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Brettw

Sunstar electric clutch resolved, thanks!

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Brettw
Well, if you have been following my restore post, you know I have been working on a Sunstar. I put a new PTO switch in the tractor, adjusted the clearance on the clutch itself, and it works well. No problems, smooth engagement and no slipping that I can determine. After some use however, if it is shut off it doesn't want to re-engage until it cools off. No PTO light on the dash, no nuthin'. It does not cut out on it's own, it works great, until manually shut off. Deck is A-1 with no issues. Driveshaft A-1, nothing binding. Help? Ideas? Thanks in advance for the help as the shake down cruise continues!

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WITom
If there is no light on the dash, it sounds to me to be an issue with something other than the clutch itself. Interlock module, seat nanny switch, etc. I tend to think if the clutch was the problem, you would have the light no matter what.

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bnolte
If you have adjusted the air gap to specs, there is no reason the clutch would not engage, unless there is an electrical issue. I would check the continuity of the clutch coil itself while it is still hot. Except for the light going out, it sounds exactly like the symptoms my Landlord exhibited after running it a while, except the light would come on. It takes a lot more current to pull the clutch in that it does to hold it, so if the coil and switch check out, I would make sure the air gap is within specs anyway. On my Landlord, the spec is .012 to .015 inches.

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1Litre
Hi Brett , The unit you saw at my place has the v twin engine and it has what I call a new style electric clutch that is not mounted to the engine block. It has a stamped metal housing that is held on some studs with springs behind it. The nuts hold it on and set the clearance from stator to armature. You can see some slot(windows) in the housing and that is where you place a feeler gage to set the clearance. If the clearance is to wide it will have a hard time engaging. The housing also acts a brake to keep the movable half of the clutch from spinning when turned off.That is the sliding , squealing sound you hear when you turn off the clutch.I think it is to have a clearance of .010" to .012". Old style clutches have the same adjustment just assembled in a different way. See wht you have. Ken

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Brettw
This clutch is mounted to the engine block. I have heard no "squeeling" either on engagement or shut down. I have set the air gap at .012 through the "windows" as found in a forum search (thanks to ol' Maynard may he RIP) The clutch does have a good patina of rust on everything, not nasty but a good patina, and I do not think this clutch had been used in years (tractor was supposedly used to haul floats, etc in parades and such, not to cut grass, hence no deck). Ron, that sweet sounding engine could not possibly have a knock. Even if it did, with my ear muffs on I couldn't have heard it or you!:D

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Brettw
quote:
I would check the continuity of the clutch coil itself while it is still hot.
Bruce: Thanks for this info and I will check as you suggest. The question is, how do I check the continuity of the coil?

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Brettw
quote:
Check the resistance across the 2 wires going to the clutch or, if 1 wire, from that wire to ground. Should be a few ohms.
What is "a few" ohms? I have checked, and there 5.4 ohms across the two wires that come out of the clutch. Is that too much? A second clutch I have from another tractor I picked up, is 3.3 ohms. The problem is intermittent, and it will run until shut down. It seems to act up only when hot. Again, no light on the dash when it's not willing to engage. There is absolutely nothing, and then it may work after a bit.......or not. I have also rechecked and made sure I am running .012 gap at the clutch plates through the "windows".

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PhanDad
On my Homelite T-12, the electric clutch and "on" light are wired in parallel (each connect separately to ground to complete their respective circuits). If your tractor is wired the same, then the electric clutch isn't getting +12v when you're having the problem. You have a switch or switch power feed problem when hot. When the clutch won't pull in, I'd turn the clutch switch "off" and run a wire directly from the +12v battery connection and connect it to the electric clutch, if it pulls in (and the light goes on), you have a switch or power feed problem. If it doesn't, then the problems with the electric clutch. Another option would be to measure the voltage at the electric clutch when cold and working and then when hot and not working. Maybe the switch has too much resistance when hot and the low voltage at the clutch isn't enough to have it pull in (but I'd think you'd see a dimly lit light if this were the case.

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CarlH
Those resistances sound fine. It determined by the current required to engage the clutch. You should check when the clutch isn't working. That would indicate the winding is opening when hot.

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Brettw
Thanks Bill & Carl. The PTO switch is brand new. The ignition switch is brand new. The seat nanny switch appears to be working correctly and fine, seat light on the dash stays lit when your rear is planted and it appears to interact properly with ignition and shut down when you get off the seat. One thing I had noticed is when I first put the new switch in, the dash light lit up but no engagement. In checking everything after all of the disconnecting, trouble shooting remove/replace the hood, etc I found the clutch was not plugged in. Plugged it in and it worked fine. Point being, dash light came on even when clutch was not plugged in. So, Bill, I see your point. No dash light, likely no power to the clutch and probably not a clutch problem but a wiring or switch issue. Funny part is, when it's working, it will continue to work until you or the seat nanny shuts it off. It does not shut down during use. So that makes me think about the PTO switch or nanny part of that circuit and how those generally work. When you get up off the seat for instance, it shuts down the PTO, and even if you get back on before the engine dies, you have to turn the switch off and re-engage the PTO for it to come back on. That has me thinking. I suppose even a new switch could be bad. I'll be trying all of your suggestions to hunt down the problem and continue to diagnose. Thanks.

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PhanDad
From what you said is new, I'd bet on the interlock module not working correctly when hot. On a couple of my newer Sovereigns, I've seen them do strange things. In all cases the PO(s) have messed with the wiring. I'm thinking they are sensitive to polarity and a wiring mistake probably messes up part of the interlock functionality. Is it easy to wire "around" the interlock module for the clutch? If so, I'd give that a try. With some more thinking about this (without a wiring diagram), the above would only apply if the interlock module controls the +12v feed to the clutch switch or the ground for both the electric clutch and light pass through the interlock module. I was thinking the light would just be directly grounded, but then the light could be on and the clutch not energized if only the clutch ground went through the interlock module.

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Brettw
Well, Bill, I took the interlock module out of the latest Sunstar with the blown cam, and swapped 'em out. Ran around, cut grass, on / off a number of times and no issues. So it would appear as though the interlock module was the culprit. Thanks all for your help, I think the restore is now 99% and ready to use or market.

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