Engine/Transmission (1998.5 - 2002) Warning to others about throwout bearing noise

[BigPapa]

Yes, we've met and seen each other several times. You remember Anthony. We could be brothers, I'm just shorter. You'd recognize me if you saw me, just older, grayer, less hair, and heavier... ... ... .

 

[BigPapa]

Yes, we've met and seen each other several times. You remember Anthony. We could be brothers, I'm just shorter. You'd recognize me if you saw me, just older, grayer, less hair, and heavier... ... ... .

 

[WaltHess]

Yes, that is correct. The squeal started when the clutch was depressed. The bearing came apart, balls at the bottom of the bellhousing, which decreased the throw enough that the clutch could not disengage. I have the parts, and they were due to be changed. If I get a chance I shall post the pics. I really can't complain, thi struck hasn't cost me that much considering the mileage I have put on it since I bought it in 05 with 101,000 miles. 214,000 miles that I have put on it since then , and a lot of them with a trailer behind. 1 APPS sensor, brakes all around, water pump, lift pump, and a clutch. Oh, and the center link after running over a dead 1,200# steer on the road... . The power steering system will be next, starting to leak out of the gearbox.

 

[MakeItShake]

...as the disc spins down the pilot bearing starts doing its job.

This is the first I've heard a statement like this.. What exactly is its job? I have assumed that this bearing helps keep input shaft play & vibration to a minimum when it is not loaded through the clutch disk. Does it serve other purposes?

I am having a short squeal from the clutch upon letting the clutch pedal off the floor...so I am very interested in the content of this thread. It does not squeal when depressing it, only letting it out. I've also felt as though the clutch may be slipping slightly, but I can't pin it down yet with all this salt, sand, and ice on the roads the past several weeks.

It's SB ConOFE with 14K miles. The squeal started not long ago.. 1K or so. Hard to remember as it does not do it every take-off.

I had had some releasing issues earlier as the truck would 1) bump forward when putting it into 2nd gear and 2) be very hard to get into gear/take a long time to get into gear. I called SB and spoke with them. They suggested to test the throw-length to disengagement, and then remove the 1/8" shim off the slave cylinder if the throw was OK. I did this and the shifting into gear has gotten somewhat better, but still a bit tough, and still squealing. From what I've read hear and elsewhere, I think I'm still in the market for a new throwout bearing.

I still owe them a follow-up on my results.

 

[SAndreasen]

BIGPAPA,



Can you post a picture of the clutch bearing and fork return spring or system that creates the freeplay?



A bit more detail.



The slave cylinder has a spring in behind the piston body pushing from the housing or casting. It pushes the fork forward and applies a preload to the bearing. The bearing turns continously. The hydraulic system is at ZERO PSI with your foot off of the pedal. When you push on the pedal, the master cylinder closes a valve (incoming fluid supply) and creates pressure, the slave cylinder pushes forward and we get release travel.



To demonstrate on you own, next time someone has a trans out (with bellhousing if NV4500) install the bearing and fork then install only the slave cylinder from an old system, no fluid, no line, no master, just the slv cyl bolted up.



Now, try to push the bearing back in to its mid point of the travel range, feel the resistance, thats the proload.



Or with the clutch and trans installed, take a used slv cyl (retaining straps already snapped) and try to install it. You have to push it into position and hold it while you bolt it up. Why, its not the fluid, that peacefully just changed location and went to the reservoir. You're compressing the spring inside the slv cyl.



Simpler demonstration, find an internal slave cylinder from a Ranger or 96- Chevy C/K series. Make sure it doesn't have any fluid in it and leave the bleed screw open. Now compress the bearing back against the housing, feel the spring? There is a spring behind the bearing that applies a constant preload to the system.



Bearing design used to REQUIRE freeplay. Freeplay was an actual air gap between the bearing face and the levers or later fingers that allowed the bearing to NOT TURN with your foot off ot the pedal. The bearing of choice was a thrust bearing or aka step shell by some folks. Great for a direct inline with the input shaft load, but at high RPM the ball bearing actually want to fling out and cause wear internally. The current bearing design of choice is called angular contact. The load thru the ball is at about a 45 deg angle, so it does just fine with thrust or radial loads. Combine angular contact with self aligning and actuate with a hydraulic system and that is todays clutch release system.



