TOWER parts for OS .40FP - CAUTION

I had read on this forum about using TOWER .40 parts for the OS .40FP. They are cheaper and shipping is free. Sounds like a good deal. So I bought 2 sets of piston/liners, connecting rods, and piston pins. However, looking at the new connecting rods I was shocked to see the difference between the TOWER replacement rods and the original rods in my OS .40FP and TOWER .40 engines. The replacement rods have significantly less material supporting around the "big end" bushing (please see photos below). So. My question is should I be worried about these rods? Will they provide the same longevity as the originals or will they "hand grenade" during a fast run? Has anyone else gotten rods that look like this from TOWER?
Thanks for any input and help.
DennisV

P.S. Looking at the replacement piston/liner sets the piston seems appropriately tight toward the top of the liner. However, at the bottom of the liner the clearance is so large the piston can actually rock back and forth in the liner bore. I've never notiticed this amount of clearance with the original parts.

On the rod, it looks like they bored it just slightly off. But it looks like there is an equal job on the top (more material) which would make me think the distancce between centers is still correct (maintaining deck height). I have seen other rods that thin--some after market rods for the OS 35S were thinner than that. I should think that it would be OK since the wear part is the bushing.

On the piston, how loose is it? If there is a lot of rock, that is one thing. However, it is normal to have a "little", especially if you pull the piston down far enough that it is sticking out just slightly. I can do that with OS liners, with Magnums, even with a new piston/liner I have here for a PA 61. The cold compression fit is at the top, and when the piston heats up, it will expand to fit the bottom of the cylinder.

That rod is not made right, it was machined off center. Send it back with an explanation and get a replacement. Why take a chance on such a critical component.

If the taper is too big on the sleeve, you might have problems hand starting or holding a steady setting. Measure the difference between top and bottom, shouldn't be more than .003".

Hope that helps,
Giffy

I'm with Giffy on this one, the rod was not placed in the machining fixture correctly. While most of the forces on a connecting rod are in compression, there are instances where the rod is in tension. I would be concerned with the big end stretching and the bushing coming out. I would not use this part and would make every effort to have it replaced with a correctly made one.

Holding two Tower 40 rods up by your picture, I would agree that the holes are off. I wonder if they were put in the drilling fixture upside down. Send them back. Looking at one piston and liner, yes the piston will rock a good bit at the bottom of the liner, but it has to go down much further that it is supposed to before it rocks. It doesn't rock that I can feel when the piston is level with the bottom of the exhaust.

Hope this helps.

Great! I'm still logged in!
From the photo it does look as if the drilling is off, but a) the rod is not full square to the camera, and this may influence the impression it gives. b) Also make sure it's not a trick of the light. A highlight will make something look bigger. Best to measure it.

LAST EDITED ON Aug-05-03 AT 07:49 PM (CDT)
 
Ian,

I guarantee you that rod is machined incorrectly, no amount of light distortion will make an error look that pronounced. I've made plenty of little rods, this one's off.

Not tryin' to be a wise guy, this one's just obvious, to me anyway.

No problem Randy. It was just a thought. Looking at the photo of the rod still in the bag, it is taken from the other side and still looks off. I agree your conclusions. Regards

I have a tower rod and it does not look like yours. you can have it if you send me your address