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Wheel Cylinder Spring

JR66

Gold Level Sponsor
Just rebuilt & installed original brake wheel cylinder on Series V (self adjusting) brakes on left side following WSM then oops noticed a spring sitting on the bench. It's not shown in WSM or SS catalog Looking at the right side parts not installed yet it looks like the only place it could go is behind the seal between the piston and the closed end of the bore. It's a fairly wimpy spring 1 ½ inch long 5/16 on one end and ⅜ on the other end. Hard to believe it could do much considering the friction between piston seal and bore but I guess I should use them. Is anyone familiar with these springs and can confirm I'm correct about where they fit.
 

puff4

Platinum Level Sponsor
The spring, with the attached flared plastic end cap, helps keep the rubber seal flared out and properly aligned in the bore.
 

JR66

Gold Level Sponsor
Thanks, that sounds logical but mine don't have a flared end cap, just the bare spring. I assume the 5/16 end fits on the piston extension. Do you think it would do any good without a flared end cap? I can't find any illustration showing the spring.
 

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puff4

Platinum Level Sponsor
Ah, yeah, you’re right. I was confusing my cylinders. Yeah, that spring just returns the piston up the bore - no end cap on that one. It doesn’t have a lot of push, but enough to do the job.
 

puff4

Platinum Level Sponsor
I should have remembered better… I designed and made new pistons for my own cylinders out of silicon bearing bronze to prevent them from rusting like the steel ones. That, and sleeving the cylinder bores with brass is making my brakes last a very long time, with any luck. I've had stainless pucks in the front disc calipers for over 24 years now - no problems. I noticed the rear brake piston problem when I went to rebuild my rear axle and noticed that the pistons had seized in the bores. Silicon bronze should never deteriorate, and with a brass liner the cylinder never will, either. I bead blasted the outside of the cylinders and coated them with Hammerite silver - so that should be good for about 30 years. Job done.
 

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puff4

Platinum Level Sponsor
For those wanting to make your own pistons to replace the fatally (and unavoidable) rusting originals, I offer this:

upload_2022-8-18_1-32-28.png
 

bernd_st

Bronze Level Sponsor
Kevin,
excellent job. Are you in the biz now :rolleyes:? Would like to order a pair of those pistons..
 

puff4

Platinum Level Sponsor
Kevin,
excellent job. Are you in the biz now :rolleyes:? Would like to order a pair of those pistons..

Thanks, Bernd. I appreciate the accolades, but no, I'm retired and only make things for myself. I do occasionally 3D print things for friends and such, but my machining work is for me... it just takes too long and at 66 I value my time a lot more than money. :)

That being said, I will put my designs out there in case others want to make them. I've done so many times here on the forum - for example I've posted my designs for the Alpine front bumper badge and lamp bar, BW35 stone screens, the rare lighter knob and escutcheon, etc.

If you want a set of those pistons, you could take the drawing I posted to pretty much any machine shop (online or in person) and they should be able to easily make it for you. I have no idea what they'd charge, though, since I do all my own machining and have zero experience in hiring it out.
 
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bernd_st

Bronze Level Sponsor
Noted. Anyway thanks for the drawing. I'm just trying out a local machine shop for some other bits. If they perform well, perhaps I'll give them the next job...
 

jdoclogan

Platinum Level Sponsor
I'm with you Kevin. Working in the shop is a joy, but, I only have time for my own projects.

As for the goal to have my Sunbeam brakes outlive my ability to drive. I would say the odds are in favor of the brakes regardless of what Puff4 magic I do to them.
 

puff4

Platinum Level Sponsor
I'm with you Kevin. Working in the shop is a joy, but, I only have time for my own projects.

As for the goal to have my Sunbeam brakes outlive my ability to drive. I would say the odds are in favor of the brakes regardless of what Puff4 magic I do to them.
Well, I’m trying to prepare each of my cars to outlive me, so that my sons - or whom ever gets them - will be able to enjoy them and not just warehouse them. Same with my boats.
 

JR66

Gold Level Sponsor
Kevin, thanks again for the info on red rubber grease. You suggested Demon Tweaks but they say they can't ship to my address in Massachusetts due to it being classified as a hazardous product. Maybe some BS Mass. regulation??? I ordered from Granville on eBay instead. Supposed to be here from UK by Sept 16. Keeping fingers crossed until they actually ship to my address! As far as I can tell it's only available from UK.
 
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