A theory on pulling front drum brakes - I need some schooling!

[moparedtn]

Patient: 1968 Plymouth GTX "Fred"
Background: Totally stock suspension, drums all around
Condition: ALL drum brake components replaced, yet persistent pulling to left

Symptoms: I've about driven myself (and poor friends like @khryslerkid John) nuts trying to figure out why,
despite my totally rebuilding the entire braking system on Fred, the car insists on pulling left
at times when braking.
It seemingly makes no sense at all, what with the careful selection of all new components, all made in USA....
and the system flushed and bled to death repeatedly.

It has recently occurred to me however - a seemingly unrelated component might actually be the culprit here.
Fred has the stock front sway bar:




A while back, I replaced the links as well as utilized new bar to k-member mounts to the bar,
since all the original rubber was trashed - and whilst doing so, I discovered the bar was "shoved"
over to one side quite a bit before disassembly.
This would be easily explained, the more I thought about it - I had discovered that he had been
in a minor front end collision in his past before me and I had to do some rudimentary repairs to
items behind that shiny bumper as a result, so the bar being pushed over wasn't a shocker either....

(The previous owner had relayed a now almost forgotten story of a long past Friday night bit of
hooliganism, whereby he and his best buddy had been doing burnouts in the doorway of his shop
and Fred, he of always questionable brakes, had gotten away from him and ran into the inside
shop cinderblock wall, explaining the slightly damaged grille and shiny new repop bumper).

Here's the thing that's dawned on me recently though:
When I had that factory bar on the workbench, scrubbing and such....it was obvious it had been
tweaked a bit in whatever collision had occurred, because the ends of the bar did not sit on the bench
equally at rest.
No matter which way I tried it, there was an obvious torquing to the bar - and no amount of my he-manning
on it would straighten it any, it being burly, beefy, springy steel and all...
It wasn't tweaked a lot, but enough to be noticeable.

Duly noted, I re-installed it on Fred with all the new hardware and tried to even it out side to side as best as
I could. Looked ok when done, I thought (see pics).
When the car actually handled noticeably better and didn't pull to one side or the other afterwards, I was pleased
with the efforts.
BUT...
I'm starting to put two and two together here now.
When one hits the brakes, the weight of the car shifts forward a bit of course - which puts the suspension, including
that tweaked sway bar, in compression - and if one side of the bar tends to be higher/lower than the other side and
that situation exascerbates under braking - could this be the source of the pulling?
I'm beginning to think so - because all other possibilities have been exhausted.

Does this make sense to anyone else?
Does anyone have an old factory sway bar they don't need, perhaps?
TIA.

 

[dodgeboy440]

Patient: 1968 Plymouth GTX "Fred"
Background: Totally stock suspension, drums all around
Condition: ALL drum brake components replaced, yet persistent pulling to left

Symptoms: I've about driven myself (and poor friends like @khryslerkid John) nuts trying to figure out why,
despite my totally rebuilding the entire braking system on Fred, the car insists on pulling left
at times when braking.
It seemingly makes no sense at all, what with the careful selection of all new components, all made in USA....
and the system flushed and bled to death repeatedly.

It has recently occurred to me however - a seemingly unrelated component might actually be the culprit here.
Fred has the stock front sway bar:
View attachment 1700392
View attachment 1700393
View attachment 1700391

A while back, I replaced the links as well as utilized new bar to k-member mounts to the bar,
since all the original rubber was trashed - and whilst doing so, I discovered the bar was "shoved"
over to one side quite a bit before disassembly.
This would be easily explained, the more I thought about it - I had discovered that he had been
in a minor front end collision in his past before me and I had to do some rudimentary repairs to
items behind that shiny bumper as a result, so the bar being pushed over wasn't a shocker either....

(The previous owner had relayed a now almost forgotten story of a long past Friday night bit of
hooliganism, whereby he and his best buddy had been doing burnouts in the doorway of his shop
and Fred, he of always questionable brakes, had gotten away from him and ran into the inside
shop cinderblock wall, explaining the slightly damaged grille and shiny new repop bumper).

