The Stovebolt Site Forums The Shop Area Driveline Emergency Brake Rod replacement

Hi all,

Looked all through this thread and didn't see a topic on this... so please point me if there has been.

I have run into an issue disassembling my 75 year old (1950 Chevy 3100 truck) emergency brakes rods and was wondering if you folks knew of an instructional video to remove and install a replacement rod set (I got mine coming from Classic Parts of America) ?

Mine rods apparently are original 75 year old parts, and most joints for adjustment are solidly connected/fused. I am struggling to separate them for replacement, especially just below the floor-board at the emergency brake pedal pivot bar. The pin holding the rod in place to the pivot bar is inaccessible and it is unclear how to remove the pedal assembly/pivot bar so as to disconnect the existing rod end to allow replacement from the new kit.

I got into this mess trying to adjust the parking brake tension (setting the brake still allowed the truck to roll/move). In the process the U-joint/hook on the end of the brake rod broke off, so I'm having to replace the rod system. The system consisted of 2 rods, 1 connecting to the emergency brake pivot bar off the pedal, and a 2nd connecting to the first and attached to the rear wheel pivot bar connecting to both rear wheels. This 1st to 2nd rod connection swivels but the bolt/pin is corroded to the 1st rod and so I am unable to remove and just replace the bad 2nd rod. I'm going to try heating the joint and seeing if I can then knock the rods apart.... but failing that I am going to need to replace both rods, by disconnecting at the pedal pivot point (which I cannot see a way to disassemble.

Any insight, pictures, videos, or links would be greatly appreciated.

Joe

Your issues are common to all of these trucks.
I heat the pins with propane torch until they are quite hot, then spray with Kroil. I them let it cool for a day and repeat the process for as many days as it takes. They have always given up before I did.
Heating and allowing to completely cool expands and contracts the steel pin and the cast iron rod ends. Once they do that enough times, it leaves space for the kroil to get in and do it's job.
The best part to me is that when I am done, I can reuse my original parts which I know will fit.
Besides that, its the only way to get the old ones off without a cutting torch.

Thanks... had not considered the multiple heat/cool cycles. Will give that a try.

Joe - Can you take pictures and post of your existing "2 rods" coming off the brake pedal pivot bar? A diagram in the 1947-54 Chevy Truck FAM shows the rod from the brake pedal pivot bar to parking brake cable pivot bar to be a single piece. I've also attached a picture grabbed from one of our usual vendors on what they offer as a replacement for that rod assembly as it is a single rod that corresponds to the one in the FAM.

BTW - Is this the "replacement rod set" from Classic Parts you mentioned ordering?

Joe,
Hope you get this issue resolved. It makes me want to go under my truck and lubricate all my emergency brake pivot points, for I rarely ever use the emergency brake and just a couple days ago, I suddenly had to. Worked fine but.....what if.

Thanks Dan for the pics. Good reminder as to where the pivot points are.

Thanks Dan.

Indeed the picture of the part from Classic looks to be what I ordered, but possibly not what I need. In their picture I mistook the attachment tab for the pivot point in my truck. Possible the folks that restored it used a non-standard pair of rods, instead of the original single rod (as it looks like it was in the drawing).

I'll upload a picture tomorrow (already changed out of my grungy clothes for the day :-).

But now my problem becomes even worse. I've got room to work to get the mid-length pivot point loose. At the pedal pivot bar at the firewall, there is no room whatsoever and seems not obvious how to take the assembly apart as the pedal is seems welded to the pivot bar at 90 degrees making it nearly impossible to maneuver off (I know it can be, since it had to be put together, but its totally not obvious).

Send some pictures of the pedal connection end as well and we will see what we can do to offer some help.

