Stock piston removal cracking.....
02-16-2012, 06:30 PM
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Stock piston removal cracking..... Anyone with experience have this issue while removing the pistons from the rod?
Sent my stuff to the machine shop and they cracked two of my pistons while removing them from the rods. They tried saying it happens all the time while dealing with stock stuff...... I say BS. I've had this done multiple times and haven't had an issue until I use a different machine shop due to relocation. Any thoughts? And they said I need to pay for the new piston....
Name of the shop is QMP performance, chatsworth California.
Sent my stuff to the machine shop and they cracked two of my pistons while removing them from the rods. They tried saying it happens all the time while dealing with stock stuff...... I say BS. I've had this done multiple times and haven't had an issue until I use a different machine shop due to relocation. Any thoughts? And they said I need to pay for the new piston....
Name of the shop is QMP performance, chatsworth California.
Last edited by mcfarlnd; 02-16-2012 at 07:55 PM.
02-16-2012, 06:38 PM
#2
the only way i now to crack a piston during removal is to drop it on the ground when your pushing it out of the block. The engine is on the engine stand turned upside down, they undo the rod bolts/caps and push the piston out onto the concrete floor. I have removed several sets of stock pistons from LS blocks, never dropped or cracked one
02-16-2012, 07:43 PM
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the only way i now to crack a piston during removal is to drop it on the ground when your pushing it out of the block. The engine is on the engine stand turned upside down, they undo the rod bolts/caps and push the piston out onto the concrete floor. I have removed several sets of stock pistons from LS blocks, never dropped or cracked one
02-16-2012, 07:50 PM
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Correct, pressed wrist pins. LM7 are dished correct? I was trying to get them to remove the dished pistons and install the flat tops from the 4.8 on the 5.3 rods. Then re-balance everything. It was going to be a cheap upgrade while I'm rebuilding the motor.
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02-17-2012, 02:01 AM
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Could you please enlighten me on the proper technique? Or anyone know the "correct" process? From what I have seen done from my previous machine shop, they used a small oven with a fixture and used different combinations of press dies depending on application. I asked QMP if they used heat, and they said, "they only use heat for install." I would think heat would make the two malleable and less prone to cracking.
02-17-2012, 02:06 AM
#10
It takes a special adapter to remote ls pistons from rods. Most machine shops try to use the standard sbc adapter and that is what cracks them. I took a set of mahle pistons to a machine shop that I sold, he busted the first one and I asked him if he was using the ls adapter and he said they were the Same. I packed the remaining 7 up and went to a different shop that had the adapter and didn't have any trouble with the rest.
That being said, I ate the cost of a replacement piston.
That being said, I ate the cost of a replacement piston.
02-17-2012, 02:17 AM
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It takes a special adapter to remote ls pistons from rods. Most machine shops try to use the standard sbc adapter and that is what cracks them. I took a set of mahle pistons to a machine shop that I sold, he busted the first one and I asked him if he was using the ls adapter and he said they were the Same. I packed the remaining 7 up and went to a different shop that had the adapter and didn't have any trouble with the rest.
That being said, I ate the cost of a replacement piston.
That being said, I ate the cost of a replacement piston.
02-17-2012, 02:34 AM
#13
They tell you that after they bust a couple because most people don't know any better and just assume that's the case and let it go.
The people at the machine shop know its not common and know they fucked up, they just don't want it coming back on them.
I can see it happening sometimes on a piston/rod assembly that is 50 years old and sitting in the woods for 20 years, but not an ls engine that was most likely running recently.
The adapter must sit flush on the wrist pin boss and not on the ring lands or skirt area. The sbc adapter will sit on the bottom ring land just a little and end up busting the piston just above the pin boss and usually all the way across the top of The piston to the other pin boss.
Is this where yours cracked?
The people at the machine shop know its not common and know they fucked up, they just don't want it coming back on them.
I can see it happening sometimes on a piston/rod assembly that is 50 years old and sitting in the woods for 20 years, but not an ls engine that was most likely running recently.
The adapter must sit flush on the wrist pin boss and not on the ring lands or skirt area. The sbc adapter will sit on the bottom ring land just a little and end up busting the piston just above the pin boss and usually all the way across the top of The piston to the other pin boss.
Is this where yours cracked?
02-17-2012, 02:38 AM
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You have me really curious about this. Do you have a part number or manufacturer of "said" adapter? I would like to atleast look at a photo so, I can compare it to what they use.
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02-17-2012, 09:37 AM
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02-17-2012, 09:58 AM
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I need to sell my pistons and get them off the rods still. Guess I'll attempt it myself and try your method above, give me good practice for someone whos never done it before.