Jeff
McCulloch engine starting - EXTREME SLOW MOTION
Moderator: Rob Voska
-
Jeff Campbell
- Site Admin
- Posts: 580
- Joined: Tue Jun 12, 2007 7:52 pm
- Vintage Karting items owned: 1961 Fox Go-Boy MC20's
Robron Chaparral dual MC101
Margay Cheetah MKIII - Location: West Bloomfield, MI
- Contact:
McCulloch engine starting - EXTREME SLOW MOTION
...I made it to Brodhead, and have a ton of great video and photos .... this one is one of my favorites. It was shot at 1200fps, watch the exhaust gas puff out of the muffler along with fuel splatter. The vibration and motion of the clutch at engagement is darn interesting to watch....
CLICK HERE to watch in Large HD Video mode (requires high speed Internet connection)
Jeff
Jeff
-
ted johnson
- Posts: 1685
- Joined: Fri Jun 15, 2007 7:59 am
Re: McCulloch engine starting - EXTREME SLOW MOTION
Nice vid, Jeff! It's like watching a little kid with a cold! Seriously, it's amazing how much things jump around. TJ
-
steveohara
- Posts: 411
- Joined: Thu Jul 19, 2007 2:29 am
- Vintage Karting items owned: 1969 Bug Sprint Mc 91B1
1965 Dart Gran Prix twin Mc100s
1963 Bug Scorpion ESll Mc45
Re: McCulloch engine starting - EXTREME SLOW MOTION
Jeff,
Great post! For all you guys looking at the clip, the movement you see in the clutch is the result of runout in the nut/bearing combo that holds the clutch hub on the crank. It is one of those often overlooked areas in the prep and can usually be easliy fixed with a flat plate and a little sandpaper and patience. It is not uncommon for the mating surface of the nut to be out of square with the threaded hole and what you see in the video is the result. To check the runout you need a dial indicator on a stand so you can put the finger of the indicator on the OD of the bearing and then turn the motor over.... best done with the plug removed to make the motor turn easy. Once you identify the high and low position of the bearing the nut can be marked and then removed and lightly sanded on the tip that faces the hub with a bit of bias to one side to square it up with the threads.
The problem can also be caused by a messed up hub or even the end of the crank being bent but those problems are rare compared to the out of square nut in my experience. BTW.... leaving them running out is a fast track to a broken crank and clutch zooming by at a high rate of speed.
I've never lost a clutch or broke a PTO end of a crank in all the years since I began checking the runout. It also makes a noticable difference in the performance and the amout of vibration you feel when driving the kart.
Whoever owns that nice kart needs to fix the runout before he breaks his nice stuff!
Regards,
Steve O'Hara
Great post! For all you guys looking at the clip, the movement you see in the clutch is the result of runout in the nut/bearing combo that holds the clutch hub on the crank. It is one of those often overlooked areas in the prep and can usually be easliy fixed with a flat plate and a little sandpaper and patience. It is not uncommon for the mating surface of the nut to be out of square with the threaded hole and what you see in the video is the result. To check the runout you need a dial indicator on a stand so you can put the finger of the indicator on the OD of the bearing and then turn the motor over.... best done with the plug removed to make the motor turn easy. Once you identify the high and low position of the bearing the nut can be marked and then removed and lightly sanded on the tip that faces the hub with a bit of bias to one side to square it up with the threads.
The problem can also be caused by a messed up hub or even the end of the crank being bent but those problems are rare compared to the out of square nut in my experience. BTW.... leaving them running out is a fast track to a broken crank and clutch zooming by at a high rate of speed.
I've never lost a clutch or broke a PTO end of a crank in all the years since I began checking the runout. It also makes a noticable difference in the performance and the amout of vibration you feel when driving the kart.
Whoever owns that nice kart needs to fix the runout before he breaks his nice stuff!
Regards,
Steve O'Hara
-
Scott Kneisel
- Posts: 477
- Joined: Mon Mar 24, 2008 7:48 pm
- Vintage Karting items owned: '63 Rupp Grand Prix, 66 Rupp Chappy, Mc6's, Mc8, Mc10's, Mc20's
Lotsa' other Macs - User Agreement: Yes
- Location: Farmington, NY
Re: McCulloch engine starting - EXTREME SLOW MOTION
Steve,
Good advice for me on all my outboard clutches. I will use a dial indicator just like you said and tweak the nut to be true. Thank you.
Question,
Does the same apply to the inboard clutch in the video which centers the hub on the taper and the drum on the shaft? The nut then just holds the hub in place and nothing is running on it. Looks to me like the clutch in the video has some bearing/bushing issues.
Thoughts?
Good advice for me on all my outboard clutches. I will use a dial indicator just like you said and tweak the nut to be true. Thank you.
