I'm giving it another try. Looking for any help, thoughts, insights into fixing my parking brake. Background: I have adjusted the rear brake cylinders so there is just a hint of drag. I have installed a new pb cable. The concentric bolt holding the pb lever is properly adjusted. Slotted rod attached to the front shoe is in place. Problem: when the brake cable is fully engaged (ie the pb lever is almost touching the backing plate near the axle and can not move forward any further) the slotted rod which is connected to the pb lever does not engage the leading brake shoe. The lever does not travel the full length of the slot in the rod. Observations: slotted rod needs to be longer or slot needs to be shorter or missing a piece or ?????
Jon if you have any pictures (images) that will be helpful. I've repaired a few of these (including reconstructing one where the parts were missing), but I can't tell what yours might be doing (or not doing) without some help.
Here are the pics of my problem. First pic is of BP lever fully engaged (ie touching the backing plate and can not go any further) Second pic (although hard to see) is the slotted rod with the BP fully engaged. The BP lever does not reach the back of the slot and therefore does not push on the brake shoe to push on the drum. What am I missing?
My guess is that since you are not able to cause the shoes to contact the drums by pulling on the disconnected cables, you may not have the mechanical parts between the drums and the backing plates installed correctly.
Thanks for you help. I'll look for a pic of properly installed mechanism and reassemble the parts accordingly.
I have never seen a good picture of rear Huck brake parts arrangement. The axle hub is always in the way. You should be able to visualize what may be going on once you pull the drum back off. Its probably something simple which is easy to miss. Its like a jigsaw puzzle where all of the pieces are the same shape.
Here's a pic I took when I was trying to figure out where all the parking brake parts were located (Right Rear). Also, another diagram. Note the springs and lock pins (NSS Part of 5.043 Pin Unit) that secure the brake shoes to the backing plate. Yours appear to be missing and that would allow the entire assembly to shift when the PB is applied. You can see them installed in my pic.
Last edited by HandyAndy; Sun Feb 09 2020 10:08 PM. Reason: Pics added.
HandyAndy, thanks for hanging in there to help. Here are answers to your questions: 1) Don't remember. 2) Don't know. Unfortunately once I installed the new shoes I tossed the old ones without checking. Won't do that again. 3) Yes 4) Same answer as #2 5) Yes
With reference to your pic - this is exactly what my brakes look like. From my way of thinking if the slot in the rod was shorter, the lever would engage the rod sooner hereby pushing the front shoe forward to contact the drum before the lever hits the axle on the backing plate.
I went back and looked at this THREAD. Did you ever get the frame rail end of the cable(s) secured correctly? What's shown in the photo of your cable isn't right and would likely cause that lever to make contact with the backing plate. Can you show us how the PB cables are mounted at the frame rails?
Attached is a photo of the machined end of one of my old PB cables. Note the notch, that's where the bolt in the frame rail clamp rides and secures the cable so it won't move. I believe that's your problem: your cable end is past the frame rail clamp and that's why the lever hits the backing plate. The frame rail end of your cable doesn't look right to me.
Last edited by HandyAndy; Mon Feb 10 2020 10:05 PM. Reason: Pic added.
HandyAndy Here are pics of both ends of my new PB cable. The rail end does not look like your pic. You can see how it is clamped in. I don't think this is the problem. The rail clamp only secures the casing that the cable slides thru. It does not impact cable length. The only solution I can see right now is making the slot in the slotted rod shallower thereby allowing the leading brake shoe to contact the drum sooner. I know this is not how it was originally.
Here are my thoughts. An engineer somewhere decided how long the PB inner cable and the cable housing should be. If you increase the length of the cable housing between the anchor points you will in effect, shorten the remaining balance of the inner cable. By doing this, the extra slack in the cable you now have will be less. I don't know if it's enough of a difference to make it operable, but I believe it's worth a try. I would certainly try it before you modify any of your perfectly good PB components.
See the inked version of your photo. The blue arrow is where the end of cable housing is now. Relocate it to the rear somewhere between the clamp bolt and the red arrow. By taking the slack out of the inner cable the PB lever should move without hitting the backing plate.
It was great to talk with you this evening. Attached are the parking brake adjustment procedures, specifications of my PB cables, and a picture of my new cables. BTW, my cables were made by Madison Power Systems, Rochester Hills, MI. I'll look in my Huck brake parts cache for some of the components we discussed and make some measurements for the sake of comparison.
Let me know what you find after your work tomorrow, thanks.
Last edited by HandyAndy; Fri Feb 14 2020 12:43 AM.
I dug up the lever and extension. You can see the overall length. The slot in the extension is 5/8" long and it's 1 1/4" long from the shoulder to the end. Note the PO's grinding marks on the lever. That's why I located and replaced all of my PB components. Let me know if you want/need other measurements.