Why the long answer? Not to disprove BIGPAPA's statement, but just an attempt to offer the inner workings of the system to help other diagnoise the problem. We (the clutch industry) have seen a lot of clutches blamed when the problem was elsewhere and the next clutch installation they either got lucky or learned from the previous failed installation.



I take a bunch of tech calls, my US record for most NV5600 R&R clutch fix attempts on one truck trying to get it to release... ... ... ... drum roll please... ... ... .



14 R&R's back to back, one tech, one truck, untold lets try THIS BRILLIANT idea!!!!!!!! next. Then contact the supplier, he's our best account, we gotta , oh never mind.

So what ended up bieng the problem ?

 

[Sticks]

This is the first I've heard a statement like this.. What exactly is its job? I have assumed that this bearing helps keep input shaft play & vibration to a minimum when it is not loaded through the clutch disk. Does it serve other purposes?

I am having a short squeal from the clutch upon letting the clutch pedal off the floor...so I am very interested in the content of this thread. It does not squeal when depressing it, only letting it out. I've also felt as though the clutch may be slipping slightly, but I can't pin it down yet with all this salt, sand, and ice on the roads the past several weeks.

It's SB ConOFE with 14K miles. The squeal started not long ago.. 1K or so. Hard to remember as it does not do it every take-off.

I had had some releasing issues earlier as the truck would 1) bump forward when putting it into 2nd gear and 2) be very hard to get into gear/take a long time to get into gear. I called SB and spoke with them. They suggested to test the throw-length to disengagement, and then remove the 1/8" shim off the slave cylinder if the throw was OK. I did this and the shifting into gear has gotten somewhat better, but still a bit tough, and still squealing. From what I've read hear and elsewhere, I think I'm still in the market for a new throwout bearing.

I still owe them a follow-up on my results.

Is it the squealing on release coming from your transmission, or your pedal (squeaky pedal is common, a little graphite will cure it).

I would look at the entire master/slave system before that clutch assy, especially since it only has 14k miles - presuming you are not riding the clutch, and slipping it to hold inclines at stops.

Love it when people dig up old threads.

 

[MakeItShake]

I had a squeaking clutch pedal in my Tacoma, so I understand what you're getting at...Haha... Please pardon my mis-characterization: it's not so much a squeal or a squeak, but it's more of a howl just as the truck starts to move forward (the noise lasts only about a half a second). It also doesn't sound like it's coming from inside the cab by my feet. It doesn't happen every time. I've maybe heard it only 10-12 times in the last month. I drive highway mostly, with some city driving, so I'd guess my dead-start count is not excessive.

I had replaced my hydraulics with the SB heavy duty hydros at about 105K (truck now has 146K) when the truck had the previous clutch. The guy at SB said sometimes the hydros can wear-in to that particular clutch and may not work correctly with a subsequent clutch. One of his proposed next steps after the throw test and shim removal is what you said... assessing the hydraulics and possibly replacing them since the clutch has been changed.

I will confirm your presumption in that I do not ride the clutch nor do I slip for holding on hills....I also shift to neutral and let the clutch out at anything that takes longer than a stop sign.

 

[SRath]

This is a terrific thread to be bringing back up, and the timing is great, too! One of these days I'm going to be putting the NV5600 in my shop into my '96 which has 200k and the original clutch (working fine) even after years of snowplowing. Having over a quarter-century experience driving big rigs means I know how to avoid abusing a clutch, so that certainly helps. I have South Bend clutch that will go in with the NV5600.

Meanwhile, my 20 year old son came home from USMC boot camp for a few days' leave and promptly disappeared for a day or so last July. When he showed back up, he was driving an '85 Chevy K20 with big ol' stacks belching black smoke from a 12valve Cummins under the hood. It has an NV4500 behind it. He found the truck for sale 100 miles south of here, and I have no doubt he paid way too much, but it's his money and his pride and joy.

