What did you do with your H3 recently? NEW

[awalsh]

Agreed^


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[woodwardsh3]

how well do they work at night?

 

[Ghostbuster]

Awesome. Post some output shots.

 

[rascole]

Started my Rancho lift project today, will start a separate thread soon. Made some mods to the lift and will be doing a SOA on the rear.

 

[RamRod]

Made up some custom little brackets to mimic the mounts for the stock headlight units, and installed these new LED lights

View attachment 21571
View attachment 21572

I should've done a small writeup and build thread on how I did it, but I was too caught-up trying to get them in and working before today :emb:

Merry Christmas and Happy Holidays everybody!

I have those exact lights sitting in the spare room waiting for a chance to look at house to mount them.... Now thatyu have done it would love to see a pic or write up of how you did it!


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[4speedfunk]

Wheel chocks!!!

H3's don't have a locking Park gear. Instead, Park is created by putting the front output shaft in reverse, and leaving the rear output shaft in forward. This essentially "binds" the drivetrain, and holds the truck in place by the tires. This works great as long as all four wheels are on the ground. But, lift either end of the truck...and it is free to roll, so make sure you use wheel chocks to keep from getting crushed.

 

[SuperBuickGuy]

Wheel chocks!!!

H3's don't have a locking Park gear. Instead, Park is created by putting the front output shaft in reverse, and leaving the rear output shaft in forward. This essentially "binds" the drivetrain, and holds the truck in place by the tires. This works great as long as all four wheels are on the ground. But, lift either end of the truck...and it is free to roll, so make sure you use wheel chocks to keep from getting crushed.

no - the 4L60e has a parking prawl that locks when you put your vehicle in park.

H3 are awd, meaning when the transmission is in park, it will hold it in place as long as all 4 wheels are on the ground. However, lift one end and it will roll away because of the viscous coupler in the transfer case transfers 'power' (holding in this case) to the end that has the least resistence. You can stop that by putting the rig in 4 lock - then jack to your heart's content. But the 4L60e has a parking prong. Granted, if anyone saw what that looked like, they'd be far less likely to put huge stress on it and would use their parking brake when winching.

it actually reacts the exact same way an open differential reacts when one tire is lifted off the ground on a hill....

 

[4speedfunk]

Wrong. An H3 will roll when either end is raised, IN ANY T-CASE MODE. This is why you should use the parking break whenever you are traveling with the front driveshaft removed (or chocks when working on the driveline). There are several people on this forum that have learned it the hard way.
Also, H3s don't have a viscous coupler. They use a mechanical differential to do the variable F/R torque split. It doesn't matter...the result is the same. If you jack either end of an H3, while parked on a grade...get ready! It's going whether you believe it or not.

Seriously, be careful. An H3 can kill you in seconds, if not properly chocked. PARK does not work with either end raised.


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[SuperBuickGuy]

H3's don't have a locking Park gear. Instead, Park is created by putting the front output shaft in reverse, and leaving the rear output shaft in forward. This essentially "binds" the drivetrain, and holds the truck in place by the tires. This works great as long as all four wheels are on the ground. But, lift either end of the truck...and it is free to roll, so make sure you use wheel chocks to keep from getting crushed.

This is what I disagree with because you are wrong. There is a parking prawl in the 4L60e transmission. GM did not elimate it. Why it doesn't lock? I've never been stupid enough to try that so frankly I don't know or care.... there is a viscous coupling in the transfer case that would allow it to roll if it weren't in 4 lock. Perhaps it doesn't work on whatever one you tested - but end of the day... there's a parking lock in the transmission. Sorry - it doesn't happen often, but this time you are.

 

[4speedfunk]

SBG...go park your H3 on a hill...lay down in front of it...and jack up the front wheels. Go ahead I'll wait.


