One more NV4500 swap... hopefully with details and pics

[Hink]

So I was able to finally roll my truck into the shop today. Just getting set up and started is always the hardest part on these projects it seems, but changing the NV4500 transmission in my ’93 GMC 4X4 actually looks like a straightforward process.
As per the Factory manual the steps are essentially to remove or disconnect;

1- Shifter
2- Oil
3- Drive shaft/Transfer case
4- Slave cylinder
5- Inspection cover

And now you’re ready to…
6- Support the tranny with a jack
7- Remove the crossmember

And
8- Remove the four bolts from the bellhousing

Now pull her loose!

And of course, things in reality aren’t so simple so I’ll go through some details as I go along.

First, I jacked her up and set her on the best jack stands that I could find.

My shifter screwed right off by hand and I removed the four screws holding down the boot collar.

And then the screws holding the boot.

I pulled the gaskets off.

Then I went down below and pulled the skid plate with a torx T50, disconnected the linkage with a screwdriver (it just pops into a rubber grommet), the vent hose, electrical, drained the oil and removed the driveshafts. I also pulled the carrier bearing mount loose so I could move the rear driveshaft aside.

Now I removed all four tranny mount bolts, lifted the tranny until I could pull the mount out and slid a 2x4 across the torsion bars right where the mount was and lowered the tranny.

Now I drained the oil from the transfer case, removed the six bolts and pulled it loose.
Lowering it was a bit hairy but it came down ok.

So here I sit.

I removed the four bolts supporting the transmission to bellhousing and am ready to lower it down but the shifter stub is getting in the way and I can't figure out how to get it off!

I know it's push and turn but that's not working. Anyone have detailed info?

 

[Hink]

O.K. I got the shifter stub figured out thanks to Ferm and GM Guy. I made a vid for my up coming web site to help the next guy...

 

[DieselSlug]

Not to derail, but that transfer case was the hardest part of my 4L80E rebuild. Its so awkward to hold up on your chest and re-position back into place!

 

[tanman_2006]

T case doesn't sit on a trans Jack very well, this is fact!

 

[Hink]

O.K., after the transfer case was dropped and the shifter stub figured out, I ran into my biggest issue. Mainly, dealing with the mess the last guy I had work on it left for me.
After all the engine work was done, I had him put in a full clutch hydraulic set and Southbend Kevlar clutch (I thought) and I've had nothing but trouble ever since.

The transmission pulled out with no issues. After supporting it with my jack, I removed the four bolts to the bell housing and the electric plug on the top and alternated lowering a bit and pulling back until it was out.
Then I could get to the six bolts holding the bellhousing onto the engine easier and took them out. The bellhousing took a little thumping and wiggling but it came out easy enough.

Now, here's my issue...
@GM Guy and @tanman_2006 , have you guys ever seen or heard of this on the NV4500?
The stud on my ball pivot was broken off. That's not so unusual but what caused it still has me stumped.
My clutch fork (that was supposed to be new along with the ballstud) was interfering with the bellhousing rib on either side and wore a huge chunk out.

I put in a new ballstud, hoping that it was just worn and allowing the fork to ride to low but nope (top pic).
I had heard a rumor of a tech bulletin about choosing the proper fork for these things so I took a week to hunt it down. It doesn't exist that I can tell. And I called everybody that I could think of from Ryan at Southbend to personal friends and mechanics, no luck, no info anywhere.
BUT! I went ahead and had my local NAPA bring in a new one to look at (you can get it from Amazon too) and this is what I found...

A slightly different shape right where it was rubbing.

And some minor differences on either end (one was higher than the other on either end).

I already had the ballstud installed so I put everything together with all new parts, ballstud, fork and throwout bearing to make sure everything was lined up properly and it STILL rubbed! Not as bad but it definitely interfered enough to cause more havoc even after the old fork wore away the rib in that spot, WTF?
I had nowhere else to turn so I did some minor clearancing on the bellhousing. Why am I having to modify my bellhousing, dammit? This clutch system worked fine for the nine or so years that I've driven it.

Here's what I ended up with...

After the minor surgery I slid the tranny in last night, hooked up the hydraulics, screwed the shifter on and said "Welp, God hates a coward!" and slowly pushed the clutch pedal down.
Smooooth as silk. Everything felt and sounded fine so I ran it through the gears (engine off). Then I went ahead and started 'er up (she sure bellers loud straight out the manifolds!) and ran it through the gears again. Everything seems great.
We'll see with time and I hope I didn't weaken the bellhousing by grinding on it but so far it seems good.

Anybody have any ideas?

 

[tanman_2006]

I doubt you hurt the Bell housing although that kind of modification shouldn't need to be done.

What condition is your pilot bearing in?

Mine went together fine but I used a LUK kit which is what south bend bases their kit off off.

Iirc aren't there some dowel pins to line up the Bell housing? Did the mechanic put those back in? Sounds like an alignment issue to me

Edit: another thought is did you change anything on the flywheel that could cause clearance issues?

 

[GM Guy]

I wonder what a new GM fork looks like?

