HarleyTechTalk

Technical Forums => Milwaukee-Eight => Topic started by: BVHOG on August 27, 2019, 02:21:06 PM

Title: And yet another weak point
Post by: 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.
Title: Re: And yet another weak point
Post by: VDeuce on August 27, 2019, 02:37:29 PM
Wow, interesting find. First I've heard of.
Title: Re: And yet another weak point
Post by: mike jesse on August 27, 2019, 02:47:27 PM
My question is, was it broken when it came in or at assembly?
Title: Re: And yet another weak point
Post by: 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...

Title: Re: And yet another weak point
Post by: 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.
Title: Re: And yet another weak point
Post by: rbabos on August 28, 2019, 05:42:49 AM
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
Title: Re: And yet another weak point
Post by: MakoHD on September 18, 2019, 04:29:43 PM
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!
Title: Re: And yet another weak point
Post by: Sunny Jim on September 20, 2019, 06:28:33 AM
Was it noisy?
Title: Re: And yet another weak point
Post by: hd06 on September 22, 2019, 04:45:27 AM
 Has any broke on stock motors?
Title: Re: And yet another weak point
Post by: Don D on April 21, 2020, 02:48:19 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...
Does 2 failures = a trend?
Had one break, 100lb seat pressure springs.
Title: Re: And yet another weak point
Post by: FloridaJim5 on April 21, 2020, 05:22:24 PM
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.
Title: Re: And yet another weak point
Post by: Don D on April 22, 2020, 10:39:45 AM
You decide, 140# vs 200# seat
Title: Re: And yet another weak point
Post by: Dan89flstc on April 23, 2020, 04:21:14 AM
Two failures posted on the forum over the past 8 months.

Failure reports not exactly pouring in...
Title: Re: And yet another weak point
Post by: 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
Title: Re: And yet another weak point
Post by: 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
Title: Re: And yet another weak point
Post by: Don D on April 23, 2020, 02:29:22 PM
 :up: exactly
Title: Re: And yet another weak point
Post by: sandrooney on April 24, 2020, 05:59:19 AM
I bet that made a hell of a noise.
Title: Re: And yet another weak point
Post by: 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.
Title: Re: And yet another weak point
Post by: RTMike on April 24, 2020, 08:28:06 AM
Just like the M8 compensator sprockets,breaking at the thin areas.
Title: Re: And yet another weak point
Post by: sandrooney on April 24, 2020, 09:30:33 AM
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.