Rebuild this master cylinder or buy new?

[rodneyramjet]

Should I rebuild this or buy new?  And what do you think about the power assist unit?  Looks nasty...is this easily dealt with or?  1968 383 with power drum brakes...

[Gold Rush]

The question in my mind is two fold.  First how does the master cylinder bore look?  If it is clean a light hone and rebuild kit should bring it back to service.  Second question is does the power booster actually function still?  If it dose the rust and nasty can be cleaned up.

When I pulled the master cylinder from the '74 SE I'm restoring I found mega rust in the bore.  No chance of rebuild.  The power booster looked about like yours but it did work so I taped off all the openings and sandblasted the outside then primed and painted it.    

[Dino]

Yeah if it's salvageable then rebuild it. Nothing like having the original parts. Much of this new stuff is rebuilt as well, and sometimes badly.

[Pete in NH]

Hi,

If the bore can be cleaned up with a light honing you can try rebuilding it. Don't be surprised though to find a rebuild kit costs close or more to a new part. All the new master cylinders these days, even the major brands like Raybestos, seem to be coming out of China.

On the power booster, I would not trust a 40 some year old part. I'm in the process of pulling the booster out of my 71 as it has failed and needs to be rebuilt. The rubber diaphragms get hard and crack with age.

[lukedukem]

Your looks way better than mine. i bought new. and upgraded to disks at the same time. but your looks like it would be good. like others have said
If the bore can be cleaned up with a light honing you can try rebuilding it
Here is mine after clean up.
Luke

[M5Ivan]

On the power booster, I would not trust a 40 some year old part. I'm in the process of pulling the booster out of my 71 as it has failed and needs to be rebuilt. The rubber diaphragms get hard and crack with age.

I pulled my booster off a few weeks ago to have it rebuilt and I'm expecting it back this week. My diaphram was cracked.

[birdsandbees]

Master cylinder... about 30 bucks for a rebuild kit. Come with both new piston assemblies and the check valves and seats. I lucked out and found it on amazon.ca  Can get the part number for you if you desire..

The "midland" Vacuum booster, mine was a mess.. but I got lucky and was able to buy a nice one on Ebay.

[rodneyramjet]

thanks all...

Removing the upper right nut that holds the power booster looks like a bear.  Do I have to take more stuff apart under the dash just to get at it?

You can obviously tell I'm not a car mechanic...was a welder/fitter for about a dozen years in the 70s-80s and engineer with a desk job ever since.




If I left the power booster for later and it doesn't work would I essentially have a car with no power brakes or would it be worse than that...no brakes at all?

I really just want to take this thing around the block since I got the motor running 2 weeks ago...was really temped to just use the emergency brakes that day but ruled that out.

Maybe I've reached the point where my skills don't cut it and it is time to pay someone to do this right?  My end goal is to get this car road worthy, drive it for a couple months, and then decide whether to keep it or let it go.  I'm not rich and I don't have a bunch of spare time to learn how to be a all-around restoration wizard.

I guess I do have time to whine and vent though....sorry about that.

[Mopar Nut]

Taking out the cluster will make it easier getting to upper right nut.

[Dino]

Power brakes with a busted booster means it will be hell to stop it.

Like Nut said you can remove the cluster to get better access but you can do it with some wobble extensions as well. Tricky but not impossible. Pull the front seat so you have some room. Only 4 nuts.

[Pete in NH]

I just pulled the booster out of my 71 yesterday. As Dino said you can reach that one upper nut with extensions and a deep socket. I used a 1/2" deep socket and a 12" extension on a 3/8" drive set. It took me about five minutes to get the nut off. Much easier than pulling the dash apart.

With a failed booster my car did stop but nothing like it normally did. My 71 always had excellent brakes. With a bad booster what I was left with were very poor manual brakes, worse than conventional manual brakes.Stopping distances were greatly increased and the need for a panic stop would not have ended well.
'

[rodneyramjet]

Thanks all for the encouragement and information...mission successful!  Couldn't have done it (without having to undo it and redo it several times) without ya.   

[375instroke]

24" wobble extension is what I use.