H3 5-Speed Clutch or Transmission?

Morning Folks,

I'm hoping someone out there can help a fella out. I’ve noticed the Clutch in the H3 is having to travel farther and farther out (off the pedal) before catching 1st Gear, over the last several months.

I've taken her in to Cottman Transmission and low and behold, the "Certified Transmission Specialist" there didn't even know they made a Manual Transmission H3...

He thought the truck drove fine and seemed more thrilled that he got to drive my H3, than actually diagnosing anything.

Anyone out there have any idea as to whether the Clutch is wearing out or if the Transmission is going?

Any thoughts or input is gratefully appreciated!

I have always had to really mash the pedal down to change gears. As the syncros have worn, first grinds more. I now use my old habit of dropping into second and the move onto first. I also tend to keep my foot to the right side of the pedal cause I tend to get the floor before I am fully depressed.

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Clutch wear. That's very common on high-mileage clutches (on any vehicle)...motorcycles, cars, trucks, whatever. The reason it grinds is that you are not getting enough travel in the throw-out bearing, and the flywheel and pressure plate don't fully separate. The clutch disc resides between the flywheel and the pressure plate, and when you press the pedal down...the disc is still getting a small amount of "squeeze" from the pressure plate. Its not fully releasing the disc, and this creates a slight drag. This happens between all gears but, you don't notice it because the tranny is spinning, and the syncros sort of mask the problem. But when stopped, and going to first gear (or reverse) its especially prone to grinding because the tranny is not rotating. That's the classic worn clutch symptom. Any "specialist" should know that.

The H3 uses a hydraulic throw-out bearing, and its essentially "self-bleeding" and not adjustable. As the disc wears...the stroke at the pedal is automatically adjusted. This is the downside to the hydraulic system. If it were an old-school mechanical bell-crank linkage...you would be able to adjust this problem to some degree. But on a hydraulic clutch, there is no adjustment and once the disc wears and the throw-out adjusts itself to the limit...its simply time to replace it. Clutch life is somewhere between 70k and 130k miles. Expecting any more than that from any clutch is asking alot.

Get a complete clutch kit...(disc, pressure plate, throw-out bearing, pilot bearing), and it will be good as new. You might also want to replace or re-surface the flywheel at the same time. Syncros are separate problem, and cannot be diagnosed with a worn clutch as the symptoms mimic each other. 9 out of 10 times...a new clutch will correct the grinding issue. Driving around with a dragging clutch is hard on the gearbox, so don't ignore the first gear/reverse grind.

Well, you could do a Billy-Bob job and just replace the friction disc and pressure plate if the wear on the flywheel in minimal.

How many miles on your vehicle? Depending on your driving habits modern clutches/ clutch components can last a long time. Some GM vehicles use a sealed pilot bearing and they can last forever. First thing I would do and what I have done is flush the fluid. That's a tricky job since you can drain the MC in an instant since so little fluid is actually in the system. The GL type of transmission oil in the trans makes a difference in shifting also.
Now as far as parts go I'm wondering about that myself. I have 120K miles on my truck but it hasn't exhibited any shifting problems for me. If it would work I would install an LS7 clutch kit in my truck. It sure works well in my 4th gen Firebird. When I overhauled the drive train in my car the clutch showed little wear on the plate and flywheel. What caused problems at the time was that the roller pilot bearing disintegrated into rust dust and made the T56 difficult to shift at times. It was amazing it did as well as it did. One thing I'm not sure of but I'm thinking possibly the I5 is internally balanced and maybe the clutch components are generic to other GM engines like the LS-series.

alrock said:

https://www.rockauto.com/en/catalog/hummer,2006,h3,3.5l+l5,1431872,transmission-manual,flywheel,5348

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:huh:
Well this is embarrassing. I looked twice on rockauto, and searched for it every way I could think of. I am going to order it and see what shows up and let you know. Thanks a million for posting that link up!