Andy, here's my next step. Attached is a pic of my slotted rod and PB lever. As you can see they are the same as the ones you posted. I have posted a second pic which shows the lever and rod installed and with the brake cable fully released. at this point the slotted rod just barely engages the rod (arrow). The slot in the rod is 5/8" deep. I also measured the distance from the lever to the backing plate at the axle. It is 1". This should mean that if the slot is 5/8" deep and the distance between the lever and the backing plate in 1" when the PB cable is pulled tight the brake shoe should engage the drum but it does not! Hmmm?????? The new 'original' style PB cable I ordered from Jim Carter should be here early next week. I'll see if that make any difference.
Thanks for the update. I have a couple of questions for you:
1. Did you confirm the lever is adjusted correctly with the eccentric bolt as per the manual?
2. Can you confirm that you have the correct wheel cylinders on the rear backing plates?
It appears to be a lot of adjustment (too much) on the rear shoe. I don't know if it's possible to install the front wheel cylinders on the rear and vice versa, but I do know they are different part numbers. Rear bore size is 1 3/16" and front bore size is 1 1/4". Maybe just the incorrect rear wheel cylinders? Just a thought, since all the other components appear to be correct. Refer to my first post/picture in this thread. There's a notable difference. With that much adjustment on the rear shoe, the lever will never be able to properly engage the extension to activate the front shoe (PB).
When we spoke last evening, you mentioned the adjusters on the wheel cylinders. I can see the amount of over adjustment of the rear shoe in your photo. Unfortunately, I don't have a picture of my driver's side, but do have a passenger side. Note how the arc of the shoes follow the backing plate in my photo. Look at where the arc of the shoe is in your photo. Again, there is no way the lever can engage the extension with the wheel cylinder adjusted that far out on the rear shoe. Bring that adjuster in, manually operate the cable watching for the cable to pull the lever, and watch for the lever to move the forward brake shoe. If this works as it should, maybe the drums aren't correct. If you have to adjust new brake shoes out that far something isn't right. Did you replace the rear brake drums? Maybe you inherited the wrong drums............ I'm just thinking out loud here.
At this point, we need to confirm that 'all' of the correct components are in play. Let me know, thanks.
Good to know on the drums. I looked online for a brake drum specification, most are listed as an 11" drum. This REAR BRAKE DRUM from Chevs of the 40's calls out a maximum diameter of 281.7 mm or 11.090 inches. If you still need me to pull a drum and measure it, let me know. I should have some time Saturday afternoon.
I also want to point out the difference in brake drums for the 1947-50 (Huck) and 1951-55 (Bendix). They are not interchangeable as shown below.
Carl/Andy, Had to switch back to the forum from PM since PM does not allow pictures to be attached. Anyway, thanks Carl for your insights. To catch anyone else following this thread, based on everything that Andy and I have checked you think that the only two potential problem areas left are brake drums or brake shoes. Andy and I thought about the drums (in fact were hoping that my drums had been 'turned' to much). Not the case. I measured the inside diameter of my drums and they were 11". Andy found somewhere on line that new drums were 11.09" inside diameter. So we concluded the drums were not the problem. That leaves only the shoes. I will order a new set of rear shoes tonight from Classic Parts unless you or Andy have a better idea. I did receive a new rear wheel cylinder today from Classic Parts and it is the same size as the one that I have installed. I have attached a photo of my rear cylinder adjusted so that there is just a hint of a drag on the drums. As you can see the adjustment screws are 'way out' rather than close in as you would expect with good drums and new rear shoes.
If you have time, I would still like to know if you can 'manually' pull the PB cable and engage the lever/extension bar to move the forward brake shoe with the adjuster turned in. If you can activate the PB doing that, your brake shoes may be the culprit........
Andy, I will check it on Friday. Carl/Andy, I will also order a new set of rear shoes tomorrow. I'll let you know what happens. I Andy/Carl, just out of curiosity if either of you have new or near new rear shoes can you measure the thickness of pad material? Tkx
Andy, I am out of town for the next week or so. I will check your measurements when I return. I have to tell you I am not encouraged that the shoes will be the problem. I think the pads would need to be 3/8" thick to make a difference.
Just to bring closure to this thread. I purchased a new set of rear brake shoes to see if that made any difference. Shoes were the only thing I didn't triple check. Any suggestions i got from Stovebolt I tried but nothing worked. Unfortunately the new shoes did not fix the PB problem! The PB lever still hits the axle before engaging and the wheel cylinders are still screwed out way to far to get the slightest hint of a drag. I'm stumped! Thank you to all who helped. Looks like I'll be driving without a parking brake.
