Author Topic: Help with rear disc brakes!!  (Read 8915 times)

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Offline Angelo

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Re: Help with rear disc brakes!!
« Reply #30 on: November 16, 2014, 12:23:39 PM »
Oh got it, I bought one but never used it. You only need that if your brake light gets stuck. Basically if there is more/less pressure on the front or back then your brake light will go on by that port in the prop valve. If you have your brake light wiring hooked up correctly your brake light will go on if that is not centered in the prop valve.  Its a safety feature to indicate if there is a loss of pressure to the front or rear. Is your brake light on? Is it wired correctly?
81' ex-Turbo Trans Am - Resto-mod

Offline randr

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Re: Help with rear disc brakes!!
« Reply #31 on: November 16, 2014, 12:50:51 PM »
I believe it's wired correctly. Light isn't on. I was wondering if using a vacuum bleeder could cause it to shift back and forth and therefor give me a problem bleeding brakes. Any link on showing exactly how to adjust e-bake? Thanks for all the help.

Offline Angelo

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Re: Help with rear disc brakes!!
« Reply #32 on: November 16, 2014, 01:55:43 PM »
I referenced the service manual (I don't think the Chiltons type books will explain how to do it right). You can now get a USB thumbdrive with the entire service manual on it from this site.

I can give you a quick run-down though, assuming calipers are already on the car with rotors and pads in place.

1. With the ebrake lever off of the caliper, ratchet with a wrench (turn in the direction the caliper is pulled when the e-brake cable is pulled) until the caliper pads make contact with the rotors and stop them from spinning by hand. Repeat with the other caliper. Remember, one ratchets  clockwise, the other ratchets counter clockwise.

Just a site note, when you loaded the calipers (put the pads in them), you had to push the caliper piston back, turning counter clockwise while pushing the piston in. If you simply use a c clamp and compress the rear piston, you more than likely damaged the ratcheting mechanism inside the caliper.

test ratcheting the caliper also gives you the ability to test that it is working.

Just another comment, you can clamp down on the ratcheting mechanism with a wrench until it snugs up the pads on the rotors, but as soon as you turn back off a 1/8-1/4 turn, the piston can flex back enough to allow for the rear rotor to spin again.

2. Once you have the caliper adjusted with a wrench, re-assemble the emergency brake lever parts to the caliper. You will position them so when pulled they will lock the pads against the rotor (as you did with  your wrench). When pushed back you should be able to turn the wheel.

If your lever parts are bent or damaged, I highly recommend getting a set from scarebird on ebay, they are way stronger and plated: http://www.ebay.com/itm/Pontiac-Trans-Am-Seville-WS6-rear-disc-brake-caliper-parts-spring-lever-bracket-/371086849463

When all said and done the ebraake brackets will be bolted onto the rotor with the spring loaded pushing the lever back enough that the pads are not locked against the rotor. You should be able to lake a large pair of pliers and pull on the ratchet lever (compressing the spring) and manually tighten the rear pads to lock the rear wheel.

Tip: I used 3 zip ties to compress the spring I got from scarebird's kit. Once in place, I cut the zip ties. Don't think that's necessary for the factory springs.

3. Attach the emergency brake calipers (make sure they move freely before doing so), then adjust under the drivers side of the car (remember to adjust with the emergency brake of)

4. Here comes the fun part. Engage the emergency brake, then check to see if both wheels are locked. As I recall, the first time I did this it didn't lock, I had to release and readjust after one pull as everything got stretched into place. The second time was the charm, I only had a very small amount of adjustment to make after that.

5. Repeat engaging and unlocking the emergency brakes a dozen or so times, this firms up the ratcheting mechanism in the calipers.

6. Bleed the brakes with the emergency brake set.
81' ex-Turbo Trans Am - Resto-mod

Offline randr

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Re: Help with rear disc brakes!!
« Reply #33 on: November 16, 2014, 03:07:52 PM »
Think I may have found my problem. The cable going to the right rear is binding up between the exhaust and body. When I apply the parking brake it doesn't compress the spring on the caliper. I put headers and true dual exhaust and there doesn't seem to be a clear path to run the cable. Would this even have anything to do with my spongy brakes?

Offline RENOVATIONS

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Re: Help with rear disc brakes!!
« Reply #34 on: November 16, 2014, 03:26:56 PM »
I've posted this before but I'll put it up again in case someone else needs it.













Jeff

Projects:
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1978 Trans Am
1970 Camaro
1970 'Cuda

Offline Angelo

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Re: Help with rear disc brakes!!
« Reply #35 on: November 16, 2014, 05:58:24 PM »
That rear disc brake article is interesting. I think GM abandoned this ratcheting caliper setup, Honda's use it, albeit without the problems.

