post #5 of 7 (permalink) Old 07-22-2014, 05:16 PM Thread Starter
 
 
Join Date: Sep 2012
Location: Sweden
Posts: 10
 
Ok, that sounds like a strange construction, but i still do not understand how the caliper can feel any difference if the rotor are moving front or backwards..
I do not know if it is Cadillac parts, but they are mounted with two thick pins with threads on them. Do you recognize that?.
Yes, the cailpers are centered, and i have cleaned both rotors and shoes when i mounted them. I have also used them for about 500 km.
Soon i will throw the calipers in the dump and put on something ells. Do you know if there are something better to buy, that fits straight on?.
Thank you for your help!
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post #6 of 7 (permalink) Old 07-23-2014, 09:48 AM
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Personally I prefer drum brakes in the back, unless I am building a road racer. Disc brakes are used on passenger cars because they are cheaper to make and install than drum brakes which is why the factory switched over originally.

Imported German sports cars made in a country where they have unlimited speed limits on many intercity roads have disc brakes due to the speeds at which they drive. Just like in road racing excessive speed can overwhelm a drum brake, requiring a large heavy disc to absorb and shed the heat from the brakes. After that it was just a case of Monkey see Monkey do, as Cadillac perceives BMW and MB as their major competitors. If they have rear disc brakes then Cadillac needs them as well even though there are few unlimited speed limit roads in America. If they had copied the brakes instead of trying to make a cheaper version it might have worked.

If I were looking for a GM sourced part I would use the PBR rear brake used on the 1989-'92 Camaro and Firebird with a secondary mechanical actuated caliper for the E-brake, instead of a drum with tiny shoes that look as though they came off of a boat trailer.

http://www.partsgeek.com/g7x2281-che...+Brake+Caliper



There are companies that sell the complete rear brake system with everything needed.

Big Dave
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post #7 of 7 (permalink) Old 07-26-2014, 04:11 PM Thread Starter
 
 
Join Date: Sep 2012
Location: Sweden
Posts: 10
 
Maybe i should have built my own kit like i thought about first. But when a complete kit didn´t cost more than than the calipers i was looking on here in Sweden, i took the "easy way". I googled before i bought it, and many said that the company sells good parts, not like the stuff i have got...
I will probably use euoropean calipers instead, that i know works well.
But i feel very disappointed with the company, that makes kit with calipers that doesn´t work even when they are new
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