The man who did all the work is a professional welder and he fabricated all kinds of really cool goodies for the truck. My son and I always planned to do a 12-valve Cummins conversion in my big '88 V-30 (old body style) 1-ton, single rear-wheel, crew cab. Turns out he couldn't wait for the '96 Dodge I drive to fall off the 12-valve &NV4500 in it. Can't blame him. I almost wish the body of the Dodge was in far worse shape so I'd have the excuse to yank the Cummins and scrap the Dodge.

Anyway, the worst issue with his K20 Cummins is the incredibly crappy clutch setup. The doggone clutch has almost zero pedal travel between released and fully-locked up and is harder to push than any semi's I have ever driven. Making it both miserable and embarrassing to drive until you get a real feel for how touchy it is. (You'll kill the engine several times on your first attempt to drive the truck.)

Combine that with the ridiculously high torque of the turned-up Cummins and there is almost no way to keep from roasting the tires on DRY pavement. Which means it would be the scariest thing imaginable to drive on snow or ice covered roads. There simply is no way to "ease the clutch out". It's either fully engaged or fully disengaged within what feels like an inch of pedal travel - and so bloody stiff there's simply NO pedal "feel". Like flipping a light switch.

My own truck (cummins dodge) has had so many issues this winter that I haven't had time to really delve into finding the reasons and solutions to the miserable clutch in my son's new toy. Combine that with the fact that neither he or I actually have the slightest idea what the guy who built the truck used for components (Valair dual disc is what he told my son).

What I DO know for sure is that the clutch master cylinder is barely mounted to the Chevy firewall, moves and wobbles with every pedal stroke, and doesn't even look like it's close to being inline with pedal pushrod. How much is Chevy, Dodge, or home-fabricated is hard to tell.

My son, gone now since July, begs me to drive his truck regularly to keep it from sitting too long. I absolutely LOVE old Chevy's AND 12-valve Cummins with manual transmissions, so you'd think this would be a pleasure to do. NO WAY! Not with that crappy clutch and the weather we've had all winter.

Never mind the fact that I don't have a USMC ID card to show the cops who WILL pull that obnoxiously LOUD, black-smoke-belchin, straight-stacked kid's toy over every time they see or hear it! He even confessed to me after driving it two weeks (before shucking the wimpy corporate 10-bolt front axle under the weight of the Cummins) that he'd been pulled over almost every day. Around here, most cops are former military (mostly USMC probably) and they just chatted with him and let him go after he showed them his ID and explained he was just home on leave and had just bought the truck. Which is cool. But I'm 52 and definitely not a Marine, so I doubt I'd get cut the same slack.

Besides undoing and replacing all the crappy wiring the builder did (some people just should NOT be allowed to play with copper conductors and crimp connectors! lol), my main goal before my son gets another chance to visit home is to fix that horrible clutch! The last time I felt a clutch that crappy was when my buddy back in high school engaged the throwout bearing onto the clutch fork incorrectly in his old Camaro.

I have a complete factory hydraulic clutch setup from pedal to bellhousing, including MC and slave from one of those old Chevy's gassers that I was saving for the V-30 Cummins conversion someday. They're hard to find. Using it would assure the proper mounting and alignment of the pedal, pushrod, and MC, but I don't know if I can mate the NV4500 slave with the early Chevy MC? Later Chevy's had NV4500's, too, but I don't know how or if the MC from those trucks will mount on an older truck's firewall.

This can't be all that complicated, and if the builder used the same overkill-to-the-point-of-ridiculous approach in selecting his clutch that he used with his adjustable fuel plate and oversized turbo and ridiculous exhaust stacks, I don't know if there will ever be an easy solution to that super-hard pedal. Since all engagement & disengagement takes place in the first inch of pedal travel, the throwout bearing cannot be destined for a reasonable life span and must be hard up against the pressure plate fingers/levers.

If it was an old linkage clutch setup, it could be easily adjusted for freeplay. But I know of no way to adjust a hydraulic clutch. Anyway, sorry to write so much, but I'd sure like to surprise him with a driveable truck and maybe even drive it myself occasionally, as he requests. This might be better posted in the conversions forum, but it's a clutch issue and this thread really got me thinking about it. I'm open to any ideas, thoughts, or suggestions that don't involve breaking the bank or the kid's heart. It really is a cool truck and once the two feet of snow on top of it are gone, I'll post some photos.

