1960s 1968 DeVille Brake Pull to the left

[TJ Hopland]

Very interesting about 40 clicks.  How many teeth on the wheel would effect that but I can't imagine that they got a lot more teeth on a wheel than what I am used to seeing.  The threads on the shaft that I am used to are also already pretty fine. But maybe they got a few more and a little finer?  Maybe they wanted to keep things able to self adjust real close?

Now when you have stuff that doesn't have self adjusters its the other way.  The threads tend to be more coarse and the wheel has many fewer teeth.  I don't know how often that was done on cars but trailers are pretty common to be that way and its still common to find those with drums and not self adjusting.

Anyone have an adjuster laying around?  I am curious how many teeth they tend to have and then the thread pitch.  40 teeth could be the ballpark so that would only be one turn and it is a pretty fine thread.   Also when releasing them we have the arm that makes the clicking pushed back so we are not actually 'clicking' it like when going tighter.  So maybe when I and possibly others are talking 4 clicks we are talking tool strokes which maybe are more clicks so we are talking 10 actual clicks?  But it aint 40.  I'm thinking 40 is what you need to clear a big old wear/rust ridge to get a used drum off.   

[tcom2027]

 You have done an excellent job of troubleshooting and applying possible solutions. Do you have access to a lathe? If so check the runout on the machined surfaces of the drum(s) as one may be out of round enough to cause the momentary pull but not enough to transmit a pulsation in the pedal. Possible a reach but you have tried a lot of other solutions with limited success.

 Maybe time to consider the suspension. I believe Mikes' thoughts on suspension arm bushings is worth following up on. Additionally excessive toe out on the left, too much negative camber? Badly worn ball joints, etc. That said, if either of those adjustments were way out you may have noticed it by the eyeball method. But... If the specs are close you have eliminated a potential, however remote, cause of the problem.   

tony

[ChrisTabat]

Thank you - as an amateur/hobbyist, I frequently refer to myself as stubborn and stupid:  too stupid to know what I shouldn't tackle myself and too stubborn to quit once I start.  But advancing years are slowly curing me of both.  And I guess that what hobbies are all about - learning skills while learning ones' limitations. 

I had considered the suspension factor but I don't notice any issues when not braking,  even at 75mph on the freeway. 

Anyhow,  here's the latest and probably last update for a while:  I took it for another test drive today - made no adjustments to anything since the last test drive.  After re-reading the manual, it sounds like every time I tinker/adjust on something, I'm taking a step or two backwards in the break-in process.  I simply drove it on perhaps a 10 mile scenic route near our house,  and did not critically analyze every stop or braking event.  Summary is that if I hadn't been thinking about it, I don't think I would have noticed anything amiss.  When I got home, I made a couple of stops without my hands on the steering wheel.  There was a barely perceptible twitch to the left.  Still not quite sure how to explain the exaggerated pull during the "warm up" other than perhaps the left brakes being too tight created some kind of thermal condition that evened out again as both brakes got hot.

My conclusion is that I had the left front adjuster too tight all along,  and that behavior/feel of the wheels when on a lift is not a reliable indicator of what to expect on the road,  at least not this car.  I expect that as I drive it more, any hint of a pull will continue to fade away.  If it doesn't,  I will back off both front adjusters some more and follow the manual to the letter.   

[bctexas]

Hi Chris

I have had the same experience with my '65 CDV pulling to the right under braking.  I am pretty sure your '68 has the same brakes.  It is pretty much resolved at this point, and I *think* I know why.

First, I found that the "teeth" on the adjuster wheel on my car were badly worn, with some teeth missing.  So I bought replacements at my local parts store.  I found that the replacements were different in that the distance from the end of the adjuster to the star wheel was much shorter on the replacement than on the original.  As a result, the star wheel was not contacted by the correct part of the adjuster arm.  The pic below shows the stub on the star wheel end of the adjuster.  On the left is factory, the right is the replacement and the center is one I made.  The diameter of the center pin on the adjuster necessitated the home made replacement.  This correctly positioned the star wheel on the adjuster arm.  I will make no claim that this helped, but I like the setup better.

However, I suspect primary issue lies elsewhere.  We no longer "arc" new brake shoes, so the radius of the new lining does not exactly match the radius of the drum.  Once upon a time shops would measure the diameter of the drum, then set the shoes up in a grinding machine set to match the radius of the shoe lining to the drum, ensuring full contact between shoe and drum from new.  Such machines (and knowledge) are now rare and we have to "arc" the new shoes in service.  I suspect that once we run the new shoes enough, they wear to the radius of the drum and the difference in contact area between left and right sides equalizes, thus eliminating the pull.  Here is a youtube vid showing the arcing machine and process:

https://www.youtube.com/watch?v=H-ZF200ZSVs

Happy Motoring!