1989 Force 85 piston - does this look right?

[Nemesis98]

I am ready to install my piston in a 1989 Force 85, but something looks 'fishy' Can anyone check out this pic and let me know if this is correct?
The connecting rod can slide side to side and as you can see, the piston bearing pins are exposed a bit. They do not fall out, but you can see them when the connecting rod slides to one side. Everything else is solid and tight.

I looked at diagrams of the piston both online and in my repair manual, and followed the assemble as best as I could, but something seems wrong. I do not have the special tools for assembly, so I had to improvise, adapt and overcome just a bit.

Is this good to go, or am I still missing something?

Thanks!

 

[Frank Acampora]

Re: 1989 Force 85 piston - does this look right?

No! That is not correct! Everything is there BUT---The wrist pin keepers (steel collars) should be tight against the piston interior allowing the needles room to move sideways a bit.

The wrist pin is the inside race, and the small end of the rod is the outside race with the needles completing a bearing set. Even though the tolerances are quite close, the rod can slide sideways AND can slide over the needles if they are jammed.

I can not tell from the photo but I would be willing to bet that the two keepers are jammed against the needles. This will cause the small end of the rod to slide over the needles instead of them rotating within it. This will lead to premature wear. Also, since the wrist pin is a light interference fit to a close running fit in the piston, improperly installed keepers may allow the wrist pin to move sideways during operation and score the cylinder liner.

Since you put it together without the proper tool, you must now wedge two pieces of tapered steel on either side of the small end of the rod at the same time to force the keepers out toward the piston walls.

You must also be certain that when you do this they move evenly so that the wrist pin will not protrude from one side of the piston and score the cylinder liner.

 

[Nemesis98]

Re: 1989 Force 85 piston - does this look right?

Yes, The steel collars are up against the needles, so the two steel collars must be tight against the piston interior instead.. It's ok that the rod slides side to side a bit?

Are the wrist pin keepers installed in the right direction (smaller edge facing the middle of the piston?)

 

[Frank Acampora]

Re: 1989 Force 85 piston - does this look right?

Yes! Everything is installed in the correct relation with the exception of the collars squeezing the needles. the collars are normally installed with a removeable .310 spacer between one collar and the rod. This puts them very close to the piston walls. They do not need to be dead tight against the walls -- close is good enough.

Yes! As I wrote before, side to side movement of the rod is normal. It is held centered by the crankshaft cheeks bearing on the big end. It is a fairly close fit.

SO: When you go to reassemble it, you will need to rock the rod and twist a bit to get it to enter the cheeks and crankpin. The rod cap is cracked cap technology and will fit on the rod ONLY one way. Be certain to align the cap using the ground and polished flats before you torque the bolts to 180 inch pounds. If you tighten the bolts before the cap is properly aligned, or with the cap improperly aligned, you will ruin the connecting rod.