Originally Posted by Bikerscum

I had mentioned in another thread about an ANNOYING tapping sound from my '15 Limited Low's top end that got exponentially worse after putting in cams. It was at, and only at 2300-2400 rpms. And it was one, and only one valve/rocker/pushrod/lifter/ that was doing it. It was getting to the point of my not really wanting to ride the bike. It seemed like I was always riding at that rpm. I decided to either do something about it or get rid of it.

My plan was to take the front rocker box off (I could tell the tapping was coming from there) & run the engine at 2300 rpms, poking around in there until I found what the cause was. Well, I chickened out on that idea. Not that it would hurt anything, it was the thought of spending the next 6 months cleaning the engine.

In fact, I almost didn't get started at all. For a wethead, the service manual says you have to drain the coolant & remove the coolant lines to get the front rocker cover off. I've been very fortunate not to have any coolant leaks so far and the thought of ruining that was huge. So I looked, pondered, thought about it.... it sure looked like it would come off without doing that.... and it will. Put blue painer's tape across the top front of the cover to protect it from the stabilizer mount, pull up and back on the hoses as far as you can, turn it clockwise, angle it, lift it, and it will exit out the right side. In fact it's only that hard because I have lowers. Off to the races...







This was one of those times where you really hope you find the smoking gun. The broken part. The obvious problem. Not going to happen. I took everything apart, measured everything, all seemed in order. No wear on the shafts or rockers, end play wasn't great, but at .011/.009 it was in spec. Well ****.

More pondering. SOMETHING is causing that noise. Then I got to looking at the ends of the rocker shafts. There appeared to be some evidence of galling.... where the shafts ride in the aluminum carrier....









Odd I thought, there's nothing that really puts any pressure there, there's not even a bushing. In fact, there's not really anything holding them in at all.

BINGO. The only things holding the shafts in are the 4 carrier hold down bolts. The shafts have notches ground in them that the edges of the bolts pass through. But the notches are way too big. The bolts keep them from sliding out but they are free to rock back and forth along with the rockers.
I can see zero reason they should be allowed to do this. In fact the manual says to knock them out with a brass drift punch if necessary. The same manual that says there can be up to .0035 clearance. WTF??

SO I put the shafts back in on the bench, put the bolts through, & find this... (you may have to turn your volume up)
Loose rocker shafts - YouTube


EXACTLY what my tapping sounds like. So then I inspect the hold down bolts, & find the rocker shafts have been klacking against them hard enough to put dents in grade 8 bolts...





I have my smoking gun.

Now this isn't technically something defective, it's just a **** poor design. I take everything back apart, clean it squeaky clean, and put it all back together with assembly lube, & with Loctite 609 on the ends of the shafts. 609 is tough stuff.. it's specifically made to keep shafts & bearing races from turning in their bores. Just the ticket.

=edit= Have since found that Loctite 620 would be a better choice, 450f max. temperature.




So, put everything back together, clean off all the thousands of fingerprints, and start it up. 2300 rpms &...

Nothing. Silent. The tapping is completely gone.... I am indescribably happy.

Just an afternoon's work and... no, they DON'T all do that.

=edit=...

The standard disclaimer....

I'm just some guy on the internet with a problem & a solution that works for me. What you do, if anything or nothing is entirely up to you, and at your own risk.

Carry on...

Originally Posted by rcornelius