Rear disc conversion issue - Suspension and Brake Forum

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Rear disc conversion issue
Friday, July 30, 2010 7:34 AM
I searched first didn't find an answer. I did the disc conversion a while back and have had no problems with it until now. I was driving home last week and the drivers side rear brake caliper closed up on my disc so that it would not release it so it was dragging all the way home. It was smoking and when I got home I noticed that the rim and brakes were 100 times hotter than all the other brakes (even the center cap of my rim bowed a little cause it was so hot).

What I did was change out the caliper: same issue
Removed the 10Lb in line valves (I gutted them and put them back in so I didn't have to run new lines): same issue
I added 2Lb valves (From Jegs): same issue

Now both the back wheels are doing it. When I looked in the brake reservoir I noticed something strange

(Left side front of car) See on the left side there are two plastic tabs that appear to be pushing the round thing to one side, could that be the problem? They appear to be bent, are those tabs supposed to be like that?

They only thing I haven't touched is the master cylinder and components and the box that has the four lines coming out the top for each wheel. Also, there is no brake nor warning light on either. Any Ideas?

Re: Rear disc conversion issue
Friday, July 30, 2010 2:44 PM
I am of no help to you sorry, I have 12" corvette rear brakes and 100% stock brake line and master cylinder install (13" Baer in the front). Not one issue and no lock up at all... perhaps the mc is bad.



Re: Rear disc conversion issue
Friday, July 30, 2010 4:14 PM
If it started off with just one wheel doing it, and then progressed to both, my first bet would be the ABS module or proportioning valve, not the MC. Does your car still have ABS?

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Re: Rear disc conversion issue
Friday, July 30, 2010 4:49 PM
You probably didn't adjust the e-brake properly I had the same problem with my rear disks. Just give that a check.



Re: Rear disc conversion issue
Saturday, July 31, 2010 1:29 PM
First thing you need to do is figure out if it was the caliper or drum that was locking up. You can tell by taking the caliper off and seeing if your rotor is jammed up.

If so the drum is fine and you were still maintaining pressure, you might have a problem with your abs module. Unplug the ABS fuse and see if that throws it into full open mode.



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- Sold my beloved J in April 2010 -
Re: Rear disc conversion issue
Saturday, July 31, 2010 8:26 PM
I still have abs and I changed the caliper and checked the drum/e-brake stuff and after all that it still does it. If I take out the fuse and it releases the caliper then does that mean I need to replace the module?
Re: Rear disc conversion issue
Sunday, August 01, 2010 8:25 PM
Ravaged83 wrote:I still have abs and I changed the caliper and checked the drum/e-brake stuff and after all that it still does it. If I take out the fuse and it releases the caliper then does that mean I need to replace the module?


it could be, have you checked your brake lines, if theyre pinched it causes your brakes to lock up



Re: Rear disc conversion issue
Monday, August 02, 2010 9:36 PM
I'll check for that but someone told me it may be the MC because now after bleeding all the lines after a complete stop the calipers release slowly. So the piston in the MC is probably gone bad and is not returning as fast as it should. Does that sound right?
Re: Rear disc conversion issue
Tuesday, August 03, 2010 3:42 PM
maybe the problem is around the combination valves since both your rear locks up



Re: Rear disc conversion issue
Tuesday, August 03, 2010 6:11 PM
I've never heard of a master cylinder going bad and not releasing. That really sounds to me like some kind of restriction. It almost sounds like there may be debris of some kind in the lines somewhere, and when you bled the system you moved it to another point. I would try gravity bleeding the rears into containers so you can see what the fluid looks like. Get yourself a lot of fluid to do this with, though, and make sure to use hoses on the bleed valves.





Re: Rear disc conversion issue
Wednesday, August 04, 2010 4:19 PM
Quiklilcav wrote: I would try gravity bleeding the rears into containers so you can see what the fluid looks like.


I may sound dumb by asking this but how do you gravity bleed the system? By the sounds of it, I would imagine opening the rear caliper bleed lines and the cap refilling it as it gets low and leaks out the back. Is that right or is there more to it?

On another note I went to the junk yard and got a new master cylinder from a 2003 Cavy and I got the junction box, but the car did not have abs so it was just a box with six lines and no electronics. I thought all cars came with abs nowadays but I guess I was wrong.

Re: Rear disc conversion issue
Thursday, August 05, 2010 6:15 AM
Ravaged83 wrote:I may sound dumb by asking this but how do you gravity bleed the system? By the sounds of it, I would imagine opening the rear caliper bleed lines and the cap refilling it as it gets low and leaks out the back. Is that right or is there more to it?
No, that's it. You're just letting the fluid flow from the master to the open point in the line. As long as you are keeping the reservoir topped off, it will effectively bleed the system, and it should also clear out any small debris in it. The thing is you want to have a clean catch container so you can see what the fluid looks like. Otherwise you're just guessing that you got any potential debris out.





Re: Rear disc conversion issue
Thursday, August 05, 2010 3:51 PM
Ravaged83 wrote:
Quiklilcav wrote: I would try gravity bleeding the rears into containers so you can see what the fluid looks like.


I may sound dumb by asking this but how do you gravity bleed the system? By the sounds of it, I would imagine opening the rear caliper bleed lines and the cap refilling it as it gets low and leaks out the back. Is that right or is there more to it?

