Installing Rings On Small Pistons?

[SteveSr]

Hello,

I have a small 34mm diameter piston that that I will need to put a new ring on. Are there any good/recommended techniques for doing this to minimize the risk of breaking the ring? For larger pistons I have seen start at the pin and work your way around. Does this technique still hold for small diameter pistons.

Thanks,
Steve

 

[ericm979]

If you start at the pin and work around (by hand) you stand a good chance of twisting the ring.That will make it not seal as well. A ring spreader will open the ring up enough to let it slip on without twisting it.

 

[Mad Professor]

I still use my fingernails. Get the ring onto the piston then work it down to the groove evenly.

You can buy cheap expanders ($3.50)

https://www.autozone.com/test-scan-...ol/p/oemtools-piston-ring-expander/532267_0_0
Or expensive ones ($65.00)

https://www.mcmaster.com/6674A11/

 

[SteveSr]

If you start at the pin and work around (by hand) you stand a good chance of twisting the ring.That will make it not seal as well. A ring spreader will open the ring up enough to let it slip on without twisting it.

Does this hold for the cast rings that are in our engines? I saw one video where a guy twisted a ring and it just bent and never broke.

 

[ballisticdoughnut]

Steel rings will bend, cast rings don’t really bend and give no warning before they break. Having said that, I’ve never damaged a ring by expanding and sliding it over the piston.

 

[SteveSr]

I still use my fingernails. Get the ring onto the piston then work it down to the groove evenly.

It looks like this is what I am leaning towards

You can buy cheap expanders ($3.50)

https://www.autozone.com/test-scan-...ol/p/oemtools-piston-ring-expander/532267_0_0

These are recognizable.

Or expensive ones ($65.00)

https://www.mcmaster.com/6674A11/

These not so much... Looks like an alien contraption of some sort.

 

[SteveSr]

Steel rings will bend, cast rings don’t really bend and give no warning before they break. Having said that, I’ve never damaged a ring by expanding and sliding it over the piston.

Good to know. Just get it on right side up the first time!

 

[Mad Professor]

It looks like this is what I am leaning towards


These are recognizable.


These not so much... Looks like an alien contraption of some sort.

Those are designed to spread the whole ring, it grabs the circumference, not just grab it at the gap/ends.

 

[stihltech]

Fingers and work it into the groove only expanding enough to get it into the groove. Have not broken or twsited one in 40+ years. Take your time.

 

[pioneerguy600]

A simple little tool that can make ring install easy for those like myself with big thick fingers but usually most times I still just use what fingernails I have left to get them on and off.

 

[Chevboy0167]

I got 2 of these off of eBay. Works well.

 

[Evan]

I had to shake my head as i realized these guys are buying a tool to put rings on a chainsaw piston.

 

[DougMN]

The ring I ever broke was using a ring expander!

 

[Backyard Lumberjack]

Fingers and work it into the groove only expanding enough to get it into the groove. Have not broken or twsited one in 40+ years. Take your time.

The ring I ever broke was using a ring expander!

i have done piston ring installs both ways. i like an expander best. i had a modded engine, Harley, and when time to slip jug down on pistons, had to ring them first. i had a hot-shot Harley wrench, worked at a local Harley engine shop/store helping me. i said, used the expander, here! he said no, i can do it by hand just fine!! well, it blew oil out oil on first start up like a pig! researched it, tore it back down.. (as i knew it should not be smoking!!) and suspected his hand job!! and sure enuff... the hot-shot mech had bent an oil control ring! i was a bit other side of pii**ed! i dry fitted the rings to the bore one day, and sure enuff... daylight! that eve he stopped by, we can use a light to see the ring and bore. i said no need to i already did it and u bent the &^%* ring! we din't get on too well that evening...

it got reringed and no more oil smoke!

 

[Lightning Performance]

On small pistons you can cover the piston with a plastic bottle. Think of it as a wrapper. If you shrink it on you have to peal it off. Put your ring around it first. I use them for putting in seals on pistons for hydraulic cylinders or caps on the ram with poorly finish end. Works the same with steel rings and no scratches on the piston or broken fingernails.