Howdy all,

I just rebuilt the front master cylinder on my 76 FLH and it now has a good firm brake lever. I ordered the Drag Specialties kit that matched up to Harley's part number 45063-72. The parts in the kit look like this:


Notice the piston cup in this kit is all rubber. When I looked at the parts I took out of the cylinder I noticed that the piston cup had a metal spring cup in it. It is circled in this drawing (number eighteen):



The brake seems to work fine now but I was wondering if not having that spring cup in there will cause problems down the road. As I search the web for 45063-72 rebuild kits about half of them have the spring cup in them and about half of them do not.

Does anyone have any knowledge about this scenario? It was a nightmare fighting that circlip to get everything back together again but if I have to go back in there I will.

Thanks again for all the help y'all have given so far.

 

Well Hoyt, you probably know the correct answer to that question ...

It might work for a long time, but that's not the way it came from the factory (for good reason) and you already have the Spring Cup


The kits that don't have it probably expect you to re-use your original part ... it's not really a "wearing" part, but probably could be a "corrodable" part

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super +1 mr. multi!

that cup prevents spring wear to the cup and is necessary. if you do not have one, use a stainless washer.

 

Thanks y'all. I didn't know if the little cup was built into the rubber seal or not. I'll see if I can get it back apart without putting my eye out or tearing up the seal.

I got to thinking I'd like to replace the big fender type washers on the plunger on either side of the wiper (part number 12) but can't seem to find them online. They have gotten concaved a bit over the years.

 

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Thanks Multi.

Do you know of a good online resource for part numbers for these older bikes? When I look around these days I can't seem to find much beyond the Evo years. I used to have tons of catalogs but I don't know where they all went to over the years.

 

Do you have a dealer close? Should be still available, but they may have to order.

Here's a 10-pack, but there will be "shipping"

6811W - $8.91



Depending on how bad they are ... I might try to flatten them as much as possible and probably flip them over

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go to a fastener shop and get a stainless one. all it does is hold the wiper packing in and acts as a shield.

 

Get the right part. It keeps the spring centered. If it shifts, forced will tend to let cup seal wobble. Just my opinion and common sense from 46 years of being a mechanical engineer in a nuclear ship and boatbuilding outfit.

 

I got to thinking about centering the spring myself after a bit. The spring cup I had taken out with the old seals was still in good shape so I took everything back apart and put it inside the new piston cup and reassembled. Seems to be working well.