 

[Hink]

I doubt you hurt the Bell housing although that kind of modification shouldn't need to be done.

What condition is your pilot bearing in?

Mine went together fine but I used a LUK kit which is what south bend bases their kit off off.

Iirc aren't there some dowel pins to line up the Bell housing? Did the mechanic put those back in? Sounds like an alignment issue to me

Edit: another thought is did you change anything on the flywheel that could cause clearance issues?

Pilot, flywheel,clutch, T/O bearing, fork and ball stud are all new.
Dowel pins are in and the pictures that I posted above with the fork hitting the bellhousing are all with the transmission out so alignment can't be an issue.

I even thought the guy may have changed bell housings on me but I brought up old pics during the engine build and it's the same.

 

[Hink]

I wonder what a new GM fork looks like?

Yeah, I'd like to compare sometime but I needed to get one here quicker and just get the issue solved.

BTW, I have some factory part numbers if anyone needs them...

Fork - 15588262 or 12385352
Ball stud - 15552866
Bushing for ball stud (no longer available to my knowledge) - 15552867
Retainer for ball stud (I just used double nut) - 1603620
8mmx1.25x12mm Flywheel bolts - 10220397
Inspection cover (no longer available to my knowledge) - 15699054

 

[tanman_2006]

I'm just spit balling ideas of what I would check but I wonder napa's clutch kit has gone down hill.

Did you have this issue with your first new clutch? Maybe it's the combo of Napa, south bend/luk

 

[Hink]

Yeah, I appreciate the spit balling.
No, I had a new clutch, ball, and fork put in about nine years ago and everything has been fine. And it's completely unrelated to the clutch because I see it when hand operating the fork and t/o bearing by hand with the tranny on the floor and away from the clutch. The issue started when this guy supposedly put in a new clutch fork and ball. Funny thing is... the ball and fork was worn out like it had been in there for 20 years but had less than 100 miles on it. So, you'd think that just a new ball and fork would solve it, but nope.
The only thing that I can imagine would cause it would be a bent/incorrect fork but the new one is not bent and every piece of information that I can find says that I got the correct fork. It's like @GM Guy said; if the GM made fork is a lot different then maybe.
BUT, the one I took off was a GM fork and when compared, it wasn't that different.
Dead ends everywhere so far.

I should have it on the road today and we'll see if she goes.

 

[schiker]

I have the concentric slave and its been years since I have taken apart a system with a fork. For those with forks do you see it get really close to the bell housing normally on full stroke of pedal? I have light clutch engagement at roughly half pedal stroke.

Was there ever any difference in the pedal's point of engagement? Where is the pedal engagement? Is there any engagement shutter or chatter? Does the fork only hit when the pedal is near or at the floor? Do you have to push it until fork hits the bellhousing for it to disengage fully? Any extra spin down time? I wonder if the pressure plate fingers are closer to the engine? Was the flywheel resurfaced or new? Is the throw out bearing shorter between the fork and PP fingers? Is the slave mis matched to master or vice versa such that its over stroking the fork travel?

Where are you seeing so much wear on the fork? Was the ball stud also worn down? How does throwout bearing wear look or PP fingers?

It has something to do with the stack up. Shotgunning that could be mainly a flywheel, clutch disc, pressure plate, and fork issue. Or a throw out bearing, ballstud, bellhousing, or master/slave & pedal mismatch. Anything else? No change in floor pan so pedal strokes a bit farther like taking out carpet/rubber and insulation etc ?????

 

[tanman_2006]

My thoughts were in the clutch/flywheel Stack or Bell housing somehow misaligned on the block causing a geometry change.

 

[schiker]

Check that I just drove it. I can get full spin down with 1/2 pedal stroke just takes a second. I get soft engagement about 1/4 pedal stroke. It's nearer the top than half way to floor

You can feel it takes 1/16 -1/8 pedal stroke to start hydraulic pressure and it starts to disengage pretty quickly.

I don't have to push the pedal much at all to shift rolling nor to floor ever. Just at a stop will I usually hold it to floor or real close.

 

[tanman_2006]

Mine seemed to take full stroke from what I remember, the engine has been apart 4-5yrs. Maybe 3/4 pedal to fully engage

 

[GM Guy]

Most of my 95 and older rigs pretty much take the full stroke to disengage.

I used to prefer the external slave, but I am getting to the point that the internal is not all bad, considering it eliminates all of the fork system. Oh well, both have their pluses and minuses.

 

[Hink]

I see where you guys are going with the stack ideas but if you look at the first picture of post #5 above, you can see the interference and it's not in the truck. No clutch, no flywheel. And if you look at where the stud is poking through the fork, the t/o bearing is way back at the point where it was hitting. Meaning that it is hitting through most of the stroke of the fork with no involvement of the clutch or flywheel at that time.

I have the concentric slave and its been years since I have taken apart a system with a fork. For those with forks do you see it get really close to the bell housing normally on full stroke of pedal? I have light clutch engagement at roughly half pedal stroke.