On another note I went to the junk yard and got a new master cylinder from a 2003 Cavy and I got the junction box, but the car did not have abs so it was just a box with six lines and no electronics. I thought all cars came with abs nowadays but I guess I was wrong.


ABS was standard for every GM vehicle (or almost every) in early 2000 or so but then for some reason they got REALLY cheap and removed the ABS on standard models starting in 2003. My sister had an 04 without ABS.



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- Sold my beloved J in April 2010 -
Re: Rear disc conversion issue
Saturday, February 26, 2011 6:57 PM
So once again I am having my problem and yes I know i'm bringing this back from the dead but like I said I'm having this problem again. Well was having the problem, I think I have remedied it. My new caliper and the drivers side back again closed up on my rotor and I ended up smoking my way home. Next is what I did.

I took the 2LB valves out bleed the lines, same problem.
I changed the MC and ABS box bleed the lines, same problem.
Checked the lines up and down no problems with the lines but same problem with the caliper.
I got an indicator put it on the rotor and it had over .025" run out.
Frustrated, I took the rotor to O'Reily and asked them if it was wrapped and the guy said (after scratching his head), "Um, I'll have to put it on the machine and cut it to see." I ask how much and he tells me $15.00, so I bought a new one $19.99. The guy then tried to push the piston back into the caliper at the store with a c-clamp and sure enough it took some sweat, muscle and time but the piston went in about a quarter of an inch. I ended up getting a new caliper and brake pads too changed everything and prayed. As I sat there spinning the new rotor in place I noticed something. The caliper was only about an inch or so away from the stock muffler.

Now could it be that the heat from the muffler was causing the problem and making the caliper piston seize up? Does everyone who has done the swap/conversion have aftermarket mufflers (you know the round ones), thus keeping the heat away from the caliper and not giving anyone else this problem? I really want to find out.

I ended up removing the stock muffler and replacing it with a 27" round glass pack for like $30 bucks with a mounting stuff and clamps (no welding for now).
Re: Rear disc conversion issue
Saturday, February 26, 2011 7:45 PM
In 2000 GM changed the ABS/brake system on the J and then carried Rear Brake Proportioning, I'd check the valve.



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-----The orginal Mr.Goodwrench on the JBO since 11/99-----

Re: Rear disc conversion issue
Saturday, February 26, 2011 8:20 PM
I gutted them when I made this posting back in July 2010 so that is out of the question but I really want to know about the mufflers in relation to the caliper. Pictures would be nice.
Re: Rear disc conversion issue
Sunday, February 27, 2011 3:05 PM
here is what mine looks like




my exhaust is not even near mine.


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never let anything slip away
Re: Rear disc conversion issue
Sunday, February 27, 2011 7:45 PM
And you haven't had any issues right?
Re: Rear disc conversion issue
Sunday, February 27, 2011 9:43 PM
same here no issues at all.. ive had this done for 2 years now no single issue... my exhaust isnt close either... i have the dynomax super turbo muffler too so its just like the stock one so i highly doubt heat would cause this... i agree with everyone else about the abs... i would take it to a dealer and have them cycle the abs with the tech 2 to attempt to bleed the master cylinder..



Re: Rear disc conversion issue
Wednesday, March 23, 2011 8:34 AM
I think I found the problem. The factory Chrysler hose I used was rubbing on the side of the muffler and wore out the outer rubber of the hose in a spot. I changed the muffler to a Thrush straight pipe muffler (sounds great) then replaced the hose, caliper, rotor (the rotor was wrapped) and brake pads (on both sides). It seems that the problem has been fixed and I don't feel the drag anymore. Only time will tell though.
Re: Rear disc conversion issue
Thursday, March 24, 2011 9:57 PM
that wont effect it, if the line got worn through you'd loose the fluid and have no braking, it would not cause them to get stuck on.




Re: Rear disc conversion issue
Friday, March 25, 2011 12:13 PM
And it shouldn't be the heat from exhaust as your brakes get fawking hot anyways, I know rears less but they still get really fawking hot!

Are you sure you properly spaced your rears when you put them on. I haven't put mine on yet but I know everyone has to use some washers to space them out properly it wouldn't make sense for this to happen they way your describing but just a quick question.




Re: Rear disc conversion issue
Tuesday, March 29, 2011 6:19 PM
it could be because if the outer part was worn that would cause it to expand and maybe under heavy braking the caliper clampped but the hose flexed and maybe it wasn't allowing any release.

maybe mosy of the fluid was expanding the flex line insted of accually goin to the caliper.

its plauseable but i woul ddefinatly monitor this issue thats what a happens when you put a chysler part on a GM



JBO since July 30, 2001
Re: Rear disc conversion issue
Monday, April 04, 2011 9:12 AM
NOTa2_4 wrote:it could be because if the outer part was worn that would cause it to expand and maybe under heavy braking the caliper clampped but the hose flexed and maybe it wasn't allowing any release.

maybe mosy of the fluid was expanding the flex line insted of accually goin to the caliper.

its plauseable but i woul ddefinatly monitor this issue thats what a happens when you put a chysler part on a GM


That is what I was thinking so far I haven't had an issues but I'm still keeping an eye on it.
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