Difference in balancing?

Reply Subscribe

Thread Tools

Search this Thread

Jul 25, 2019 | 10:17 AM

#51

LQQK_OUT

Seasoned HDF Member

Joined: Nov 2006

Posts: 5,890

Likes: 1,903

From: East Coast, USA

Quote:

Originally Posted by Mattbastard

There's a video out there of a guy with a HUGE breaker bar doing stress tests on S&S cranks that shows welded cranks aren't what they're made out to me. Lemme see if I can find it.

I think S&S removed that particular video.

Jul 25, 2019 | 08:28 PM

#52

Mattbastard

Grand HDF Member

Joined: Nov 2009

Posts: 4,315

Likes: 1,663

From: Tampa

Quote:

Originally Posted by LQQK_OUT

I think S&S removed that particular video.

It was actually a longer version of the one you put up there. They did the OEM crank, a welded OEM crank (which didn't hold any better than the OEM unwelded), and the S&S crank.

Kinda makes me wonder. Darkhorse uses this thing they call a "Pro Pin". It's said to be much better than OEM at preventing scissoring, but I'm wondering how it works and why it's so special.

Jul 25, 2019 | 09:05 PM

#53

TwiZted Biker

Club Member

Joined: Mar 2009

Posts: 66,115

Likes: 51,405

From: Niles Canyon Ca.

Quote:

Originally Posted by Mattbastard

It was actually a longer version of the one you put up there. They did the OEM crank, a welded OEM crank (which didn't hold any better than the OEM unwelded), and the S&S crank.

Kinda makes me wonder. Darkhorse uses this thing they call a "Pro Pin". It's said to be much better than OEM at preventing scissoring, but I'm wondering how it works and why it's so special.

I suspect they have over sized crankpins which would give a tighter interference press fit when assembling, they'd just match hone the rods to the new pin & rod rollers or have new rod sets already to size. Pretty much the only way you'll change the dynamic on press assembled cranks, different materials alone won't do it.

This is how you rebuilt the old 5 pc flywheels & rods before decent quality new rod sets became easily available & affordable.

Last edited by TwiZted Biker; Jul 25, 2019 at 10:10 PM.

Jul 25, 2019 | 10:07 PM

#54

LQQK_OUT

Seasoned HDF Member

Joined: Nov 2006

Posts: 5,890

Likes: 1,903

From: East Coast, USA

Quote:

Originally Posted by Mattbastard

It was actually a longer version of the one you put up there. They did the OEM crank, a welded OEM crank (which didn't hold any better than the OEM unwelded), and the S&S crank.

I asked S&S about this missing YouTube video. They responded, "Issues with music, we will redo at a later date".

Jul 26, 2019 | 07:46 AM

#55

Mattbastard

Grand HDF Member

Joined: Nov 2009

Posts: 4,315

Likes: 1,663

From: Tampa

Quote:

Originally Posted by TwiZted Biker

That would make sense, and leave the hole in the flywheel the same size so you need a 50T press to put the thing together.

Truing that thing must be a bitch tho

Jul 26, 2019 | 11:35 AM

#56

splattttttt

Ultimate HDF Member

Joined: Jul 2014

Posts: 5,649

Likes: 430

From: MASS_hole

I saw a video moons a go of someone using a steel pin/dowel that went between the two flywheel pieces that spun off one another and created the unbalance. The pin/dowel goes in between the two once a correct balance has been achieved and then welded

Last edited by splattttttt; Jul 26, 2019 at 11:57 AM.

Jul 26, 2019 | 11:54 AM

#57

TwiZted Biker

Club Member

Joined: Mar 2009

Posts: 66,115

Likes: 51,405

From: Niles Canyon Ca.

Quote:

Originally Posted by Mattbastard

That would make sense, and leave the hole in the flywheel the same size so you need a 50T press to put the thing together.

Truing that thing must be a bitch tho

I still have oversized rod bearings in .0001” increments in my parts stash, you’d be surprised the difference .0005” makes in a tight assembly.

For pressing & truing I’m sure they use a precision blanking die set that holds the wheel halves exactly true and parallel to each other. Almost bought one myself years ago, just didn’t do enough work to justify the money.

Last edited by TwiZted Biker; Jul 26, 2019 at 11:59 AM.