NH 488 Slip Clutch

[Draagyn]

Mower turns over by hand but slip clutch won't grab. Any temporary fixes until I can get it fixed properly?

 

[RickB]

Weld it together.

 

[holeycow]

Disassemble entire clutch. Clean friction surfaces with solvent, wire brush, sandpaper, bla, bla, bla. Reassemble cleaned, degreased components and preload springs until it doesn't do that anymore.

 

[holeycow]

Or weld it together and pray you don't swallow something that stops the machine.

 

[Draagyn]

Disassemble entire clutch. Clean friction surfaces with solvent, wire brush, sandpaper, bla, bla, bla. Reassemble cleaned, degreased components and preload springs until it doesn't do that anymore.

Done all this. Removed springs and torqued down bolts as hard as I could and still slips.

 

[Draagyn]

Think I'll give it four little tacks with the MIG and hopefully they break if I hit something.

 

[holeycow]

Is there a friction disc in there?? If its steel-on-steel it will only slip.

 

[holeycow]

Obviously it is a very simple set-up....

 

[RickB]

Obviously it is a very simple set-up....

Obviously the friction discs have checked out, or it would drive with the springs taken out and bolts fully torqued. What is left of the assembly is probably junk anyhow. He may as well weld it and learn how that can end.

 

[Draagyn]

Obviously it is a very simple set-up....

This is really poor advice. But thanks for trying.

Have you worked on a NH slip clutch like this before? They are something special!

 

[Draagyn]

I'm working on making my own friction discs before I weld it

 

[Tx Jim]

This is really poor advice. But thanks for trying.

Have you worked on a NH slip clutch like this before? They are something special!

488 slip clutch also looks fairly simple to me very similar to other slip clutches I've worked on. Friction disc PN is 127434 @ $103.33 ea

 

[holeycow]

This is really poor advice. But thanks for trying.

Have you worked on a NH slip clutch like this before? They are something special!

I have worked on several. Obviously it is a simple setup..

Just to clarify: I own 2 488's, one of which I bought as a wreck and rebuilt to as good-as-new. That's the one we had going today..

 

[Draagyn]

488 slip clutch also looks fairly simple to me very similar to other slip clutches I've worked on. Friction disc PN is 127434 @ $103.33 ea

I like your price better than mine! I was quoted $160 each

 

[Draagyn]

So let's get some things straight here! It is interesting how NH calls them 'friction' discs and in the picture above they are clearly illustrated with texture different from the rest of the clutch.

However upon removal of the discs they are just a 'special' (NH dealers words, not mine) type of metal with no friction material on them. Now doesn't that just mess with ones mind? How is (smooth) metal on metal on metal going to hold? Why have a $160 special metal disc where you could easily have a $5 disc of brake pad material?

Now this mower is new to me, is in rough shape, and has many parts already thrown at it by me and the previous owner. The rolls are near the end of its life and I'm concerned about spending too much fixing little things, like over $300 on the slip clutch.

Anyways when I removed my slip clutch on my 478 to try it on my 488 I noticed the special friction discs were conical where my 488 discs are perfectly flat. Maybe this is how they get friction with extra tension on the clutch.

Well the story ends good. The clutch was fine the whole time. It's the female end of the rear PTO drive shaft that is broke!! Popped the one of my 478 and onto the 488. In less than 2 minutes I'm running again!

 

[holeycow]

WooHoo! Good news.

Those 488's are good machines. That's why NH still makes the same machine today. If they suit your purpose, they are well worth rebuilding. New ones are freakishly expensive for what they are.

 

[Tx Jim]

Anyways when I removed my slip clutch on my 478 to try it on my 488 I noticed the special friction discs were conical where my 488 discs are perfectly flat. Maybe this is how they get friction with extra tension on the clutch.
!

According to NH 478 parts catalog 478 & 488 utilize the same friction disc(127434).