What did I do wrong? NV4500 Swap Issues

83Burban · May 15, 2026

Backstory....spent several years now sourcing parts to put a later model NV4500 in my 83' K10 Suburban. Total Frankensteins monster. Finally got it all in...fired it up.... Much to my dismay there was a terrible knocking sound coming from the bell housing. Finally got time to pull it all back out....here is what I found. Its a Luk clutch and slave.

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Everything seemed to bolt up fine? But I guess the throw out bearing is grinding on the clutch disc? Did I buy the wrong parts? Or did I goof the install?

Edit: Just so all part numbers are in one place.
Flywheel # NFW1041 73-80'
97' K2500 Luk Clutch Kit - 04154 (04-154)
97' K2500 Luk Slave - LSC265B

Rustisbest · May 15, 2026

I dont know if its your issue or not but when I swapped in an internal slave NV4500 to my Tahoe it called for a different flywheel and clutch kit than the NV3500 for the same model year. I never dug any deeper on the differences though.

83Burban · May 15, 2026

Its a 454 truck that was previously a TH400. I'll have to check but im pretty sure the flywheel was for a mid 90s 454 truck with a NV4500.

Bextreme04 · May 15, 2026

83Burban said:
Its a 454 truck that was previously a TH400. I'll have to check but im pretty sure the flywheel was for a mid 90s 454 truck with a NV4500.

Do you have a 90's 454 in it? The flywheel for a Mark IV will be very different than one for a Gen V or Gen VI 454. Gen V and Gen VI are both one piece main seal, but have different flywheel weights on them... so that would also be a problem.

83Burban · May 15, 2026

Bextreme04 said:
Do you have a 90's 454 in it? The flywheel for a Mark IV will be very different than one for a Gen V or Gen VI 454. Gen V and Gen VI are both one piece main seal, but have different flywheel weights on them... so that would also be a problem.

No...pretty positive a mid 70s 454. Or at least the block is. I'll call up to O'Reilly's and see what the flywheel was. Pretty sure I tried to match it to the transmission and not the motor. Did not realize there would be a difference.

Finally found the clutch kit and slave part numbers. Or at least what rock auto had them listed as. For a 97 K2500 454.

Luk Slave # LSC265B / Luk clutch kit # 04154 (04-154)

83Burban · May 15, 2026

Bextreme04 said:
Do you have a 90's 454 in it? The flywheel for a Mark IV will be very different than one for a Gen V or Gen VI 454. Gen V and Gen VI are both one piece main seal, but have different flywheel weights on them... so that would also be a problem.

Just got off the phone with O'Reilly's. Flywheel part# NFW1041. Says it's for a 73-80 454. So at least I did that right

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Bextreme04 · May 15, 2026

The LUK slave cylinder is the right one. LUK made the rebranded AC Delco clutch and slave cylinder parts and they are the exact same. The flywheel size and face fitment is the same across all Mark IV though Gen VI BBC, so that shouldn't be the issue either. What bellhousing did you use? Did you actually measure the offset heights from clutch face to bellhousing mounting pads and bellhousing face on the NV4500 to slave? It looks like the slave is pushing out too far and contacting the clutch disc. Is the noise there all the time.. or just when you press in the clutch?

83Burban · May 15, 2026

@Bextreme04 Bell housing came out of a 97 K2500 when I bought the original swap. And no I never did take measurements. Couldn't tell you where but I'm pretty certain I'd read that I needed that bell housing. Drive shafts and cross member fit exactly like it should.

It makes the knocking sound as soon as I fire the truck up. Depressing the clutch doesn't seem to make a difference. Wont go into any gear. The trans tunnel is out of it so I could kind of see the slave / fingers actuating through the vents on top when I would engage the clutch.

vr1967 · May 15, 2026

83Burban said:
Just got off the phone with O'Reilly's. Flywheel part# NFW1041. Says it's for a 73-80 454. So at least I did that right

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Looks like there is no pilot bushing installed in this photo. Be sure to install one if you haven’t already

Bextreme04 · May 15, 2026

83Burban said:
@Bextreme04 Bell housing came out of a 97 K2500 when I bought the original swap. And no I never did take measurements. Couldn't tell you where but I'm pretty certain I'd read that I needed that bell housing. Drive shafts and cross member fit exactly like it should.

It makes the knocking sound as soon as I fire the truck up. Depressing the clutch doesn't seem to make a difference. Wont go into any gear. The trans tunnel is out of it so I could kind of see the slave / fingers actuating through the vents on top when I would engage the clutch.

That should all fit correctly then.

The symptoms make me think you assembled something wrong and therefore didn't have the clearance you should have had. It's hard to explain with words that you need to "look for things that don't look right". Are you sure that you:

1. Put a pilot bushing in
2. Used red loctite on the flywheel bolts and TORQUED all bolts appropriately
3. Put the clutch disk on correctly
4. Aligned the clutch disk and pressure plate correctly before tightening everything down.
5. Aligned the slave cylinder appropriately and fully seated it over the transmission input shaft

Dmack · May 16, 2026

It looks like the throwout bearing is grinding in the clutch disc hub. Any chance it's the wrong disc or possibly the disc is installed backwards?

bluex · May 16, 2026

With a 97 trans an internal slave you need to use the 97 pressure plate too. Looks like you did so I've got to go with something being installed wrong as well.

This is the same basic setup in my C10, just with a NV3500. Flywheel to match my engine, clutch disc back matches the trans. The parts you have should work together with no issues.

83Burban · May 16, 2026

vr1967 said:
Looks like there is no pilot bushing installed in this photo. Be sure to install one if you haven’t already

I did for sure install the correct pilot bearing. Test fit on the shaft before it went in.

83Burban · May 16, 2026

Bextreme04 said:
1. Put a pilot bushing in
2. Used red loctite on the flywheel bolts and TORQUED all bolts appropriately
3. Put the clutch disk on correctly
4. Aligned the clutch disk and pressure plate correctly before tightening everything down.
5. Aligned the slave cylinder appropriately and fully seated it over the transmission input shaft

Pilot bush went in for sure after being test fit on shaft. Bought red locktight and new torq wrench just for this the job. Also, I did make sure to use new bolts. Lol the rest all SEEMED like it was done right. The slave cylinder just drops over the shaft and is held in place by two bolts. I don't think its possible to clock it wrong and hook up the hydraulic lines.

Is there a chance that input shaft on trans is protruding too far due to improper install? Any body got one out they could put a tape on for me to compare. Trucks in my buddies shop 40min away from me. I'll try to get better photos with measurements tonight

CountKrunk · May 16, 2026

Kind of seems like your only options are to find someone local who knows this stuff or take it all back apart and start from step 1 again.

What did I do wrong? NV4500 Swap Issues

83Burban

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Rustisbest

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