VCCA Home Forums TECHNICAL - 1945 AND EARLIER 1937-1945 41 master cylinder

The master cylinder on my '41 coupe is leaking, and today I received the new master cylinder from Chevs of the 40's. I had hoped that seeing the new master cylinder would make my visualiztion of the installation easier, and it has, but only just a little. That area under the car is really packed with stuff! I've looked at the Shop Manual, and it doesn't help much. Obviously, I have to unhook the brake line to remove the old cylinder, and it appears 2 bolts hold it to the frame. What has me puzzled is the 2 large holes on the front of the cylinder with bushings in them. I assume the pedal shafts ride on those bushings? The frame off restoration on my '31 seems easier at this point. At least with the body off I could see everything more clearly on it. Swapping a master cylinder on a 50's and later car is also easier. Any advice would be appreciated.
Sid

Sid,
Just took mine out today. This was after having to struggle with a stuck key. More about that later.

Basically here are the steps (work underneathe the car):

A. Datatch the brake light wires

B. Take a line wrench and carefully unscrew the line on the rear of the cylinder. Mine twisted off. I'll have the acquire a new one.

C. Remove the plug from the front of the cylinder. Run something in and grab the key. Pull it out. Mine was stuck tighter than an over-torqued lug nut.

D. Pull the two pivots out. You must detach the two piece clutch and brake arms at their mid-points.

E. Undo the two bolts holding the MC in place. The bolts and nuts are 9/16ths. It will come out rearwards.

F. Reassemvle in reverse order.

Good luck,
Charlie

BTW: If you twist the line, get a new one from a parts store. It attaches from rear of MC to junction on passenger side frame. If you want to replace it with an original type then you can get them at Chevs of the 40s or FS. I think.

Correction to list of things to do:

D. Merely position the two arms (clutch and brake) to where they will clear the frame.

I implied that the two arms are to be removed before taking the MC out. That is not the required and would be really hard to do. Sorry.
Charlie

Thanks for the help Charlie, I'll crawl under there and try it soon.
Sid

Thanks to Charlie's help, I removed the old master cylinder yesterday. The plug on the front that he referred to came out easily using a bent paper clip. but I wondered how the pedal shafts get lubricated. That "plug" had a smaller plug screwed in it. It looks like there should be a grease fitting screwed into that "plug".

The bushings for the pivot of the brake and clutch arm are lubricated. There is no need to install a grease plug. If you go to "Search" you will find that we discussed this some short time ago. There was some real good information offered.

Glad you got it out all right.
Charlie

You must be talking about the '37 brake/clutch pedal discussion from a few weeks ago re: sintered bronze bushings. In light of that discussion, I will wipe the new grease out of the bushings in my new master cylinder and oil them before installation. I presume that during future lubrications of the car I would remove the plug and squirt oil in the hole? I bet many of these cars still in use in the 50's and 60's never got any lubrication in that area. A grease monkey was trained to look for grease fittings and squirt grease in them. I know, 'cause I was one.
Thanks,
Sid

Could you explain what you mean by detach the two piece clutch and brake arms at their mid point? I will be removing my master cylinder this weekend and just a brief look under the car has me scratching my head.

Do the arms just pull out of the bushings or do you have to remove the arms from the pedals?

The pedal arms are in two pieces, bolted together in the center. These bolts need to be removed to separate the upper pedal arms from the lower. After removing the key from the front of the master cylinder, as Charlie described, you can then pull the lower arms out of the master cylinder. I bought my new master cylinder from Chevs of the 40's, and I have two concerns - 1. the fitting for the brake line was not the correct size, and I had to install the rear fitting from the old master cylinder. 2. the bushing for the brake arm was a hair too small, and by brake pedal is stiff now. I will have to work it back and forth several times to "wear it in". Had I test fitted the brake arm before installing the master cylinder, I could have honed it a little to avoid this problem.
Sid

A few pictures, along with Charlie's good directions, may help you take the master cylinder out. You can see in the first picture where the pedals are connected to the master cylinder arms. You do need to take the pedals off before trying to get the master cylinder out. You can also see in the first picture what an arm looks like when it is disconnected from the front end of the MC. You can also see the two small parts that must come off the front of the MC to remove the MC arms. In the second picture you can see the plug that fits in the middle of the MC, between the arms. This plug contains a brass screw in plug. It is through this plug that grease can be added to the bushings for lubrication of the two arms with grease. The screw is adjustable and by tightening it more grease is forced into the bushing. This is similar to the fitting on the side of the distributor used to lubricate the distributor shaft with grease. You will also see in the bottom photo the key that keeps the arms secured to the master cylinder. If you look carefully at the top of the key you will see that it is threaded. It is threaded all the way through the key. The thread can be used to remove the key. You can screw in the right sized screw and then pull out the key with the screw, or fish the key out with a paper clip (good luck with a paper clip, if the key has not been kept lubricated).

To clearly answer Gary's question. The arms pull out of the bushing after removing the large 6 sided plug on the front of the MC, and the key behind it. This is done on your work bench after removing the MC from beneath the car. To get the MC to slide out from where it is anchored on the frame of the car. you need to disconnect all the linkage attached to the two arms. In the first picture you can see that the top arm is being held in place by a bolt/nut/carter pin attached to the pedal stop (the part under the rubber boot is called the pedal stop). Removing this bolt allows the arm to move up and down so it can easily pass through all the obstructions under the car body and frame. Good luck, Mike

Hello 6wheel -

This is probably too late to be of much help to you, but, if you go to page 6-57 of the shop manual, under clutch and brake pedal mounting - passenger cars, it details all that you need to answer your questions about removing pedal shafts from their mountings and about the greasing of the shafts in their respective brass bushings. This may be a help to anyone else if they have questions regarding this issue. Fig 120, 121, 122, and 123 shows all. This is 42-48 manual. Also, if anyone interested, if you order a M/C from The Filling Station, there will be a problem with rear brake line fitting when installing. Would not work with my 48, so finally ended up buying a used 41 and having it sleeved and using it. FS was very gracious in helping me with my problem and promply refunded my monies. Great people to work with!!!