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[4speedfunk]

Parking pawls don't "lock" the rear wheels on AWD vehicles. Instead they lock the output shafts together...so the vehicle cannot roll (as long as the tires are on the ground). I don't know why this is but, they all work this way. Ask any tow truck driver.
You can back a tow truck up to ANY AWD vehicle...raise the front wheels...and drive off with it. You'll notice that the front wheels (now in the air) will spin in reverse, as you tow the car forward. True...you can't really haul it around like that but, the important thing to note, is that there is no PARK gear and you will not drag the rear wheels like a 2WD vehicle. The only thing that keeps it from rolling, is that all four wheels are on the ground, and because the output shafts are locked together in PARK. Raise either end and it will easily roll. It doesn't matter what mode the case is in, and it doesn't matter which end you raise. This is "AWD-101" and all H3 (and Jeeps) act this same way in PARK. So beware.
https://youtu.be/kFTfcrnsUwU
I work on H3s every day, and have since 2008. They all act this way, and they do NOT have a viscous coupling in the t-case. Download the PDF file from Schwarttzy to see an exploded view of the t-case.

 

[4speedfunk]

God I hope he didn't really do that! SBG...let us know if you're okay.


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[650Hawk]

Yes, the H3 does have a parking pawl in the trans, but that only "parks" the transmission output. The transfer case does not have a viscous coupler; it is a mechanical center diff that is open when in 4Hi (unlock). But.... In 4Hi lock (and 4Lo lock) that center diff is locked in the TC. That's what allows you to drive with either the front or rear driveshaft removed as long as you are in Lock mode. So wouldn't that mean that as long as you are in Lock mode and have one axle on the ground, putting the tranny in park would hold the truck, right? If not, what am I missing?

 

[4speedfunk]

No. You do not have a PARK gear with the front driveshaft removed. Normally the front & rear output shafts rotate in opposite directions. In PARK they get linked together...so the truck won't roll because they fight each other. There is no real lock pin or rigid device to prevent rotation, as SGB suggests. The only thing stopping rotation is the binding that occurs by tying both outputs together, and having the tires on the ground. This insures the binding and keeps the truck from rolling. But if you disconnect either end, you break the only link that keeps the truck from rolling. When you remove the front shaft...it basically mimics jacking up the front tires. This is why H3s like to magically jump off of jack stands...or roll down the street without a front driveshaft.

Stick shifts? Hmmmm. I honestly don't know if they would exhibit the same trait with the front shaft removed. The clutch acts different from a torque converter in these scenarios...so that's a different discussion.

 

[amrg]

Joined the under 10 miles per gallon club (if it exists). 9.5 mpg to be exact, 80% city 20% highway! I think with more highway I could do 10.5!

 

[chaos254]

No. You do not have a PARK gear with the front driveshaft removed. Normally the front & rear output shafts rotate in opposite directions. In PARK they get linked together...so the truck won't roll because they fight each other. There is no real lock pin or rigid device to prevent rotation, as SGB suggests. The only thing stopping rotation is the binding that occurs by tying both outputs together, and having the tires on the ground. This insures the binding and keeps the truck from rolling. But if you disconnect either end, you break the only link that keeps the truck from rolling. When you remove the front shaft...it basically mimics jacking up the front tires. This is why H3s like to magically jump off of jack stands...or roll down the street without a front driveshaft.

Stick shifts? Hmmmm. I honestly don't know if they would exhibit the same trait with the front shaft removed. The clutch acts different from a torque converter in these scenarios...so that's a different discussion.

And this would explain why the jack kit in the back door has wheel chocks

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[SuperBuickGuy]

I work on H3s every day, and have since 2008.

Really, since all the way back to 2008? lol you have much to learn young one. :roll:

 

[4speedfunk]

Right.

 

[650Hawk]

No. You do not have a PARK gear with the front driveshaft removed. Normally the front & rear output shafts rotate in opposite directions. In PARK they get linked together...so the truck won't roll because they fight each other. There is no real lock pin or rigid device to prevent rotation, as SGB suggests. The only thing stopping rotation is the binding that occurs by tying both outputs together, and having the tires on the ground. This insures the binding and keeps the truck from rolling. But if you disconnect either end, you break the only link that keeps the truck from rolling.

So just what is it in the transfer case that ties those two outputs together? How does the TC know that you have put the tranny in park? There is nothing from the tranny shift cable that goes to the TC (correct me if I'm wrong) and the only electrical to the TC is the encoder motor (which is nothing more than an electronic replacement for a 4wd shifter).