Here's the thing that's dawned on me recently though:
When I had that factory bar on the workbench, scrubbing and such....it was obvious it had been
tweaked a bit in whatever collision had occurred, because the ends of the bar did not sit on the bench
equally at rest.
No matter which way I tried it, there was an obvious torquing to the bar - and no amount of my he-manning
on it would straighten it any, it being burly, beefy, springy steel and all...
It wasn't tweaked a lot, but enough to be noticeable.

Duly noted, I re-installed it on Fred with all the new hardware and tried to even it out side to side as best as
I could. Looked ok when done, I thought (see pics).
When the car actually handled noticeably better and didn't pull to one side or the other afterwards, I was pleased
with the efforts.
BUT...
I'm starting to put two and two together here now.
When one hits the brakes, the weight of the car shifts forward a bit of course - which puts the suspension, including
that tweaked sway bar, in compression - and if one side of the bar tends to be higher/lower than the other side and
that situation exascerbates under braking - could this be the source of the pulling?
I'm beginning to think so - because all other possibilities have been exhausted.

Does this make sense to anyone else?
Does anyone have an old factory sway bar they don't need, perhaps?
TIA.

Heavens Ta Murgatroid !!!

FRED is a tweekkerrrrr???

Took a while to figure it out eh!
Yeah buddy !

I always was real careful with any car I was
Wheeling that had front drum brakes ….
It’s no fun changing lanes when you don’t want too ….

I’ll betchya by Crackie as the phrase goes
Your Inner Sherlock Is Deducing Correctly !
You would Make Inspector Closeau Proud!

I’d be inclined to put a new away bar on
Ol FRED & See How He Likes Ett!

Mopar2ya!!

John

 

[pnora]

I seriously doubt its the sway bar. Do you have an alignment print out? I would like to see where the wheels are pointing.

 

[dodgeboy440]

I seriously doubt its the sway bar. Do you have an alignment print out? I would like to see where the wheels are pointing.

How About A Frame Check ??
Put that Puppy OnDa Rack & Check For Any
Unseen Damage With The Laser…

Is The Car
“Square” & Equidistant Side To Side ???

I’ve Seen Diffrent Wheelbases Over The Years On Cars that exhibited Unusual tracking traits …. Saw one with a broken spring bolt on one side that wasn’t evident until disassembled….
Any accident can mess up the dynamics of a vehicle at speed ….

Mmmmmmm Said Sherlock…..

 

[Don Frelier]

As bad as your picture quality is.... (not being critical)

It looks to me like the inside of your drivers side tire is getting chopped.

 

[haywire 440]

I had a hard pull to the left when first time braking. It was with disc brakes. The car wasn’t driven real often but I had to hold the steering tightly on the first time when braking.

It was easy after that but as I think about it now I believe that instinctively after that first pull left while braking I just compensated for it by pulling the steering wheel right.

I had the front suspension replaced and if I remember correctly there was a worn component on that left side, a ball joint, tie rod, I don’t remember right now. It was worn enough that there was rubbing on the lower control arm or something like that. Boy I wish I could be more specific but check around those areas.

Damn the new suspension is so smooth now.

 

[sam dupont]

How do the tires lock up? I'm guessing little to no marks from the front right.

 

[R/T Boy 67]

Disconnect the end links, and go for a spin.

 

[oldbee]

Alignment checked lately? Strut rods checked?

 

[Don Frelier]

Disconnect the end links, and go for a spin.

Good idea.
If it gets worse then I would look at the strut rod bushings and lower control arm bushings.
The sway bar might actually help hide movement from those.

But I do think the camber might be off on the drivers side wheel.

 

[0DegreeEngineer]

I've got a second front end sway bar in my shop but I am in southern MN

 

[Rishi]

I had a car that pulled to one side when braking (all manual drum) and it had a sloppy worn front end. But after rebuilding the front suspension, with new ball joints, tie rod ends, bushings, etc., the problem went away before I could look harder at the brakes.

And I am with others, in that the front anti-sway bar may NOT be the culprit. Especially when braking in a straight line. If you removed the front anti-sway bar (or removed one link to disable it) , and tested the brakes again, I suspect it will still pull to one side.

