need help with LS/Centerforce clutch combo after clutch replacement

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Hi all,

I'm looking for information regarding a problem I have after a motor swap. I had a block failure of an aluminum 5.3 in my Fj45 after 10 years of solid and reliable performance. After some research, I decided to replace it with an iron 6.0. The engine I chose was the GM Performance LS364/450. This would allow me to re-use some of my existing hardware and ease some of the financial pain of replacement.

image0.jpg


While there, I chose to resurface the flywheel and replace the clutch components with new parts from Advanced Adapters. The old clutch was a LUK, and the new is a Centerforce unit (as AA no longer carries the LUK). Looking at the Centerforce unit, I saw that it appeared to be a gold painted LUK with added weights. I reused my old clutch master and slave, along with it's mounting bracket and hardware.

Engine - LQ9
Flywheel - Adv. Adp. LS (resurfaced)
bell housing - Adv. Adp. aluminum bell housing to accomidate NV4500 or Ranger Torque-splitter (which I have)
Transmission - Ranger Torque Splitter connected to an H42
Transfer - Orion 4:1

image11.jpg


Unfortunately, after getting the truck running, I have been unable to adjust/bleed the clutch enough to allow full disengagement. I've done some searching and reading here, but found no hard data. I saw references to a Downey Chevota clutch, different throws with different combinations of clutch slaves and masters, etc.

Can you guys point me in the right direction?

Has anyone faced a similar situation and come up with parts to solve it?

Do some slave cylinders have longer throws than others?

TIA,

Jim
 
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GLTHFJ60

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To start, measure the free play of the throw out bearing. Remove the slave cylinder and actuate the fork by hand to see how far it will move from all the way in to all the way out. Measure where the slave cylinder presses on the fork. Shouldn't be more than half an inch or so, preferably less.

Next, hook the slave back up and compare the position of the fork with your prior measurements. That will give an indication of how close the throw out bearing is to the clutch when the clutch pedal is up. Should be real close to touching, basically just far enough lifted from the clutch to not be spinning the throw out all the time.

Finally, measure the throw of the slave cylinder. Should be an inch or so.

All of this data will help determine the corrective action. If the fork when hooked up to the slave is not close enough to the clutch when the clutch pedal is up (my suspect) then you can extend the slave pushrod by whatever to get it to work the way you want. Maybe a 1/4 or 1/2" pushrod spacer would work. Not sure which slave you're running, but the toy slaves come apart pretty easy, and you can either make a new one entirely or just weld on an extension.


All of this is to say that if the clutch is intended to be a direct replacement, and nothing else changed, then perhaps they took just enough off the flywheel during resurface to cause this problem. You may well need just another 1/8" of fork travel to disengage all the way.
 
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It looks as though the clutch slave I was running is a replacement part for '75 to '85 Land Cruisers. I saw some reference to the idea that '74 and earlier clutch slaves are better suited for this application?
 

EWheeler

4 Cruisers, No Garage !
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Hi all,

I'm looking for information regarding a problem I have after a motor swap. I had a block failure of an aluminum 5.3 in my Fj45 after 10 years of solid and reliable performance. After some research, I decided to replace it with an iron 6.0. The engine I chose was the GM Performance LS364/450. This would allow me to re-use some of my existing hardware and ease some of the financial pain of replacement.

View attachment 2746386

While there, I chose to resurface the flywheel and replace the clutch components with new parts from Advanced Adapters. The old clutch was a LUK, and the new is a Centerforce unit (as AA no longer carries the LUK). Looking at the Centerforce unit, I saw that it appeared to be a gold painted LUK with added weights. I reused my old clutch master and slave, along with it's mounting bracket and hardware.

Engine - LQ9
Flywheel - Adv. Adp. LS (resurfaced)
bell housing - Adv. Adp. aluminum bell housing to accomidate NV4500 or Ranger Torque-splitter (which I have)
Transmission - Ranger Torque Splitter connected to an H42
Transfer - Orion 4:1

View attachment 2746400

Unfortunately, after getting the truck running, I have been unable to adjust/bleed the clutch enough to allow full disengagement. I've done some searching and reading here, but found no hard data. I saw references to a Downey Chevota clutch, different throws with different combinations of clutch slaves and masters, etc.

Can you guys point me in the right direction?

Has anyone faced a similar situation and come up with parts to solve it?

Do some slave cylinders have longer throws than others?

TIA,

Jim
I don't think anyone is going to be able to solve your problem remotely, this sounds like either a setup issue or part incompatibility with new clutch and you need to collect some data and select the correct parts.

