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)


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...

 

Holy crap! Your tenacity and determination have impressed the hell out of me, dude. Well done and thanks for the update! Oh, and congratulations, too!

 

You are a genius. Thank-you for investigating this, It's now on the list for checking during winter maintenance.

 

Well done!

 

Excellent and a happy ending. Some very good info shared also, Impressive.

 

x 2, great work

 

Thanks guys, it's a journey I'm glad to be home from

 

X3 Nice detective work, just wondering if HALF the dealers would have.....

A found the problem?

B Been bothered to investigate that thorough??

C Fobbed you off??

Ady

 

Really, really, excellent work... I bet you've just solved the problem for 95% of the people who complain about excessive valve train noise.

I will say, I've seen that looseness before and done nothing about it thinking the rocker pressure would keep it from rotating. I will be trying the Loctite 609 from here on out.

The MOCO should have created a boxed/keyed end to stop that rotation because as you've said, there is no reason at all for it.

Really great work man.

Admin, request Sticky... great find.

 

Damn nice job! There's not a Harley "tech" on earth who would or could have had the intelligence and gumption to find that!

I'm totally impressed, and if/when mine develops that noise, I'll know exactly where to look.

You rock, Man! Congratulations and ride safe.

JP

PS: If the loctite DOES break loose at some point in the future, a solid fix would be to drill & tap 1/4 inch holes in the flat spots on the left-top of the rocker shaft carrier and install hardened set screws that lock the shafts in place once and for all! Since the other end of the shaft would still be free-floating, there would still be accommodation for the heat expansion pointed out by CSMHOG. If it voids the warranty for rocker box issues, so what? You've found and cured the problem - permanently.