 

[moparedtn]

I seriously doubt its the sway bar. Do you have an alignment print out? I would like to see where the wheels are pointing.

Alignment checked lately? Strut rods checked?

Good idea.
If it gets worse then I would look at the strut rod bushings and lower control arm bushings.
The sway bar might actually help hide movement from those.

But I do think the camber might be off on the drivers side wheel.

When Fred first became car-like again, one of the first things I did was take him to a good alignment shop
in the area, figuring surely he needed one after so many years inactive.
First time through, we went through everything under there and discovered the need for ball joints on
both sides, as well as the need for a new idler arm - so I got those replaced with Moog stuff.

The pleasant surprise from the return trip to the alignment shop was that the car only needed minor toe adjustments
after the repairs. Other than that, the numbers were actually quite good - and when the old school mechanic fella
decided to "pull corners" on the car, it was discovered that Fred was damn near "square" to boot - the diagonal
dimensions between the four corners was within a 1/2" of identical!

The gentleman asked how Fred went down the road and I told him the car tracked shockingly straight - to the point
of my being able to "one finger" the steering wheel when going down the highway oftentimes.
Fred still does that to this day, despite the manual steering box; the car ain't bent.
I've had my share of manual steering big blocks in this life and this car rides and tracks the best of them all by far.

 

[moparedtn]

As bad as your picture quality is.... (not being critical)

It looks to me like the inside of your drivers side tire is getting chopped.

I had a hard pull to the left when first time braking. It was with disc brakes. The car wasn’t driven real often but I had to hold the steering tightly on the first time when braking.

It was easy after that but as I think about it now I believe that instinctively after that first pull left while braking I just compensated for it by pulling the steering wheel right.

I had the front suspension replaced and if I remember correctly there was a worn component on that left side, a ball joint, tie rod, I don’t remember right now. It was worn enough that there was rubbing on the lower control arm or something like that. Boy I wish I could be more specific but check around those areas.

Damn the new suspension is so smooth now.

I had a car that pulled to one side when braking (all manual drum) and it had a sloppy worn front end. But after rebuilding the front suspension, with new ball joints, tie rod ends, bushings, etc., the problem went away before I could look harder at the brakes.

And I am with others, in that the front anti-sway bar may NOT be the culprit. Especially when braking in a straight line. If you removed the front anti-sway bar (or removed one link to disable it) , and tested the brakes again, I suspect it will still pull to one side.

Damn, Don....
"Your baby is dog-ugly (not being critical!)..."
Yes, admittedly the pics suck. Old phone, even older photographer.
That said, the purpose of the pics was to show:
a)the type of bar on the car is the "right" one for a '68 (outside the k-member)
b)the passenger side link leans noticeably more than the drivers' side one

When I reinstalled the bar with new hardware, I made special effort to install it as neutral as possible -
I wanted to get the bar to sit naturally in the straps so as not to pre-load it to either side, of course.
What you see is the best compromise I could come up with as a result, but the new hardware just
confirmed what I was seeing already - namely, the bar is bent.

Yes, it is in the cards for this winter to go ahead and replace the rest of the front end ("rebuild").
I've been dreading it since I don't have a lift (and I'm medically heading south at an accelerated rate)
but it's time to, regardless of how well Fred drives now.
I owe that to the next steward of the car.

BTW, the tire wear is actually quite even - the pics just suck, as Don says.

 

[moparedtn]

How do the tires lock up? I'm guessing little to no marks from the front right

Disconnect the end links, and go for a spin.

You're correct, Sam - if/when the car actually manages to lock one up (only happened a couple times),
it's the left front that locks (same side it pulls towards). Only makes sense, right?
I've literally swapped left for right on all the brake hardware (the parts that actually are swappable,
anyways) and shoes to no avail; ditto for drums, hubs, anything interchangeable (which leaves out the
wheel cylinders, naturally). No change....
I've removed the self-adjusters on the front end (added, since the car didn't come with them) that I paid
extra for. No change.
I've adjusted the shoes more times than I care to count, just to allow for new shoe break-in differences.
Nope...
At this point, I have no evidence that any of all those brand new brake parts are causing anything bad.
Leads me to believe it's something beyond the brake system itself that's the culprit.