Your clutch fork and slave cylinder should be adjusted such that the throw out bearing does not rest against the pressure plate fingers, having ~1/32 - 1/16" of clearance. You would then need to make sure your slave cylinder provides enough throw of the throw out bearing to fully disengage the clutch. It sounds like this is not the case, but you may not have the throw out bearing adjusted close enough to the pressure plate?

I am assuming everything is re-assembled and back in the truck?
 
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Yes, everything is re-assembled and back in the truck. All parts are the same with the exception of the following:

LUK clutch/pressure plate swapped with Centerforce (both supplied by AA)

Flywheel was resurfaced (observed more agressive pattern than when flywheel was new)

Original clutch master and slave were sourced from SOR as a kit (018-01-KIT)

Slave was replaced some years ago with a NAPA part number P8727 sourced while on the trail. Reference shows its part number crosses for 75-84 Land Cruisers.

I also see that SOR claims to sell a "V8 conversion kit" comprised of a clutch master and long throw slave for the low-low price of $174.
 

EWheeler

4 Cruisers, No Garage !
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Yes, everything is re-assembled and back in the truck. All parts are the same with the exception of the following:

LUK clutch/pressure plate swapped with Centerforce (both supplied by AA)

Flywheel was resurfaced (observed more agressive pattern than when flywheel was new)

Original clutch master and slave were sourced from SOR as a kit (018-01-KIT)

Slave was replaced some years ago with a NAPA part number P8727 sourced while on the trail. Reference shows its part number crosses for 75-84 Land Cruisers.

I also see that SOR claims to sell a "V8 conversion kit" comprised of a clutch master and long throw slave for the low-low price of $174.
This is what I would try. Unbolt & remove the slave cylinder. Manually manipulate the clutch fork and find out where the throw out bearing touches the pressure plate fingers and somehow mark where that point is so you can reference it later. Reinstall the slave cylinder. Adjust the slave cylinder rod so that the clutch fork is in alignment with your mark you made earlier. Test and see if you can now disengage the clutch. If not, you are not getting enough throw out of the slave cylinder.
 
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So, I have a solution of sorts. I spoke with AA and they said I did one of two things wrong. The first was that I put the clutch disk in backwards, or I did not sink the pilot bushing/spacer combo in deep enough in the back of the crank. Bad news was that the trans/OD/transfer lump had to come out.

I had also taken some measurements of the clutch fork throw and found it to be about 1 inch. AA said that they felt that was fine.

After pulling the trans, it was found that I had sunk the pilot bushing and spacer as deep as it would go and that the clutch disk was installed correctly. There was a sticker on the disk saying "this side toward flywheel". I even wondered if someone put that sticker on the wrong side as a cruel joke.

Tech support at AA was very helpful and stuck with me throughout this whole troubleshooting process. I took pictures of everything and made measurements that they asked for. We even put the trans back on the engine without the flywheel and took a picture thru the clutch fork window.


image1.jpg
image0.jpg
 
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So back to the drawing board.

We put the old and new pressure plates on the bench for a "side by side" exam. It ended up that both parts were the exact same LUK number, with the Centerforce being painted gold and having the centrifugal weights installed. I decided to pull the weights and reinstall the new parts, as the old clutch worked fine for 10 years and looked like new. The old pressure plate still showed the manufacturing machine marks on it's surface.

I tried to call AA back to discuss this idea, but they had closed for the day. We re-assembled the whole mess and noticed that there were two sets of holes that could be used on the flywheel. One set had threads to the top of the holes, the others had countersunk threads. After a discussion, I decided to use the holes with full threads.

We started to bolt the clutch back up to the flywheel and I found an email from AA telling me that another possible failure of the original assembly could have been that I did not use the countersunk holes for my initial install. This could impede pressure plate throw because the plate was not torqued far enough down. Solution was to use the countersunk holes or add a lock washer to the bolts for additional spacing.

Note: My ARP bolts did have lock washers...... :confused:??
 
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This is a picture of the original assembly of the clutch on the back of the motor.

clutch.jpg


Looks pretty tight to me, but we adjusted the clutch to use the countersunk holes and removed the weights. Torqued to 74 ft/lbs and reassembled.

I am happy to report that all is well in mudville. :cheers:
 

GLTHFJ60

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What exactly did you countersink? The bolt holes for the pressure plate in the flywheel?

Doesn't make sense that's what fixed it.
 
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There are two separate sets of 6 holes in the flywheel (total of 12 holes). One set is threaded to the flywheel surface, and the other has the threads countersunk into the body of the clutch. If you look at both sets of holes, the countersunk set has a slightly larger hole drilled 3/16th inch deep, then necking down to the normal 3/8 x 16 threads.

Hope that helps to make the mental picture.
 

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