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And yet another weak point

Started by BVHOG, August 27, 2019, 02:21:06 PM

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BVHOG

18 streetbob 120 build 504 Andrews cam S&S springs. broken rocker shaft. Seems strange but it is VERY thin in that area.
If you don't have a sense of humor you probably have no sense at all.

VDeuce

Wow, interesting find. First I've heard of.

mike jesse

My question is, was it broken when it came in or at assembly?

Dan89flstc

August 27, 2019, 03:57:31 PM #3 Last Edit: August 27, 2019, 04:05:31 PM by Dan89flstc
Quote from: BVHOG on August 27, 2019, 02:21:06 PM
18 streetbob 120 build 504 Andrews cam S&S springs. broken rocker shaft. Seems strange but it is VERY thin in that area.

It didn`t break in the thin area...

Another weak point?

These rocker shafts have been out since 2017, first post I`ve seen about a rocker shaft failure.

One failure does not indicate a trend...although it sucks for sure...

US Navy Veteran
A&P Mechanic

BVHOG

Quote from: Dan89flstc on August 27, 2019, 03:57:31 PM
Quote from: BVHOG on August 27, 2019, 02:21:06 PM
18 streetbob 120 build 504 Andrews cam S&S springs. broken rocker shaft. Seems strange but it is VERY thin in that area.

It didn`t break in the thin area...

Another weak point?

These rocker shafts have been out since 2017, first post I`ve seen about a rocker shaft failure.

One failure does not indicate a trend...although it sucks for sure...
The break certainly did start in the thin area, or at least travel to it if it started on top, dead center of hole on bottom. Personally I think it's a fluke and not really worried about it happening again. Assembly shouldn't have put any stress on it as it was installed and then SS quickees after that.  I did not use studs either and the standoffs for the shaft is perfect. My bud was right behind me when it happened and lets just say it was nothing gradual, bolts still had full torque on them.
If you don't have a sense of humor you probably have no sense at all.

rbabos

August 28, 2019, 05:42:49 AM #5 Last Edit: August 28, 2019, 05:48:39 AM by rbabos
Quote from: BVHOG on August 27, 2019, 05:57:58 PM
Quote from: Dan89flstc on August 27, 2019, 03:57:31 PM
Quote from: BVHOG on August 27, 2019, 02:21:06 PM
18 streetbob 120 build 504 Andrews cam S&S springs. broken rocker shaft. Seems strange but it is VERY thin in that area.

It didn`t break in the thin area...

Another weak point?

These rocker shafts have been out since 2017, first post I`ve seen about a rocker shaft failure.

One failure does not indicate a trend...although it sucks for sure...
The break certainly did start in the thin area, or at least travel to it if it started on top, dead center of hole on bottom. Personally I think it's a fluke and not really worried about it happening again. Assembly shouldn't have put any stress on it as it was installed and then SS quickees after that.  I did not use studs either and the standoffs for the shaft is perfect. My bud was right behind me when it happened and lets just say it was nothing gradual, bolts still had full torque on them.
It broke exactly where it should. Just outside of the bolt retention area of the hole. Fluke, possibly but it does point to a weak point. Uneven clamping surface, bad heat treatment, local stress risers in the hole area with possible cyclic flexing over time. If more show up, then it's a poor design for the task. Time will tell, as it will be mileage related for failures in that case. It is pretty lame structurally if you ask me.
Ron

MakoHD

Yup!!! Happen to one of my customers bike. It was a stage 4 from Harley so I took it apart to do some head work and change the cam and I found that!

Sunny Jim


hd06


Don D

Quote from: Dan89flstc on August 27, 2019, 03:57:31 PM
Quote from: BVHOG on August 27, 2019, 02:21:06 PM
18 streetbob 120 build 504 Andrews cam S&S springs. broken rocker shaft. Seems strange but it is VERY thin in that area.

It didn`t break in the thin area...

Another weak point?

These rocker shafts have been out since 2017, first post I`ve seen about a rocker shaft failure.

One failure does not indicate a trend...although it sucks for sure...
Does 2 failures = a trend?
Had one break, 100lb seat pressure springs.

FloridaJim5

2 failures = Huh?

Would these be stronger aftermarket springs?  If so, what is the stock or factory spring pressure?  Just curious, but still probably shouldn't have broken.

Don D


Dan89flstc

Two failures posted on the forum over the past 8 months.

Failure reports not exactly pouring in...
US Navy Veteran
A&P Mechanic

genzer

My dealer has had a few broken, trend? I don't know maybe a bad batch

rbabos

Quote from: genzer on April 23, 2020, 01:21:33 PM
My dealer has had a few broken, trend? I don't know maybe a bad batch
Look at the design. Hole edge distance is seriously lacking in the design. Basic engineering fk up. I'm surprised all of them don't break eventually.
Ron

Don D


sandrooney

I bet that made a hell of a noise.
Patience is such a waste of time .

Scooterfish

Quote from: rbabos on April 23, 2020, 02:23:28 PM
Quote from: genzer on April 23, 2020, 01:21:33 PM
My dealer has had a few broken, trend? I don't know maybe a bad batch
Look at the design. Hole edge distance is seriously lacking in the design. Basic engineering fk up. I'm surprised all of them don't break eventually.
Ron

"Eventually "takes time and  HD probably counts on a high percentage of low mileage bikes within the 24 months warranty.
Northern Indiana

RTMike

Just like the M8 compensator sprockets,breaking at the thin areas.

sandrooney

Quote from: Scooterfish on April 24, 2020, 06:16:38 AM
Quote from: rbabos on April 23, 2020, 02:23:28 PM
Quote from: genzer on April 23, 2020, 01:21:33 PM
My dealer has had a few broken, trend? I don't know maybe a bad batch
Look at the design. Hole edge distance is seriously lacking in the design. Basic engineering fk up. I'm surprised all of them don't break eventually.
Ron

"Eventually "takes time and  HD probably counts on a high percentage of low mileage bikes within the 24 months warranty.

They have been counting on that for years. That's why they have no problem offering an unlimited mileage warranty.
Patience is such a waste of time .