1974 TX650 Front Caliper Dragging/Locking Up

[kopcicle]

Okay, after a cup of coffee and a kick to the head...

One ) if the stock lever adjustment screw is buried in the lever up to the lock nut or the lock nut is missing then under some curious design and manufacturing tolerances the relief port will never uncover.
Two ) Someone please measure that damn piston with something a bit more accurate than a yardstick.
Years ago I eradicated all vestiges of the cast iron menace MamaYama called a front brake. I'll only accept rebuilds/restorations with NEW pistons and the understanding that NONE of the original finish will remain. Short story is I have none of these parts remaining here.
Three ) I may have an extremely low cost alternative for the pieces of cubic dollars otherwise called a caliper rebuild kit.

 

[Thedawkter]

Well everyone, you seemed to have solved it. I pulled them apart, pulled the rubber seals out, and tried to slide the piston in. No go. Grabbed the old one, and it fell right in.

Took some measurements with the Vernier Calipers, and the new pistons came in at 1.8915 inches, where as the old ones measured 1.8900 inches.

Not much, but obviously enough to create an issue. I am going to try and clean all of the brake fluid that is now on pretty much everything in my garage, and then try and get it back together with the old pistons. The new rubber seemed fine, I did not see any noticeable issues with that.

I find this quite frustrating because I replaced these parts to ensure that i did not have any fitment issues.

Thank you all for your help, I will let you know how it reassembles.

 

[Thedawkter]

Okay, after a cup of coffee and a kick to the head...

One ) if the stock lever adjustment screw is buried in the lever up to the lock nut or the lock nut is missing then under some curious design and manufacturing tolerances the relief port will never uncover.
Two ) Someone please measure that damn piston with something a bit more accurate than a yardstick.
Years ago I eradicated all vestiges of the cast iron menace MamaYama called a front brake. I'll only accept rebuilds/restorations with NEW pistons and the understanding that NONE of the original finish will remain. Short story is I have none of these parts remaining here.
Three ) I may have an extremely low cost alternative for the pieces of cubic dollars otherwise called a caliper rebuild kit.

I checked the lever adjustment and made sure the piston in the master cylinder was completely retracting, so we are good there.

I measured the pistons, which seemed to be the problem, write up was in my next post. The new pistons seemed to be the problem.

It seems as though my rebuild kit is okay, the rubber pieces that is, but I am always open to better alternatives!!

 

[Jim]

but I am always open to better alternatives!!

I like K&L rebuild kits. You can usually find 'em on Ebay.

 

[Thedawkter]

I like K&L rebuild kits. You can usually find 'em on Ebay.

Should I be avoiding Mikesxs? I’ve had some issues in the past but chalked it up to variations in model years, but this piston situation has me pretty frustrated. No real excuse as to why this were not correct.

I will check out those rebuild kits, I’m rebuilding a 1980 front brake and will be needing parts for that as well.

 

[gggGary]

It's kinda a "thing" for me that I always drop in the pistons before installing the seal. Prolly cuz there was a life lesson a lot like yours back sumwhere's in the mists of time..

 

[Thedawkter]

It's kinda a "thing" for me that I always drop in the pistons before installing the seal. Prolly cuz there was a life lesson a lot like yours back sumwhere's in the mists of time..

It has been learned. I’ve always equated new with tight, and since it went in with some force I figured that’s how it was. The old ones were corroded, so they didn’t come out easy and were hard to compare to. They cleaned up though.

 

[Jim]

Should I be avoiding Mikesxs?

Just speaking for myself, I treat Mikes as the source of last resort. And by last I mean I'll look for used on Ebay before I resort to Mikes.

I will check out those rebuild kits, I’m rebuilding a 1980 front brake and will be needing parts for that as well.

I've rebuilt 3 calipers and 2 masters off an 80 using the K&L kits. Nary a problem with any of 'em.

 

[GLJ]

Something I learned the hard way a long time ago.
"Just because it's new doesn't mean it's good."

 

[Thedawkter]

SOLVED. Thanks everyone. It was the oversized/incorrect pistons that just were not letting them retract quite enough. 0.0015" was probably the perfect amount off to let it fit in, but not quite move properly.

Got it rebuild and it is free like it should be, and stopping the wheel like it should be. Again, very much appreciative of everyones input.

 

[Mailman]

Congratulations! That one was a challenging puzzle.