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K3500 dualy parking drum brake fail

Steak&Eggs

Active Member
Messages
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Location
Missouri
My '95 gmc K3500 with drum brakes on the rear has had new shoes installed and the driver side short emergency brake cable replaced. (due to broke cable at the wheel. The shop that did the work must not do drum brakes much.... The truck would stop very well, but the pedal did nothing until about halfway down its travel. I took it back and they took the drums off and inspected the parts - noticed the shoes were worn on the top edge, a slight bevel. They warranted the shoes and put new ones on. Still had the same problem but they had no solution. The parking brake had no effect even after they ran the adjustment to maximum force. So I took it home and checked the tension on the brake pads with the rear wheels off the ground. No drag was found so I ran the adjustment out till both rear wheels had some resistance. Stepped on the brake pedal and it was at the top of its travel and solid. I had also ran the parking brake adjustment back to about halfway before setting the brake shoe drag. The parking brake had no effect - I could pull on the cables sideways and it felt like the brake pads engaged and the springs pulled back to released position. So I adjusted the parking brake cable until it was at the end of the adjustment and it had some effect (it would stop if going 3 miles an hour on level ground) but no way would it hold the truck on a hill! It acts like it would work fine if the cables were shorter. It worked before the new shoes? Is there another place besides on the frame in front of the driver rear wheel to shorten the cable? Or any other ideas? It is a pretty simple arrangement but I don't seem to be able to figure it out!

Thanks !
 
If you have the rear's still up in the air, post a pic of the brake shoes with the drum off and how the parking brake cables are attached. it's possible they installed something incorrect. as for the cable length, we somehow need to verify the cables they replaced are the same length as the old ones. it is a possibility they just ordered by application then slapped them on without comparing to make sure the new ones were correct.
 
Thanks for your replies! The truck is used for today, I'll need to put it back up on blocks to pull the drums and take a pix. Unfortunately they do not keep the old parts and I did not think to request the old cable back. :-( As a side note the drums are new, they stated the old drums were saturated with oil and brake fluid... Over many years I can not count the times I put old drums back on that were soaked in oily stuff - never had a problem. ('course I cleaned them up first) Since they were doing the job and warranting their work I let them change the drums, but kept the old ones. There was NO wear visible where the shoes ride inside the drum. That is a first for me after 28 years or so of service - original parts as I got it new in '95. But only 130 K miles or so. I will get back to it and send some images!
 
Nope the only cable replaced was the broken one, the brake did work before the shoes were changed.... I had adjusted it once due to brake pad wear. On the primary shoe - is it the longer one? It has been 20 or 30 years since I replaced any drum brake shoe. Wait - I did put shoes on the front of a '72 c-60 chevy truck, but that was in '06 and I don't remember that either! (but the brakes did work after). I was using the K3500 to haul gravel out of the creek to fix the crossing and road due to the rain washing it away. Then a bucket hose started leaking on the left side, it was high enough I spotted it before all the fluid ran out! That saved me $100. Wednesday I have to help a friend wash his house siding. So it will be Thursday to get the old hose off the machine and get another. It will be Friday (if I'm fortunate and nothing else happens) soonest to get back on the 3500.
 
OK, the short shoe appears to be toward the front of the truck. When the parking brake is applied it just takes up the slack in the linkage to the primary shoe. There is about 1/4 inch gap before the slack is taken up in the linkage and pressure started to apply to the shoe. That is with the adjustment all the way toward tighter on the parking cable. I would guess they put a cable back on that is too long? Pix attached....BrakeAdjustArm.JPGAllOfItCentered.JPGBrakeCableAttach.JPGTopCloseUp.JPGTopView.JPG
 
Hmmmm, I measured the new left side cable while on the truck, came up with 88 inches (+ - .5'') The break pad just starts to move with the break pedal at the floor. It is ext. cab. Don't know the WB. I looked online and a replacement is 86.5''. If all that is true and I loosen the adjustment 2" from the most tight position the shorter cable will still be longer than needed? (it might work but be at the end of its adjustment...)?
 
