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Brake Question for the pro's

Pruittx2

Pruittx2

Been around a bit
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Lake Odessa, Mi
95 Suburban K1500 with JD7 brake option. I pulled the rear hubs to measure the shoes,, and they are 13" X 2.5" . But on the Drums,, they seem to have the room to use bigger shoes. SO,,, Can I get the 13X 3.5 shoes,,, with out having to change anything else? or should I just stick to the 2.5's. I did get the K3500 Wheel Cylinders with the larger then 1" bore.
 
You don't want to change the hydraulics. Everything is matched and changing the cylinder size can have a drastic - and very unsafe - result. Better to stay stock or change everything from the master cylinder on.
 
swinters said:
You don't want to change the hydraulics. Everything is matched and changing the cylinder size can have a drastic - and very unsafe - result. Better to stay stock or change everything from the master cylinder on.
Click to expand...

Many have done it with great results. I plan on doing mine this summer when I flush my brake fluid again. GM screwed the pooch with the stock braking system, and let the front do way to much work. The 3500 DRW wheel cylinders is a drop in replacement to get some more oomph from the rear brakes. As for the shoes, others have said they have put the wider shoes in, but I have never tried it myself to confirm it as mine came stock with the 3.5" wide shoes.
 
THEFERMANATOR said:
Many have done it with great results. I plan on doing mine this summer when I flush my brake fluid again. GM screwed the pooch with the stock braking system, and let the front do way to much work. The 3500 DRW wheel cylinders is a drop in replacement to get some more oomph from the rear brakes. As for the shoes, others have said they have put the wider shoes in, but I have never tried it myself to confirm it as mine came stock with the 3.5" wide shoes.
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That's the first I've heard of putting the 1 ton cylinders on a 1/2 ton. I've heard of it being done on 3/4 ton trucks. Okie Dokie.
 
Surprised it doesn't mess up the bias but if the general screwed it up in the first place then that explains why not. However, if you put the wide shoes in, along with the big bore wheel cyls then it could have way too much rear bias. Just be aware of it at first.
 
Well I don't have the funds to do the cool proportioning valve from the truck as it's about $150,, So the bigger bore cylinders is all I can do now, 1 is bad and leaking,,, so right rear wheel is locking up on dirt roads,,, first thing in the morning. I will just put the 2.5's back in. Now what would be the best shoes?? they are ranging from 30 bucks to 129. from Auto Zone,, to Napa,,, Don't really see a reason to put anything in but standard duty pads. And I have to buy them local. time only permits me to do the job Friday eve. Going to harbor freight to get the cool 1 man bleeder system that hooks to the air compressor. It's go great review's on thier site. I'll post back how that goes.
 
RAYBESTOS blue shoes are the ones to use. The OEM stock shoes SUCKED, and the RAYBESTOS blue shoes are a HUGE improvement(they're the same as the GM DURASTOPS that teh brake TSB says to use if you have the 3.5" wide shoes). And GM screwed the pooch BIG time with the brakes on the BURBS. They capped the rear brake pressure at 600 PSI, which causes wandering under braking from to much front braking. The TSB valve raises the rears up to 800 PSI, and if you have the wide shoes they have you switch over to the more aggressive DURASTOP friction material. I know my BURB after 200K miles still had almost all of the shoes left because the rears do so little for braking. You will rarely if ever wear out the rear shoes with OEM stuff in there. The stock wheel cylinders for the 2.5" shoes are 1", the 3.5" SRW are 1 1/16", and DRW trucks have 1 3/16". I know a few here have done the TSB proportioning valve, DURASTOP shoes, and the DRW wheel cylinders, and said the brakes were MUCH better than stock ever was, and felt like it actually had a good brake bias.
 
When I pulled the hubs to measure the shoes,,, there was some dust,, but they lookd to me about 70% pad left!!! this with 149,000 miles and appear to have the stock drums,, with NO ridge on the shoe edge?? The drums and axle hub area,,, were rust free, and the drum slide off pretty easy.

