Clutch disc thickness

[Zjohnsonua]

My truck has no clutch issues at the moment, but I'll pulling the driveline to replace the rear main seal and that's a fine time for a clutch kit if it'll need one soon. I'd rather have the kit on hand to knock the job out in a day on my buddy's lift, and since Aisin kits are tough to come by locally, shipping needs to be planned in. But I'm not trying to throw money at a kit I don't need either...that's what spec's are for. I checked the FSM and searched around and it seems all clutch disc spec's are taken via rivet depth. That's not very useful when the driveline is intact, which brings my question:

Does anyone know or have an idea of what the minimum rivet depth translates to for disc thickness in practical use (i.e. you're-in-there-and-this-one-is-too-far-gone)? I get that this is going to be ball-park-ish, but I figure we can put together a close-enough spec to help others plan a bit.

Here's to hoping that there will be a few old and new clutch disks lying about in the Mud-iverse that y'all could put some calipers to.



Zach

 

[OSS]

Clutch disc wear can easily be seen without dropping the transmission. Just remove the flywheel cover under the truck and take a peek at the disc sandwiched between the flywheel & the clutch cover.

Rivet heads are just slightly below the surface of the bottom of the disk. About 0.1 mm.

When gooves can still be seen when viewing the clutch disc under the car, the rivets are not hitting the flywheel and there is that much clutch material left.

When NO gooves can be seen when looking at the disc under the car, the rivet heads still may not be grinding, but the disc must be replaced ASAP, as there is only 0.1 mm of disc material left before the rivet heads start grinding on the flywheel.

For reference, I've included two examples. First picture is of a brand new disc with zero miles on it, and the second photo is the 20 year old disc that had 200,000 miles on it before it got replaced ... but it wasn't even 1/2 worn yet. (Clutch was rebuilt because pilot bearing was shot).

When ordering replacement clutch parts, only order from a kit designed for your year of cruiser or individual items for your year of cruiser. You don't need to know the dimensions of anything. The vendors won't have it anyway. The manufacturers have already figured it out.
Whatever you do, don't buy generic clutch parts that "should fit". If you do, chances are pretty much certain that they won't fit correctly, work correctly or you'll be replacing them soon.

If you can scrounge up a couple extra dollars, I highly recommend using the Toyota clutch disc that has the rubber shock absorbers. I've tried both (spring & rubber) and the aftermarket spring dampened clutch transmitted noticeable judder when easing out the clutch.
I didn't like that feeling ---- so I removed the transmission again and installed a Toyota disc. Released smooth as butter. Also lasted over 200K miles and only 1/2 worn.

 

[Zjohnsonua]

Easy peasy. That rattled several cobwebs out. For internal parts, I'll just about always go OE. It's too much hassle to do the second time around because of part failure...

I'll give the radial depth a look this afternoon. Thanks.