Anyone still using nylon buttons to retain piston pins?

[PackardV8]

Back in the bad old days, it was common to use nylon or other composite buttons at each end of the piston pin. With the improvement of spiroloks, truarcs and others, it's not seen as much. In fact, the last I saw was some years back in a nailhead Buick.



I've got an obsolete engine application which could use an OEM Chevy piston which does not have snap ring grooves in a Packard rod which uses a bushing. Of course, one could machine snap ring grooves in the Chevy piston, but the idea occurred that buttons might work as well.

Your thoughts?

[statsystems]

I've run buttons on crap I had to pull apart a bunch. A bit heavier but MUCH easier to deal with on an engine that requires frequent maintinence.

I don't really see a problem except for a bit more weight.

[Keith Morganstein]

Teflon buttons are still used in various applications. Popular with VW builders, motorcycle and others. They can last a long time, I say go for it.

Teflon not plastic. I know someone who had buttons made of nylon or Delrin for his V-Twin. It was a disaster as they melted.

[modok]

It works ok when the piston is full round where the pin goes, and the pin is LONG.

Most pistons these days are slipper skirt, or have at least flat sides, pins are short, so the bushings make no sense at all.

[63qcar]

Used them all the time on my VW race engines ( mini stock ) and I turned right at 6500 rpm . Also used them on my E/P Porsche Speedster in SCCA with no problems .Reused them many times .... sometimes ignorance is bliss !

[DCal]

The main issue is that they will spin as the assembly travels up and down the block bore if the wristpin bore is not centered in the piston. That will quickly kill them if you're using aluminum buttons. I don't think Teflon likes it either. The other thing to check is that the total length of the two buttons and the pin together is about .020 less than the cylinder bore.

[CharlieB53]

I can see the weight issue as the only buttons I've seen are solid pieces. But why not drill them? No reason I can see that they must be solid.

[pamotorman]

if this is a car where there would not be a lot of miles per year i would do it.

[PackardV8]

Thanks for all the replies and the reminder the material should be teflon.

It may be moot, because most of the pistons which used this old tech were the full-round-barrel shapes, where the pin bore opening is near the cylinder wall. The pistons I was considering using are a semi-slipper skirt with maybe just too much space between the pin bore and the cylinder.

So how much teflon hanging out there would be too much? Maybe be less expensive to go with custom forgings than find out the pin button experiment didn't work.

FWIW, I've also figured out two different methods of cutting snap ring grooves if it comes to that.

[Dave Koehler]

I still use alum buttons. nitrous or blown. Stuff that needs to come apart often.
Needs a straight wall pin to work or a modified tapered pin.
They are of the top hat style. Hollow and with a generous OD radius where they contact the wall.

[pamotorman]

Thanks for all the replies and the reminder the material should be teflon.

It may be moot, because most of the pistons which used this old tech were the full-round-barrel shapes, where the pin bore opening is near the cylinder wall. The pistons I was considering using are a semi-slipper skirt with maybe just too much space between the pin bore and the cylinder.

So how much teflon hanging out there would be too much? Maybe be less expensive to go with custom forgings than find out the pin button experiment didn't work.

FWIW, I've also figured out two different methods of cutting snap ring grooves if it comes to that.

i have machined lots of pistons for spiral locks and even double ones. just make a expanding mandrel to hold the piston in a lathe. i made this jig to check the spacing for cutting the pin lengths

[Mark O'Neal]

Does anyone make pins with button registers anymore?

[Mark O'Neal]

Thanks for all the replies and the reminder the material should be teflon.

It may be moot, because most of the pistons which used this old tech were the full-round-barrel shapes, where the pin bore opening is near the cylinder wall. The pistons I was considering using are a semi-slipper skirt with maybe just too much space between the pin bore and the cylinder.

So how much teflon hanging out there would be too much? Maybe be less expensive to go with custom forgings than find out the pin button experiment didn't work.

FWIW, I've also figured out two different methods of cutting snap ring grooves if it comes to that.

We also made the piston with support for the buttons.

[Dutchman]

Nylatron is what we used ,drill a .250 hole in the center. Pressure builds up in the pin and scuffs the walls.
Stopped with the holes. .010-.020 less than bore worked well. Air cooled m/c application.

[hoodeng]

I built a 69 Genny Shovel for myself in 77 ,just married no money build , i cam ground some old pistons to suit the bores ,the pistons had damaged retainer grooves so i put bronze buttons in the pins ,i lived on that thing as i was working in the bush at that time and it was the comuter rain or shine. I found some pins that were longer than the stockys and had a parallel bore so the buttons were quite short although these pistons had a full round skirt.
I have made Ertalon buttons in the past ,but mainly aluminium for customers that insist on buttons , Its a hangover from the days when a Shovel head could kick a clip out and groove the bore ,the main reason they did this was due to out of true crankshafts that were quite common when people discovered impact wrenches to tighten compensators .
In the application you have ,can you get a longer parallel bore pin and run buttons in them? but the overhang of button on the end of the pin will need to be minimal . Your option of grooving the piston pin bores looks to be optimal for the bit of extra effort.
I found one of the old pins from the past! as you can see there is virtually no wear on the button.

Cheers.