The Stovebolt Site Forums The Shop Area Driveline brake issue...I'm totally stumped

Totally stock '52 half-ton Chevy. Has pulled left (toward driver's side) under hard braking for as long as I can remember. Only a problem when you get surprised and have to really hit 'em hard, like when a deer or dog bolts in front of you.

But she's had a leaky wheel cylinder lately, so it's time for some brake maintenance. I changed pretty much everything: new shoes, new wheel cylinders, new flex hoses, and even swapped drums left to right to eliminate the possibility of uneven warping or wear...although there's no ridge in the drums and I'm certain they're excellent. Same story for the rear, new shoes, swapped drums, etc.

So....she still pulls left. I'm thinking "what the heck??" Maybe it's an alignment issue although she tracks straight and true and I'm sure alignment is good. Or perhaps that right front spring sags maybe a quarter inch more than the left and causes her to dip more on the right and steer left.

EXCEPT...and I feel this is important...I'll crawl under and measure the drum temps after a run using one of those infrared thermometers from Harbor Freight. Left front is always 55F or so hotter than the right. Like today left was 175F and right barely nudged 120F. Rear drums seem normal...both less, about 110.

Uneven drum temps gotta rule out anything in the alignment realm. It's a shoe/drum friction issue...something is causing the right shoes to not grip the to drum as tightly. Obviously! Right???

Racking my brain, I decide now would be the perfect time to convert the old single reservoir master to a modern dual system, complete with re-routed lines.

Maybe the original system with one short line to the front left and the other line shared between the other three could have something to do with it. That just don't seem right.

Long story shortened, and because I'm tired of typing, I've completed the dual conversion and even that makes no darn difference!! Still pulls left under hard braking!!

Other than finding a solution, what I'd also like to know is whether anyone else's AD pulls left but don't wanna ask because I doubt there's anyone who'd admit it. Anyone???

I'm stumped but guess I'll have to live with it. At least she's got all new brakes and a dual master cylinder, so the work hasn't been for nothing.

Question, with both front wheels up and on jack stands does the left side drag more than the right. Each side should have just a slight resistance when turned by hand. With the difference in temps left to right it would suggest one side is working harder than the other.

Left and right are adjusted as equally as I can get, very light drag with axle up on jackstands. I agree, left is working harder and applying more pressure under braking than right but I can't for the life of me figure out why.

I have a similar issue with my 48 truck. Didn't really think too much about it because i'm not to familiar with old hard riding 3/4tons with big wheels and skinny tires.. When i did motor mounts and front harmonic balancer sleeve w/seal i cleaned 70 years of crap covering the brake line going to r-front. I now remember it is dented/kinked. Can this line be not pressuring the right brake cylinder correctly and be making the left brake overworking? I didn't think much about my issue till i read ur conundrum.

u can see the line here, u can't see the dent as its down and behind the c-support.

Hy Skooter, If I am remembering correctly 52s have Bendix brakes, correct? If that is the case are both front brakes assembled the same way, primary (shorter) shoe to the forward side? Are both the rear brakes the same temperature after some braking? We had a vehicle at work that pulled to the right, we tried to figure out why but couldn't find anything obvious, so we stripped the whole front end down and we found the right side backing plate to spindle bolts were a bit loose, tightening everything up and reassembly of the original components revealed no more pulling, hope that helps.

No not Bendix and no kinks in the all-new front lines from the dual MC to both fronts. Have also adjusted the anchor pins on both sides (and both rears) as prescribed in the shop manual. Both front wheel hub/bearings also adjusted per manual.

I've never been a professional mechanic but I've owned this truck 37 years and have done a ton of mechanical work in my life on this and many other vehicles. So I've been around the block. This one has me mystified.

...and beginning to think uneven braking is a characteristic of ALL or MOST non-proportioned drum systems. Can anyone verify whether I'm correct in this assumption??

Excuse me, I'm getting Huck and Bendix confused...the '52 doesn't have the older one (while I search for a pic...)

pic...

Is your photo drivers side or passenger side?

Pulling hard to one side on a hard stop is very rarely caused by brake issues. Exceptions would be one side having the primary and secondary shoes backwards, one side wet with brake fluid or grease, or one drum glazed.
More than likely you have a worn tie rod end, drag link ends, one loose kingpin, or loose leaf spring bushings. (You ruled out wheel bearings.)
Carl

The fly in the ointment is unequal drum temperatures. Don't know how any suspension or alignment issue could cause that, unless it was extreme wear or weight distribution, and she hasn't hauled a load in almost 20 years.

