Continuing rebuild of my 2005-built S&S V96 EVO. Found rear rod out of align with top of case by .018”. The front rod is spot on.

There is also side play of the rods but I can’t find a service limit in my manual.

My question is, is there a procedure of straightening the rod or is it time for a full on bottom end rebuild?

I have a beautiful newly machined top end with new pistons. Don’t feel like reassembling without addressing this rod issue.

Thanks

 

I'm curious what procedure you used to measure the 18 thou.

The only way I know of to straighten ("true") a rod is with the bottom end disassembled.

 

Used the Lowbrow Customs alignment tool. Used a feeler gauge under the tool on left side. Could see a little airspace. The front rod I used the paper under the tool method and it is spot on.

 

Best way is with a press and either a jig or a new, straight pair of rods. But if the bottom end is together, that's not a happy option. I have seen them corrected with a big pipe wrench (rolling eyes) but it's easy enough to make a tool to do it. I'm hesitant to describe the procedure for "in engine" correction since it's not for the faint at heart.

So far as side play, depends what you mean. Is it how much wiggle you have moving the wrist pin end right to left, or are you referring to how much they slide left to right on the crank pin? If the latter is the question, .005 - .025 is the book spec. but anything at or under about .035 will work just fine. S&S allows that up to .045 is tolerable but that's a bit much for me.

 

The manual only says “side play” of the rods. The Harley manual adds “at the crank”. So I just thumbed them over the pin and used a feeler gauge. I’m at .022. Unbelievably the service limit is .40 in my manual.

As far as mis-alignment of the rods, the rear wrist pin bushing is the culprit I’m thinking. Found it had either been installed about 100 degrees off (oil hole not at top of rod) or it moved in there. Evidence of rear overheating with oil coking in the skirt area, where the front is clean.

Going back to a machine shop for wrist pin replace because we need to determine if that Rod is damaged. Or hole needs machining, in that case they’ll make a custom bushing. I’m fresh out of desire to purchase more special tools.

We’ll get it solved and put back together. I think it will be a sweet motor.

 

Correct on the side play method. Sounds like someone may have already changed the wrist pin bushing and got a little off when reaming. That's very easy to mess up and end up not parallel, in fact, it's extremely hard to do and get right. But to install one with the oil hole not lined up is just careless. They don't rotate after installed in the rod. The interference fit is so tight, that's why you have to ream them.

 

My factory HD EVO (pg 3-35) manual says the rods can't be straightened. If they are bent they should be replaced. So hopefully you can correct with the wrist pin bushing.

Older manuals, Knuckle, Pans and side valve engine showed how to straighten a rod in the engine and had a tool for it. It appears that is no longer a recommendation.

Paul

 

You can look at the witness marks on the piston skirts and know if a rod is out of alignment.