Slip clutch spring tension / spring rate

pripyat · Aug 4, 2020

I have a slip clutch that is at least 50 years old, It came off of a Long Mfg 5' brush hog. I want to replace the springs as they were all bottomed out when I received the unit. There are more springs on this unit than most the slip clutches I'm seeing online, so I'm not really concerned about not having enough spring tension (assuming I went with a "standard" replacement spring).

Does anyone have any idea what the spring rate is for these springs? I order nearly all my stuff from this industrial supply store, I've got everything in my cart (replacement oil seal, replacement bolts) but wanted to see if I could get the springs from them as well. I spent a while on google but can't find anything about spring rate.

ericm979 · Aug 4, 2020

You can measure the wire diameter and count the coils to calculate the spring rate. I have it in a book somewhere but I bet there are calculators on line. The type of steel doesn't matter significantly for the rate, only for durability.

Someone may have bottomed out the springs because the clutch was worn and slipping.

pripyat · Aug 6, 2020

For completion - I don't want this thread to die without adding something that might be useful..

There are 12 springs on the plate. Wire diameter = .234", outer diameter = .915", Free length = 2.00", Active Coils = 8.

Seems like this thing has to be compressed from its original length? I find it odd that it is exactly 2" long. The ID of the spring can be calculated but is ~ .45"

I'm 90% sure, considering the pitting on all the plates and the absence of usable friction material, that I would be better off buying a new unit.

DieselBound · Aug 10, 2020

I'd recommend total replacement. You're going to have to spend to get the necessary replacement parts anyway, not to mention all the time needed in the entire process.

New PTO shafts with clutches aren't very expensive. It's also possible, if you know what the shaft is, to just get a new clutch.