wrist pin bind
Thread Starter
Racer
Joined: Aug 2007
Posts: 367
Likes: 0
From: Jackson MO
wrist pin bind
Picked up my block from the machine shop to day along with the pistons/rods. I noticed that one of the wrist pins was not centered very well and brought it to the machinist attention. He politly pressed it to the center. When I got home and started assembly, the pin that he pressed is binding and doesn't float nearly as easy as the others. What should I do? Will this loosen up later?
Le Mans Master
Joined: Nov 2008
Posts: 5,691
Likes: 12
From: columbus oh
Picked up my block from the machine shop to day along with the pistons/rods. I noticed that one of the wrist pins was not centered very well and brought it to the machinist attention. He politly pressed it to the center. When I got home and started assembly, the pin that he pressed is binding and doesn't float nearly as easy as the others. What should I do? Will this loosen up later?
Racer
Joined: Nov 2008
Posts: 297
Likes: 3
tight wrist pin
normal assembly of the wrist pins usually involves the use of a heater to heat the small end of the rod very hot, which enlarges the hole enough for the wrist pin to be pushed in with very little force. If the piston was put into a press and the pin pressed in under force, it could have damaged the piston. I would not put that in a engine I was building. I will say this, it is possible that there is a newer way to assemble that I am not aware of. Any machinist know of another method other than heat?
Le Mans Master
Joined: Jun 2004
Posts: 6,231
Likes: 65
From: Seattle WA
St. Jude Donor '14
The pin is pressed into the rod, and floats in the piston. They're still assembled the old fashioned way of heating the rod end, although most shops do it with an induction heater rather than the old propane units.
If he pressed - as in, in a press, - the pin cold I have no doubt it's no longer centered on the pin bore and so it's galling in the piston pin bore.
So, first - time to head back to the shop. There's no way to "fix" what he's done other than to provide a new rod, pin and piston. Second - any shop that would do that (frankly) probably has other questionable practices...so be darn careful checking everything as it goes back in, and/or have someone with an experienced eye look everything over.
Sorry
If he pressed - as in, in a press, - the pin cold I have no doubt it's no longer centered on the pin bore and so it's galling in the piston pin bore.
So, first - time to head back to the shop. There's no way to "fix" what he's done other than to provide a new rod, pin and piston. Second - any shop that would do that (frankly) probably has other questionable practices...so be darn careful checking everything as it goes back in, and/or have someone with an experienced eye look everything over.
Sorry
Burning Brakes
Joined: May 2009
Posts: 1,232
Likes: 6
From: Tucson AZ
St. Jude Donor '12
It sounds like the pin is no longer square in the rod end or the press somehow damaged something. I agree with Buddy1980 on not putting it into the engine. Take it back to the machine shop and talk to the supv. Hopefully he will do what's right.
Team Owner
Joined: Apr 1999
Posts: 21,953
Likes: 1,444
From: Reno Nevada
2024 C3 of the Year Finalist- Modified
Picked up my block from the machine shop to day along with the pistons/rods. I noticed that one of the wrist pins was not centered very well and brought it to the machinist attention. He politly pressed it to the center. When I got home and started assembly, the pin that he pressed is binding and doesn't float nearly as easy as the others. What should I do? Will this loosen up later?
Corvette Stories
The Best of Corvette for Corvette Enthusiasts
10 Revolutionary 'Corvette Firsts' Most People Don't Know
Joe Kucinski
5 Reasons to Upgrade to an LS6-Powered Corvette; 5 Reasons to Stay LT2
Michael S. Palmer
2027 Corvette vs The World: Every C8 vs Its Closest Competitor
Joe Kucinski
10 Most Common Corvette Problems of the Last 20 Years!
Joe Kucinski
5 MOST and 5 LEAST Popular Corvette Model Years in History!
Joe Kucinski
2027 Corvette Buyer's Guide: Everything You Need to Know!
Joe Kucinski
10 Things C8 Corvette Owners Hate (But Won't Tell You)
Joe Kucinski
10 Best Corvettes Coming to Barrett-Jackson Palm Beach 2026!
Brett Foote
Every Corvette Grand Sport Explained! (C2, C4, C6, C7, & C8)
Joe Kucinski
Burning Brakes
Joined: Jan 2007
Posts: 1,057
Likes: 4
From: Concord Calif
Pins are installed (press type) by useing either a rod heater (best way) or useing equipment such as a Sunnen pin press. There is no way to remove or reposition a pin without a pin press. Useing the wrong reduceing ring from the Sunnen pin press equipment and or miss alingment while pressing will fold over the edge of the piston some and cause the tight pin to piston fit. You will probaly find that the pin is much freer with the pin pushed to one side compared to the other side. If this is the case you can scrape that edge off and be fine, but I would do it the right way which is to remove the piston completely and re-hone the pin bore in the piston and rechecking to be sure you do not have to much clearance now. If you have to much clearance now you can use an oversize pin, but I wood not advise that, just replace the piston is best.
Thread Starter
Racer
Joined: Aug 2007
Posts: 367
Likes: 0
From: Jackson MO
Thanks guys for the input. I took Midyearvette's advice and worked in a little more oil and it loosened up. I also took it to a local machanic that has a great reputation, and he said it's a little tight but OK. I'm just a little protective of my baby.
Le Mans Master
Joined: Nov 2008
Posts: 5,691
Likes: 12
From: columbus oh
