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79, C-3500, crew, dual, w/89 RV 454, TH400, and a brake problem


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Got Donx
New User

Nov 13, 2009, 11:06 AM

Post #1 of 6 (1757 views)
post icon 79, C-3500, crew, dual, w/89 RV 454, TH400, and a brake problem Sign In

Hi All!

I'm new so if I miss any of the normal poiliteness' of the site please forgive me.

I do need some help though. My truck is newer to me and I'm still working through all of the monkey marks on it,

My big problem now that with the bad weather, I positively MUST address is the brakes. I've gravity bled and flushed the entire system. The pads and rotors on the front are obviously new. I was told the rears are too. I was told the entire system had been gone thru.

So here's the problem. My left rear (drivers side) is the only 1/4 that works. If I bleed the fronts before I take off they will work through most of the day if driving in town, but I rarely drive in town, I do hay hauling with this truck so it sees about 300 miles round trip, over Snoqualmie Pass every other day or so with about 18,000 to 19,000 LBS, GCW. So by the time I get into the suburbs of Seattle where I deliver most often,, the left rear is once again the only real stopping power I have other then to hand brake using my electric Johnson on the trailer.
This is a consistent issue. And for a 1 ton,, this is still a bit of weight to stop, so only have 1/4 of my brakes is dangerous, especially with the snow and Ice being here now.

When on gravel, that LR, 1/4 is the only one that will leave a mark,,, if I sit and pump up the peddle, then take off and hit the brakes, the other 3 still will not leave a scratch on the gravel.

I have never worked on the rear brakes in any of these old trucks of mine and I'm not in a financial position to send it in to a shop. So I have to find a way to fix this myself. I have tools and no fear that with instruction,, I can fix a good many things, but I need direction and help in diagnosing the problem.

Oh,, there are No leaks on any of the 4 quarters and the diaphragm on the reservior cover looks good, I can see no discernible leaks on the master cylinder or in the leines, not kinks, no pinches, no crushed spots,, although I did have some seepage from the power steering lines,,, Since replaced those too.

Any advice on how to find my specific problem would be very appreciated. I have not addressed this because I don't want to tear into things that are not broken, and end up fixing more then is really needed.

Thanks again,
Paula

I can be directly reached at deleted


(This post was edited by Hammer Time on Nov 13, 2009, 4:41 PM)
Attachments: attachment icon Ruby showing off.jpg (53.3 KB)


Loren Champlain Sr
Veteran / Moderator
Loren Champlain Sr profile image

Nov 13, 2009, 5:31 PM

Post #2 of 6 (1741 views)
Re: 79, C-3500, crew, dual, w/89 RV 454, TH400, and a brake problem Sign In

Paula; First, let me say that that is a beautiful horse. Have never owned one, but have always loved them.
Now...I probably don't need to tell you this, but driving with questionable brakes is unacceptable. If you are not capable of doing it yourself, you MUST get this inspected and repaired before you drive it anymore. I would want to inspect, and if okay, adjust the rear brakes first. From the sounds of it, you are more than likely (at the very least) looking at replacing the rear linings. Brake hoses can 'deteriorate' internally. You have three. Two in the front, and one in the rear. It's unlikely, from your symptoms, that they may be a problem, but need to be checked. Also, the master cylinder and proportioning valve. Snoqualamie Pass is not a place to be without brakes. It's not only YOU. It's the innocent folks you may kill.
Loren
SW Washington


Got Donx
New User

Nov 13, 2009, 7:06 PM

Post #3 of 6 (1735 views)
Re: 79, C-3500, crew, dual, w/89 RV 454, TH400, and a brake problem Sign In

Ruby is not a horse.

I'm asking for help because with out fixing the problem I'm not able to make that truck make a living,, I understand the laws of physics,,, explaining the safety ramifications are not needed. I wasn't asking for an ultimatum.

I was asking for some one that knows more then I do 'what to look for'. I know how to replace my fronts,,, already did it, along with the seals and bearings, tranny and I put an upgrade engine in it,,,, I am rather mechanically adept, but I'm not familiar with the idiosynchrocies of drum brakes, This could be a simple matter of a worn spring on the rear, but I don't know what the specs or signs are to look for.

The rear pads and drums are already new (previous owner installed @ a GM Goodwrench shop), the master cylinder was rebuilt (previous owner @ GM,,, ). When I bleed the lines there is never any air in them. The GM shop has seen the truck 3 times, they bleed the lines and think it's fixed. I can't afford to keep taking it back and not getting any results. They only know how to hook up a computer and tell you what a code means,,,, All the old school mechanics that know a pinch have been laid off while the kids that will take a cheaper wage remain. I'm on my own with this one. I need to know what to look for.

For all I know,, one of the kids at the GM shop where she took it re-used a worn out part.

I can't have been the only person in the entire history of these trucks to have seen this problem.

Paula


Loren Champlain Sr
Veteran / Moderator
Loren Champlain Sr profile image

Nov 13, 2009, 7:31 PM

Post #4 of 6 (1729 views)
Re: 79, C-3500, crew, dual, w/89 RV 454, TH400, and a brake problem Sign In

Got Donx; Ruby isn't a horse? The attachment showed a beautiful horse. Hmmmm. Anyway...
Drum brakes are very simple. They've been around since Tom G was a kid. If the brake linings are worn, out of adjustment, or have any type of fluid (be it brake or gear oil), it's going to have a problem. Rebuilding master cylinders is pretty much a thing of the past. I won't even sell a rebuilt master cylinder. Only new. It doesn't matter how good a vehicle looks or runs, it's gotta be able to stop. Brakes are the most important thing on a vehicle. So, you only have one choice. If you can't do it yourself, and can't afford to have it done professionally, park it. I hate to sound 'blunt', but you have no other choice. The rear brakes need to be inspected. Whether you do it, or you pay someone to do it.
Period. Hope to God you aren't behind me. We both live in WA.
We had a GM truck in a few weeks ago that 'had all the brake work done'. Upon inspection, we found missing springs, the 'self adjusters' installed backwards, ect., ect. Just because 'new' parts were installed, doesn't mean that they were installed correctly. With brakes, you cannot 'assume'.
Loren
SW Washington


Tom Greenleaf
Ultimate Carjunky / Moderator
Tom Greenleaf profile image

Nov 13, 2009, 9:37 PM

Post #5 of 6 (1725 views)
Re: 79, C-3500, crew, dual, w/89 RV 454, TH400, and a brake problem Sign In

Guess: This smacks of a bad master cylinder and rear brakes need be known adjusted properly with no axle grease on shoes. At the age that wouldn't be uncommon. A combination valve could also be an issue but rare - also called a proportioning valve. If stuck hard it wouldn't recenter and send all hydraulic force to one end or the other. It should also set off a red brake warning light if failed or needs attention to other brake parts,

T

BTW Loren - I still own a vehicle without hydraulic brakes at all! Just mechanical via rods!



Tom Greenleaf
Ultimate Carjunky / Moderator
Tom Greenleaf profile image

Nov 13, 2009, 9:49 PM

Post #6 of 6 (1722 views)
Re: 79, C-3500, crew, dual, w/89 RV 454, TH400, and a brake problem Sign In

Paula,

Loren isn't giving you ultimatums! He works hard here as many do for FREE no less! This vehicle does not have overly expensive or complicated brakes. Rears are drums and the spring kit is only about $10 bucks for those. Doubt that's the issue but grease or way out of adjustment OR a frozen wheel cylinder could cause issues. In HD trucks the back brakes work hard! Cars they are not as hardworking as they don't calculate a load in the rear. If you can't afford to tend to this then park it - that I agree with Loren on!

T







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