So I'm at a light....(PIC'S)

[BobbyK]

10:30 at night, I'm sitting at a red light coming home after a 16hr day.
I had decided to take the Blazer to work for one of the last times this summer.
Top is still off as the last warm spell of the season is about to end.

Light turns green and I get on the gas....POP...not a boom but a big POP.

Truck now won't move.

I I think I lost a u-joint or something. So I put it in 4wd to get it to the side of the road...nothing....crap.

Luckily there was no traffic and I was able to push the Blazer onto a side street out of the way of traffic.

Look under the truck, no fluid leaking and the u-joints are still there.

Anyway...I had forgot my cell at home and no one would stop even when I waived my arms like I needed help.

Luckily the Police drove by and lent me his cell for a wrecker.

Next day I start to pull thing's apart looking for answers. I didn't need to look very far.

Here are the pic's.

Got the transfer case out 1st. Damn that thing is heavy!





Took a quick look at the T/C 1st. Can you see the prob.?




NIIICE I said to myself.






Output shaft of the trans broke in half.





It's a 700R4 by the way.






So after unhooking the trans cooler lines , linkages and wiring I drained as much of the trans fluid as possible and dropped the trans.









A fair share of ATF fluid got all over the driveway in the process.
I had just got the trans on the ground when my 5 year old got home from school.

He asked if he could help..I said go change and I'll put you to work.

Here he is cleaning up.




washing the trans.






I power washed all the part's I removed and then stood the trans on it's tail so all the ATF would drain out.

That's not grease on the T/C,just bare metal.











That's where I stand at present.


It's a TCI built trans and the out put shaft is from Advanced Adaptors.

I only run a mild 350 and 33" tires.

That output shaft broke clean. The splines where it meshes with the T/C adapter were perfect.

The trans only has about 15000 miles on it and hasn't really been abused.

You think this would qualify as a manufactures defect?


I don't even know what type of warranty A/A has on a part like this although I will be calling them.

So It' look's like a complete tear down just to replace the output shaft, never mind if I decided to replace the internals.




I'll post here with pic's as I do this repair.





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[blue_69]

somone had that output shaft for sale on the parts board a couple days ago. It think it was an advance adapters shaft new in the box. If you cant get it replaced under warranty maybe that would save you some $$

[mustardjimmy71]

I like the the kids shirt! Hockey and old chevys are up there with air and water

[Bentblazer]

I think your right with the defect, pretty clean break. IMO

[68panelman]

Looks familiar, I did the same thing to my 72 K-20 yrs ago. That's what is called a "Line Shot". My output shaft had the same clean break like your's. Mine had everything ruined in a line, trans, t/c ,rear.

[coyote72]

What a bummer! I just put a 700r4 in my blazer with that shaft, it looked like a nice piece. I hope thats not what I have to look foward to. So much for trying a launch in 4-low with the hubs unlocked! Great pics though, are you planning to replace the shaft yourself?

[BobbyK]

Originally Posted by coyote72

What a bummer! I just put a 700r4 in my blazer with that shaft, it looked like a nice piece. I hope that's not what I have to look forward to. So much for trying a launch in 4-low with the hubs unlocked! Great pics though, are you planning to replace the shaft yourself?

I wouldn't worry too much... my situation was prob. a freak incident.
Yes I'll be doing this repair myself. I'll be taking pic's and posting as I make the repair.

someone had that output shaft for sale on the parts board a couple days ago. It think it was an advance adapters shaft new in the box. If you cant get it replaced under warranty maybe that would save you some $$

I quickly looked and couldn't find it. Thanks though.



I just got off the phone with A/A and I have to say they aim to please.
I explained my situation and asked about any type of warranty.
I'm out of luck on the warranty but he did give me a DEEP discount on a new output shaft.

Back in 1999(when I 1st installed the A/A output shaft in my TCI trans) I paid $263.72

A/A site has them for $165.70 now.

They "worked" with me and I'm getting one for $85+ shipping.
About $97 out the door.
Not bad I'd say.






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[BobbyK]

I found the ad on the part's board.
He want's $150, only $15 less than what A/A wants.



.

[Firebirdjones]

wow Bobby, you have me worried now

I just did a 6.0 LS with a 4L60E behind it in mine, and I used Adavanced Adapters for the trans to transfer case with their output shaft, coupler etc....

I also run 33's on mine too. These 700's/4L60's don't have a reputation for strength and that was biggest fear as being the weak link,,,, so I built mine with billet hard parts, red alto clutches and coleen steels, harndened input shaft, beast sun shell etc....
Supposed to hold 700 hp.

Now I have to worry about the output shaft??? I was hoping that was a stronger piece then stock, since it's aftermarket.

I have about 7,000 miles on my swap now, and have the engine dialed in and tuned, runs real strong, shifts hard, lays rubber etc..been having a blast with the power it has. Now I'm feeling like I should tip toe this thing. UGH!!!