I appreciate the insight. Wish it were something as simple as shoes on backwards or glazed or wet! Perhaps(?) some small merit to loose leaf spring bushings. I rebuilt tie rod ends, kingpins and all that steering stuff maybe 40K ago but have kept them lubed religiously since.

That's the driver's side pic before they were redone. Small shoe on front, big on back, then as now with new components.

As Carl is indicating: May not be brakes.

I expand and agree on his thoughts.

Check upper control arm bushings first. Then lower.
Checking these is like checking ujoints. You will have to use heavy leverage and watch closely. Compare sides.

See if you can detect spring sag on one side or the other. You can't think on some of this that left side wear is doing it, actually could be something on the right . Just always check both. King pins and all that. If something "leans" due to weight transfer during stopping, it may seem like the brakes. This type of anomaly is not easy to catch. The pulling may have nothing to do with brakes. It may be "tracking", lean, sag...forcing, which you call pulling. Pulling connotes brakes in our minds. Not talking hauling weight. All vehicles have a fairly large weight transfer to front when stopping. This will cycle the offending mechanical suspension component. If that's the problem. You won't feel it or see it. May have to have a good mechanic put up on a lift and jack around, hard, on everything.
Could even be a decades old dog tracking... or from a collision.... or big pot hole, many moons ago.

Don't dismiss these out of the box items. Think of others. It's not normal. It's been doing it a long time. It's something you don't expect because you have done all the normal tune up.

Approach it with whacky ideas because the normal approach is not producing.
Normal approach:
1. Shoe adjustment
2. Oily shoes
3. Collapsing hose
4. Needs bled
5. Bad wheel cylinder
6. Plumbing
7. Tire pressure
8. Wheel bearing
9. Bent rim
10. You weigh 600 lbs

You have covered all this.


OR...........live with it as you have done.

This may be a wacky idea, but just thinking out of the box.
You have a rear parking brake on it, right? Not a transmission brake?
If so, wonder what happens if you engage only your parking brake while driving? Taking the front brakes out of the equation, would it still dart to the left?
Just an idea.....

Again...would worn suspension cause mismatched drum temperatures left/right?? Regardless, the weekend plan is to jackstand the frame letting suspension drop and do some forceful prying. Guess ya never know.

Beyond that I'm thinking of re-routing the front lines again. Right now the front half of the master exits to a tee on left side of frame. From that, one line goes straight to the left front and the other across frame to the right front. Maybe it should all run through the right front first then extend across radiator support to left front...more initial pressure to right front that way?? Several forum members have done it that way, including Wrenchguy's picture above seems to show that. Seems a roundabout way to get a line to that left front though.

You probably know this, because I understand you have extensive experience working on this stuff. But....after the plumbing is done - no matter how it's routed - it makes no difference to the brake wheel cylinders. Pressurizing the system will create the same amount of pressure to both cylinders. I plumb my trucks the way you have yours; T at the left, with a line that serves the right.

I'm with you on the different drum temperatures. It makes no sense to me, if you have them properly adjusted and everything is working as it should. From all I've read, it seems you have done that. I just keep coming back to the right brake. If it's receiving the same pressure as the left, what could prevent if from expanding the same amount as the left? A pinched flare fitting, dirt in the wheel cylinder, or faulty wheel cylinder? And then I remember you saying it's been doing this since you got it, and before you did all the work on it!

You may need to call and exorcist! Good luck and I look forward to what you discover!

Agreed, line routing should make no difference. Uniform pressures everywhere. So don't really wanna route another line if it ain't gonna help. Maybe should dissassemble that right front and look for burrs or something on the backing plate that might limit shoe movement.

If you do decide to take it back apart remember to put a little dab of grease on the backing plate where the shoes rub when you go back together.🛠

Always a good idea....and sometimes I forget to do that.

I agree with you about the temp. You say it only happens once in a while. So was the temp taken after a trip with no panic stops? The no. 1 reason for high temp, at a one wheel only, is bearing. Of course, there are other reasons.

You could have constant "shoe drag" if it pulls to left while coasting straight.

In the old days we used to turn drums and arc shoes. So that we got even contact. Is there any way you can see if the shoe wear is odd?...if drum wear is odd.

160-180 degrees could be normal. Get the other side tighter/Get the temps near equal.

Check your other vehicles to see if front temps are near equal to each other.