Not trying to be difficult, just trying to get my head around the inner workings of this system.

 

[JPaul]

Geez guys, go take a nap or something, you're both partly right. If anyone thinks that using the parking pawl by itself is sufficient, then either you live where there are no hills, or you just don't understand how automatics work. You should always be using the foot (or if it's another vehicle the hand) actuated parking brake which uses a second set of pads inside the rear brakes to hold the vehicle in place.

Newer cars are eliminating the manual parking brake and instead are using the electrically assisted main brakes to apply and hold pressure on all four wheels using the main brakes. The Ford Fusion rental car I drove in NH had this, you push a switch and it applies the brakes for the parking brake and holds them in place. It's a smart idea really.

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[4speedfunk]

650...that's a great question. I've wondered the same thing for a long time. I've had four or five BW3393/4's apart...one of these was from a stick-shift model, and I can tell you there is no difference between the AT and the 5-speed t-cases. I'm not aware of anything mechanical inside (like a PARK fork) that physically locks the outputs together. Also, there's nothing external that physically connects the trans to the transfer case (like a cable or lever). So the question remains...how do the outputs get tied together in PARK? I don't know.

However it is done...its not special to the H3. I say this because some full-time 4WD Jeeps, and many other AWD cars do the same thing and have, for many years (probably before computers). I get the feeling its a by-product of the transmission being in PARK, and has nothing to do with the t-case. Otherwise the stick-shift case I worked on would have been missing the "AT-park-interlock-thingy" but, it was identical to all the other AT t-cases I had apart. So I'm not convinced the "park mechanism" has anything to do with the t-case. Perhaps its done via the encoder by a signal from the t-case controller? I doubt it. I know some old-school Jeep guys that were aware of this same issue way back in the 80s (quadratrack). I'm as stumped as anyone on this, and I will poke around on the net to try and find more info about this strange AWD PARK phenom. Its nothing new and tow-truck drivers know it well.

One thing for sure, the H3 will easily roll away (in PARK) without a front driveshaft shaft (in any mode). Another thing for sure, is that the H3 will easily roll off jackstands (in PARK) with either end in the air. So based on these two observations...I can say with 100% certainty that the wheels must be on the ground and the driveshafts must be installed if you want a PARK gear. Period. Exactly why that is...I'm not totally sure. The interesting thing is that if you hook onto the front of an H3 with a tow-truck...lift the front wheels off the ground...and pull the truck forward...the front wheels will spin backwards (while in PARK). AND it does this with near zero resistance! That's why I think the two outputs are somehow bound together in PARK. Its the only thing I can think of that would make a parked vehicle act this way.

 

[Ghostbuster]

Cut the muffler off of my CE.

It is not as loud as I thought it would be.

It has a nice rumble at idle like the Yukon Denali's with the 6.2l. It just quiet a bit louder when you accelerate.

It had some drone getting up to 65mph, but once I got to 65mph you couldn't tell that I just cut the muffler off.


I'm installing a Flowmaster 50 series muffler tomorrow.

 

[4speedfunk]

I got it! (I also got a migraine from thinking about this - lol). Here's whats goin on...

The H3 PARK works just like any normal car. The tranny gets locked and cannot rotate when in PARK just like any normal car. However, it only locks the INPUT shaft of the t-case. Both output shafts are still able to free-spin just like axle shafts in a single-track differential. This also explains why the lifted wheels spin in the opposite direction of the wheels being towed. Think of the front/rear driveshafts of the H3, as if they are the right & left wheels of a standard rear axle with a single-track diff.

Pick any old car (we've all done this). You can jack up the rear axle and rotate one wheel forward, and the opposite wheel will spin in reverse. This happens even when the car is in PARK. This is because the spider gears inside the diff allow the other side to freely rotate, in the opposite direction. Notice however that the car's driveshaft stays still (because its locked by the PARK gear). This same scenario is happening on the H3...except its happening entirely inside the t-case. The same basic parts are there, except their motion is rotated front-to-rear, instead of right-to-left. The H3's front & rear driveshafts are the old car's right and left axle shafts. And the input shaft of the H3's t-case is the old car's driveshaft. The H3 t-case (and most other AWD vehicles) works EXACTLY like an open diff on an axle except all the moving parts are rotated ninety degrees.