In my opinion, you do not have a parking brake issue. Given that your wheel cylinders are nearly cranked all of the way out in order for the shoes to make contact with the drums, leads me to believe that your issue is elsewhere. None of the parking brake parts can have any affect, nor can they overcome the cranked out cylinder screws. Don't know if that helps. Its just my 2 cents.
Thanks Carl. Don't know where else to look. Tried new shoes. No effect. Tried new cylinders. No effect. Measured inside of rear drum. Same inside diameter as a new drum (11"). Handy Andy and I have tried everything we can think of.
I'll be happy to re-measure any of the components as the camera angles certainly can be deceiving. The thing that bothers me about this matter is the amount of adjustment needed on the wheel cylinders to contact the brake drums for even a light drag. I have to wonder if the brake drums are past the service life spec of 281.7 mm or 11.090"?
Ok everyone here is my update. I have replaced my rear wheel cylinders, brake shoes and brake drums. All of that hoping to resolve the problem that when I adjust the wheel cylinders so there is a slight shoe drag on the drum the adjustment screws are way to far out considering everything is new (see pic above). I got all my parts from Classic Parts in MO. There is certainly something wrong with the either the wheel cylinder, the shoes or the drum. I am truly at a loss in solving this problem. I am down to welding tabs on the shoes where they interface with the adjustment screws to reduce the outward adjustment. Just can't figure out how this was set up in the factory.
I can attest to Jon's attention to detail on his Huck style brake problem. This started out as a parking brake cable installation; however, it quickly turned into a brake problem. In order to get the parking brake functional the brake adjuster dilemma has to be resolved. You can see from the pictures Jon has posted, the amount of adjustment needed on the brake shoes/wheel cylinders to obtain a slight drag on the brake drums. The adjustment appears to be excessive, even with new shoes, wheel cylinders and drums.
About five years ago, I went through the same Huck brake rebuilding process. I replaced all lines, M/C, wheel cylinders, and brake shoes, albeit from another local vendor. The brake drums were good. My parking brake components were long gone. After I acquired the needed parts, all were assembled without any problems resulting in new Huck brakes and a functional parking brake.
Could reproduction parts be an issue, specifically the wheel cylinders? Have any of you Stovebolters experienced this problem? It seems odd to me that all new brake components result in the situation at hand. Let us know, we want to hear from you, thanks!
OK, lets back waaaaay up. What is the history of this truck, specifically the rear axle and all of the parts associated with the brakes? What did you throw out and replace? For the geometry to be so far off for the wheel cylinder adjusters to be turned out so far to make contact with the drum, I have to wonder about the correctness of the parts attached to the bottom pivot pin, or the location of the holes in the backing plate for the two bolts down there.
Carl, I've had the truck a number of years but never got around to its restoration. That is now nearly done. The individual i purchased it from was using it as a daily driver. Don't know much beyond that. As far as I know everything was original (a few minor exceptions). Don't really know how I would determine if the backing plate or rear axle was ever replaced. As far as the brakes go everything is original with the exception of the brake shoes and wheel cylinder (unfortunately I threw the originals out prematurely). I did purchase a new drum just to see what the actual ID of a new drum was. The replacement shoes and cylinder came from Classic Parts. I called them today to see if they could help or had any ideas. They said they have never encountered this problem and provided no help. I will check the bottom pivot pin and bolts location with Andy as we have been using his 48 or 49 (i forget which) as a reference since his brake geometry seems to be just fine.
Andy, I compared your measurements with my truck and they are the same (+-)! The geometry is the same. So I am back to square one. The Problem has to be in the shoes, cylinder or drum. Except we have checked all of those. Guess I will have to run the truck with the adjusted screws out to far and no parking brake unless someone with more knowledge than me has a solution. Again, thanks for all your help. jon
Based on all of our measuring, comparing, and component swaps. I believe the only variable left is in the internals of the wheel cylinders. The piston, cup, or spring (or all) in the wheel cylinder must not be as thick/long as it (they) should be, causing you to have to crank the adjusters so far out. See Fig.50-Wheel Cylinder Parts Layout [chevy.oldcarmanualproject.com] from the 1948-51 Chevy Truck Shop Manual. Since the geometry all checks out, my recommendation would be find another source for the rear wheel cylinders.
Keep us posted.......
Last edited by HandyAndy; Sat Apr 04 2020 06:03 PM. Reason: Spring added to text.
I am going to bring an end to this thread that I started. Originally it started as a parking brake issue but I (we) realized that it was really a brake issue. The Problem had to be with The drum, shoes or wheel cylinder. The Problem was when the brakes were fully assembled with new repro parts in order to get the slightest drag on the drums the wheel cylinder adjusters had to be adjusted 1/2" out (way to far). After trying many things the conclusion is that the wheel cylinder body length is to small. I have tried new cylinders from several sources without any luck. So I am going to have to live with the set up i have. Thank you all for your advise, ideas, suggestions and help.