VCCA Home Forums TECHNICAL - 1945 AND EARLIER 1937-1945 Master Cylinder removal procedure ??? 1938 HA MD

Tried to remove master cylinder today on the 38 MD ..Think I'm going need a MD before I'm finished..looks like you need to remove pedals with cutting torch and maybe part of frame as well ..sc

Hi Spencer,

Have you read the entire article on your brake system in the 38 manual? Page 120 explains removal of the Main Brake Cylinder (Master Cylinder).
Main Brake Cylinder. After a careful reading of the entire article on 1938 brakes then explain the problem you have.

You will need a Flare Nut Wrench to remove the brake line attached to the main brake cylinder. You should plan on replacing all your brake lines if they are original to the car or are of dubious condition. It is common to have the lines rust internally so you are unaware of their condition. While the brake system is probably the most important system in your car it is also expensive to replace components and to hire the work done. Previous posts have described some of the problems.

If you do not have a clear idea of what you are doing at least realize that it is easy to spend over $1000 on repairs. As with all repair work you need to document what you are doing so you know how to put things back. I document all my work with a narrated video.

Why have you decided to replace your main brake cylinder?

Good luck, Mike

P.S. Found this post and it has discussion on the main brake cylinder about half way through the post. 38 Chevy Rebuild and another good post on 38 Brake Work.

I also notice that you bought your car on August 8, 2016. You want to be real careful to come up with a plan on repairs you want to make. It is not advisable to take on too many repairs all at once. Try to complete one project at a time so you do not get overwhelmed and frustrated. I do not multitask well at age 68 so I deal with one problem at a time and if I am waiting for parts I take on simple tasks like polishing the stainless, vacuuming the interior, etc. I noticed that the first project you took on was gas tank related. How has that worked out?

Thanks Mike for a good reply,yes at 71 I get overwhelmed with poor design and I cuss a lot when I come up against such idiotic design such as this is..I have worked on Studebaker and dodge and Ford brakes they are a whole lot easier,,it seems to me I need to get brake pedals off ,I got the bolts out of the pedals and put PB blaster but they won't budge.I will study the links you sent maybe that will help, I got all lines off and bolts out of main body to frame and one pedal at cylinder just about off but got stuck there and could not proceed,yes I'm putting all new brake parts in,looks like it was all new back in the early 60's then left to set for 50 years ,drums had been turned and cylinders look new but dirty of course..S

All you need to do with the pedals is take them apart at the upper joint. Those joints by the way can be easily broken. I received my 38 with the clutch pedal joint broken. I think someone tried to assemble it with the clamp bolt installed loosely and there isn't enough space for that. The casting was fractured right at the fork of the pinch joint.

Are the pedals screwed in ? ..I was looking today kind of looked like threads at the clamp point..more likely need to pound them off ? heat with torch first and PB blaster ? make a jig to hold long pedal shaft and have something to pound against ?? any ideas ??? I had to walk away from this nightmare but need to get back at it ..Spencer

The pedals fit into holes in the arms and are secured by pinch bolts. The arm castings are threaded at one side to receive the bolts. The tricky detail here is that the pedal shafts look round at the end. In fact there is a flat spot in each that makes room for the pinch bolt. The flat spot does not go all the way to the end so there is no room for the pedal shaft to come out, even with the bolt loose. If you can manage to remove the arms from the master in place, you might be better off working on the arm to pedal joint on the bench. When the parts are all cleaned up, the pedal shaft still take a bit of finesse to get it to go into the arm. They are a very snug fit. Also the casting can be broken quite easily.

Got Master cylinder out OK..so the procedure is to PB Blaster brake to shaft bolts and pressed in connections,remove bolts let sit for a day +-..with hammer and drift tap out brake pedals from shaft,they came out fairly easy do this from inside engine compartment..unbolt all lines and wires,I had to take off clutch pedal to get it out, but maybe there is a way without removing clutch off Mas Cyl...now to rebuild and reinstall......also working on rear brakes not an easy job ,nothing on this car seems to make much sense design wise, well at least the two things I'm working on ..S

The mechanical design is pretty primitive in some ways but you need to remember the era this car was built in. Engineering has come a long way.

Hi Spencer,

Tiny's comment is correct that you need to remember the "state of the art" for car design 70+ years ago.

Plus you need to be as patient as possible when trying to remove and disassemble things. Expect to encounter many pieces of frozen hardware. And then expect that even after you have removed all the hardware and retaining devices it will still not come apart.

Please continue to use this forum for support. Collectively we have done just about everything that can be done to these great old cars. And we are very willing to share our experiences.

Question got mas cyl back in but have an extra part left over a round metal cup 1" dia about 3/4" tall with 1/2"hole in it where does this go its external... I know it does not go in mas cyl ..??I not a newbie to old cars..newbie to 38 Chev been foolin with old cars 1915 to 1956 for 50 years +-..also I don't remember what holds the clutch chain on ?? looks like there should be a retainer of some sort on the front ? should have taken a picture i guess..sc

I don't know about the cup but when you get your clutch adjusted, you will not be able to remove the chain. There should be a groove in the clutch arm that prevents the chain from coming off. In addition I think you have to have that last link in a certain orientation to slip it over the arm. The last link on my chain has a large and small end to it.