Odd brake issue

Hello all,

My Maxim has an unknown Seca front end but it appears to be the kind of brakes which have the mounting block and pivot pin and it is giving me a hard time.

The brakes make a knocking/rattle somewhat regularly but not all the time. I have inspected them and whilst I am holding off on a rebuild to fully freeup the piston I noticed the front right caliper has a lot of play between the caliper and the mounting block makes the same knocking noise when I wiggle it around.

I plan on pulling it apart tomorrow but can anyone tell me if there is a bushing or sleeve that wears down or is it likely the pin/block themselves that has worn out of proper diameter?

I also noticed there is a shim between the block and the caliper which is very loose and just seems to be sitting there where as the left side is firmly clipped on. Can it wear out and cause this?

Thanks
Dave

 

Can you post some pics?

 

Took it apart today and there is a lot of slop at the pivot pin but I also noticed I was missing a shim so I fab'd a new one from a beer can and it seemed to help though the joint is still loose.

See the pin at the end of the arrow is the joint that is sloppy and the second arrow is showing the excess play between the caliper and the mounting block. The shim helps to close this gap which I did but unless the shim on one side is ok to be much thicker than the other it seems to be worn on either the pin or the hole the pin goes through.



Thanks
Dave

 

That is what we call a "holding block" style caliper, and they appear (with some variation) on the 550s, 750 Secas and 1100s.

I'll give you a little "tech briefing" as soon as I have a free second to do some serious typing and upload a couple of additional pics. Bending the shim plate isn't a good idea.

Here's a "corrected" (the fiche is sadly lacking) exploded view:

 

I look forward to the tech briefing though I only bent the shim plate back to match the otherside and enough to hold it onto the holding block.

There is a part missing from your "corrected" fiche (at least when compared to my bike) which is a small shim between the holding block and the shim plate. I found one on the left (good) side and it was missing on the right (bad) side. So I cut up a beer can which was a very similar metal and thickness to the shim I found on the left side in order to fabricate a shim for the right side which helped close up the gap between the caliper body and the holding block.

The joint does however still have a lot of play in all directions so I was hoping that the boots or the holding block would have some sort of sleeve or that the pin would be made of a softer material which would have worn down but I am starting to believe that the port in the holding block which the pin slides through is worn out and giving me my slop.

So I will see if your tech briefing may answer my question but I mainly want to know if I put more shims between the holding block and the shim plate to take the slop out of the joint will it harm anything as it is still very loose.

 

Sounds technical tech briefing lol. Listen to fitz he won't steer you wrong

 

Oh yes, I remember fitz from my old time on the site. (have had 3 maxims in history but went the last 2 years without a Maxim) and I know with him saying it is a shared part with the 550's means he is the best man to be helping me with the issue.

 

PM sent. It's not a 750 Maxim front end with that caliper, at least not USA-market. Two discs or only one? Anti-dive?

 

It's a Seca front end. Dual disc, with anti-dive.
PO switched it so I don't know year or model it came from.

See my other thread to identify the front end