P30 brake parts help

[dirtmover]

I've recently acquired a new to me 1994 Damon Challenger 28' class A built on a Chevy P30 chassis

The breaking is not exactly what I'd call good. Pretty firm but requires a LOT of force to get any bite. Could be best described as trying to stop a car with the engine off.

The front brakes were serviced by the previous owner (new calipers and hoses). I check the rears, adjusted them and they're OK.

Steering is very light so don't suspect the PS pump. Next stop the booster. I'll change out the master cylinder at the same time because it's "weeping" a bit, the lid is very rusty and it's a cheap part.

I'm looking for replacements at RockAuto but not quite sure what to choose. I can rule out a lot of them visually but the choice is still not clear .

I'm sure others must have gone through this. What did you use?

[DieselTech39]

Glad you're aboard. Best of luck in finding an answer. May want to type P30 Brakes in the google search window above and leave it set to irv2. That should bring up threads possibly with the info you are searching for. Enjoy your adventures and be safe.

[Cougarkid]

Did you verify the front brakes are working?
Press the pedal and see if the pads are moving to the rotor. I've seen new caliper put on the wrong sides and not bled. Only back brakes are hard to stop with.
I gather you made sure the back shoes were moving when the pedal was depressed.
You can try bleeding the brakes again, too.

If the master cylinder is weeping, do replace it.

Good luck



Sent from my iPad using iRV2 - RV Forum

Mike and Carla
1998 Overland Larado 42' DP 1-slide
Full timing in 1 place -for now.

[TeJay]

You sound like you know what you are doing since you're willing to tackle some of the brake issues.

Just because the PO said they replaced this or that is no assurance that it was done correctly. I've experienced many, many a "Mechanic" that said they knew what they were doing but actually they didn't. Many mechanics do what they do because that's what they've always done. Technology changes but sometimes they don't.

You know what GLAZED pads and rotor are. Once pads are glazed they must be replaced. Rotors need to be machined.

IMHO and the industry standard is to always machine rotors when pads are changed. Not every one believes in that standard but I do and it's not failed me yet. You might get by with not machining the rotors but if you don't you will compromise the brakes to some degree. Brakes work because two surfaces rubbing together create heat. When the job is finished the pads must be properly burnished or broken-in. One must also use GOOD pads. If any of those 3 steps are not followed the brakes won't work to their best ability.

You've already hit on the hydraulic aspect of the system. Maybe a complete flush is also in order.

TeJay

[terry735001]

some of the times you well find just calling out your year in a GM 1ton well find most of the parts you need and like you said look over them and make sure there the right ones

i had 14 truck working under me from 79 to high 80s and really calling out a 79 work 99% of the time ... i know yours is newer year so dont to that LOL

[dirtmover]

Thanks for the welcome DieselTech39. I've spent quite a bit of time searching but still haven't got a 100% conclusive answer.

Cougarkid, the fronts are working. The rotors are clean from the friction. The pedal isn't soft so I don't suspect air. Can't be 100% sure about the status of the MC. That fluid could have been backup/overflow from when the callipers and hoses were changed but for $40 I'm not going to leave the original there.

TeJay, I've been working on vehicles since I was a kid but never something quite so generic as this. You're correct, it's clear what was changed at the front but not quite so clear what wasn't changed. These callipers could have been put on without changing the pads but from what I can see the rotors look like they've been machined fairly recently.

This is the sort of thing I'm up against at Rockauto:

CARDONE SELECT Part # 131982 {#14066425} w/ Reservoir
Rear Drum brakes; with Forward Control Chassis Cab; without Cab
Rear Drum brakes; with Motorhome Chassis; without Cab

DORMAN Part # M39435 {#14066425}
Rear Drum brakes; Bore: 1.3125 In.; Forward Control Chassis; Exc. Motorhome; 9,000 to 14,500 Lb. GVW


Note that they both refer to the same GM part #14066425. Cardone looks like the correct part but then Dorman tells me it's not for a motorhome! To make matters worse, when I look at the Dorman website the MCs they specify for the motorhome look nothing like what I have.

So, who is right?

[jeepthrills]

1994 with drum rears? yikes...thought they were all disk from 89 and up.

according to the vin...what is the GVWR?

[dirtmover]

Originally Posted by jeepthrills

1994 with drum rears? yikes...thought they were all disk from 89 and up.

according to the vin...what is the GVWR?

Not sure how to tell from the VIN but according to the sticker the GVWR is 12300lbs

[DonDee]

GM Brake Codes
JB7 (Vacuum booster) - Front Disk, Rear Drum
JB8 (Hydroboost) - Front Disk, Rear Drum
JB9 (Hydroboost) - Front Disk, Rear Disk

[jeepthrills]

this may help.