Rear Disc Brake Upgrade Update

[John Cunningham]

My apologies ….. not wanting to hi-jack the thread, just indicating that were I to do this upgrade, a "Parking Brake" would be a necessity (where I live) …..

As I originally stated in my original post about the pawl: …. " I hate being THAT internet guy " …. because of the ensuing point and counter point that ALWAYS seem to follow.

Where I'm at, …… without the PROPER use of the "Parking Brake" (it can be engaged incorrectly) , it wears the pawl and teeth to the point it can release or move out of "Park" all by itself …. such is the case of the fleet vehicle that rolled down a hill, off a short retaining wall and wedged itself in a gully. Whole thing was caught on the plant's video surveillance ….. the thing is, the video clearly shows the driver (my co-worker) applying the "Parking Brake" …. which was practically ineffective upon the ensuing investigation.

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Once again, my apologies ….

John, that is simply not true, as indicated by my co-worker's incident stated above.
……. It's not engaging "Park" that wears the pawl/teeth … it's pulling it "OUT" of park when bound up under a load. The two bound up metal pieces makes an all to familiar "pinging" sound when forced to release. Wearing, chipping and even breaking the pawl and/or teeth.

Even the Owner's Manual (my '95) has a section regarding the use of the "Parking Brake" while on a hill ….. It's to avoid "Torque Lock" , where the load of the vehicle can bind the pawl and keep it from releasing and prevents shifting out of Park because of the load on the pawl.
Manual states "you may need to have another vehicle push yours a little uphill to take some of the pressure from the transmission so you can pull the shift lever out of Park (P).


I'm not wanting to continue this on this thread (hi-jack) but I simply wanted to let John know there is a possibility of that pawl breaking or wearing, as it does happen …. I wasn't smart enough to see his location …. He's right, probably won't ever need it down there in flat land.

Once again, my apologies … for being THAT internet guy. Lol.....

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Back on topic, though.
I really like this idea of the rear disc upgrade …..
I've had really poor luck/results out of both of the GMT400 Suburbans I've owned. Both 14-bolt rears with HUGE drum brakes … that just seemed to never adjust themselves and always caused a lot of pedal travel.
John, thank you for all the info you've provided … I hope to have disc brakes on mine one day. I appreciate your efforts and knowledge on the subject.​

 

[John Cunningham]

Today I took a vacation to a Florida state park..in my 30 ft motorhome..I forgot to set my parking brake when I parked..broke out in a cold sweat last night when I realized I forgot to set it!!!

Ps....if you dont change over to discs in the rear so you can stop as fast as a more modern car or truck are you dangerous?

 

[letitsnow]

Ps....if you dont change over to discs in the rear so you can stop as fast as a more modern car or truck are you dangerous?

Haha - That is actually a good point. Unless the oem brakes are working/adjusted perfectly on these gmt400's, the brakes are dangerous. Pretty awful. Like, makes me want to punch an engineer bad... With updated brakes, I can drive my 3/4 ton truck around like a modern car. No comparison.

 

[ryeguy2006a]

Sorry I missed it but what kit are you using for the rear disks

 

[Racer X from MKE]

John, I have a 1997 C1500 and it stops horribly. I have the standard vacuum booster and drums in the rear with an ABS system for all of it. I thought maybe after I blew a line that air was trapped in the ABS module. My truck at work is a 1996 C2500 with a hydraulic lift platform in the bed and this thing stops on a dime. Same ABS system. I was thinking of going to 4whl disc and scrapping the ABS for an adjustable proportioning valve. Any thoughts?

 

[bugdewde]

Ps....if you dont change over to discs in the rear so you can stop as fast as a more modern car or truck are you dangerous?

John, I agree..... Modern cars can really stop well. That's why I have to increase my following distance a great deal when in the Suburban. Or the old Vega, or the Jeep .... Seems the only thing I have that brakes well is the old '91 Miata. Lol.

I've got new calipers/pads & rotors awaiting install, but still not liking the rear drum setup .... anticipating the same ol' non self-adjusting issues as my previous '99 (which also had a non-operating parking brake).

Racer X , you should get a good picture of the rear brake mechanism on that work truck to see how it's configured or if it's been modified. If it works, it works...., lol.

John, I'm liking the idea of your 4 wheel disc brakes more and more.

 

[Gibson]

I was thinking of going to 4whl disc and scrapping the ABS for an adjustable proportioning valve. Any thoughts?

The 1500 brakes are nothing to write home about,, the jb7/jb8 brakes, while not fantastic, can work pretty well with good set-ups.
Yep,, 4 wheel discs are the best, but don't automatically assume that getting rid of the ABS makes your brake system better.

 

[John Cunningham]

Haha - That is actually a good point. Unless the oem brakes are working/adjusted perfectly on these gmt400's, the brakes are dangerous. Pretty awful. Like, makes me want to punch an engineer bad... With updated brakes, I can drive my 3/4 ton truck around like a modern car. No comparison.

 

[John Cunningham]

We should all be glad there are aftermarket hackers and guys wanting to make their trucks better without resorting to new purchases of 60k and upwards!

 

[John Cunningham]

Sorry I missed it but what kit are you using for the rear disks

Many out there..I purchased one from lugnuts..had some problems with the furnished rotors..fixed it and made him aware of the issue..hard to bleed his brakes because of the bracket caliper position but can be done..all your really buying is the bracket..
He was clueless about the master cyl and told me the existing works fine= WRONG!..Not a technical person I guess