Teflon buttons

[harryset]

Any opinion on the use of teflon buttons vs snap rings for retaining the wrist pins? I've used them on my last three rebuilds, because they were trick, way back when.

[Dale M.]

I like them.... Keeps the "snap" ring (that is not there) from popping out and scoring cylinder wall....

Dale

[sideshow]

Buttons scare me, I would rather have rods that run true than have a button mask the signs something out of wack.

Stop clips weight less, trap less oil, don't wear groove in the side of the cylinder.

[Bugfuel]

unconfirmed rumors of buttons wearing and scuffing cylinder walls.
I use spiral locks. You know, the kind that are insanely hard to take out when you are TRYING to.

[Marc]

A motor built right, with a stiff enough crank to resist flexing and true rods, should never need buttons. The liabilities sideshow pointed out are real - I can attest to that based upon experience with low-budget race motors that were flogged beyond their capacity - but they're still preferable to the damage incurred when a clip fails. For a sensible combination that's at little risk of clip failure I'd go with the stock clips (or Spirollox if the application warranted the hassle) but if you're building a grenade the buttons have their place. One thing to look out for is too much wristpin endplay - if there's even a little to start with, they'll beat themselves in with high-RPM abuse. They should be tight enough on initial asembly that you can just rotate the wristpin - any looser and you should step up to longer ones, even if that means having to spend lots of elbow grease taking their length down on sandpaper 'til they just fit.
Long story short, don't use 'em unless you've got a damn good reason/excuse to.

[Bruce2]

Buttons scare me,

Wuss!

Stop clips weight less,

True

trap less oil,

Not if you drill holes in them like everyone does.

don't wear groove in the side of the cylinder.

Any wear from a teflon button comes from grit in your engine getting trapped or imbedded in the teflon. A proper filter, changed often prevents this. In this case, teflon isn't the cause.

[Turbo_Manx_Maniac]

Buttons weighs 9 times what a snap ring weighs. 1 gram vs 9, times eight buttons = 64 grams added to the ricprocating weight.

Who's really had a snap ring come out and do damage?

[Glenn]

Who's really had a snap ring come out and do damage?

I had a friend who's engine overheated. When I tore it down one of the stock wire snap rings was not to be found and the wrist pin wore a groove in the cylinder wall.

Just make sure you spin them to make sure they are seated and you'll never have a problem.

[Turbo_Manx_Maniac]

Who's really had a snap ring come out and do damage?

I had a friend who's engine overheated. When I tore it down one of the stock wire snap rings was not to be found and the wrist pin wore a groove in the cylinder wall.

Just make sure you spin them to make sure they are seated and you'll never have a problem.

Do you think the engine was assembled without the snap ring? Good point on spinning them, good habit to catch issues.

[Glenn]

Do you think the engine was assembled without the snap ring?

Can't say, but I never found it.

Besides the cylinder and piston being dead, the rod and crank were blue from being overheated.

Good point on spinning them, good habit to catch issues.

Yup... its a sure way to see if they are correctly seated.

[Bruce2]

Buttons weighs 9 times what a snap ring weighs. 1 gram vs 9, times eight buttons = 64 grams added to the ricprocating weight.

They don't weigh 9g when you drill holes in them.
Either way, 9g on top of the mass of the piston and wrist pin amounts to 2 tenths of F-all.

Who's really had a snap ring come out and do damage?

I had a clip come out of a NPR piston. Ground out a big groove in the cylinder, clip was pulverized and never found. No, I didn't forget to put it in.

[Turbo_Manx_Maniac]

Buttons weighs 9 times what a snap ring weighs. 1 gram vs 9, times eight buttons = 64 grams added to the ricprocating weight.

They don't weigh 9g when you drill holes in them.
Either way, 9g on top of the mass of the piston and wrist pin amounts to 2 tenths of F-all.

Who's really had a snap ring come out and do damage?

I had a clip come out of a NPR piston. Ground out a big groove in the cylinder, clip was pulverized and never found. No, I didn't forget to put it in.

Technically it's 18 grams, but who's counting...

In any case, I've never heard of a clip failing other than on the internet. Gotta imagine it's pretty rare and can be attributed to something other than the clip actually failing. BTW, I have always used the buttons, have them in both motors now, never a problem.

[perrib]

A snap ring makes a mess of the cylinder wall when it pops out. I have cylinders that have 40k miles with no wear from the teflon buttons.

[Bruce2]

I've never heard of a clip failing other than on the internet.

Since I told you about a clip falling out via the internet, does that mean you don't believe it happened?

[turboblue]

Who's really had a snap ring come out and do damage?

This engine was together for about a year then decided to push out a snap ring.
Customer had mail ordered it from a west coast "builder".