What master cylinder should I get?

[strang3majik]

My 72 510 has a locked up master cylinder and I can't even get the piston out to rebuild it...it broke in pieces upon removal with the end still in...and, well they don't make them for them anymore...lol

 

What should I do?

 

I can find them for a 73, but they have a different part number than a 72...not sure if the piston size is different, or the thread for the lines....etc.

 

So, any ideas? Using it with stock brakes for now. Can I use a 280z one and just be a little easier on the pedal? Lol.

[hobbes_the_cat]

did you try rockauto.com? I am surprised you cant find a stock one. either way a 280z one will fit and the lines will thread in just fine but the piston is bigger, 7/8 I think. great upgrade if you plan on going with 280zx brakes in the front and stock drums in the back. with stock brakes and a 280z master the pedal will probably be a lot stiffer.

[strang3majik]

I don't mind a stiffer pedal, and in the future I do plan on doing the 280zx brake swap...so...that be a safe upgrade?

 

I upgraded to Minivan brakes on my Omni and put a Dodge Ram master cylinder in it...its tough to push and only has about an inch of travel, but...I don't mind it...lol

 

If its like that then I'll go that route. But...any clue?

 

And, I found some on Ebay, but, they're over priced and who knows what quality. I don't want to put cheaply made crappy brake related parts on.

 

EDIT: I swore I checked Rock Auto before :/ But, they do have them...but, once again, for 75 clams...I might as well do the 280zx brake/strut upgrade and get a new $20 master cylinder for that.

[datzenmike]

There's two, a front (rear brakes) and a rear (front brakes) piston with a spring between them. So maybe it's just the front piston that's stuck?

 

Try slamming the hole end down hard on a piece of 2x4. Hard! The piston will be forced down and out.

 

You have the stopper screw removed that holds the pistons in right? I'm sure you must.

[hobbes_the_cat]

All I can say for sure is that I ran a stock master -3/4" piston with 280zx front brakes and the pedal almost went to the floor and was real spongy. I stepped up to the 280z master- 7/8" and it's perfect. I have heard other people try a 280zx master -15/16" with zx front brakes and stock rears and the pedal was like a brick, super stiff. 280z master and stock brakes will PROBABLY be pretty stiff.

[datsunaholic]

I believe '73 had vacuum assist brakes. '72 did not. If so, that'd be one reason for the part number difference. Using a power assist brake master with no power assist booster makes the pedal very stiff and you lose a bunch of controlability.

[ggzilla]

If you want EASIER on the pedal, then go with a smaller master cylinder. A bigger master cylinder piston will be HARDER on the pedal. In other words, you'll have to press down harder on the pedal to stop the same amount.

[strang3majik]

Ah...thanks for all the info everyone.

 

And, yes...the master is completley dismantled...I got the rear part of the piston out with 175psi of air pressure while banging it against the bench...the other end is stuck. Plus, as nasty, grimy, and corrosion rampant it is...I'd rather just replace it. And after the last little attempt...not so sure it'll seal anymore :unsure:

 

So...the 280z master is the front disc, rear drum and the only slightly larger piston? As I said, a stiffer pedal doesn't matter...as long as its stiffer then the pedal it has now...lol Plus...that way I'll be one step closer for when I do the 280zx brake upgrade...which I'm planning on doing very soon anyhow.

 

And, datsunholic, thats a very good possibility. In which case, only the rod would be longer, right? And didn't the 280s have power assist?

[Stitebunny]

strang3-

Not trying to hijack the thread, but my master needs some attention also. I was wondering if you were able to find the seals to rebuild. And if so where? My pedal needs to be pumped up once before it starts moving fluid. I think the fluid is leaking past the seals.

[strang3majik]

Rock auto has the seal kits...yes.

 

And...just ordered the 280z master...picking it up this afternoon. Hopefully I can make this thing stop with the original calipers...hahahaha.

 

I broke them free, but, that doesn't mean anything.

[Stitebunny]

Hmm, I'll look again. I didn't see it there....

Let me know how it goes with that master cylinder. I may end up doing that also!

[strang3majik]

Will do...my problem is that I need a solution NOW...so...I'll experiment...lol

 

And...I lied...they don't have them. I saw them somewhere though...some Datsun part website I think.

 

Here...don't no how credible they are.

 

http://www.new-datsun-parts.com/datsun-1200-parts-exterior.html

[banzai510(hainz)]

there were 2 types of brake masters cylinders.

only thing I can see the brake line spacing is slightly different. 1 the lines are closer together. the more common they are farther apart . U could just bent to the line. and use a NEW master. The taiwans are not great but better than rebuilding them yourself as I dont think they last. So dont be a cheap MOFO and get a new one Better a Jap made one.

 

try Rockauto.