Dumb question of the evening

[GPster]

They used to call it an Emergency Brake. Now if you Google it it comes up as Parking brake. Our 2004 Jeep Cherokee Laredo was mistakenly driven with the brake set for a while and we tore it down and nothing appeared to be hurt so we put it back together. Wouldn't hold so it wsa checked again. Even had the discs/drums turned and they were with-in tolerance so we put it back together. It will now hold if things are at rest but put it in gear (automatic trans full-time 4 wheel drive) and it will creep even at idle. Our last Jeep a 2001 had a transfer case that we didn't have to deal with full time 4 wheel and the emergency (?) brake held on it and we never paid attention (100,000 miles) on this one till we thought we had hurt it. Are we trying to fix something that won't happen? Back in the '70s when Ohio had on-the-road vehicle inspection my father-in-law was one of the inspectors and I know they expected the brake to hold under power. Is that something that was lost in modern times or are we not fixing something right. Any information I can find on the Internet tells you how to do it but nobody tells you what to expect when you're done. GPster

[wayne petty]

just curious...

i am taking that you have rear disc brakes with an internal expanding parking brake that works like a drum brake inside the ROTOR hub..

when the rear rotors were machined.. did they machine the parking brake area also.. thats usually really hard to do on most..

were you able to adjust the parking brake adjuster so the shoes are almost touching the drum surface of the rotor..


parking brake section...

http://www.autozone.com:80/autozone/repairinfo/repairguide/repairGuideContent.jsp?pageId=0996b43f802d7b78

[1800guy]

Assuming that the shoes have been adjusted to compensate for the wear from the 'mis-adventure', I would be looking for glazing of the shoes.  It may not be readily apparent so take a good close look.  The excess heat may well have cooked the resin in the friction material into a glaze.

I would expect any parking brake should hold a car at idle and/or on a slope, but maybe not all will.

[GPster]

The drums inside the rear discs were turned (separate machine operation, separate charge) and were still with-in tolerance. The shoes were adjusted. Unfortunately they were adjusted with the car on the lift and held there but let it move when on the ground. Then we made the decission to turn the drums and re-adjusted which held but let it creep in gear. Maybe glazing is the problem. Which brings about a tid-bit of information. My local parts store also has a warehouse which is a distributor of some major brands, Wagner Brake parts being one of them. Wagner rotors are made of the same OEM material that that manufacturer uses. Using cheaper after-market rotors will accellerate wear on Wagner pads. We were told this bit of information  while trying to start a discussion of why we were charge six re-surface machine operations on four rotors. I guess when it goes back on the liftto replace the muffler that is separating at the seam will be a good time to replace those shoes. Sure is hard to see how they could cost so much. GPster

[wayne petty]

hmm...

thats CREATIVE about needing wagner rotors to match the wagner pads...

since rotors and a lot of other brake parts are made from Turnings from machining processes..

i neglected to mention glazed parking brake shoe surfaces.. as i personally scuff them up.. but thats not what i would do in a shop situation without proper wash and catch devices..

be sure since you are going to DIVE back into this..

that you also replace the parking brake hardware.. looks like this..

http://contentinfo.autozone.com/znetcs/product-info/en/US/bx2/H7421/image/4/

when the parking brake gets overheated the return springs might loose some tension...