Drum Brake Wheel Cylinder Evaluation

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Dennis Vogel
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Drum Brake Wheel Cylinder Evaluation

#1 Post by Dennis Vogel »

How do you evaluate if a drum brake wheel cylinder is good enough to rebuild and reuse? The factory workshop manual basically says tear it apart, inspect for wear and damage, reassemble.

It seems like master cylinder rebuild kits are readily available from the usual vendors, but not so much for the wheel cylinders. They only seem to want to sell new replacement cylinders. The only exception I've found in the US is Parksklassic.

If I rebuild them, is there anyway to test if I've been successful short of installing them on the car and testing the entire braking system? :?:

The car has been sitting for over 20 years, so I'm planning to replace all the rubber and springs. Anything else I can safely salvage I will for originality and personal satisfaction.
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Bruce Smith
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Re: Drum Brake Wheel Cylinder Evaluation

#2 Post by Bruce Smith »

Dennis - Here's an article I wrote for the magazine last year. I think it has your answers. - Bruce

http://www.sparkingplugs.com/resources/ ... 282$29.pdf
http://www.sparkingplugs.com/3.html
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Re: Drum Brake Wheel Cylinder Evaluation

#3 Post by Don Gale »

The 356 repair kit with new cups and boots is 644.351.912.01 and Stoddards lists them. The VW kit also has new pistons, p/n 113.698.273 available on ebay. Excellent write-up Bruce. The Porsche service manual doesn't list a tolerance for the piston to cylinder clearance but Elfrink does, 0.002-.004" and to replace them if honing pits takes them beyond that. The fronts and rears are the same. $225 to $250 for a set of 6 new complete cyls from numerous vendors.
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Jim Liberty
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Re: Drum Brake Wheel Cylinder Evaluation

#4 Post by Jim Liberty »

I go for the ATEs on all my restorations. Only two things count 1.) steering 2.) stopping. .............Jim.
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Re: Drum Brake Wheel Cylinder Evaluation

#5 Post by Wes Bender »

When you put the new ones/refurbished ones back on, pay particular attention to the direction the star wheels face. Installing one or more backwards will give you little to no braking on that particular wheel.
Some days it's just not worth chewing through the restraints.....

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Re: Drum Brake Wheel Cylinder Evaluation

#6 Post by Jim Liberty »

How do WE know about this Wes. ...........Jim.
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Harlan Halsey
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Re: Drum Brake Wheel Cylinder Evaluation

#7 Post by Harlan Halsey »

It is cheap and therefore fashionable to replace brake cylinders these days. But it wasn't always so. Brake cylinders corrode much more than they wear, and I noted that the corrosion pitting was usually at the bottom and at the edge of the cup stop. The rest of the cylinder was usually OK. A cylinder could often be saved by shortening the piston so that the cup travel didn't include the pit. Alternativly, White Post would sleeve the castings in brass cheaper than new cylinders. Sometimes it is better to understand the problem rather than throwing new parts at it.
I solved the corrosion problem years ago by going to silicone brake fluid. At least I think I did: In 1974 I completely renewed the brake system of my Convertible D. I have never since had a leak, nor have I added any brake fluid. The car has covered may be 30,000 miles since then, but I have never had occasion to disassemble a cylinder and asses its condition.

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Joris Koning
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Re: Drum Brake Wheel Cylinder Evaluation

#8 Post by Joris Koning »

I have hears some rumor about the non ATE branded new cylinders sometimes having issues. Is this correct?
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Dennis Vogel
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Re: Drum Brake Wheel Cylinder Evaluation

#9 Post by Dennis Vogel »

Bruce Smith wrote: Sat Nov 26, 2022 1:36 pm Dennis - Here's an article I wrote for the magazine last year. I think it has your answers. - Bruce

http://www.sparkingplugs.com/resources/ ... 282$29.pdf
http://www.sparkingplugs.com/3.html
Thanks so much Bruce. That is exactly what I was looking for. I searched through the Registry Technical Library, but didn't see it.
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Re: Drum Brake Wheel Cylinder Evaluation

#10 Post by Martin Benade »

I’ve had a set of the cheaper wheel cylinders for about 11 years with no problems.
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Re: Drum Brake Wheel Cylinder Evaluation

#11 Post by Jim Liberty »

I have had problems with the cheap wheel cylinders also. When they are faulty "Out of the box" I'm finished. Harlan, I switched to silicone fluid decades ago. Never had a problem. At first I feared dripping fluid on my paint, being the klutz I am. ..................Jim.
PS. Please tell everyone to look at BaT. My Glaser is on it now. "Baby needs new shoes".
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Re: Drum Brake Wheel Cylinder Evaluation

#12 Post by Dennis Vogel »

I can't be sure that they were original, but the rears are toast either way. One had the zirk fitting snap off. Then my removal tool snapped off inside of it. For the other side, the cylinder has a sizable crack in the lip. Hopefully I'll have better luck with the front.
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Re: Drum Brake Wheel Cylinder Evaluation

#13 Post by Wes Bender »

These's a limit as to how far gone they can be before you try to bring them back. From the looks of those, buy new all the way around. Jim Liberty has it right. You can't take chances with brakes or steering.
Some days it's just not worth chewing through the restraints.....

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Re: Drum Brake Wheel Cylinder Evaluation

#14 Post by Brian R Adams »

>> Only two things count 1.) steering 2.) stopping. ..... Jim

And for me, not necessarily in that order.
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Welcome to the era of policy-based evidence-making.

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Re: Drum Brake Wheel Cylinder Evaluation

#15 Post by Al Zim »

Throw all your brake stuff away!!!!!! Including all the metal and rubber lines. Also replace the master cylinder with a dual stage master cylinder which were mandatory on all cars/trucks manufactured after 1967. Pay someone to help you on the installation. ZIMZ NEVER REBUILDS MASTERCYLINDERS!!! Zim
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