Just a thought here and if it helped anyone - good -

Jim.

After looking at the master cylinder it was fairly easy to remove. It is out and on the bench. Have to decide to rebuild or buy new. It looks good, no leaks but I know the front wheel cylinders were corroded so I can assume the lines need to be cleaned as well. Thank for the heads up

I am not much of a mechanic so am hesitant to rebuild a master cylinder. To me it is just too risky to not have a 100% dependable part working the right way to stop my car! Money is no object to me when it comes to good working brakes. The first repairs I did to my car were to replace the entire brake system with new brake cylinders, master brake cylinder, shoes, brake lines, and misc fasteners. A well running drive train, or nice paint job, etc., will not compensate for bad brakes! Good luck, Mike

P.S. Brake lines normally corrode from the inside out. Which means you can not usually tell if they are about to fail. I strongly recommend replacing 61 year old brake lines.

I agree, good brakes are most important. My initial thought was to replace the lame stock brakes and suspension with modern shocks, suspension and disc brakes. Rebuilding the master cylinder and wheel cylinders is not difficult. I will at least know they were rebuilt properly and will function as designed. If they do not meet specs they will be replaced.

Changes over to more modern brakes depends on the speeds you will be driving. I rarely drive over 45 and mostly drive at 35 or less, so the original brakes are more than adequate for my driving. If you were regularly driving on expressways or above 55 then you might want to consider switching. I would try maintaining the old technology until I found out it was inadequate. If I were changing over to a hot rod I would definitely go with a modern brake system.

I would also be considering seat belts as another priority in getting your car road worthy!! The topic of seat belts has been discussed on the forum in previous posts. Good luck, Mike

My thanks to Jim for the reference to the 42-48 manual. It did provide some helpful pictures. My brake system is back together, but I'm still dealing with problems. As I indicated earlier, the brake pedal is too stiff, and will not release. I found a replacement spring today and will see if that helps. I also noticed that my clutch is engaging in a different spot, presumably because I had the pedal shafts apart. I'm also still not clear about grease vs. oil for the pedal shafts where they pivot in the master cylinder. Both lubricants have been discussed in this thread. I oiled the bushings as we discussed, but do I put grease in the opening for the key in the front of the master cylinder?
Thanks guys,
Sid

Dont put mineral type grease or oil where it can contact brake rubber parts, brake rubbers need a vegetable type lubricant.
Tony

For people who plan to install a new master cylinder I should recommend inspecting it throughout before installation .
The reason: 3 years ago I installed a new Master cylinder in my 48 Fleetmaster ( its similar to 37-42 cars )
It came from one of the top USA brake companies so I did not bother dismantling it for a complete inspection as I should do with a less known company's product ( it had inspection marks from the factory ) . After using the brakes a few times the cylinder wall cracked open and I lost all brake fluid in one time rendering the brakes useless.I was lucky I was not driving on a public road at the time or I sure should end up with a crash.
After examining the master cylinder in detail I found out that the cylinder bore was machined out of center leaving only a very thin wall on one side that simply collapsed with a moderate brake pressure.
I do not wish mentioning the name of the brake company or send any pictures but I have evidence material in case I will ever be asked officially.

Jianis

I pulled that brass plug out of the front and installed a grease zerk into that per the manual and used a grease gun and pumped grease into that area until grease came out from around the pedal shafts. Than I wiped off all the excess grease coming from around the pedal shafts and that took care of the lubricant. Don't want any grease dripping onto the rubber boot on the front of the master cylinder. That should take care of the lubrication for the duration of time I will own my 48. The type of grease I always use for most everything is Lithium general purpose grease.

If brake pedal not releasing after a good grease job, perhaps too tight a fit in the bushings??

If everything put back together correctly as to pedal shafts, would think clutch should engage in the same place as it did before.

Just some thoughts here Sid.

jdv123 , installing a grease zerk is the smart way to go. I have replaced the shaft bushings that were "goosey loosey" and in bad shape because they were'nt ever greased. The cross shaped key was thunder to get out also. On a 51 thru a 54 it is easy to remove the key and peddle arms without removing the master cylinder IF YOU CAN FISH THE SHAFT KEY. The master cylinder is easy to remove and install with the peddle arms off. I have mentioned here before that on one diffucult key removal I tapped the center hole in the key (51-54 locking keys aren't threaded) with a 10-32 tap and used a long 10-32 machine screw to work the key out. only a novice would fail to lubricate the peddle shafts before completeing the installition of a new master cylinder. Unless you drive on a lot of salted highways, one lubrication of the peddle shafts thru the zerk will last many years, probably outlasting the innards in your master cylinder .

Thanks for the help guys, I'll add a grease fitting to the master cylinder soon.
Sid

Hey, I am having trouble taking parts off of my old master cylinder and putting them on my new one. I cannot figure out the way the brake arms go and almost everywhere I go on the internet, none of the master cylinders have the long break arms that attach to the clutch, and the brake. Have any pictures or tips on which way they should go?

Are you talking about a 1941 master cylinder ?