If the caliper on one side is not positioned then yes. When I mean positioned, I mean the emergency brake ratchet system is ratcheted down enough to allow the caliper to press the pads onto the rotor.

Does the car pull to one side when you drive it and hit the brakes?

I'm not sure of the situation under your car, but under mine the cables go under the exhaust system. You would think this is not a good idea, but that's how the factory did it. As long as the cables are not running along something where they could bind you should be ok.
81' ex-Turbo Trans Am - Resto-mod

Offline Angelo

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Re: Help with rear disc brakes!!
« Reply #36 on: November 16, 2014, 06:02:55 PM »
Just to clarify, the factory ran the cable below the exhaust, not above (in between the exhaust and body). If you're looking under the car, the first thing you see are the cables, then the exhaust, then the body.

I'm going to have to deal with this when I get frame connectors, the sub frame on the drivers side has a designed dent where the cable should ride in. Frame connectors will make this disappear I believe.
81' ex-Turbo Trans Am - Resto-mod

Offline randr

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Re: Help with rear disc brakes!!
« Reply #37 on: November 16, 2014, 08:18:28 PM »
My cables we're run between the exhaust and the body. I moved them like you described and they seem to be much better although they definitely rub along the exhaust.  Cable will now ratchet down on both sides although it still seems to pull tighter on driver side.  The e-brake now seems to work. Can apply e-brake and put car in drive and it doesn't move. Rebled the rear calipers and the brakes seem 10 times better.  Still feel a little spongy to me but maybe I'm just used to modern day cars.  Not sure though.
« Last Edit: November 16, 2014, 08:40:06 PM by randr »

Offline Angelo

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Re: Help with rear disc brakes!!
« Reply #38 on: November 16, 2014, 08:34:41 PM »
RENOVATIONS posted the article with a couple reasons for spongy brakes. They should not be spongy.
81' ex-Turbo Trans Am - Resto-mod

Offline randr

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Re: Help with rear disc brakes!!
« Reply #39 on: November 16, 2014, 09:08:20 PM »
When they say the e-brake should be " ratcheting" is that literally?  When I pulled off the cable and the spring at the right rear caliper and tried putting a wrench on it to manually adjust it I did not hear anything but it would definitely apply brake pressure. This week I'm going to try to do every thing 1 more time from scratch. From bench bleeding on back. If  still  the same results I think I'm on to putting the S10 calipers on the rear and going without an emergency brake. And thank you Angelo for spending your Sunday helping me out.
« Last Edit: November 16, 2014, 09:11:04 PM by randr »

Offline Angelo

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Re: Help with rear disc brakes!!
« Reply #40 on: November 17, 2014, 07:04:56 AM »
It does not make clicking sounds like a Craftsman ratchet, it's smooth. Ratcheting may be the wrong word to use for this, but it's what I've herd others refer to it as in the past. If you put the caliper on a bench, and compress the piston (compressing it and it rotates back into the caliper), then take a wrench and turn the ebrake shaft, you will see the piston slowly come back as you turn it one direction. When you turn it the opposite direction, the piston does not move. You can compress it back a little bit at any point if you turn back the ratcheting action a little, this demonstrates how it relieves a little pressure when you disengage the e-brake.

I'm not saying which way you ratchet because each caliper ratchets one way or the other. When you go the opposite direction it doesn't reverse the piston position. The only way to do that is to compress back in the piston. Once the piston is compressed back in, you have to rotate the piston to get the D lined up for your pads. The piston needs to be able to rotate though it doesn't rotate once the pads are loaded into it. Confusing I know.

No problem, this needs to be discussed, these calipers are not that complicated but when you start trying to explain it takes a lot more words than it should, which means it is complicated.
81' ex-Turbo Trans Am - Resto-mod

Offline randr

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Re: Help with rear disc brakes!!
« Reply #41 on: November 22, 2014, 04:12:54 PM »
  OK. Re-Went through everything. Bench bled and the rebled the old fashioned way with somebody pressing the brake. I was using a vacuum bleeder. Brakes seem to be much better. Finally have a nice feel to it. Thanks for all the help.

Offline Angelo

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Re: Help with rear disc brakes!!
« Reply #42 on: August 20, 2018, 04:19:52 PM »
For reference details how to use front 80's s10 calipers on a 79-81 rear disc brake TA car: http://transamcountry.com/community/index.php?topic=34085.0
81' ex-Turbo Trans Am - Resto-mod