I rebuilt my front wheel cylinders in 1997 with 'Wagner' rebuild kits from a local parts store. Started experiencing brake pull this year(after ~1500 miles max)- pulled apart the wheel cylinders and found rusty oil residue outboard of piston between the piston and the rubber boot. The internal brake fluid in the wheel cylinder is not rusty, it is clean and clear. The residue was in both RH and LH cylinders both from and rear ends of cylinders. Examining my 63 shop manual I noticed that section 5.8 shows an 'expander' behind the piston cup (seal). My rebuild kit did not contain this part. Is it needed? Is its absence the reason that I had the rusty residue. Was the purpose of the expander to prevent fluid leakage past the seal under no presure or high pressure? Thanks for you help.
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Re: 63 front brake wheel cylinder rebuild
Looking at the expanded view on page 5-8 of the '63 Shop Manual, the "expander" appears to be a steel spring seat - similar to the valve spring seats used on aluminum heads. This to prevent the spring end from galling the aluminum piston. Could be that the spring end in you kits was designed to seat against the pistons without the need for a dedicated seat, however, you shoulds check with the Wagner to ensure that the kits were complete! Also check to see if the spring end has galled the pistons.
The "oily residue" you refer to is likely brake fluid. No hydraulic seal is perfect and some brake fluid migrates past the seal with use. It can then absorb moisture and corrode the bore even though this area is protected by the rubber dust boot.
Since wheel cylinders are readily available and inexpensive, my recommendation on drum brake rebuilds is to buy new wheel cylinders, especially if you plan on keeping the car a long time. You never know if a rebuilt cylinder is perfectly round and smooth after honing, so they can end up seeping more than a new factory honed wheel cylinder, which is likely to be rounder, smoother, and straighter with the bore diameter closer to nominal blueprint dimension than what you could achieve in the field by a quick honing.
Like knurling valve guides, honing an rebuilding wheel cylinders is okay as a quickie fix to get the car servicable, but's it's not a good way to go for a keeper car.
Duke -
Re: 63 front brake wheel cylinder rebuild
Just for the record in case someone else has this same question - I found the answer: The rebuild kit (Wagner # F-33159) specifies that the piston return spring is designed to act as an expander, therefore the expander ring should NOT be used with the rebuild kit. ThanksComment
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