Mr_Rich said:

How many miles on your vehicle? Depending on your driving habits modern clutches/ clutch components can last a long time. Some GM vehicles use a sealed pilot bearing and they can last forever. First thing I would do and what I have done is flush the fluid. That's a tricky job since you can drain the MC in an instant since so little fluid is actually in the system. The GL type of transmission oil in the trans makes a difference in shifting also.
Now as far as parts go I'm wondering about that myself. I have 120K miles on my truck but it hasn't exhibited any shifting problems for me. If it would work I would install an LS7 clutch kit in my truck. It sure works well in my 4th gen Firebird. When I overhauled the drive train in my car the clutch showed little wear on the plate and flywheel. What caused problems at the time was that the roller pilot bearing disintegrated into rust dust and made the T56 difficult to shift at times. It was amazing it did as well as it did. One thing I'm not sure of but I'm thinking possibly the I5 is internally balanced and maybe the clutch components are generic to other GM engines like the LS-series.

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Great question. I do drive a bit off road and that has taken its toll on the old clutch. I did flush the slave cylinder until clear fluid came out this past January and that helped out a ton, but its gotten bad since I was last out on the trail. I was thinking about a stage 2 clutch, but I've not thought about the LS7 clutch before. I will look into that!

H3Trex said:

:huh:
Well this is embarrassing. I looked twice on rockauto, and searched for it every way I could think of. I am going to order it and see what shows up and let you know. Thanks a million for posting that link up!

Click to expand...

I've noticed a couple parts that were only listed under 2006 model year that are applicable to all years. So I usually search under 2006 for parts for the H3

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Flywheel p/n 19177876
Bolts x 8 p/n 12568932
Pilot Bearing p/n 12557583
Pin, sometimes they shear p/n 11503504

This discussion got my curiosity up and I searched Ebay. There are several original H3 flywheels available for sale. I saw an H3 flexplate for sale that was pictured and it showed eight mounting holes to the crank. That kind of surprised me but it was verification. I also did a search for pilot bearings and it was shown that the H3 has a sealed pilot bearing. I'm comfortable with that knowledge. On my 4th gen Firebird the bearings themselves rode directly on the pilot shaft of the trans and when the bearings ran dry they deteriorated quickly. The LS6 crate engine that I installed in my car years ago was actually a Cadillac CTS/V engine crate engine and I sold the parts off the engine I couldn't use in my car like the 80# (actual weight) dual-stage clutch that is stock on that car. That had a sealed pilot bearing also and was not compatible for use on my Firebird.

I believe in 2008 they increased the size of the clutch

atvspeed4 said:

I believe in 2008 they increased the size of the clutch

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I’ve seen mentions that the disk went from 260cm to 285cm when going from the Colorado to the H3, but can you post a source for the sizes? I’m trying to get the right parts together before I drop the transmission. Oh and do you really have 6 of these H3’s? One keeps me busy enough. Lol

Traxx said:

Flywheel p/n 19177876
Bolts x 8 p/n 12568932
Pilot Bearing p/n 12557583
Pin, sometimes they shear p/n 11503504

Click to expand...

Thank you for posting this up!

alrock said:

I've noticed a couple parts that were only listed under 2006 model year that are applicable to all years. So I usually search under 2006 for parts for the H3

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Click to expand...

Thanks for the tip! I’ve needed new steering knuckles and could not find them in there. I’m good now, but this also explains why I could not find that flywheel before.

alrock said:

https://www.rockauto.com/en/catalog/hummer,2006,h3,3.5l+l5,1431872,transmission-manual,flywheel,5348

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I’m making an assumption here that the flywheel for the 3.5L is the same as that for the 3.7L? Can anyone confirm?

The old link I had saved is dead but when they switched to 3.7l in 2007 they went to 280mm even in h3. They are interchangeable from what I have read so I'd just get the 280mm and be done since you have the 3.7L.

Lol yes six of these things right now in various levels of build need to sell one off soon to find the new project one

Traxx said:

Flywheel p/n 19177876
Bolts x 8 p/n 12568932
Pilot Bearing p/n 12557583
Pin, sometimes they shear p/n 11503504

Click to expand...

What pin is this? Do I only need one?

Alignment pin I am guessing

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Yes the alignment pin, sometimes they shear off and they are only a couple bucks so something to have on hand.

Traxx said:

Yes the alignment pin, sometimes they shear off and they are only a couple bucks so something to have on hand.

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Thank you for the tip! I'll be sure to order one.