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Working through a gen 3 5.3 build for a Toyota Land cruiser, so nothing crazy high HP or anything like that, just looking for decent torque and reliability. I had a spare set of connecting rods laying around that I was planning to use for this but after taking a look at them they seem to be not as straight and true as I hoped. For the hell of it, I took them over to the press and messed with them a bit and seem to have gotten them to line up a bit better. Is that a viable way to go about it? Or is it one of those things where once they go out of true it's pretty much garbage? I typically follow the "buy once cry once" method so it's not the end of the world if I have to replace them to be sure it will work well, but I also don't want to spend money where it's not needed. Before and after pics below. Thanks so much!
Wait, what? You put the rods in a press to bend them? I see the gaps before and lack-of afterwards, but those gaps mean nothing, against each other. The rod pin must be exactly perpendicular to the wrist pin. You can’t look at gaps while the rod is laying on its side, and assume its bent. The small end was machined square with zero consideration to how the rods stacked up among each other. Those are now wall art.
Wait, what? You put the rods in a press to bend them? I see the gaps before and lack-of afterwards, but those gaps mean nothing, against each other. The rod pin must be exactly perpendicular to the wrist pin. You can’t look at gaps while the rod is laying on its side, and assume its bent. The small end was machined square with zero consideration to how the rods stacked up among each other. Those are now wall art.
I pulled the rods out of a box to check on them to use for this project, and saw that they had that slight bend in them. I suspect it was from whoever pressed out the pins last, and must have done it in some sort of home setup that ended up bending the rods in that direction. I figured I'd see if I could get them looking straighter on a press, though knowing that they were essentially garbage. I was just curious if by chance going about it that way may salvage them, but I obviously know it's much more of an exact science than that. Seems like this is a good opportunity to upgrade to gen 4 rods I suppose!
The sides of the rods are "supposed to be" perpendicular to the piston pin at the small end and the crank CL at the big end. So yeah, it's not a good thing to have those "gaps" in your stackup.
However, given factory production tolerances, I don't know that that's a certainty or anything like that. It's mostly just an artifact of their machining methods, since it's faster (cheeeeeper) to flatten the whole rod all at once, than to break it up into 2 separate operations. Especially since at the small end, whether that's the case, makes no difference at all to the end result; after all, the sides of that end of the rod touches nothing.
I'm with Che70velle about that. I'd guess that the odds that those rods are now scrap, are pretty high. Although in your photo it looks like maybe the next to the top one had a "bow" to it, and now it doesn't. But in the end, having the pin bore parallel to the crank CL and the big end sides perpendicular, are the major concerns.
I agree with Scott-I've been doing this stuff for over 50 years, and I've never seen anybody check rods like that. Ever. The gap that was there means little. The small end edge surfaces don't necessarily have to be parallel with the the big end edges. The only correct way to inspect them is on a surface plate with an indicator and gage blocks. I have no idea what condition they were in when you started, but I'd shitcan them now. Also, once a forged piece of steel has been bent, even if you straighten the piece, they have a tendency to return to their bent state in a relatively short time. There's no way I'd use them now. My opinion.
I agree with Scott-I've been doing this stuff for over 50 years, and I've never seen anybody check rods like that. Ever. The gap that was there means little. The small end edge surfaces don't necessarily have to be parallel with the the big end edges. The only correct way to inspect them is on a surface plate with an indicator and gage blocks. I have no idea what condition they were in when you started, but I'd shitcan them now. Also, once a forged piece of steel has been bent, even if you straighten the piece, they have a tendency to return to their bent state in a relatively short time. There's no way I'd use them now. My opinion.
Appreciate it, that's what I figured as well. Might as well do it right the first time, and not have that nagging thought in the back of my head of the rods that may be junk in there. Seems like there are decent enough deals out there for a good set of floaters that aren't geared for some crazy application and therefore super high priced.
Working through a gen 3 5.3 build for a Toyota Land cruiser, so nothing crazy high HP or anything like that, just looking for decent torque and reliability. I had a spare set of connecting rods laying around that I was planning to use for this but after taking a look at them they seem to be not as straight and true as I hoped. For the hell of it, I took them over to the press and messed with them a bit and seem to have gotten them to line up a bit better. Is that a viable way to go about it? Or is it one of those things where once they go out of true it's pretty much garbage? I typically follow the "buy once cry once" method so it's not the end of the world if I have to replace them to be sure it will work well, but I also don't want to spend money where it's not needed. Before and after pics below. Thanks so much!
Hey, it's you! I'm the guy on Reddit who told you not to use those.
02-21-2024, 11:11 AM
"Reconditioning" Connecting Rods 