All these suggestions/tests we are giving are to get some information, hopefully you will get ideas from the data.....and possibly find the cause.

Drums can sometimes warp when they are hot and then hit cold water. So if you were driving and using the brakes quite a bit and had them pretty hot, then hit one drum with a puddle of water, Instant pull, and it would not always just go away after some driving time.. I am sure you have tried this but if not, maybe consider taking the drums to the machine shop and have them take a little cut from them, just to square them up, as noted above. Then take the shoes off and put them up against the drum and see what the contact pattern is. They should both be equally not in contact (just the ends, this is where years ago you would arc them to get full contact) ) or equally in contact.

you probably have this covered... is the brake hardware reasonably new? Weak springs can cause some brake drag, as I'm sure you are aware. Just another thought I haven't seen covered in the conversation.

I'm confused, you said you didn't have Bendix and posted a pic of Bendix brakes. Bendix brakes are correct for '52.

One thing I would definitely do, if my truck was doing that, would be to disassemble the wheel cylinders and make sure one side is not stuck. I do that stuff because I don't know what I'm doing.

I see you still have the single reservoir, but I think that's good as I think It points to the wheels as that is where the issue is. eel cylinders, again, mostly because I don't know what I'm doing. Sounds like it might be time to take apart the wheel cylinder that is pulling and/or check the lines to make sure fluid is not leaking.

Sorry about that, guess there's alot to read and it's easy to miss stuff. I posted this right before the picture:
Then I posted the pic to be clear everyone knew what I had.

It does get long and certainly confusing! Many valid suggestions by everyone, many thanks.
Since I'm getting kinda tired of jacking 'er up, pulling wheels, triple checking known good parts (such as brand new wheel cylinders), because it seems I've done it a million times over the last few weeks!

Gonna let 'er sit for a few days at least, but will be sure to check back in when and if a solution is found. Meanwhile keep the suggestions coming. Thanks again!

I understand the frustration. There must be something fundamentally wrong.

Do the shoes move in/out if you pull on them? Do they seem solid when mounted?

I don't think I can help much more than that since you said the cylinders are new. This is presuming they are assembled correctly.

I just took my '50 out for a 100 mile trip and had to hit the brakes pretty hard and the steering wheel pulled hard to the right. It never did that before. When I got back home, I jacked up the left side and found way too much movement when I grasped the top and bottom of the tire. Worn kingpin.
You say that you have 40,000 miles on your kingpins. That is a lot of miles believe it or not. The Book says to grease them every 1,000 miles. I have never grease them that often. I wonder if anyone does (except for Denny Graham).
Check yours out. Jack it up and grasp the tire at the sides and feel for movement. If it moves, its probably loose wheel bearings.
Now grasp the tire at top and bottom and try to feel movement. If the brake backing plate also moves, you need a new king pin/bushings.
Carl

That is a head scratcher getting different temp readings after swapping drums and using all different (new) parts. I would start by eliminating the pressure/volume issue. For pressure an 8oo# gauge with a 3/16 or 1/4 female inverted flare fitting adapter on the gauge port would work. For volume a helper and a graduated cylinder is needed. The line you removed to check pressure is left open and when the one working the pedal says "down" the other puts his finger over the end of the line till the pedal worker says "up". Repeat twice and the when you hear "up" hold the graduated cylinder in a position to catch ALL the fluid till the pedal man says "down". Fill master cylinder and get at least one more reading. Repeat on other side. If both pressure and volume are the same then I'm baffled and no help. If not check the v/p at any T-block or other fitting that could be restricting the flow to the RIGHT side. If not for the temperature difference one could suspect all the various front end components but this difference in temp pretty much restricts the problem to the brakes themselves. Please reveal the fix if it happens.

Next time you are in the front wheels, measure the inside of both wheel cylinders to make sure they are the same size. If one wheel cylinder has a bigger cup diameter than the other, braking power will not be equal.

The holes drilled through those brass tees can also close up if the brake line is over tightened at some point.

I've read this with great interest. Seems you have touched on everything possible. My two cents. I would be leaning towards a weak brake sring. It doesn't pull on a normal stop only on a hard stop, right? It just seems to me one of the strings could be weaker than the rest. Just a thought. Someone else has mentioned this so I tend to agree with them. I will keep u with this and see what happens. I am almost in the process of replacing all the brake lines on my 49 1/2 ton and also the master cylinder. Hey, at least you have brakes. I have none and can't get them to bleed. Oh well, I'll get it. Good luck.