So here are 2 short videos (using Dropbox since Stovebolt doesn't provide sufficient upload size for videos)

1st is showing the 2 rod solution there, from the rear wheel pivot end.
https://www.dropbox.com/t/KbW9h7s19GlhF8OQ

2nd is showing the movement of the emergency brake pedal pivot end... tight space here so hard to get a good view. The 1st rod going from pedal pivot to the 2nd rod shown above is just at the tip of the pedal pivot bar here. The cotter pin is on the inside of the thru-hole of the bar and the bracket the rod is tied into, making accessibility to remove (or worse try to separate from rust), nearly impossible. To the right of side where the rubber is, is where the emergency brake pedal bar is seemingly welding to the pivoting bar. And to the right of it is a frame hole where the bar then goes thru with a cotter pin on the other side of it. Removing this pin, doesn't allow the bar to slide to the left as one would expect, because the welded brake pedal bar can't be disconnected (correction, I can't see how it can be disconnected). In short, I see no way at the firewall/pedal end to move the pivot bar so as to be able to remove the cotter pin and slide (or brake) out the 1st rod.
https://www.dropbox.com/t/LZfQk4GTuT7rOHWN


Thanks for any suggestions on this... I'm sure others have done this, but I'm out of ideas other than the heat/cool/heat/cool trick (which isn't working yet :-)

Hi all,

Wasn't really happy with the 2nd video above, so I reshot it, adding voice and issues I'm seeing with how to replace the rod between the pedal pivot and rear wheel brake pivot.

One thing to note, after comments about the rod being a single piece, and the part I received today BEING a single piece. While my vehicle has 2 rods, and they are bent in such a way the rod pivoting is needed... there seems to be no reason why it needed to be done that way, from the pedal pivot back a straight rod should work. Now all I need is ideas on how on earth to remove the existing rod in order to replace it (watch the video link and you'll see what I mean.

BTW, if folks are uncomfortable clicking a Dropbox link... just let me know (I understand :-)... and I'll see if I can capture it good enough in pictures to explain my issue. For now, here's the better Video #2.

Pedal End Issue

Joe - This video is better with the close up. Yes, you're on track to replace that odd-ball 2-piece rod with the correct single piece unit. I see 2 possibilities for getting the front rod clevis detached from the pedal arm:

1 - Use some tools like these (pictured below) to snag the end loop of that cotter pin (visible in your video), twisting/pulling it to get as much of the loop exposed as possible, then grabbing it with some needle nose pliers and twist, pull and drag that cotter pin out of the yoke pin. You should be possible to hook that cotter pin eye and twist it 90 degrees to try and get a better grip on it with the pliers and work it out. Once the cotter pin is out you should be able to get a putty knife/screwdriver under the head of the yoke pin and wiggle it out of the yoke, thus releasing the yoke from the arm.

If unable to win that battle:

2 - Unbolt the inner pedal tube support bracket (4 bolts, nuts, washers visible in your video) from the floor pan and slide it towards the pedal side of the tube. Once that's pushed over, you should have a better shot at getting to that cotter pin, including bending straight the legs on the opposite end of the loop, to be able to pull the cotter pin and remove the yoke pin and yoke.

Hoping this will help you win the battle.

Yeah, I'd about convinced myself to give it a try... worst that can happen is the Emergency Brake doesn't work... oh wait, it doesn't NOW. So nothing to lose :-)

Thanks for the feedback. Removing the cotter pin isn't my main concern, I'm afraid the push-in pin is rusted in... but crossing my fingers.

You have a GREAT July 4th.

Joe - Hope your 4th of July is GREAT too! Let us know how the effort pans out.

PS - You ought to be able to grasp the head of that pin on the left (more exposed side as viewed in your video) with a pair of pliers and attempt to rotate it in the yoke. If it doesn't move, give it a dose of penetrating oil like PB Blaster to soak and work on loosening the pin while you enjoy your 4th.

Many,if not all of the earlier ADs came with a 2 piece brake rod. Somewhere around "54 they went with a one piece red, probably to save a few pennies per truck.
The FAM has a some misleading information. Much of the information is '54 centric which leaves out a lot of accurate information about the earlier ADs.
The one piece rods do work just fine on earlier ADs.

Carl - I can't ever recall seeing any "2 piece brake rod" setups on AD series trucks, so thought I would do a deeper dive into a couple of pre-1954 Chevy Master Parts Books to settle my curiosity. I agree with you that the 1947-54 FAM often omits earlier 1947-53 parts/designs, which can lead to frustration sometimes when trying to figure out what's right or not for the earlier trucks. I go to the Master Parts books to try and sort those out as best I can.