 

[Sticks]

It the truck has been turned up, it might have a dual disc clutch in it to handle the power, which the original ones were stiff and touchy.

 

[GCroyle]

So what ended up bieng the problem ?

Not really sure as he didn't call back with follow up. But his original complaint was no release, could not shift cleanly.

In stock config the NV4500 and NV5600 have one of the most robust release systems, easiest to test the hydros and clutches that release when given the correct release stroke. After I listened to the litany of horror stories tried this, changed that it was clear to me that the efforts were at best a shot in the dark approach to his failure to release. Heres what I remember suggesting to him.

Assemble the clutch that you want to use on the bench on a flywheel, just like normal, no air tools etc.

Create a release system and release the clutch. Use a 1/2" piece of threaded rod, some washers and nuts to push something down against the spring tips even using the new bearing, it will not hurt it. Make initial contact, turn nut compressing bearing about 7/16". Release and repeat a couple of times. Now make the initial contact, just about finger tight and repeat the 7/16" travel. Now carefully inspect for the discs ability to spin freely w/o drag except on the F/W surface.

If it releases on the bench, why didn't it release in the truck?

Possibly pilot bearing binding, but thats even a stretch if he installed a new one and didn't destroy it on stabbing.

Hydraulics. The stock hydro's will release a stock clutch w/o any issues. But only if there is NO AIR in the system. Don't jump on the it ain't got a bleed screw it can't be bled watch this http://www.youtube.com/watch?v=AWxpUYiBHKQ

This could go on all day about how many times we hear the Yeah its bled followed by a laundry list of did that done this heard that but not one statement about testing the system INDEPENDANT of the clutch.

Pull S/C leave it hooked up to line. Remove push rod and dust boot, install steering wheel puller, block piston with puller screw, push with HAND on clutch pedal until good firm pressure. DO NOT TRY TO PRESSURE TEST, thats not the issue. The issue is does the pushrod travel greater than 1/8" before it gets rock hard? Greater than 1/8" that was an air bubble. The air bubble reduces total travel at bearing = marginal release or no release.

I gave him a bunch of suggestions and offered additional tech support but that turned into the end of the story.

Gary

SRATH,

I'll re-read yours again later and might have a comment or two.

Gary

 

[GCroyle]

SRath,

How about a pic of the master cylinder? Under hood and under dash too.

Gary

 

[NIsaacs]

SRath,

How about a pic of the master cylinder? Under hood and under dash too.

Gary

I would guess Gary is on the right track. It sounds like the master cylinder bore might be bigger than the slave cylinder bore, thats why it is hard to push and makes for a quick acting clutch engagement. If the firewall is not buchered up I would start with the factory OEM master for the truck, it has a .699 bore, the Dodge slave bore is 1 inch, that should work easy (peddle pressure) and slow down the release. Who knows whats on the truck now, sounds like just something out of the junk pile. I would think the hydraulic line would be the same diameter but I don't know that for a fact.

Nick

 

[GCroyle]

Nick,

Don't exactly know what is going on yet.

If the clutch is any of the NV4500 config's should be able to get it going OK IF.....

1. The slave cylinder gets its required "shot" of DOT 3 and fully strokes the release bearing.
2. ANY air in the system really screws up the entire system, short stroking at the bearing, your leg is out of synchronization with the pedal position and ergonomics.
3. No additional mechanical problems exist. Like release bearing not sliding easily on the retainer because they didn't grease the collar bore, oh yeah it happens. The pushrod on the M/C must go in as straight and true as possible to prevent side loading and wear in the M/C piston to bore. Ran into that on a stock '97 7.3L huge mechanical friction on that one.
4. Conditions unknown due to built in backyard VIN.
5. Pedal cluster issue? Already reported something about loose and moving or something.
6. Complete mis-match of hydro's, big displacement M/C moving bearing way too far, requires extra leg effort. Leave the stock bore NV4500 S/C as starting point and see what is possible on M/C side of equation.

Pic's might tell us more.

Gary