The cable length shouldn't be a factor here so long as the ends are attached in the same place as the origional. there is another adjustment up under the truck where the two cables come together into a bracket. there the cable from the pedal comes back to this same bracket and there should be a threaded rod with some adjusting nuts. make sure all that is adjusted properly. the cable from the wheel to this bracket might be longer than the origional but can be routed is a mannor so that the extra length is up out of the way. what matters is the length of the inner cable to the outer sleeve or to better explain it. the distance from the end of the sleeve to the end of the inner cable on both ends. if that is too long, it will cause issues.
 
OK, the short shoe appears to be toward the front of the truck. When the parking brake is applied it just takes up the slack in the linkage to the primary shoe. There is about 1/4 inch gap before the slack is taken up in the linkage and pressure started to apply to the shoe. That is with the adjustment all the way toward tighter on the parking cable. I would guess they put a cable back on that is too long? Pix attached....View attachment 83582View attachment 83583View attachment 83581View attachment 83580View attachment 83579
I believe that there is different lengths of cables for different wheel length base trucks.
IDK if that applies to the main cable from the cab or if it refers to the rear individual cables.
Might try a search of the innernet to see.
Rock Auto might even show the differences.
 
For references, maybe check the applications list in this site.
I am not promoting anyone buying from this site, I never have, I take My business to one of our sponsors before I look elsewhere. RA gets most of My business.
But for reference purposes look in here. You will need to change the year, make, model, etc to what Your vehicle is.

 
It looks like the cable is longer than needed. Applications that I have found show the same cable for regular and ext. cab. (shorter than the one installed by the shop).
I have adjusted the cable up next to the frame. (max tight) it is still too long.
I plan to (temp.) shorten the new driver side cable and test the shoe travel and see what happens...

I will let you know what smokes!
 
like this @ak diesel driver ?

 
Well, I contacted Autozone (where the original new cable came from) I had them look and they found a different cable for a 1995 GMC K3500 cab and chassis 155" WB. I did a rough check on my WB and 155 looked right, it was shorter than the first one so I had them order it. I picked it up today and it is way different - no way to connect it. I can rig a kluge up to shorten the first one but not this one! Of course we do not have the original to compare.... Usually when something works before I worked on it and then not after - I suspect something I did.... or in this case something they did. But it just looks like the cable is longer than it needs to be 5 - 7" longer.

I guess If I can not find the right one, I will get the first one back and shorten it permanently. It did work with a temporary short fix..

Thanks for all the Ideas, I'll let you know when its resolved!
 
Update - the 3rd try was close - but no cigar. (some smoke from under my collar maybe!) This one was 82.09" It almost went into the cable splice connection. If it did it would have been 'ON' with the brake pedal all the way 'OFF'. I found 3" travel in the cable going to the brake pedal. So figured another inch or so would be in the middle of the park brake pedal travel. Went looking and found a raybestos cable about 1.5 " longer at 83.4x". Autozone did not have a cross for that one. Or any cable that length. So called O'reillys they had one (AC/Delco) 83 7/16" but its special order. I'm waiting to see if they can get it. It fits a crew cab and cab and chassis (what I have). They say I can return it if it does not fit. The pix looks like it will be ok, if that is an image of the real cable;-). I don't know of a local raybestos dealer - I may have to order online. I will post the results when it is on and working! Never Give Up. :)
 
I'd suggest getting an exact idea of your wheelbase- just measure center to center of each hub front to back. In looking on RockAuto's website there are 155" and 159.5" wheelbases so splitting hairs there may get you closer to what you need. Is your truck crew cab/ 4 door? The cab & chassis is a slightly longer wheelbase than the regular truck equivalent. Sounds like you're getting close but just double check that all cables are properly matched for your wheelbase configuration.

Also not sure if it applies to your situation but this video shows how to properly re-connect your cable to your parking brake, perhaps some of the slack may be taken up in the pedal assembly itself

 
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