Pics below (titled according to the original books the info came from) indicate almost every AD series trucks, with the exception of 1948-53 DUBL-DUTI and 1951-53 COEs (which did use 2 different rods per the application listings), used the one piece "TYPE A" rod. There were differences in lengths for 1/2 ton & 1 ton (which used the same length oddly) and 3/4 ton, but the same one piece design overall. Not sure if there is any difference between Chevy and GMC AD series on these parts as I didn't try and track down any GMC specific resources to verify that or not.

Anyhow, back to trying to help Joe resolve his problem.

My ‘51 has a 2-piece emergency brake rod, FWIW. I have a 1 piece rod that someone cut just behind where it goes through the cab support. It came off I believe a ‘53 chassis (whichever had the lower rear frame hump - maybe it was a ‘54 )

I have had 2 "52 3100s which both had the two piece rods, and the joint ends were made of cast iron and were ornate, common to the era.
That has been my experience. That's all that I have to offer.

I have a 52 with a 1 piece rod, but I can't see why the two piece rod wouldn’t work. The rod is only part of the system that functions in conjunction with the two cables going to the backing plates. On my 52, I had trouble finding the correct cables. Is it possible that the cables are not the correct or incorrectly installed? The cable length directly affects the position of the lever on the cross shaft. Having the correct cables, properly installed may enable you to connect the clevis of the pull rod assembly to the cross shaft.

Compare your setup to the drivers side picture I provided of mine, which is properly installed. Particularly compare the position of the lever on the end of the cross shaft. As you can see, mine is at approximately 5 o’clock. This may give you insight as to what is wrong

I bought my cables from LMC. Cables from Classic Parts (unless corrected) and many other vendors from are not correct.

I am using the P/B assembly out of a 37 in my 36 resto mod attached to a 4l60. I was able to chuck up the P/b assembly in the vice and use map gas and krill oil on all the joints. All the rods and linkage came out in piece and I needed to disassemble the rods and the clevis pins. It took a couple of day but it did come apart.

There's no reason that you couldn't use aircraft cable between the pedal and the cross-shaft. You'd just need anon-adjustable clevis on the front end and an adjustable one on the back end. The rod gets pulled to engage the brake. You might need to rig a spring on the pedal assembly in addition to the one on the cross-shaft that releases the emergency brake.

What Phil said about the cables to the wheels from LMC being the correct ones. I bought a set from RockAuto that didn't fit and a set from one of the vendors that also didn't fit and got sent back.

Hi all, hope everyone had a Great 4th of July

Thanks for all the comments and suggestions. I did get the single-piece rod from Classic Parts to work, but it wasn't the correct part for the 1950 3100. In short, the clevis was both too wide and too thick. On (at least) my 1950 there is an oval shaped hole in the firewall and then a 2nd one in the framing that the rod must poke through, the part they sent would not go through. I had to hammer the ends closer together and grind the width of the clevis to about 1/2 its original width before it would slide through those holes. A proper rod I think would have easily slid in from the front towards the back, but the clevis arms were so long they could not get past the oval to fit into the pivot arm blade.... so I had to snake it from the rear side, which was a bit of a pain.

Anyway, I did get it all hooked up and I've readjusted the connecting clevis joints going to each wheel. The rear pivot bar is hard to twist (have to use a large screw-driver), but the pedal seems to do it fine without complaining so I've WD40'd it, and applied think grease on the inside and outside parts of the rear pivot bar joints.

One (hopefully final) question though
I'm a bit confused by the spring. According to the manual page provided (by Dan I think), the spring attaches to the rod clip and goes backwards towards the rear wheels. The spring is very strong, and with it pulling rear-ward that will be placing force towards locking the rear brakes... which seems wrong. There seems to be no parking brake pedal "return" (or parking brake off) spring, so it seems wrong that the only spring is towards locking the wheels. Am I missing something here ?

Thanks again.... I'm going to replace the rear shoes and check the wheel cylinders, as I have no idea when/if that's been done in the last 50 years. So hopefully all brakes and parking brake will be working at 100% when I finally get through.

