Wrist pin buttons

[exeric]

I made aluminum wrist pin buttons or my '51FL. They are a finger press fit in the wrist pin hole, however I am second guessing, (over thinking), hand wringing if this is the right way to go. I do have a lump on Teflon, but . . . I don't know. Opinions from the more experienced are welcomed. Sorry to break up the oil debate above.

piston button.jpg

[T. Cotten]

A better idea, Eric,..

PEEK has better temperature and tensile characteristics than teflon, and it won't embed as many abrasive particles to scrape up your cylinder walls.

Others have used it for buttons, and you can too!

(Twentyfivecents a gram, I'll have plenty at D-port...)
PEEKscrap.jpg

....Cotten

[exeric]

Thank you, Tom. I have some PEEK and the qualities you stated sound better than aluminum, and teflon. I'm not crazy about doing the job over, but PEEK could assure me of a good night's sleep. Your price on PEEK is very good and people should take advantage of it at Davenport. The sizes you have are perfect for seals, and washers.

[T. Cotten]

Thank you, Tom. I have some PEEK and the qualities you stated sound better than aluminum, and teflon. I'm not crazy about doing the job over, but PEEK could assure me of a good night's sleep. Your price on PEEK is very good and people should take advantage of it at Davenport. The sizes you have are perfect for seals, and washers.

If you had PEEK already, Eric,... .. .

(Nevermind.)

Do you have a radius-cutting toolpost?

I had to make mine, its simple!
RADPOST1.jpg


....Cotten

[tfburke3]

CUrious what the concern is.Does your model pin circlips become dislodged?
Tom

[exeric]

I thought the preferred material was aluminum based on some ancient advice I recalled. PEEK is the way to go. I did make a radius tool post from a print I found on the internet. I needed to make a brass sphere that would be used has part of an antique plumbing system for a friend. My first mistake was consenting to do that for my friend and I think we have all been there. Too much work, and material for a simple, 'thank you. . . And, he added, "I could really use 2 of those."

lumpa.JPG

[T. Cotten]

The problem with ancient button advice, Eric,...

Is that it was always racers: They tore down constantly anyway!

Nobody put thousands of miles of them, although I think I have a Knuck still out there with teflon from the late '80s.

....Cotten

[exeric]

CUrious what the concern is.Does your model pin circlips become dislodged?
Tom

As I said, I have no experience with wrist pin buttons but they were recommended by a talented H-D, & Indian motor builder. He had seen cylinders ruined by clips that came loose, or had broken, and I have an Excelsior cylinder that is deeply scored by a wrist pin clip that failed. Most of this is academic as I'm sure cylinder damage from wrist pin clips is very rare. Just thought I would throw this out there as I am putting new pistons in my motor right now. Oh yeah, and I love making parts on my lathe.

[T. Cotten]

... Most of this is academic as I'm sure cylinder damage from wrist pin clips is very rare......

Not that rare, Eric!

I threw a clip myself.

The culprit is usually a tired crank.

Fresh rods and mains is better than buttons...

....Cotten

[exeric]

Worn out crank, and rods make a lot of sense, Tom.

[dukekleman]

Eric,
My experience is:
A) Cylinders that are bored and honed incorrectly, along with head gasket and base gasket surfaces machine crooked (if you will) are causes for the wrist pin circlip failure.
B) Crankcases which have deck irregularities or centerline issues will also cause a wrist pin circlip failure.
C) Connecting Rod issues will also cause wrist pin circlip failure. The Most common parallelism issue I see in the Connecting rods is after someone has put in new wrist pin bushings...
Bottom line is it comes down to things being perfectly "Square" and "Parallel".
If they aren't, the angular thrust pushes on the wrist pin and circlip until it comes out.

When I used buttons, I always used Teflon on our performance street and race motors. I've seen them wear over time but never fail or cause any problems.
I have seen material, a couple of times, embedded in the Teflon button . This contamination material was coming from failing parts within the engine so it was irrelevant as being an issue with Teflon.
There again, wrist pin buttons are like a little insurance policy in case things aren't parallel and square. If they aren't and you use buttons, you'll pick up the particles in your oil sample test


Hope this helps,
Duke Kleman

[exeric]

Thanks, Duke. Everything you, and Tom said about squareness, parallelism, and perpendicularity of bottom end components, and cylinders makes a lot of sense. Things are in good shape with my motor, but I'll take the time to verify the rods are not bent. . . If they are bent, that will be my follow-up post

[T. Cotten]

...I'll take the time to verify the rods are not bent. . . If they are bent, that will be my follow-up post

Are they assembled, Eric?

How you gonna check 'em?

I'm certain there's a way...
deckchek.jpg
Straightening is a different thing.

....Cotten

[exeric]

I recall a procedure in a H-D manual using the piston skirt, with feeler gauges on a factory rod straightening fixture plate. That didn't sound like a great way to do it, but I do like the picture you posted of using parallels on the cylinder deck, Tom. I've been thinking about this today, but I'm not thrilled with my own ideas at this point. For every idea I have, I come up with 5 problems . . . Well, better than thinking about politics.