Good idea everyone on disconnecting the sway bar and giving it a go, thanks!
I should be able to make the short loop to town and back without it, I'd imagine.

 

[moparedtn]

I've got a second front end sway bar in my shop but I am in southern MN

Can you set that rascal up on a fairly level countertop/bench with the ends setting down and take a picture??
Further - would you be willing to sell it/ship it to me?

 

[Cranky]

Patient: 1968 Plymouth GTX "Fred"
Background: Totally stock suspension, drums all around
Condition: ALL drum brake components replaced, yet persistent pulling to left

Symptoms: I've about driven myself (and poor friends like @khryslerkid John) nuts trying to figure out why,
despite my totally rebuilding the entire braking system on Fred, the car insists on pulling left
at times when braking.
It seemingly makes no sense at all, what with the careful selection of all new components, all made in USA....
and the system flushed and bled to death repeatedly.

It has recently occurred to me however - a seemingly unrelated component might actually be the culprit here.
Fred has the stock front sway bar:
View attachment 1700392
View attachment 1700393
View attachment 1700391

A while back, I replaced the links as well as utilized new bar to k-member mounts to the bar,
since all the original rubber was trashed - and whilst doing so, I discovered the bar was "shoved"
over to one side quite a bit before disassembly.
This would be easily explained, the more I thought about it - I had discovered that he had been
in a minor front end collision in his past before me and I had to do some rudimentary repairs to
items behind that shiny bumper as a result, so the bar being pushed over wasn't a shocker either....

(The previous owner had relayed a now almost forgotten story of a long past Friday night bit of
hooliganism, whereby he and his best buddy had been doing burnouts in the doorway of his shop
and Fred, he of always questionable brakes, had gotten away from him and ran into the inside
shop cinderblock wall, explaining the slightly damaged grille and shiny new repop bumper).

Here's the thing that's dawned on me recently though:
When I had that factory bar on the workbench, scrubbing and such....it was obvious it had been
tweaked a bit in whatever collision had occurred, because the ends of the bar did not sit on the bench
equally at rest.
No matter which way I tried it, there was an obvious torquing to the bar - and no amount of my he-manning
on it would straighten it any, it being burly, beefy, springy steel and all...
It wasn't tweaked a lot, but enough to be noticeable.

Duly noted, I re-installed it on Fred with all the new hardware and tried to even it out side to side as best as
I could. Looked ok when done, I thought (see pics).
When the car actually handled noticeably better and didn't pull to one side or the other afterwards, I was pleased
with the efforts.
BUT...
I'm starting to put two and two together here now.
When one hits the brakes, the weight of the car shifts forward a bit of course - which puts the suspension, including
that tweaked sway bar, in compression - and if one side of the bar tends to be higher/lower than the other side and
that situation exascerbates under braking - could this be the source of the pulling?
I'm beginning to think so - because all other possibilities have been exhausted.

Does this make sense to anyone else?
Does anyone have an old factory sway bar they don't need, perhaps?
TIA.

My thoughts too....

Disconnect the end links, and go for a spin.

It doesn't take much time or effort to disconnect the bar....just tie it up or make sure it's not going to hit the ground. What ya got to lose and then you will at least omit one thing that 'might' be a problem.

 

[RJ Squirrel]

My vote is left strut rod issue, left LCA bushing

 

[moparedtn]

My thoughts too....

It doesn't take much time or effort to disconnect the bar....just tie it up or make sure it's not going to hit the ground. What ya got to lose and then you will at least omit one thing that 'might' be a problem.

Yessir - but this bar needs replaced anyways, too. Was hoping one "cure" might take care of another ill in the
process is all.

 

[Daves69]

If the sway or strut aren't the issue....
Any possibility of air in or restriction to the RF wheel cylinder?
I believe a rear brake can be a cause of pulling.
Maybe take it out on some compacted gravel and test the wheel lockup of all four.