MP3023 TC Functionality Question - Clutch Pack

[ZombieK5]

While Assembling our MP3023 Transfer Case, during the rebuild we put in new clutch frictions and steels. We put all parts together on the shaft and took all the measurements. It all seems "in spec." however we have a small gap, see photo below:



The clutch housing goes over the clutch pack. From my understanding, these clutches engage when the 4 wheel drive is turned on.

Photo below is ORIGINAL setup when the TC was torn down. The same gap exists.



For the life of me, I don't see HOW the 4 Wheel Drive Clutch Hub (thick metal plate on top of clutches) is compressed to engage with the clutch pack. The hub DOES compress. I had to compress it to install the retaining ring.

Am I missing something here?

I used the original 3mm shim on top of the clutch hub. I DID NOT replace the pressure plate on the bottom...

Anyone understand, mechanically, how the clutches engage?

 

[Blue85]

I think you show pictures of all of this in your other thread. https://ck5.com/forums/threads/2014-silverado-mp3023-transfer-case-disassembly.351759/



I think those two plates rotate a few degrees relative to each other, so the balls drive the plates further apart. The rotation is from this actuator lever.





Some of these transfer cases use a solid linkage of the front drive for "4WD" and rely on the clutch for "Auto 4WD" and it engages/disengages dynamically as traction demands change. Most of those use an electro-magnet actuator, so maybe the new supplier decided that was redundant and you could get both modes with the clutch alone. I can't imagine a clutch being a cost-effective approach if there is no form of automatic 4WD mode, so it probably has one.

 

[ZombieK5]

I think you show pictures of all of this in your other thread. https://ck5.com/forums/threads/2014-silverado-mp3023-transfer-case-disassembly.351759/

View attachment 513559

I think those two plates rotate a few degrees relative to each other, so the balls drive the plates further apart. The rotation is from this actuator lever.

OK, so the two levers (plates) with the balls between them are pulled apart which would push the pressure plate upward towards the clutch hub. The upward movement compresses the clutch pack?

 

[Blue85]

That's how I interpret the diagram.

 

[ZombieK5]

That's how I interpret the diagram.

I guess that makes sense. The lower pressure plate and both arms (plates) are "free floating" and are not splined.

 

[Blue85]

There should be a spec for the amount of gap in the clutch plate. Obviously, too little would cause drag/wear and too much might let it slip when the actuator is maxed out. In automatic transmissions, there are different thickness end plates or shim plates you can add or subtract to get the right stackup. They may have designed this to work over a wide enough range of heights that it's not usually an issue, but unless you buy the clutch from the OEM, they have no idea what you're working with.

I assume you just measured before and after and it's basically the same.

 

[ZombieK5]

There should be a spec for the amount of gap in the clutch plate. Obviously, too little would cause drag/wear and too much might let it slip when the actuator is maxed out. In automatic transmissions, there are different thickness end plates or shim plates you can add or subtract to get the right stackup. They may have designed this to work over a wide enough range of heights that it's not usually an issue, but unless you buy the clutch from the OEM, they have no idea what you're working with.

I assume you just measured before and after and it's basically the same.

I measured and bought the special tool to measure the clutch stack.

All was in spec and I used GM OEM friction and steels.




They do make shims of different thicknesses BUT they are not available and they have no idea when they'll be available.

I did not replace the pressure plate or clutch hub so all the OEM measurements were the same. The pressure plate had no wear and no observable wear patterns. The old frictions were the same thickness as the new ones. The new steels were slightly thicker... The old steels had noticeable wear.



The manual is horrible. I did as they instructed with the measurements and it all seems to have worked out.

It would have been good to have a KNOWN range for the gap once fully assembled. I am sure they know the range the two arms move when engaging the 4wd.

 

[Blue85]

I think the question is what differences the shims account for. If it's clutch housing build tolerance, then you haven't changed anything. You would think the factory steels and frictions would be quite good on tolerance, such that replacing as you did would just put it back to the same stack up it left the factory with. If anything else was wearing appreciably it should be obvious.

 

[Blue85]

The lower pressure plate and both arms (plates) are "free floating" and are not splined.

Just imagine if they were spinning.