Question,
Does the same apply to the inboard clutch in the video which centers the hub on the taper and the drum on the shaft? The nut then just holds the hub in place and nothing is running on it. Looks to me like the clutch in the video has some bearing/bushing issues.
Thoughts?
-
steveohara
- Posts: 411
- Joined: Thu Jul 19, 2007 2:29 am
- Vintage Karting items owned: 1969 Bug Sprint Mc 91B1
1965 Dart Gran Prix twin Mc100s
1963 Bug Scorpion ESll Mc45
Re: McCulloch engine starting - EXTREME SLOW MOTION
Scott,
I'm not sure I understand the question. The clutch in the video is an inboard drive setup with a cover that is supported by the bearing mounted on the nut that holds the center hub to the crank. Assuming the crank is running true and the hub fits right, the movement in the assemby while the engine is running and the kart is standing still indicates the nut is the problem. If the cover were removed, say like a Rev Grip, there would be no problem. On the outboard drive clutches the drum runs on a cylindrical stub built into the center hub and the clutch will run true as long as the crank and hub are good even if the nut is not running true.
I have seen inboard drive 9 tooth drums that have a bronze bushing that run out pretty bad. It is usually the result of a new bushing being fitted and then reamed or drilled to fit the crank out of square. In the case of the crooked bushing, it will not move like we see in the clip but it will run out when the clutch is hooked up and the kart is moving.
As a good general rule, it is wise to check all the parts for runout... crank, hub, drum and nut. Anything that is off will produce some kind of wobble that hurts the performance and can lead to failure.
Regards,
Steve
I'm not sure I understand the question. The clutch in the video is an inboard drive setup with a cover that is supported by the bearing mounted on the nut that holds the center hub to the crank. Assuming the crank is running true and the hub fits right, the movement in the assemby while the engine is running and the kart is standing still indicates the nut is the problem. If the cover were removed, say like a Rev Grip, there would be no problem. On the outboard drive clutches the drum runs on a cylindrical stub built into the center hub and the clutch will run true as long as the crank and hub are good even if the nut is not running true.
I have seen inboard drive 9 tooth drums that have a bronze bushing that run out pretty bad. It is usually the result of a new bushing being fitted and then reamed or drilled to fit the crank out of square. In the case of the crooked bushing, it will not move like we see in the clip but it will run out when the clutch is hooked up and the kart is moving.
As a good general rule, it is wise to check all the parts for runout... crank, hub, drum and nut. Anything that is off will produce some kind of wobble that hurts the performance and can lead to failure.
Regards,
Steve
-
Scott Kneisel
- Posts: 477
- Joined: Mon Mar 24, 2008 7:48 pm
- Vintage Karting items owned: '63 Rupp Grand Prix, 66 Rupp Chappy, Mc6's, Mc8, Mc10's, Mc20's
Lotsa' other Macs - User Agreement: Yes
- Location: Farmington, NY
Re: McCulloch engine starting - EXTREME SLOW MOTION
I see now Steve,
Thanks for clearing that up. I have never run an inboard wet clutch with a cover supported by the nut shoulder. I only run dry Rev Grips and the only wet clutch I am familier with is the Horstman 4 shoe wet clutch in which the cover is supported on an extension of the clutch hub itself and is esentially just a rev grip running in heavy oil.
Thanks for the info on other types. What brands have the configuration you are talking about?
I always have checked PTO and flywheel side runout on all the cranks that go into my engines and some are really almost perfect and some are really bad and I have to throw them out or return them to my supplier who is always surprised that they are bad because to the eye, they look perfect. I don't know if they came from the factory like that or if they actually get bent. Seems like it would be pretty tough to bend a Mac crank, maybe the threaded portion of the PTO but I have seen bad runout even on the straight shaft portion and even on the flywheel side.
What has been your experience?
Thanks for your input?
Scott
Thanks for clearing that up. I have never run an inboard wet clutch with a cover supported by the nut shoulder. I only run dry Rev Grips and the only wet clutch I am familier with is the Horstman 4 shoe wet clutch in which the cover is supported on an extension of the clutch hub itself and is esentially just a rev grip running in heavy oil.
Thanks for the info on other types. What brands have the configuration you are talking about?
I always have checked PTO and flywheel side runout on all the cranks that go into my engines and some are really almost perfect and some are really bad and I have to throw them out or return them to my supplier who is always surprised that they are bad because to the eye, they look perfect. I don't know if they came from the factory like that or if they actually get bent. Seems like it would be pretty tough to bend a Mac crank, maybe the threaded portion of the PTO but I have seen bad runout even on the straight shaft portion and even on the flywheel side.
What has been your experience?
Thanks for your input?
Scott