The Stovebolt Site Forums The Shop Area Driveline 1950 3100 parking brake

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 ?????

Help. As always thanks in advance.
Jon

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.

The parking brake lever attaches to the secondary shoe. You mentioned a concentric bolt, but I'm not sure what that means.
Here's a picture that may help. Compliments of Brad Allen

klhansen, I will try and post some pics next week. I'm out of town.

Oops my last reply was ment for JonG.

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?

Did you adjust the brakes before you started working on attaching the parking brake cables?
Though this may seem like a dumb question by some, it is very important.

I did adjust the wheel cylinders so there was just a hint of drag on the drums by the shoes.

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.

Most likely the illustrations in the Shop Manual are not clear/detailed enough to answer your questions?

Maybe Brad has a helpful film-strip in his on-line “library”?
If he sees this post, he will most likely post a link.

Here is one of Brad’s filmstrips (maybe that link was posted earlier in this thread?)

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.

I found this diagram of the Huck brake parts to be helpful when I was searching for my parking brake parts. The diagram is for a one-ton, but it will be a good representation of the parts.

One Ton Rear Brake

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.

Thanks Handy Andy. I'll give that a try. Everything else seems to be adjusted right.

HandyAndy, I checked my brakes and see that there are no holes in the backing plate for the brake shoe retainer springs. I am running out of 'fix' options.

I did a quick search and found this thread. Apparently, the springs were not part of the Huck brake assembly after '48.

1950 Huck 3100 truck brakes

I have a few follow-up questions for you:

Did the parking brake work prior to installing new brake shoes/cables?

Are the new shoes exact replacements as compared to the old ones?

Are the parking brake cables secured at the backing plate and on the frame rails in the clamps?

Are the new parking brake cables the same length as the old ones?

Is the eccentric bolt adjusted to the high side?

Here's another image that I found on the internet related to the Huck brake assembly.

Let us know, thanks.

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.

Sure, let's keep at it.

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.

Thanks,

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.

Jhyp,

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.

I'll give it a try tomorrow. Thanks for the ongoing help.

Handy Andy,
Moved the anchor location on the rail clamp as you suggested. It made no difference in getting the PB lever to engage the slotted rod.

Well, it was worth a shot. I think your PB cables are too long or something else has been changed. Let's move this to a PM.

Jhyp,

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.

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.

Jhype,

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).

NAPA UP3406 FRONT

NAPA UP3396 REAR

Andy,
Yes, eccentric bolt is adjusted correctly. Yes rear cylinders are 1 3/16" bore.

Okay, good to know, thanks.

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.

Andy, I will work on that over the weekend. I did not replace the drums. Can you measure the inside diameter of your rear drums?

Okay, let me know how it goes.

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.

1941-1950 Brake Drums

1951-1970 Brake Drums

Andy, thought you had something (I was hoping) with the brake drum size but unfortunately my drums measure 11" so that's not the problem.

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.

Thanks to both of you for all your help.
jon

Thanks for the update.

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........

Please keep us posted, thanks.

Those screws are way too far out from the wheel cylinders. "Money, Its gotta be the shoes." (Old Nike commercial, my apologies.)

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, with the adjusters turned in to about 1/ 4" extended the brake shoes engage. Not a lot but some. Also my brake shoe pads are 3 /16" thick.

Okay, that tells me the components of your PB will in fact engage the front shoe.

I don't have a 'new' shoe to measure; however, I took some pics with measurements for the sake of comparison. The thickness of the pad material is about 3/16" on the used shoes in the pictures.

See my next post for additional photos, thanks,

Additional pics. The camera angles make the measurements seem a little off. Let me know if you need any measurement confirmed.

These shoes were off my '47 3100.

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.