[Dieselwrencher]

Before you install that shaft you should send it and have it cyro'd to try and minimize a future breakage. That seems like an odd deal, but I've heard of them breaking just like that a few times. Your Blazer is a nice rig too btw!

[Firebirdjones]

Bobby, what rear gear ratio do you run with those 33's?

[BobbyK]

3:73's

[1972CST]

Man that sucks... you have obviously put good parts in your Blazer. I guess you just expect more from reputable companies.

What kinda mpg are you getting with that set up (350/700R4/3.73's/33's)?
Im thinking about doing the same for mine.

[blue_69]

it took a minute but i found it http://67-72chevytrucks.com/vboard/s...d.php?t=472867

[BobbyK]

Originally Posted by 1972CST

What kinda mpg are you getting with that set up (350/700R4/3.73's/33's)?
Im thinking about doing the same for mine.

Not the greatest...only about 10-11mpg.

with a full 19gal tank I go about 200miles on the highway.




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[Firebirdjones]

Originally Posted by BobbyK

3:73's

Wow small world. Your truck is scary similar to mine.

I'm running the original 3.07 gears, but I have a pile of boxes here full of all the parts needed to swap both diffs to 3.73's along with a new rear posi from Eaton.

Now you have me wondering. I also tow with mine, a small 12 foot utility trailer hauling various things, and had planned to tow a 3800 lbs. 19 foot camper with it. Just what I need is the output shaft to snap while moving that around,,,ugh...and here I figured the tiny pinion in the 12 bolt would snap before anything else (I've broken them off before).

I'm getting 17.2-17.5 mpg around town stop and go driving, and 21-22 mpg on the highway with the current setup, a 2004 6.0 LQ4 and the 4L60.

[1972CST]

I would think you would get better mpg's with your set up. Were you able to correct your speedo/odometer after putting on the 33's?

[Firebirdjones]

Yes, I had another gear reduction box made to correct the speedo.

I'm very happy with the gas mileage considering I'm using the 6.0. Not the usual 5.3 most people are using for the swap.

Over 17 mpg around town, especially in Prescott where it's mountain terrain, alot of stop and go and most of the time below 35 mph. On the scales it weighed 4,760 lbs without me in it, and it's shaped like a brick

That's better than most any new SUV with a gas engine. As a matter of fact, my father has an 03 3/4 ton with the 6.0 and he only gets a best of 14 mpg no matter how he drives it. He needs to let me tap into that computer and tune it sometime
With the old combo (355/350 turbo) it got 13 mpg city and 16 mpg highway. So it was a solid improvement.

Anyway, didn't mean to turn this into a gas mileage thread. I'm more worried about the output shaft after Bobby snapped one.
I was ready to do the 3.73 gear swap, and was even thinking Magnason in a few months for a little more power

Maybe I need to lighten the truck to take some strain off

[1972CST]

I am sorry Firebirdjones... I was refering to BobbyK's MPG's. I thought his might be a little better w/ tuneport and an O/D tranny.

Firebirdjones, your fuel mileage is killer for what your pushing around! 6.0's are NOT known for great fuel mileage but you have worked your magic somehow...

Please excuse me for hi-jacking your post BobbyK... didnt mean to get off on MPG's
Sweet Blazer btw... mine is the same paint and interior combo.

[Firebirdjones]

My bad, I thought you were talking to me.

The mileage is in the tune. Used the wideband and commanded a 14.7 AFR, also got rid of the MAF and went with a speed density tune.
To be honest the factory tunes in the trucks suck. Lame timing tables with too many multipliers, and the AFR was hunting all over the place.
It was too lean, and I'm at 5,000 feet above sea level WOT was commanding an 11.7 AFR too so that was killing WOT HP.

A good tune and these things really come alive.

[BobbyK]

There is a gear correction box on the transfer case. My speedo is bang on. I measured it with GPS.
I took out the TPI as I was chasing gremlins rather than driving it. It has a Eldelbrock 1406 right now. Too small I think.
I have a jet kit for it I need to experiment with.
The engine was WAAAY peppier with the TPI as was the mileage (around 15mpg).

I found out after that 4 of the 8 injectors were bad.
I still have the TPI and all my tuning gear and someday it may find it's way back on the motor.



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[Firebirdjones]

How are you doing on the trans Bobby?

Are you going to do anything to the new output shaft before you install it?

[BobbyK]

I waiting for parts right now.
I'm not sure what I'll find when I get in there.
I'm kinda worried about the sun shell.

I had TCI put in all the upgrades when they built it back in 99. I know replacement parts have gotten much better since then.

[SILVER_WS6]

That sucks. Im going to do a 700 also. I plan on cutting down the output though.. AA is good stuff. Hard to beilieve it just snapped.> More love for cvuttingmy gm shaft down i suppose. Im going to pm you for some swap help..

[Firebirdjones]

I read people say you can do that, but after carefull measuring of mine there just wasn't enough spline to cut the shaft, and I started with a 4x4 trans too.
All I can say is try and see.