Is It Ok for Throw Out Nearing on a Clutch to Continuously Spin

mwebfj60

The question I'm putting out is this...Is it better for the release/throwout bearing to always be in contact with the Pressure Plate or away from the pressure plate when clutch is out? Mr. T decided in mid 1984 that it should always be in contact.

FJ60s from 1/81-8/84 have a clutch slave system designed to keep the throwout bearing away from the pressure plate when clutch is released. The rod has an adjustment nut system on the end that engages the fork and a spring return that pulls the fork arm toward the slave cylinder. After 8/84, the slave is designed with a spring in the slave rod to always keep the throwout bearing in contact with the pressure plate by applying force away from the slave cylinder and pushing on the fork arm.

OEM Part # for the following parts are the same for all models it appears:
Release Bearing: 90363-52001-77
Pressure Plate: 31221-60020
Pilot Bearing: 90363-15004
Flywheel: 13405-69015
Clutch Disk: 31250-36343
Master Cylinder: 31410-60282

I did find a Pressure Plate for 1/81-8/84 production, part number 31210-36330.

Clutch slave for 1/81-8/84 part number 31470-60081
Release Fork for 1/81-8/84 part number 31204-60030

Clutch slave for after 8/84 part number 31470-60102
Release Fork for after 8/84 part number 31204-60060

So will the throwout bearing last longer if it is constantly spinning...always in contact with the pressure plate, or not spinning...away from the pressure plate when clutch is out but jarred into motion when it hits the pressure plate every time you engage the clutch? I don't often disagree with Mr. T but after reading way too much about throwout bearing chirping, I want to see what the consensus is here.

Output Shaft

My guiding light that has never failed me is — Never second guess Toyota about the Land Cruiser —

The constant contact throwout bearing must have been an upgrade to fix what they must have felt was an issue with the earlier non-contact method used in all previous Land Cruisers.
I can say with certainty that the constantly spinning throwout bearing of the later design is not the weakest link in the clutch assembly. The pilot bearing or the clutch disk will go first.

Yes, it could maybe squeak a little when it gets 20 years old, though mine never did (I've heard one that did).

I recently replaced my clutch. It had 200,000 miles and 28 years on it ('86 with the later constant contact throwout bearing design). The throwout bearing worked perfectly when I pulled all the parts. I couldn't detect any wear playing with it. But I replaced it anyway since it was out.

There's a reason these bearings cost $90 a pop. They are bomber. Don't use an aftermarket bearing!

mongoose2231

Yes 90 bucks is what I paid for mine from beno. Prolly never gonna change it again

Spike Strip

Yes, the Toyota OE bearing is more robust than any other I've seen available aftermarket (here in the USA, anyway).

Used to have pix of the OE vs. the commonly avail Toyo, side by side, but can't find them at the moment... Maybe someone ?

mwebfj60

Agreed. I never had any trouble with my clutch, 3/83 slave setup...until recently when I replaced the clutch disk, pressure plate, throwout bearing, and pilot during the H55 upgrade. I adjusted to FSM specs...pedal height, slave/fork play and such. Got a chirping/high pitch squeel off the throwout bearing barely rubbbing on pressure plate. A couple of adjustments later and a couple of adjustments after that and it's good to go for now. That started me down this rabbit hole. If I had researched all of this beforehand, I probably would have put in a post 85 slave cylinder and fork...or maybe not after going further down this rabbit hole and seeing the differences in the fork, slave, and mounting of slave to bellhousing.
@CaptClose , possibly something to consider when you're doing yours.

Shacklewhacker

Yes, the Toyota OE bearing is more robust than any other I've seen available aftermarket (here in the USA, anyway).
Used to have pix of the OE vs. the commonly avail Toyo, side by side, but can't find them at the moment... Maybe someone ?

Spike Strip - I didn't notice the engine and chassis manuals link in your auto sig area. Already have the emissions, but those other two are a big score.
Thanks.

mwebfj60

Does anyone have a side by side of the two different Forks? From reading other threads, the post 85 forks don't have the return spring hole or a hole through the cup part of the fork where the slave rod sits. What I'm getting at is will a pre 85 fork work with a post 85 slave cylinder setup?

bhk

Not side by side, but there are good images of the two setups in these threads. It doesn't look to me like the earlier fork will easily work with the later slave cylinder, but I could be wrong.

slave cylinder

Throwout bearing spinning

mwebfj60

Looks like a lot shorter rod on the newer slave? And different mounting on the bellhousing? Is there an end to this rabbit hole? Sheesh!

mwebfj60

Here's something to consider. I recently developed a knocking sound...didn't change any when removing one plug at a time. Pulled the oil pan and started pulling rod caps, all checked good, pulled main caps, all good. Checked crank thrust and it was almost .02" Spec is around .003 to .006 and limit is .012. This is after 60k on full rebuild. Just finished replacing main bearings and waiting on a new radiator then I will report back.

This is the reason I couldn't seem to keep my clutch properly adjusted.

I'm leaning toward constant contact of the throwout bearing being a little better as it may alleviate a small amount of force fore and aft on the flanged #3 bearing.

Output Shaft

If the knocking sound only happens at idle but not higher, like at 1000 rpm, it may just be the engine vibration transmitting through the transmission and knocking the tranny gears together.

To test that theory, put the transfer case in neutral and transmission in any gear at idle & let out the clutch. See if the clanking goes away (or gets worse). Try 4th gear.

mwebfj60

Good stuff OS. According to my hillbilly mechanic stethoscope (long screwdriver) it was coming from the crank area. Maybe the sound was transmitting across but when I was laying underneath with the flywheel cover off it sure seemed to be coming from inside the oil pan.

Output Shaft

Ever since I've had my cruiser (since 1988) occasionally I would hear at idle a clanking inside the engine. It was most noticeable up front like the sound was coming from the crank banging against something horizontally. Like big thrust clearance gap as you mentioned.

Sometimes the sound would go away for a long time (years) then come back again. It was only at idle. Since I purchased my cruiser when it only had 42,000 miles on the odo - and it was making that racket occasionally back then, I assumed (I think rightly) that it was just the nature of the beast.

I think that the times is was clanking was when the engine wasn't idling quite as smooth as it should.
Now with my cruiser hitting 300,000 miles and idling smooth & quiet & nice, i haven't heard that clank since.

mwebfj60

The new Flanged bearing I put in took the thrust back down to .004 so we will see. I had just decelerated through the gears coming off the highway when I noticed it. After sitting at idle for just a moment it quieted way down but was still there. Did the above mentioned troubleshooting roadside. Pulled it forward a couple hundred feet to a parking lot and it had almost completely went away. .02 doesn't seem like much until you are watching the crank clank back and forth using a screwdriver!

LAMBCRUSHER

Like a hotdog in a hallway...020 is huge

FJ40Jim

FWIW, the engineering theory behind the TO bearing change:
Early bearings had crappy grease & relatively short lifespans, so were pulled off the clutch when not needed. But the hardest thing for a bearing is being spun free/unloaded/unguided. It's why they tell you not to spin a ball bearing with a blow gun to dry it off. That cool whine & rattle noise of a free-spinning bearing is the rollers/balls chattering & rattling, potentially damaging the rolling elements & races.

As grease got better in sealed bearings, things were changed so the bearing is always pressed against the clutch so it doesn't go wha-ziiing every time the clutch pedal is lifted. 'Modern' grease is good enough that it's not a factor in the expected 10 year life of a clutch, or a modern sealed wheel bearing.

Is It Ok for Throw Out Nearing on a Clutch to Continuously Spin

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