1938 Century pulls to the left when brakes applied

[shart]

Guys, I have a problem with my newly rebuilt brake system that I can’t solve.

Prior to the rebuild the car pulled fairly strongly to the left every time the brakes were applied. It got progressively worse as I drove the car at low speeds close to my home. I purchased the car during the summer of 2020. It always pulled to the left but got progressively worse as I drove it sparingly. Beginning in late July this year I started rebuilding the brakes. I had no info from the previous owner to go by so I was starting from a clean slate. I replaced all four wheel cylinders with NOS, NORS cylinders or kits from Buick vendors we’re all familiar with. I took apart and cleaned the one or two NOS cylinders that were stuck slightly from shelf life cleaning them thoroughly before installing them. Two new front brake hoses installed. New brake springs all four corners. Cleaned all surfaces with brake cleaner. What I found was fluid that was a normal, clean color, no visible particles or crystallization or muck one usually finds with brakes that have sit unused for a long time. The shoes all around looked virtually new requiring very little sanding and cleaning. Same for the drums. None felt or looked like they needed to be turned. Decision was made to use the drums and shoes as is. Also there were no visible brake leaks anywhere in the system prior to this. I did have to replace the back shoes because I found a hairline crack in one of the shoes on one side. A rear set ordered and installed on the rear. Because of the clean nature of the fluid and wheel cylinders I opted to not remove or rebuild the master cylinder. The flexible hose at the rear of the cylinder also looked shiny and new so it was left in place.

We bled the brakes in the order stated in the shop manual (twice) which went well. I have a good pedal and the E-brake works well. Shoes on each wheel were adjusted as evenly as we could. Our first test drive was exactly the same as before the rebuild. When the brakes are applied lightly or normally the steering wheel pulls out of my hands if I don’t hold onto it. Our second attempt to correct this was today, 9-14-22. We removed the two front drums one at a time. With one drum off we slowly bled that wheel cylinder while I pressed on the pedal. No air, just a steady flow of fluid like previously. Then we did the same on the other side. We then discovered that the eccentric at the top of each front brake assembly should be adjusted (up and down only) so that the shoes are centered as closely as possible with the drum. We did that on both sides by observing the distance between the shoes and the drum through the sight hole in the drum and by feel. Then we re-adjusted the bottom adjustment so that the right amount of drag was attained on both front brake assemblies. We took a test ride today and we experienced the same pull to the left when the brakes were applied. My friend, an experienced

car mechanic (both vintage and new professionally) and retired aircraft mechanic is

out of ideas and so am I. What’s are our next steps in your opinion to solve this

dilemma?

 

[BuickTom87]

Hmmm, have you checked

 

the wheel bearings ? 
maybe the tire and rim is out of balance

hows the front end ? Maybe some

worn components on the left side ? 

[shart]

The wheel bearings and race on both sides look new. I cleaned all thoroughly

and re-packed. Have not balanced tires but swapped RF to LF with no 

change in symptoms. I believe the tires are quite old but they look great.

Lester 6-ply bias whitewalls. Car doesn't wander with my hands off the wheel at low speed just coasting. Front components are unknown. When we 

grabbed the LF tires at 900 and 300 it wiggles a little right to left. RF

does not. Does this indicate a bad king pin or what? Could a bad 

king pin cause the wild pulling the left when brakes are applied?

[Rock10]

I would suspect a bad drum.

[edinmass]

I’m going to send you a pm with my number, it’s too much typing. I recently fixed a 40 Caddy with the identical issue. 

[edinmass]

It’s NOT a bad king pin. And it’s most likely not a drum either. 

[Larry Schramm]

A plugged rubber line or are the air pressures the same in all of the tires?

 

The rubber lines are cheap enough I would replace all of them.  They are a safety item.

Edited September 15, 2022 by Larry Schramm (see edit history)

[edinmass]

Spoke to him on the phone. I think we have him headed in the right direction. We will know more in a few days. 

[kgreen]

9 hours ago, edinmass said:

Spoke to him on the phone. I think we have him headed in the right direction. We will know more in a few days. 

What do you suspect, brake shoe problems, shoes reversed, glazed?

[edinmass]

We covered a bunch of issues, including incorrect shoes, reversed shoes, and limited information was available. It's probably a half frozen wheel cylinder. 

[EmTee]

Other things to check are the anchor pin and adjustment of the the 'eccentric' on the secondary shoe is another thing to look at.  If either of those are off it can cause the brake to grab (LF) or not contact the drum properly (RF), resulting in a 'pull'.  The shop manual describes the procedures for each.  Note that I think the lining on my shoes may be thicker than the originals were because I had to grind the circumference of my LF eccentric adjuster in order to get the appropriate shoe-to-drum clearance.  This was after doing the anchor pin adjustment (which helped).

[edinmass]

EmTee, correct, as well as incorrect springs. Communication and experience are also issues, but after going over it I think it's all covered. We shall know soon.