Joe

The spring connects between the tab in the center of the single piece rod and the center crossmember just in front of the parking brake cross shaft, and pulls the pedal back. The rod adjustment is supposed to keep the cross shaft just off the stop on the crossmember with the pedal retracted.

Did you ever remove the pivot bar from the frame to clean it up?
If not. you should. They get dirty and rusty over several decades. It should be free enough to easily turn it by hand.

Thanks Kevin... still seems a bit odd to pre-load locking the rear wheels when you want to be driving... but if that's how they designed it, OK :-).

I did NOT remove the rear pivot bar. I considered it, but seemed as though the bearings or insert (whatever it is) that's suppose to rotate is impossible to find (I was just going to replace them). Didn't help I couldn't find in the shop manual what they were called either. Any idea the name of the rotating part, picture, where to buy ?

thanks again ya'll.

The rear brakes aren't preloaded. The spring actually pushes the pivot bar back, along with the levers to release the brakes.

The pivot bar runs on holes in the frame and the "bearings" are just doublers for the frame. They do support the bar, but are steel-on-steel. A little oil there can help the bar pivot freely. Not much else you can do.

I don't think that the pivot bar is reproduced.

OK... so I have to apologize for being a little dense here, I'm a retire electrical engineer and it just bugs me to not understand how and why something works (that I'm working on). I'm in no way doubting what you are saying is correct, I'm just trying to understand the operating principle as it makes backward sense to me :-(

Perhaps the rebuilder of mine did something stupid. On my setup, when the parking brake is set, it pushes the rod backwards towards the rear wheels. This rotates the pivot bar so the top U shape rotates towards the front. This action rotates the wheel line pivot towards the rear, pushing the line into the wheel assembly, which applies the braking action.

The spring applies force in this same direction. In other words, it pulls the rod rearward, which then rotates the rear pivot bar so as to engage the brakes. So it is applying rear (locking) force to the rod when the parking brake is set off (i.e. up all the way "up" in the cab). That translates to nearly engaging the parking brake in normal driving mode (parking brake up). I guess the saving grace here might be that when the parking brake is set "UP", there is sufficient holding force there so that it overcomes the spring force... and then when one does SET the brake, it happens easier and faster. Actually that makes a little sense (if correct).

Thanks for the comment on the rear pivot bar... guess I'm gonna have to pull it off anyway, and I need a pry bar to move mine back and forth with all the linkages removed. Bummer :-)

Hopefully though this discussion might help someone else in the future though, so thanks for the comments.

The rod doesn't get pushed to apply the emergency brakes. It would just bend.

Let me try and explain it. Both the foot pedal and the lever the rod connects to are on the top of the pedal shaft, so pushing the pedal pulls the rod forward. The center lever on the pivot bar is below the bar, as are the levers for the wheel cables. So when the rod from the pedal assembly is pulled forward, the wheel cables are also pulled to set the parking brakes.
I'm a retired Mechanical Engineer, and a statement made in school by and instructor was "E equals MC squared, and you can't push on a rope" (or cable in this case.)
I could never understand how you Electrical Engineers could get electrons thru a pipe when there was no hole in the middle.

It is easy to understand. Electrons bring their own holes. Look here.

I like the EE joke, hadn't heard that one in a while :-)

So I had done a quick test and concluded that the parking brake was set when the wheel cable was pushed INTO the wheel (visibly watched the shoes look to move outward, with the wheel drum removed), Apparently its the other way around then (brake is applied when the cable is pulled on. That then makes everything make more sense, and honestly the way I remember it way back in the day). Obviously an error in my data collection skills... luckily no one is around any more to give me a hard time about it ;-) So ultimately then, the spring IS pulling in the brake OFF direction, which is what makes sense. Ahhh, at least I can sleep good tonight.... pain when these simple things keep your brain awake trying to solve the problem.

Thanks guys for sticking with me through my denseness.

Joe

Hey Joe, there are no bearings in the crossbar. It's a pretty simple design. Just remove it and clean it up and put it back on.

No problem Joe, us old guys need to help each other out every once in a while.