Wrist pin bearings

[Burke Kilgour]

What are the tricks for assembling and pressing the wrist pins into the pistons without a big headache?
My plan was to make a tapered guide that fits into the end of the wrist pin to keep the bearings from falling in. My merc book suggests something similar, but with a fancy merc part number stamped on the tool.
I've never done this before with the "loose" bearings........many, many, times on a "normal" 2-strokes with the bearing cages and hand pressed wrist pins.
It seems like a pain in the a##, or is it not as difficult as I'm picturing in my head? :confused: :confused:

PS-2.4 bottom guided, if it makes a difference........

[CompKing]

I use the Merc tool and it works great.

[TTriton]

Take a OLD wrist pin and anything that can cut it.. I used a chop saw.. Then cut a chunk off the length of the top end of the rod.. About 3/4 of an inch. Debur the end and presto you have a mercury tool. I also use the other longer end left over for setting the c-clips in my c-clip instalation tool which I did buy from Mercury.

[Burke Kilgour]

I do have a bunch of old wrist-pins lying around, thanks!!
What do you think about sanding and polishing the tool a bit in a lathe to make it slide out easier? or does the press fit of the tool help when assembling?

[TTriton]

It wouldn't hert but I would only take it down a little bit.. But I have never had any problems with it.. If you heat the piston then it just slides right out. If you don't use heat and use a press then you won't have any problems there eaither. Just make sure that you deburr the tool or chamfer the end to make sure that it doesn't get hooked.

[Burke Kilgour]

Hmmmmm....... I was just going through my pins and noticed that some had a thicker shoulder about half-way down the wrist-pin. These came out of some 2.4 pistons that had "ART" on the inside. Are these better pistons? I've heard "ART" mentioned on here before, and I have 5 good ones.

[BRENT GILL]

Burk , you don't need any kind of special tool. Save your money. Here's the trick.

Place your wrist pins in the freezer for about 20 or 30 minutes.

Lay your needles all in a row ( count them and make sure their all there ) Don't trust the package , count them
Pull the wrist pins out of the freezer (1 at a time )
take some petrolem jelly and wipe it around the wrist pin.
Roll the wrist pin over the row of needles
they will be held on the pin
Next I lay the rod on the bench with the washer on the bottom
then slide the other washer on the wristpin and insert it into
the rod with a turning motion using the top washer to get the needles down in the rod.
Holding the top washer pull the wristpin out.
Now slide the wristpin into the top of the piston
Now position the rod with the washers into the piston
Since the wristpin is cold it will slide right through
just use a turning motion
And if you keep the washers in place it will keep all the needles
in place.

This looks like a big deal but with a little practice this whole process takes less than 5 minutes per piston.

[stvhelm]

screw the tools use your finger. smear some assembly grease in the rod end, then lay it down flat on the table. now put your finger in the hole and with your other hand put the needle bearings in. they will stick to the grease so you can pick it up to put it in the piston.

[Burke Kilgour]

Thanks for the info guys !!
Sounds like i'll try a combination of all of the suggestions.
I'm suprised the freezer trick works. I bought a press just for this project too........... D'OH!!!!

[novalves]

Thats the way to do it (get your minds out of the gutter)

However Never use automotive engine assembly lubes (they contain metalic compounds)

Also anything fuel or water proof is out as well and no KY either (water based).

The grease only needed to keep the bearings in place and the sooner it leaves the sooner oil and fuel (coolant) can do their jobs.

MERC's "Needle Bearing assembly compound (PT# 92-825265A1) works great.

Sealed Powers automatic transmission assembly lube also works good too and good ol Vasaline would be ok if its not too hot out.