Was there ever any difference in the pedal's point of engagement? Where is the pedal engagement? Is there any engagement shutter or chatter? Does the fork only hit when the pedal is near or at the floor? Do you have to push it until fork hits the bellhousing for it to disengage fully? Any extra spin down time? I wonder if the pressure plate fingers are closer to the engine? Was the flywheel resurfaced or new? Is the throw out bearing shorter between the fork and PP fingers? Is the slave mis matched to master or vice versa such that its over stroking the fork travel?

Where are you seeing so much wear on the fork? Was the ball stud also worn down? How does throwout bearing wear look or PP fingers?

It has something to do with the stack up. Shotgunning that could be mainly a flywheel, clutch disc, pressure plate, and fork issue. Or a throw out bearing, ballstud, bellhousing, or master/slave & pedal mismatch. Anything else? No change in floor pan so pedal strokes a bit farther like taking out carpet/rubber and insulation etc ?????

The pedal was very rough and engaged very far down the stroke as compared to the old clutch. The mechanic said he figured it was because it was a performance clutch and to let him know if I had any problems (when I did, he just yelled at me and hung up on me but that's another story). It engaged fine on release of the pedal for the one day that it worked, and then the hydraulics blew out from so much pressure. The fork hits before you push the pedal. Flywheel is new. The throwout bearing looked the same as the others I've used. although I didn't do a side-by-side. However, it wouldn't cause the fork to hit like in the first picture in post #5 above. Slave and master came pre-assembled and pre-bled from factory. The fork, ball stud, t/o bearing, clutch and flywheel are all new and still made contact at the fork. The bellhousing and pedal assembly is the same as it's ever been.

I don't know if we'll ever figure this one out guys but I really appreciate the input! With it clearanced at the point it interfered in the bellhousing, the pedal feel is great so far.
When I started it up last night it had a loud noise until I disengaged the clutch (pushed in the pedal). Now that, I believe is alignment and I will see if I can get it figured out today. Then I can get it on the road and see if engage/disengage functions properly.

 

[schiker]

Probably something is mismatched. It looks like the fulcrum or travel is off. If its hitting either the stud needs to be longer/taller or the fork needs to pivot more (the throwout bearing going back towards the transmission). As in the fork should not push back that far.

Originally it was a dual mass flywheel right. And this is a solid flywheel conversion with southbend disc. I assume a Luk pressure plate for SMF conversion of the proper year.

I would call Southbend or another clutch shop with SMF conversion experience and see what they say if there could be any mismatch in parts.

There is a break for concentric slave vs external not sure if the pressure plate and or flywheel are different and if any are compatible with the other kit. I don't think you have to change the ball stud, or fork going to SMF but don't know.

Is there any adjustment on depth of ball stud or just screw in and bottom out? Any chance its not seating correctly?

 

[Hink]

Yeah, I was thinking the same on the ball stud. I compared the new one to the old and it looked the same, but that's assuming that the one I took out was the right one. However... I ordered the new one per my application and that's the one I used. Again, everything piece of info says that it is the right one.

This is not a new conversion. I've ran a solid flywheel for the 9 years I've ran it and it had one when I bought it and it's worked flawlessly. And again, the flywheel and clutch pack have absolutely nothing to do with the fork interfering with the bell housing.

The ball stud just screws in with no adjustment. It sits into a shallow machined hole and then the front of the transmission covers it when the bellhousing is bolted up so even if it was loose, it could only move 1/16-1/32" maybe. But, I put some blue locktite on it and seated it all the way.

 

[schiker]

Just something to keep in mind I have been fooled by the flywheel rubbing / hitting the "dust cover" twice. It was intermittent and varied with vibration. When the vibration would get a little harmonic the dust cover would vibrate a little more and just enough to tickle the back side of the flywheel. Found it by laying under truck and using a wooden stick to push on the dust cover. I bent it away from the flywheel just slightly and all noise went away.

Could be a slight error to fork or something else but a thought......

Kind of a quess and sort of a question.

Isn't one advantage of the hydraulic actuation is it self adjusts the stroke a little. Meaning the pressure plate pushes back on the release bearing /fork and thus slave. The slave rejects fluid back up to the master and if any extra fluid goes back up into the reservoir. At least from a fully extended slave the first time. The master cylinder displacement controls the stroke length of the slave. It strokes the slave by as much as the master can displace fluid with one pump.

So my guess is there is still some stack up that is just a little thin such that the release bearing is starting off too far towards the motor. The system automatically self adjusts a bit. The master piston will still fill I think and try to stroke it the full distance and its overstroking the fork and the fork is interfering with the back of the bellhousing.

If the PP fingers at rest were back just a little bit farther I think the fork would move away from the interference and push excess fluid back to the reservoir and the master would stroke its same distance but not push into the bellhousing.

Also look at this page tech bulletin upper right corner for release bearing install pdf. Is the bearing installed incorrectly allowing the fork to get out of square to the actuation????

http://catalog.schaeffler-aftermark...&id=4384107&query_displacement=6.5L&qualfier=