Rear Disc Brake Upgrade Update

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John Cunningham

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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?
 

John Cunningham

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This can all be checked with a guage.
4 wheel discs with about 1100 pounds will work beautiful.The MC I used works perfect..no Prop valve was used..I have found out thru years of experience that I rarely needed a P valve..and never a residual pressure valve.
1.125 bore works good with power booster of any type..the P guage is where you can get the real world answer and a good blled is important!
 

John Cunningham

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This can all be checked with a guage.
4 wheel discs with about 1100 pounds will work beautiful.The MC I used works perfect..no Prop valve was used..I have found out thru years of experience that I rarely needed a P valve..and never a residual pressure valve.
1.125 bore works good with power booster of any type..the P guage is where you can get the real world answer and a good blled is important!
 

John Cunningham

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I say dont plumb in a prop valve until you get the 4 wheel discs installed..some ceramic pads and the correct master.
Forget slotted/vented rotors...they are dangerous and will not perform better.
The best check of a prop valve is to get on a gravel road and hit the brakes hard enough to see if they lock up before the front..if they dont no prop valve required.If they do you need to plumb one in and decrease the pressure/fluid to the rear until they stop locking the rears before the front..I think they are over rated.
 

John Cunningham

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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

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So which is more dangerous:

A. IF you dont use your E brake when parking in your yard/garage/parking lot
Or
B. If you have a truck that has lousy ,out of date drum brakes that you hate and stop horribly, although they are original you say.

If your traveling along somewhere say at 45 to 60 mph and all of a sudden a car pulls out in front of you..will you grab for you E brake or stand on your OEM brakes and pray you can stop in time?

Signed: A non E brake user when parking AKA a "very dangerous man"

Ps: What truck would you like to be driving then? One with upgraded brakes or your old hard pedal oem disc drum brake truck?
 

bugdewde

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Signed: A non E brake user when parking AKA a "very dangerous man"



Ps: What truck would you like to be driving then? One with upgraded brakes or your old hard pedal oem disc drum brake truck?


Obviously, I'd prefer a modified 4 wheel disc system .....
.... BUT, with a parking brake. Lol.

My driveway is sooo steep, that pawl would wear out in a few years unless I used a chock. Not an option, as most ANY place I park here is not level. I'm not getting out and retrieving a chock at every stop. Very inconvenient.
Also, I would incure "torque lock" as described in the owners manual. Requiring another vehicle to push my car to relieve the bind, just to get it out of park.
So I'll just continue to use a parking brake, thanks.

While I appreciate your sarcasm on the subject of being a " dangerous man " for not using said parking brake .... you're wasting it on my behalf.

It is simply a fact that I have to have a parking brake on my driveway (and most places I go). I don't think you understand the steepness of my driveway. I'll get a pic of it tomorrow to actually show you what I'm dealing with.
Pizza delivery guys without LSD on wet concrete have to get pulled out of my driveway with my Jeep. Seriously!
Here's a shot of the start of it, showing the transition from level to the start of it. Muffler dragger. Had to raise the front of my lowered '60 Bug just to get "over the lip" of the driveway.
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Regardless of how you feel about it, I require a parking brake.
But hey, it's your thread, and I love sarcasm.
Fire away.
 
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John Cunningham

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You prolly need an E brake or if you prefer a PARKING Brake.........easy to add with Calipers..they offer it....

I just have never wore out a pawl in over 50 years even when parking on hills. When I park on a hill I turn my tires into a curb...or park with my bumper on the car in front of me. Both work great. As a last resort I will chock my tires. But always will JAMB it into park for the safety part of this parking expedition. The trick is to get it into the pawl with no rocking of the car....works great for over 50 years!

Signed: " a Dangerous man"
 

bugdewde

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Another thing to consider, the parking brake is good for more than just parking......

True 'dat ......
We used to use them on open diff Jeeps and air-cooled VW Bajas & Rail Buggies to transfer torque to the non-spinning wheel ..... aka poor man's locker.

When one wheel in mud spins, progressively engage the parking brake to put resistance on the spin. That resistance is then transferred to the other axle shaft via the open diff. Takes some skill, but will get you unstuck if one wheel is on dry ground. The dreaded open diff CAN work for you, if you know how to use it.
That would be a good use of the antiquated term "Emergency Brake" or in this case "Emergency Locker" ... Lol.

John, yes I prefer the correct term "Parking Brake". That's why the release handle & the dash light has a "P" (for Park) surrounded by brake shoes. Lol.
..... Or maybe it's for P*ssies. .... Lol.

(Like I said, I like the sarcasm).

I may be wrong, but I don't think it's been called an emergency brake for a decade or two.
 
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