I found an old slip-a-just clutch in my box of parts that I never used back in the day because the rev grip worked just fine on dirt which was where I did 90% of my racing. Now that I'm doing road courses, I want to try it out this weekend at Avon. Problem is I'm not sure which way to move the shoes to get more or less slip. I tried moving them closer to the pivot thinking I'd get more slip, but, just running it on the stand against the brake, it seemed to have the opposite effect. Am I going the wrong way or is my imagination playing tricks on me?
Bill,
Moving the shoes closer to the pivot has always allowed them to slip more...
Just wondering,
Are the shoes and arms trailing the rotation?
In other words, are the pivot points "leading the shoes and arms with the rotation of the motor.
(07-26-2017, 05:23 AM)Jeff May Wrote: Bill,
Moving the shoes closer to the pivot has always allowed them to slip more...
Just wondering,
Are the shoes and arms trailing the rotation?
In other words, are the pivot points "leading the shoes and arms with the rotation of the motor.
Yes, the arms are trailing the pivot. So I am going the right way. I guess it was just my imagination. We'll see when I get it out on the track.
As Jeff said, the shoes need to be installed in the trailing position. Otherwise it will engage way too early.
See the attached photo. Refer for a moment to the shoe on the upper left. For an engine that rotates CW at the PTO (like a McCulloch), the friction shoe must be installed to the LEFT of the arm's pivot pin, as shown.
Moving the friction shoe further from the pivot pin will reduce the engagement RPM.
Any of the oils folks use in Burco's should work fine for the Slip-A-Just.
You are correct that the arms should be in the trailing position but you are off on the effect of moving the shoe away/closer to the pivot along the arms. The engagement speed goes up or down in relation to the force of the shoe against the drum. With the shoe attached to the arm as far away from the pivot as possible the force of the shoe against the drum will be less than if the shoe is placed closer to the pivot for the simple reason that the arm hanging out past the shoe acts like a lever to increase the force of the shoe against the drum.
The shoe itself will be traveling the same speed regardless of where along the arm it is mounted so the centrifugal force generated by the shoe alone will be the same in any position. However, since the arms have a pivot they will act as a lever on the shoe anywhere the shoe is located other than at the far end.
Think of your good old nutcracker and why it is so easy to crush the nut if it is placed close to the pivot versus if you place the nut out at the end of the two handles LOL
Steve O'Hara
07-30-2017, 09:13 AM (This post was last modified: 07-30-2017, 09:17 AM by Bill Peck.)
(07-28-2017, 01:48 AM)steveohara Wrote: Guys,
You are correct that the arms should be in the trailing position but you are off on the effect of moving the shoe away/closer to the pivot along the arms. The engagement speed goes up or down in relation to the force of the shoe against the drum. With the shoe attached to the arm as far away from the pivot as possible the force of the shoe against the drum will be less than if the shoe is placed closer to the pivot for the simple reason that the arm hanging out past the shoe acts like a lever to increase the force of the shoe against the drum.
The shoe itself will be traveling the same speed regardless of where along the arm it is mounted so the centrifugal force generated by the shoe alone will be the same in any position. However, since the arms have a pivot they will act as a lever on the shoe anywhere the shoe is located other than at the far end.
Think of your good old nutcracker and why it is so easy to crush the nut if it is placed close to the pivot versus if you place the nut out at the end of the two handles LOL
Steve O'Hara
(07-28-2017, 01:48 AM)steveohara Wrote: Guys,
You are correct that the arms should be in the trailing position but you are off on the effect of moving the shoe away/closer to the pivot along the arms. The engagement speed goes up or down in relation to the force of the shoe against the drum. With the shoe attached to the arm as far away from the pivot as possible the force of the shoe against the drum will be less than if the shoe is placed closer to the pivot for the simple reason that the arm hanging out past the shoe acts like a lever to increase the force of the shoe against the drum.
The shoe itself will be traveling the same speed regardless of where along the arm it is mounted so the centrifugal force generated by the shoe alone will be the same in any position. However, since the arms have a pivot they will act as a lever on the shoe anywhere the shoe is located other than at the far end.
Think of your good old nutcracker and why it is so easy to crush the nut if it is placed close to the pivot versus if you place the nut out at the end of the two handles LOL
Steve O'Hara
Thanks Steve. Unfortunately I didn't see you post until Friday. That's after I spent all day Thursday trying to get it to slip more going the wrong way. Oh well, there's no fool like an old one!
You'll all be pleased to know that the slip-a-just does work. It was just a matter of WHEN ALL ELSE FAILS, READ THE INSTRUCTIONS (duh)! I just got it going on the stand and it has more than enough slip in the second to last adjustment position. Thanks for all the help, guys, especially Bruce for furnishing a copy of the instructions.
