Master Cylinder Rebuilding

Nice write up. I just rebuilt my dual disc front MC for my '81SH. I do have a question about the part where you are talking about taking the boot off. You mention an internal wire in the boot. No mention of a retaining ring. When I disassembled my MC I didn't find a retaining ring and I'm looking for a suitable replacement.
 
itsatoy said:
Nice write up. I just rebuilt my dual disc front MC for my '81SH. I do have a question about the part where you are talking about taking the boot off. You mention an internal wire in the boot. No mention of a retaining ring. When I disassembled my MC I didn't find a retaining ring and I'm looking for a suitable replacement.
Click to expand...

Just a quick note on this - I took my M/C apart last night and I dind't have a retaining ring over the rubber boot either, just seemed to have been friction fit/pressed in place around the M/C. Its possible I could have missed the retaining ring, but I was working on a bench and I don't think I did. Perhaps the rebuild kits don't include the retaining ring because its not really needed? Obviously looking for the same answer as you... as I'll have my rebuild kit without the retaining ring shortly.
 
gggGary said:
blow up of an early master cylinder with lever parts.

full


This is a 72-73 M/C with the brake light switch held on by the lever bolt.
A cotter pin at end of lever bolt is not shown.
To remove the lever from the housing; the brass bushing is threaded onto the bolt, the steel sleeve is a slip fit, remove the cotter and nut, pry the brake switch off the retaining pins. Using aluminum or brass to protect the threads, tap the bolt and brass bushing together up out of the housing to free the lever.


72-73 Internals in assembly order
View attachment 29008

AFAIK there are no overhaul kits available for this MC
Ebay and mikesXS have new replacements for the 74-76 but they do not have provisions for the 72-3 brake light switch.
Click to expand...

What are you supposed to use for the 72-73 brake rebuilds. I need to do mine soon and it looks like this was such a short run that parts may not be available?
 
I am also curious as to what master cylinder kit to use. I am unsure if mikesxs might have something for the 73 TX650.

I am unsure of the stock m/c manufacturer or bore size.
 
Anyone have any tips on removing the threaded brass bushing holding the lever on ?
I have tried to drive mine out using the lever bolt no luck .Do not want to screw up the bushing , mine is not moving . Yes I have soaked it several times in penetrating lubes and am thinking of some way to apply heat with out damaging any thing . out .

Never mind ,I got it out . Used two screw drivers under the bolt head. Now to get the correct rebuild kit !
 
Last edited:
Trying to rebuild my 78 Special master cylinder today...
I have the MikeXS rebuild kit but I am not sure of the sequence and all I have is the crappy Haynes manual.

Here is how I think it goes back together.
092014180655_zpsf955d7f3.jpg


But what is that rubber seal for at the top? The parts diagram in the Haynes manual shows two additional pieces that were not included in my kit.

Here is the mess I started with:
071714081852_zps442e0f47.jpg
 
I think you are right gggGary. You can see what's left of my old seal on the piston in the 2nd pic. It does not seem like that little piece of rubber will fit over that end of it but, I guess it does...I'll leave it in the sun for a few minutes before I tackle it tomorrow.
Thanks,
Jim
 
I purchased the rebuild parts for my 73 master cylinder from mikes and it was leaking within maybe a week. And that snap ring tool that is longer to down in there did not help me at all. Lol
 
I am in process of rebuilding my master cylinder. I have a kit, however I do not see the large O ring to seal the base of the plastic reservoir to the aluminum master cylinder housing. I have looked on several sites for this replacement part with no luck. Do you know of a source? Or as an option a size? Also I am the owner of a complete set of SK snap ring pliers angled and strait. Inside and out side. And wouldn't you know it none of them work due to size. What works best?

Dennis Wymore
 
I am rebuilding a 77 master cylinder my question is I have a Mike's excess caliper kit. My question is regarding the very last part you put on in the rebuild the rubber sealer that goes around the plunger its base goes near the snap ring does it go into a groove or is this going to sit on top of the snap ring?
 
This is very good and helpful. My one question is how to keep the rubber cap in place over the small end of the spring. Does the plunger do that job?
 
Yes, the plunger holds the rubber cap on the spring. Once assembled, they will be in constant contact.
 
gggGary said:
blow up of an early master cylinder with lever parts.

full


This is a 72-73 M/C with the brake light switch held on by the lever bolt.
A cotter pin at end of lever bolt is not shown.
To remove the lever from the housing; the brass bushing is threaded onto the bolt, the steel sleeve is a slip fit, remove the cotter and nut, pry the brake switch off the retaining pins. Using aluminum or brass to protect the threads, tap the bolt and brass bushing together up out of the housing to free the lever.


72-73 Internals in assembly order
View attachment 29008

AFAIK there are no overhaul kits available for this MC
Ebay and mikesXS have new replacements for the 74-76 but they do not have provisions for the 72-3 brake light switch.
Click to expand...

This thread is very useful.

Actually the photo is a 73.
The 72 is a one year only master cylinder (only slightly different to 73).
 

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