rear brake problem

[yjbrett]

1076210

My rear brakes won't stop the dyno at the emissions place. I have a 91 yj w/ 33's, automatic and 4.10's. My local offroad shop, who has done all the work on my jeep, replaced the mastercylinder, proportioning valve, rear brake cylinders, turned the drums, replaced the pads, checked the vacuum and all the pressure readings. The front brakes work great, but the rears still won't stop the dyno. The owner of the offroad shop thinks it's the torque converter. He said when on a lift they can run it up to 50 mph and step on the brakes. The rear brakes will stop the tires but they will start to turn after a moment. He feels the torque converter is tight and powers thru the rear brakes. It runs about 10mph on a flat surface without hitting the gas. I have never had a problem at emissions before, however I don't know if I had 31 or 33's on the last time it was tested. Is the torque converter a possible cause? Does anyone know of a reputable jeep repair place in the denver area? [addsig]

 

[Jeepskate]

1076268

That's a lot of parts to replace without screwing up somewhere. Sounds like that proportioning valve to me(a guess, I've never had to change or adjust one). When the jeeps on the rack the wheels are free spinning. It doesn't take much pressure to stop the wheels when they're free to spin. When it's on the dyno, there is a little more momentum behind the spinning wheels, ie. the dyno rollers etc. It makes sense that they would be a little harder to stop. It might not be much difference in pressure, but that may be all it takes.

With one wheel jacked up and the jeep running and in nullneutral(be sure to block the other wheels), have someone push in the brake pedal. If you can turn the wheel by had, you obviously have brake troubles.

Does it feel like the back end rises when you pull up to a light or stop sign?

Does the parking brake work?

Don't let em sell you a torque converter till you know for sure. [addsig]

 

[Bounty__Hunter]

1076391

Install rear discs and a manual proportioning valve :-O [addsig]

 

[jay89]

1076413

It almost sounds like the star wheels are not self adjusting. Whenever you back up the star wheels are supposed to adjust to the wear of the pads. If they don't adjust by themselves the brake shoes won't grab the drum to stop the wheels. They may stop initially when the brake is stepped on but then they will start to spinn again. It could be that simple. I hope this helps. :-? [addsig]