I was playing around with my I pistons (WiseCo) and rods (Scat) the other day and noticed the the gudgeon pin was a very tight fit through the Scat rods. The pin slips very easily through the piston, but is very tight on the rod. Is the normal? I would have thought the clearance should be same between the pin and piston and the pin and the rod. Do I need to get the rods bored out a bit?
I don't know about the zed or those types but some set ups are like you said you thought they should be, fully floating, and others are like you have there, semi floating, sometimes floating on the pins and sometimes on the piston.
Shouldn't be to Tight, should be about the same clearance as your piston. you can always hone it out a fraction with a flexible honeing tool. take it to a auto machine shop for clarification if your not sure. Did you put a bit of lubrication on it before trying it.
No i didn't lubricate it. I didn't actually get the pin all the way through the rod, because it just felt too tight and I didn't want to risk damaging it. It didn't feel like it would turn very easily once in there, if at all. Just when I thought I'd finished visiting the machine shop. Oh well at least they know my name now.
Have you measured up the shaft and bore to see if they are within specifications? Probably best off contacting the manufacturer for advice also. Did you give the parts a bath in hot water first to expand them before assembling, it helps.
Nah haven't measured anything yet. Have to get my mate to borrow his tools from work. Just thought it was strange that was such a large difference between the piston and the rod. But I suppose the different construction would make the expand differently when heated? Can you give em a bath in water? Or do you need to use oil or something?
Every time Ive needed to deconstruct or reconstruct piston assemblies Ive put it all in hot water first for a few minutes (getting it hot enough to require gloves to handle the parts). If your constructing then you quickly dry off the pin and the pin bores in the con rod and piston first, then apply some oil and slide the pin through the lot while its all still hot. Using hot water is a safe and easy method of heating the parts, but you could also try sticking them in an oven set to low (just make sure the parts are totally clean and your missus does'nt bust you doing it!:biggrin: ).
Well, I haven't got a missus to worry about but I think I'll keep them out of the oven just the same. Thanks for your help Gazza, I have emailed Scat, and I'll see what they say regarding clearance. Oh what do use to dry them off with. I assume not a towel, since that would leave lint all over everything.
I shake the water off the parts then pat off the remaining drops with a clean lint free rag (like an old cotton t shirt), since the part is hot the remaining water dries very quickly.
