I'm a retired engineer and agree. While some may suggest that it's OK to get rid of it, I do believe that it will affect the life of the drivetrain. In 2008, HD finally added additional driveline damping to the rear wheel on touring models. While the main reason seemed to be curing gear rattle, it is additional drive train damping. I own a custom EVO motored softail that uses a 3 inch open belt drive primary. It's a light bike probably around 550 lbs and has a 113 ci motor in it. With the belt drive, it does not have any drive line samping at all. One thing it does do well is vibrate.. . Most of the vibration comes from rolling the throttle on. At say 3000 and no load vibration is not that bad but as soome as I open the throttle, the vibration is quite noticeable. Get on it hard and parts fall off or break. It's on it's 6th speedo / tach, 3rd front and rear fenders, 3rd tail light. Second top motor mount. 3rd clutch. It once pulled a few dimples out of a spoke steel rim.

While that is an extreme example, I have seen a TC crank without a comp twist splines. A better crank would likely help.. The M8 cranks still use the same splines as the later TCs.

 

Why would that seem silly? Parts break. Even good ones.

I'm curious - what kind of engineer are you? I'm mechanical.

Max is one of the best diagnosticians on this site. If anyone can help, he can.

 

Parts do break, I get that. But they shouldn't with less than 10k miles. I'm an electrical, so perhaps that's my bias: that mechanical parts should last longer than they do. However, I came to this bike from a 2007 Road King that had zero issues. That bike never stranded me - except as a result of stupid things I personally did. No parts ever broke on it. So that's my expectation. I'm not a hard rider and I don't put anywhere near the miles on a bike that some do. So it's a relatively low use bike. That's my bias. I don't think things should break under limited and light use.

And yeah, Max has been great. Thanks, Max!

 

You're absolutely right - they shouldn't. But still, sometimes they do. The M8 compensators have proven to be pretty tough generally.

 

just curious when did baker update his TC comp?

 

About 3 months.. For the last update. IIRC the previous version did go through a couple iterations.

https://www.hdforums.com/forum/prima...l#post18756468

 

The latest update in my saga...

Spoke with the dealer today. Turns out, I broke a rocker shaft. It snapped, not allowing the valves to work, which it why it died and wouldn't start. He's replacing it and the rocker arms. There was damaged to the cylinder, so I'm getting a new upper cylinder and new lifters. As I write this, I'm wondering why new lifters and not also new push rods? Maybe I am getting new rods and he just didn't say. I'm told the piston and rocker box are ok.

So it's not sumping. And it's not the compensator. Dealer said he's only seen this one other time on an M8, and that was on initial firing of a stock engine. He's never seen this on a Twin Cam.

So what do you guys think? Could the higher compression of Stage III have cause this? Or was it just bad luck, as mechanical things DO sometimes break?

 

Interesting find with the rocker shaft. If one were to guess, shouldn’t but will, it might be from improper assembly where the clamping force of the mounting bolt was incorrect or even loosened allowing the flange of the rocker shaft to snap.
Agreeing with your question of push rods as well as asking why replacing lifters, unless they suspect something different then my “guess” above and feel a lifter caused the issue, sorta doubt that but curious.
With the shaft broken, and not allowing the valves to operate, I can see why there would not be any damage to pistons. Valves remain closed and no contact with piston.
One thing you might ask, can you upgrade to the adjustable rocker arms while they are in there? They can aid in eliminating the slight valve clatter that some M8’s have.
Just my thoughts. Not an engineer nor a certified HD mechanic, just a mechanic of rotating machinery for 40+ years who enjoys wrenching on HD bikes.

 

This is an issue that can occur. HD did change the rocker shafts from the early M8s. IIRC the stage 3 has heavier valve springs. I assume when you say "upper cylinder" you really mean cylinder head as it probably took damage when the shaft broke as the rocker shaft mounts directly to the head. Not a common issue but has occured before.

 

You might want to ask them to open the front rocker box to do a visual inspection to make sure the same thing isn’t occurring there also. Could be a casting issue. Read about that somewhere, just can’t remember.