These are the parts I got. 1 3/16 bore dia.

http://www.autozone.com/autozone/pa...Z8knp8?itemIdentifier=710301_821797_3559_1848

Ill report back here,,, when I'm done.
 
Pruittx2 said:
When I pulled the hubs to measure the shoes,,, there was some dust,, but they lookd to me about 70% pad left!!! this with 149,000 miles and appear to have the stock drums,, with NO ridge on the shoe edge?? The drums and axle hub area,,, were rust free, and the drum slide off pretty easy.

These are the parts I got. 1 3/16 bore dia.

http://www.autozone.com/autozone/pa...Z8knp8?itemIdentifier=710301_821797_3559_1848

Ill report back here,,, when I'm done.
Click to expand...

I installed the larger one ton rear cylinders on my 3/4 ton Suburban, along with the proportioning valve. It will not disrupt the balance between front and rear. The stock set-up so strongly favors the front brakes that any increment you can get on the rear brakes will be beneficial. I got my rear cylinders for $4.95 apiece from Rockauto. They also have the proportioning valve for like $130. You should do both as the Suburbans are very heavy for the brakes they gave them.

I really want to do the conversion to the GMT-800 style dual piston front calipers. I've priced it out and when all is said and done, you'd be into that mod for $800 to $900 with the bearings making up nearly half that.
 
Have 3.5" wide shoes in the Burb and they frequently get very 'grabby' when there is moisture in the air (which is most of the year around here) and the ABS does not appear to sense / react to it seeing as the rare wheel-locks tend to occur under 5mph; friend with a '99 K1500 experiences the same thing. When it comes time for a brake upgrade, am seriously leaning to the rear disc conversion.
 
Pruittx2 said:
grabby,,, in moisture is most likey leaking axle seal,,, OR leaky wheel cylinder.
Click to expand...

I can guarantee you mine is not leaking anything, but it will lock em up after it has rained. It is just the nature of the semi metalic shoes against the drums. Surface rust is going to happen, and the semi metalic shoes bite hard into surface rust, just the nature of the beast. I know mine are BAD after it has rained.
 
I'm trying to figure out if the proportioning valve applies to my truck. In this service bulletin, it does not mention my brake code (JD7) and appears it only applies to the JB8 and C6P codes. My JD7 code translates to hydropower disc/drum 8400lb

It wanders/pulls under braking and I have long suspected the rear brakes aren't doing much of anything.

http://aplsweb.com/Topics/TopicPix/TSB99-05.gif
 
Nevermind, it does apply. I have code C6P which is just a code for 8600lb gvr

Another $150 gone lol. What's the best place to find the valve? If this is the same valve for a truck, can I get a reman or pull one from the boneyard and not spend $150 on a new one from ACDELCO.

Also i'd like to hear from the OP how doing just the bigger wheel cylinders and better shoes works out.
 
well having the new correct/same size shoes properly adjusted it and working correctly,,, is prob more of what I'm feeling as batter brakes. Did a few test 45-50mph, hammers on dirt road,, and had a controled 4 wheel skid.
Yes the ams light is on the dash,, has been for 2 years,, some times goes out when I relly power wash the rim area, then comes back on later, and stays. I prefer it off,, as A) don't have the moeny to fix it,, and B) prefer the feel of controling my own skid. Pedal is a tad firmer,, but more solid on the bottom. Maybe need to bleed, 1 more time,, for good measure. But they are better then they were 1 week ago,, by far!
 
Thanks for the report. Is there any way to know if I have 2.5 or 3.5" rear shoes without pulling it apart?

Prefer to order all of the parts and do the job in one day. I have a wheel spacer on there so its double the work to pull a drum.
 
The 3500 dually is the one with the bigger wheel cylinders. The rear shoes are hit or miss, so the only way to know is to pull the drums.
 
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