Topic: 22r rebuild, Q about wrist pin....

[bleakhorizon]

im in the process of doing a rebuild on my 22r, down to the nitty gritty i am......  Anyone ever do there own wrist/piston pins.... i understand most people take em to the machine shop, but those that do it themselves how did you make em fit and how tight did you get em

[emsvitil]

Should be floating pins, was easy to do with a 20r I rebuilt.

From the FSM

"At 80 C (176 F), you should be able to push the pin into the piston with your thumb

If the pin can be installed at a lower temperature, replace it and the piston"


With the 20r, I think I just tapped it in........ (didn't feel lose, and with circlips I didn't worry about it)

[79coyotefrg]

the pins should be snug,  but if they fall out if the clips arent in then theyre WAY too loose

the brass bushings (in the small end of the rod itself) should be installed and machined to fit by a machine shop

[bleakhorizon [OP]]

ok i didnt go into the detail i should have, i got the bushings in the rods and the pins will not go in them without a high amount of force (ie plastic hammer) so i know they need to be machined or whatever.... i was just wondering if anyone had ever done them thereselves with like a brake cylinder hone or something...pistion pin to piston fit is fine....

[emsvitil]

Need a reamer.   A brake hone isn't presise enough.

[79coyotefrg]

in theory you could use a brake hone, but you better keep your hone perfectly aligned,  USE PLENTY OF WD40

this really isnt where you want to skimp, but i understand sometimes youve gotta DO what ya gotta do

[bleakhorizon [OP]]

my biggest problem around here is that i either dont trust the machinist, or my other option is 50+ miles away lol....  i will c what i can do.....prob just end up takn it to distant machinist

[emsvitil]

The FSM says to hone the bushing.....  (not ream, sorry I'd alway heard ream)


But I wouldn't trust a brake hone.

See if you can find one specifically for piston pins.

Pin should fit with thumb pressure when oiled at room temp.

Clearance is .0002-.0004"

[emsvitil]

If you know of someone you can trust, you could just ship the rods and pins to them........

[bleakhorizon [OP]]

well i got em in there, i will post pics up of the whole setup when i get a chance.... ends up the pins seem to fit into the rod just a little bit tighter than the piston, no wobble up down or otherwise.... i did take a run-out type gauge and try to measure any play that it might have and i couldnt get them to move soooo.... i guess worse thing that could happen i could toast my pistons/rods and have to take er back apart again... not to worried bout it now

[zippo]

Heat the piston/Rod in the over to 176F and freeze the pin! If you read to FSM a little heat is ok. If it wont go with the heat. you need to move on the honing. If the Rod bushing need to be done, TAKE IT TO A SHOP WITH THE PIN. and save yourself alot of work. It goes on a stationary hone used on rods.

[emsvitil]

The pins should be looser in the rod than the piston as there is some clearance (.0002-.0004") speced...............

[bleakhorizon [OP]]

yea uh how xactly do you measure that clearance.... lol. . . i havent put em all together yet so i can still mod them if needed

[79coyotefrg]

yea uh how xactly do you measure that clearance.... lol. . . i havent put em all together yet so i can still mod them if needed

if you had to push fairly hard with the thumbs your fine

[zippo]

Try switching the pins between them? Maybe you'lle get lucky