What is a "piston expander"?

[nvonada]

Saw an e-Bay auction for "piston expanders" http://cgi.ebay.com/ebaymotors/NEW-P...ayphotohostingI was expecting a ring-installing tool but have no idea what these are. A quick google search was no help.

Thanks!
Nathan



_______________

http://stude.vonadatech.com

[53k]

quote:Originally posted by nvonada

Saw an e-Bay auction for "piston expanders" http://cgi.ebay.com/ebaymotors/NEW-P...ayphotohostingI was expecting a ring-installing tool but have no idea what these are. A quick google search was no help.

Sounds like "snake oil" to me. Shops used to knurl pistons to make them fit better in a slightly worn bore, but expanders...

Paul Johnson, Wild and Wonderful West Virginia
'53 Commander Starliner (since 1966)
'64 Daytona Wagonaire (original owner)
'64 Daytona Convertible (2006)
Museum R-4 engine
1962 Gravely Model L (Studebaker-Packard serial plate)
1972 Gravely Model 430 (Studebaker name plate, Studebaker Onan engine)

[Dwain G.]

They are spring steel inserts that snap into place inside a piston to exert pressure outward on the skirt area. This was a common item used to control piston 'slap' back in a time when labor cost was so small compared to new parts.

[img][img]
Dwain G.

[Mike Van Veghten]

Yea...it WAS an inexpensive/CHEAP, way of gaining a few thousands of extra diameter on a worn "system".
Bore a couple too big, piston worn a couple too small, expand the skirts .003" or .004".

Another way was to knurl the pistons to gain .002" or .003".

Either way was a temporary fix at best...after a coupla thousand miles...things were pushed or worn back to where they started.

Mike

[PlainBrownR2]

Interesting item though for that small space on the garage display shelf for the memorabilia aficionado

[img=left]http://i158.photobucket.com/albums/t102/PlainBrownR2/My%201950%202r5%20Studebaker%20Pickup%20with%20turbocharger/P1000137-1.jpg[/img=left][img=left]http://i158.photobucket.com/albums/t102/PlainBrownR2/My%201950%202r5%20Studebaker%20Pickup%20with%20turbocharger/P1000145-1.jpg[/img=left][IMG=right]http://i158.photobucket.com/albums/t102/PlainBrownR2/Ex%20Studebaker%20Plant%20Locomotive/P1000578-1.jpg[/IMG=right]
[IMG=right]http://i158.photobucket.com/albums/t102/PlainBrownR2/My%201964%20Studebaker%20Commander%20R2/P1010168.jpg[/IMG=right]

[jackb]

When I 1st got my 64' ragtop, 2 pistons were stuck....after honing the rebuilder suggested expanders for what I described was for "occasional use".....60K miles later the block needed a .040 overbore......

[Flashback]

Piston expanders came packaged with a bottle
of doctor feelgoods snake oil and miracle cure
tonic. Ever seen the thick pads to put under the
valve covers to "cure" no oil to the rocker arms?
Same type hype.

Tex E. Grier

[buddymander]

Who needs piston expanders or knurling? Heck, alls ya gotta do is lay that skirt up on a bar of steel and smack it about fifty times with the pick end of a body hammer. Then, if it's too big to fit back in the bore ya takes yer file and cut'er back down.

[Kdancy]

An oxy acetylene torch ?

[Dan Timberlake]

The expander manufacturer is Thexton.
Wonder if it's the same outfit around today.

http://thexton.com/index.cfm/pageid/1

They have some interesting tools on the "limited inventory page" and in their catalog.

http://thexton.com/media/content/Thexton_Catalog_17.pdf

A batch of years ago they were famous for a product called "thextonite".
Kind of like JB Weld today.
Or maybe Thextonite was made up, since thexton's own search engine came back "Sorry, no results found for: thextonite". Google just found one refence to it. And, the shop conversations I heard about its use could be counted on to end with racy one-liners with the auto tech bemoaning the fact there would be no Thextonite.

[buddymander]

The real problem with knurling is that the machinist usually only knurls up to the size needed. THe problem is that that leaves only a few high spots that wear down quickly. Knurl about .010 beyond what's needed and and then shave the skirt down; leaving lager areas of the proper size. I've done it. It works. The real problem with piston fit is at the top of the bore. You have to have ring end clearance to prevent binding in the smallest part of the bore, which is near the bottom. THe bore wears at the top, and tapers inward downward. So--with the needed clearance at the bottom; a large gap is created at the top where the ring opens up. THis wears out the grooves at an exponentially faster rate; but what the heck, the pistons are junk anyway.

[raprice]

I thought you were talking about a ring expander. THAT I can believe.
Rog

'59 Lark VI Regal Hardtop
Smithtown,NY

[JBody]

All these Ideas for rebuilding a "motor" are great, but I got a high tech one. Take your pistons, and drill numerous holes halfway through the skirt on the thrust side. Then, take pieces of Teflon dowel, and cut off enough to stick out of the hole in the skirt, toward the cylinder wall. Carefully fit the piston to the cylinder, sanding down the excess teflon so it will barely fit, and you won't have any piston knock! I figure if you only drive your car in parades, that it should last awhile.

[Flashback]

The teflon idea is what we used to call "buttons"
in race engines. Very much similar to what you are
saying. Keep it loose. If my drag car didn't smoke
I loosened it up a little more. A lot of what we are
talking about are cures from the 30's thru. the 50's
Or should I say "patches". Not our high tech. world
of today. Relics of a bygone era. "back in the day"

Tex E. Grier

[ChampTrucking]

LOL the only "piston expander" I have ever seen work is Nitrous Oxide!! Sometimes works too well.Tach it up and hit the button====WAAAAAAAA-BOOM!! CLUNK CLUNK(insert smoke-oil show here!!)