Master Cylinder Advice

[Whitephrog]

One of my spare master cylinders appears to be in extraordinarily good condition. Likely rebuilt at some point in the past. I'm debating as to whether to send it off to be rebuilt again or to just refresh it myself. I have new rubber and brass washers. From the photos below, what's the opinion of this group?

 

[nomad]

Pitting in the bore's are your main concern but I've honed and rebuilt several with no issue's other than one that seep's most likely because there was deep pitting that I never completely removed.

Kurt.

 

[Rut]

Ray,
Are those 7/8" AND 3/4" bore pistons? If the bores are good or can be cleaned up I would give it a shot before sending it off to be sleeved.
Good luck, Rut

 

[Gerard]

One of my spare master cylinders appears to be in extraordinarily good condition. Likely rebuilt at some point in the past. I'm debating as to whether to send it off to be rebuilt again or to just refresh it myself. I have new rubber and brass washers. From the photos below, what's the opinion of this group?


View attachment 27279

Ray,

Those are Roadstar pistons and can't be rebuilt with stock seals. Roadstar pistons are oversize, meaning your bore has been drilled out to accommodate the oversize pistons. If you have a set of calipers, measure the OD of the piston and you will see that are larger than .875. Roadstar seals are NLA, so your only option is to sleeve your MC back to 7/8" or 3/4" if you have disc brakes.

You probably know I provide this service, but see my web page if you're not familiar. You can see for yourself which pistons you have.

https://gerardsgarage.com/Garage/Tech/DbrakeUg.htm

I currently have one built and ready to ship if you want to buy it outright or you can send yours to me to be put right.

Let me know if you have questions.

 

[Whitephrog]

Gerard

Been to your site many time. I should have gone back to it before I asked the question.

I have a second spare as well. That one had the original 3/4" pistons in it. Everything matched the photos on your web site. One difference that I noted in my two spares was the spring length. The one with the Roadstar pistons had longer springs.

Also discovered that I apparently have a rebuild kit for a 7/8" bore (the on in the photo) as well as one for a 3/4" bore.

I will PM you later regarding the rebuild.