So when you hook onto the front of an H3, and begin to tow it...it won't drag the rear tires, like a normal AT car in PARK. Instead the rear wheels spin the rear driveshaft, which counter-spins the front wheels the opposite direction via the variable torque-splitting diff inside the t-case (via the planetary & sun gears). The automatic tranny remains in PARK, and the input shaft of the t-case is also locked motionless. But just like the yoke on that old car's axle...the shafts can still freely turn, even when the car is in PARK. On the Hummer both driveshafts are free to spin and the front one will always spin the opposite direction, even when the car is in park. This explains why the H3's PARK gets disabled when you lift it, and also why it does not have hardly any resistance to rolling when either end is lifted.

Simple huh. Now I can take that nap JP was suggesting.

 

[650Hawk]

I got it! (I also got a migraine from thinking about this - lol). Here's whats goin on...The H3 PARK works just like any normal car. The tranny gets locked and cannot rotate when in PARK just like any normal car. However, it only locks the INPUT shaft of the t-case. Both output shafts are still able to free-spin just like axle shafts in a single-track differential. This also explains why the lifted wheels spin in the opposite direction of the wheels being towed. Think of the front/rear driveshafts of the H3, as if they are the right & left wheels of a standard rear axle with a single-track diff.

Pick any old car (we've all done this). You can jack up the rear axle and rotate one wheel forward, and the opposite wheel will spin in reverse. This happens even when the car is in PARK. This is because the spider gears inside the diff allow the other side to freely rotate, in the opposite direction. Notice however that the car's driveshaft stays still (because its locked by the PARK gear). This same scenario is happening on the H3...except its happening entirely inside the t-case. The same basic parts are there, except their motion is rotated front-to-rear, instead of right-to-left. The H3's front & rear driveshafts are the old car's right and left axle shafts. And the input shaft of the H3's t-case is the old car's driveshaft. The H3 t-case (and most other AWD vehicles) works EXACTLY like an open diff on an axle except all the moving parts are rotated ninety degrees.

So when you hook onto the front of an H3, and begin to tow it...it won't drag the rear tires, like a normal AT car in PARK. Instead the rear wheels spin the rear driveshaft, which counter-spins the front wheels the opposite direction via the variable torque-splitting diff inside the t-case (via the planetary & sun gears). The automatic tranny remains in PARK, and the input shaft of the t-case is also locked motionless. But just like the yoke on that old car's axle...the shafts can still freely turn, even when the car is in PARK. On the Hummer both driveshafts are free to spin and the front one will always spin the opposite direction, even when the car is in park. This explains why the H3's PARK gets disabled when you lift it, and also why it does not have hardly any resistance to rolling when either end is lifted.

Simple huh. Now I can take that nap JP was suggesting.

Simple... And I think you are exactly right, as the transfer case contains an open diff when in 4Hi unlock. But... In 4Hi Lock, that diff is no longer open. That center diff is now locked, which is what allows you to drive with either the front or rear driveshaft removed. So I'm still confused!?

 

[Ordieh]

Hey Ghostbuster,
Cuting off the muffler (whether you install the 50 series or not) will only make more noise without a measureable performance enhancement. To improve power and economy, the crossover that goes from the left bank under the t'case tail shaft to join the other pipe has to be replaced. If you take a careful look, that pipe is crimped to the point of super restriction. One of the reasons it is crushed so deeply is to make room for the strapped on heat shield. If you don't want to invest in a catback such as MAGNEFLOW , a good exhaust shop can build a 2 1/2 inch crossover without the restrictive crimps. In either case, grab some DEI Titanium exhaust wrap because of the closeness to the wiring etc.. One engineer stated that this was the SINGLE item that made the 5.3 in the H3 to be rated with less horsepower than other GM 5.3's of the same vintage and also code 0420 showing up more frequently in the left bank.