Help me settle an arguement. PLEASE

[xjrubicon91]

geez Old-Man,

I read the small paragraph about contaminated pads wanting to grab and I really want to believe it. But, I also did another test on it last month that doesn't support that at all. I jacked up the rear end, put it in drive with the engine running, both wheels were turning. Then I stepped on the brake and only the pass side locked up. The driver side continued to spin very slowly. and I only wish this was as simlpe as the pads being switched around.

 

[old_man]

If it isn't contamination, you got something screwed up in how you got the brakes put back together. Trust me. I've been doing brakes for a LOT of years. PM JJacobs. He knows his stuff. He's been doing it professionally for a long time. Ask him for a diagnosis.

 

[xjrubicon91]

thanks for all the input. I'll figure it out sometime over the next 6 months while it's sitting in the garage safe from all this FREAKIN SNOW!!!!! uke:

 

[jrsxj98]

Just had it happen. Yes it does after they get hot. Fixed the cylinder walla problem fixed.

 

[8Mud]

I'm with Old-Man,
Some variables are if it's just started to leak, it may slip, with gear oil. With brake fluid it pretty much starts grabbing, with very little seepage.
When the shoes get full of GO or brake fluid they get spongy (soft) and grab. Brake fluid is worse, for locking up quick.
Also depends some on how much pressure you use, GO covered brakes may slip a bit if lightly applied, but will eventually grab also.
You put GO in a diff. with a limited slip and the clutches will eventually grab, so GO isn't as slippery as logic would tell you.
An old truckers trick to get a few more miles out of a set of shoes, when they are oil covered or brake fluid covered is to burn them a little with a propane torch. To much heat will separate bonded linings from the shoe though.

 

[JJacobs]

Grabs. Gear oil, immediately the rear brakes start grabbing. That's the first thing you look for with a touchy rear brake problem.

Brake fluid isn't as grabby, but as a rule it'll still make the truck a bear to drive in the wet. Now after each material has soaked into the linings, the coefficient of friction may drop. But I don't see that- I get "oh crap my brakes are acting weird, take it in."

About the only time I see brake fluid leaking at the rear axle is when someone drives their grinding brakes until the caliper pistons eat into the FINS of the rotor and then pop out. :repair: And at that point the pedal is to the floor so there isn't really a feeling of grabbing or slipping.

 

[xj trenton]

Ok let me try to answer this. gear oil and brake fluid are both liquid and the brake pad is a fiber pad that runs with little clearance against the drum untill the brakes are applied. Now soak the shoe in the liquid and it will expand hence tighter brakes the shoe also heats up more as the gear oils/brake fluid act as insulation= more expansion. the result of minimum clearance + excess expansion = lockup. experiment 1 roll t/p 1 can just a bit larger it turns very easy add 1cup water it is now stuck.

 

[JJacobs]

When the gear oil first gets into the drum, it comes out the leaky axle seal, down the backing plate and across the braking surface of the drum. It takes a while to soak into the friction.

But when the dry shoes find that heavy weight oil for the first few times, the brakes grab. Just one of those weird things.. oil + friction system = grab?? yep.