@ Gage Werke Composites = according the fiche finder there is no spring so know idea why the PO put a spring in there... *throws it over the shoulder*
Steps taken to find the cause:
1. Determine if Master Cylinder was properly functioning. It is.
2. Determine if line was ruined. It was not.
3. Determine if groove that seal fits into was dirty. It was thoroughly clean.
4. Determine if Seal was bad. It was not, brand new seal, fro the right caliper.
5. Determine if piston integrity was compromised. It is not
6. Determine if piston was pushing & retracting. It is.
What has caused the problem(with pictures):
The 76 CB750K calipers pistons are topped with a rounded cap which extends the length of the piston unlike surrounding year models which utilize a flat top that pops into the piston not changing the length. It seems, over the years the pad portion of the calipers walls become significantly worn, presumably due to combinations of typical wear such as heat, abuse, 20 years of use, etc.. Over time this wear results a very rough and scarred wall which causes the pad to catch as it is pushed out. It seems extending from the "pad screw slot" some sort of groove is present, whether this is supposed to be there or not I'm not exactly sure as it looks to even at the beginning point not to be.
This may be inaccurate as i have not seen a brand new 1976 brake caliper. Either way if you look at the picture( figure 2 ) you can see what I'm talking about. There seems to have been a raised edge or something there that dissipates as it moves towards the side opposite of the screw guide.
I feel that the combination of the irregularities and scarring on the walls along with the domed cap of the piston result in the pad becoming slanted during bleeding or use. By slanted, I'm talking a very minimal, maybe ~ 1/50" of an inch (guesstimate, no actual measurements were taken). This angle cause the pad to bind on the caliper wall, not allowing the pad to retract with the piston. The bind is not self fixing by excessive bleeding, in this case.
I drew a cross-section(quite terribly though) of what i am talking about.
FIGURE 1
*i apologize in advance to the engineers for the terribly done drawing, 5mins in paint*
Also attached is a picture showing the damaged wall.
FIGURE 2
I would conclude that these are possible solutions:
1. removal of the rounded cap will solve some of the movement problems because the piston will push on a large amount of area, more importantly flat, and wider diameter than the rounded cap does
2. The inside wall must be smoothed and polished, only to the point that it does not create a significantly large Diameter
or...
3. Throw the sucker in the trash and get a new housing
Whatever this case maybe, I would say its extremely important to inspect the inside walls of the pad are to make sure it is not scared. I don't think anyone wants the pad to lock on you when your doing the TON!!!!
Please, any feed back would be great
The one and only,
dixiedevil
P.S. : that was a lot to say and I'm really tired, if something doesn't make sense point it out and i will look at it in the a.m.
