[deluxe72]

Hi. I bought some piston pin bushings recently. When they arrived I discovered the valley on the inside was there but the hole was not. I spoke with the vendor and they said the hole is supposed to be there and that they screwed up. Those two pieces are on their way back. I ordered the same bushings from a different vendor. These bushings don't have the valley or the hole. I called the vendor and they said the valley is not needed and that I have to drill the holes myself.

Is the valley on the inside needed?

Thanks.

 

[Glider]

No, but the hole is.

You might want to get some expert opinions on reaming/honing those bushings to size once you get them in.....
I've tried to do it a couple of times with no success, as has a friend of mine. I would say it's not a job for an amateur. If not done properly there can be all sorts of disastrous results best left to the imagination.

Ideally, the rod should be out of the engine and the bushing should be precisions honed on a machine.

Still, you may be able to find someone who can do the job properly without pulling the engine apart.

 

[Greasy Nails]

Yeah you want to use an adjustable hand reamer on the bushings after you install them, usually I just drill the oil hole very carefully with a hand drill first. have to look in your triumph manual to see what size to ream the bushing too though because my memory doesn't work that good!

 

[JasonMcElroy]

Yeah you want to use an adjustable hand reamer on the bushings after you install them

While I'm not saying it's impossible, I have NEVER seen an acceptable job done a precision hole with an adjustable reamer. Particularly since most of them are cheap crap made in India.

The USA-made adjustable reamers, with just a couple thou adjust-ability and precision ground arbor might possibly do a decent job.

Given that alignment of the hole relative to the rod is absolutely critical, how would you pilot an adjustable reamer?

Not trying to be a ball-buster, I just really want to know.

I have personally had piston/rod failures from doing wrist pin bushes myself without the proper piloted reamer. And I've been doing this a while and took plenty of care.

Thanks,
Jason

 

[tat2edfuk]

I did mine with a adjustable reamer. Is there a way to tell if I did it right? I really don't want to split my cases again, but I also don't really want to seize.

 

[deluxe72]

Thanks for all your replies! Any other votes against the necessity of the machined grrove / oilway on the inside of the bushings? The bushings I have do not have the groove / oilway and I need to be confident that I can use them as is before I install them. Or I'll return them and look elsewhere. For some reason I need to hear feedback from two or three folks. I'm not discounting the knowledge of the folks who have shared so far.

 

[chassy55]

The ones I get have no inner groove, and most of the used ones I have laying around don't either, but some do. Then again, they don't require reaming, either. I pull them in (warm) and push the old out at the same time, with a wrist pin through both. But they are machined brass rather than sintered bronze, maybe that"s the difference. And I drill the hole. Much easier than trying to align, I would think. I aslo put a wood dowel in the hole when drilling, as the bit likes to jump through the brass and nick the other side. Then the hole should be be-burred on the inside. My .02

 

[RetroRob]

The important issue with reaming is getting the bushing bore exactly in alignment with the crank. Just because the size is correct on the wrist pin, doesnt mean your not going to have problems. If the bushing was reamed ascue or on an angle it could create premature wear on the bushing, piston, cylinder or all three and worst case pop off the snap ring and destroy your engine, if you've used an adjustable reamer with no pilot to keep things straight, and your still running, consider yourself very lucky.

As for the oil groove, when i rebuilt machines at GM and we had to make our own bushings we would press them in, line ream them, drill out the oil hole and take a die grinder and make a small groove by hand parallel to the bore, but stop short of breaking through either end of the bushing, thus contain the oil in the bushing. I am NOT a professional enging builder, so I'll let those with more experience chime in, but I think this would work. The groove didn't have to be precesion but it did have to hit the hole and of course not create any burrs in the bushing.

 

[deluxe72]

I've thought about this a little more. The piston and pin come as a set, so the piston moves freely on the pin. Does the pin really need to move in the bushing when the engine is running? Seems like the piston moving on the pin would be enough.

 

[Daturat100r]

Cold the piston should really just nip the gudgeon pin enough so it cannot be pushed out until piston is heated up.The pin should be totally free to move in the rod otherwise there would be no reason to put an oil hole in the little end

 

[deluxe72]

Thanks for everyone's feedback!

 

[tat2edfuk]

Not to steal this thread but it's got me worried. As I said I did mine with a adjustable reamer. I took my time and did it in increments. I know it's a good fit, but I didn't use a pilot. I'm putting a new big bore kit on, so, I really don't want to seize my motor. Is there anyway to tell if I did it right? I'm not apposed to replacing them and running with a pilot but I have no idea how to make one (I have a lathe). I would really appreciate any help. once I get this dealt with I am finish the rebuild and can ride.

 

[Jack Adams]

Tat, with your lathe, turn a bar down to the size of the pin, but long enough to go thru BOTH rods at the same time. If you did it right,and the rods are straight,the "long pin" will slide thru both of the rods at the same time. Jack

 

[deluxe72]

Keep in mind the goal of a pilot set up is to be sure a small end hole is aligned with a big end hole. I don't believe running a machined rod through both small end holes at the same time will inform anyone about alignment of one small hole with it's corresponding big hole. One small hole to it's corresponding big hole. That is the alignment concern.