Tranny went bang - The 1947 - Present Chevrolet & GMC Truck Message Board Network

odog · 09-30-2011, 10:14 PM

Ok last night I was leaving work, I backed out of my spot, placed my 69 1/2 ton 4x4 in 1st, let out the clutch and BANG, there I sat. I figured maybe a u joint, but they are fine. The tranny is an sm 420 with a rockwell t221 transfer case. I have no movement in any gear, but when I put the truck in 3rd or 4th, and let out the clutch, the gears grind horribly. Reverse, 1st and 2nd do not do this. I have tried shifting the tcase into 2high, 4high, and 4low with all the same results. Everything shifts fine, but I get no vehicle movement in any gear. What do you guys think. Did I break the out put shaft on the tranny? Maybe the t-case has an issue. I will try to tear it apart 1st chance I get, but as of now it sits at work waiting.

ETsC10 · 09-30-2011, 11:23 PM

Odog, I'm not much help here as I'm not a 4x4 person but if it was a 2 wheel drive, I would also look
to see if your linkage is intact...the fact that it won't move in any gear probably rules that
out but just a thought...

Just wildly guessing here and, I'm sure, one of our more knowledgeable folks will chime in.
Good luck!

**Boog** · 09-30-2011, 11:33 PM

Not good. When mine did that the input shaft and cluster gear fragged. I was able to run it in high gear only and made it home.

odog · 10-01-2011, 12:48 AM

Thank you guys for your input. I had a buddy lay underneath while I shifted the t-case, (truck not running of course) just to make sure the shifter was moving the linkage. My hope was maybe it popped into Neutral and the linkage was messed up. But that wsnt the case. This weekend I will take the top off and see what I can see, but I think Im going to have to drop the whole mary ann to get a good look at everything.

**nbrfd007** · 10-01-2011, 01:57 PM

There is a coupler between the transmission and transfer case. It is female splined, they get worn and slip. I had that problem with several 68-69 T221 setups. The transmission and transfer case shafts are usaully not hurt, the coupler must be softer.
Tim

odog · 10-01-2011, 08:37 PM

That gives me some hope. I guess I will find out when I drop the tranny out and pull the two apart. Where does one find one of these couplers if I find that is the problem. Are they something I can get at a NAPA or do I gotta go somewheres special?

**nbrfd007** · 10-02-2011, 12:30 AM

Quote:

Originally Posted by odog

That gives me some hope. I guess I will find out when I drop the tranny out and pull the two apart. Where does one find one of these couplers if I find that is the problem. Are they something I can get at a NAPA or do I gotta go somewheres special?

One sold on ebay a week or two ago for around $45.00. 70BLAZERx2 had on built by a machine shop, he has a thread on it. He is well versed about the Rockwell T221. http://www.drivetrain.com/parts_cata...rts.htmlCached - Similar- has them, but they are high.

Tim

hugger6933 · 10-02-2011, 09:54 AM

Just throwing this out there probably not it because of the 3-4 noise but Iwould check the center of the clutch to is if the center has broken out. That might be you next cheapest hope next to the trans coupler

odog · 10-02-2011, 11:44 AM

Thank you all for the info, I will try to get it pulled out today. I will post what I find.

Jack_71C10 · 10-02-2011, 12:16 PM

I had the samething happen to a '89 camaro.
thought is was tranny, turned out to be clutch.
But I was driving it pretty hard when it happened.

09-30-2011, 10:14 PM	#1
odog Registered User Join Date: Oct 2007 Location: Wendell, Idaho Posts: 608	Tranny went bang Ok last night I was leaving work, I backed out of my spot, placed my 69 1/2 ton 4x4 in 1st, let out the clutch and BANG, there I sat. I figured maybe a u joint, but they are fine. The tranny is an sm 420 with a rockwell t221 transfer case. I have no movement in any gear, but when I put the truck in 3rd or 4th, and let out the clutch, the gears grind horribly. Reverse, 1st and 2nd do not do this. I have tried shifting the tcase into 2high, 4high, and 4low with all the same results. Everything shifts fine, but I get no vehicle movement in any gear. What do you guys think. Did I break the out put shaft on the tranny? Maybe the t-case has an issue. I will try to tear it apart 1st chance I get, but as of now it sits at work waiting. __________________ 1969 4x4 Nothing beats a good rock drill and some dynamite

09-30-2011, 11:23 PM	#2
ETsC10 Hand Crafted C-10 Join Date: Aug 2006 Location: Burien, WA Posts: 5,180	Re: Tranny went bang Odog, I'm not much help here as I'm not a 4x4 person but if it was a 2 wheel drive, I would also look to see if your linkage is intact...the fact that it won't move in any gear probably rules that out but just a thought... Just wildly guessing here and, I'm sure, one of our more knowledgeable folks will chime in. Good luck!

09-30-2011, 11:33 PM	#3
Boog laying low Join Date: Mar 2001 Location: Searcy, Ark. USA Posts: 13,531	Re: Tranny went bang Not good. When mine did that the input shaft and cluster gear fragged. I was able to run it in high gear only and made it home. __________________ Boog 69 Chevy stepside, 358/T350, 4.11 posi, 4.5/4 drop, rallys, poboy driver primer is finer 91 Chevy sportside, Tahoe, Yukon & GMC Crewcab All GM..'nuff said. I stand for the flag and kneel at the cross

10-01-2011, 12:48 AM	#4
odog Registered User Join Date: Oct 2007 Location: Wendell, Idaho Posts: 608	Re: Tranny went bang Thank you guys for your input. I had a buddy lay underneath while I shifted the t-case, (truck not running of course) just to make sure the shifter was moving the linkage. My hope was maybe it popped into Neutral and the linkage was messed up. But that wsnt the case. This weekend I will take the top off and see what I can see, but I think Im going to have to drop the whole mary ann to get a good look at everything. __________________ 1969 4x4 Nothing beats a good rock drill and some dynamite

10-01-2011, 01:57 PM	#5
nbrfd007 Senior Member Join Date: Nov 2007 Location: New Blaine, Arkansas Posts: 751	Re: Tranny went bang There is a coupler between the transmission and transfer case. It is female splined, they get worn and slip. I had that problem with several 68-69 T221 setups. The transmission and transfer case shafts are usaully not hurt, the coupler must be softer. Tim

10-01-2011, 08:37 PM	#6
odog Registered User Join Date: Oct 2007 Location: Wendell, Idaho Posts: 608	Re: Tranny went bang That gives me some hope. I guess I will find out when I drop the tranny out and pull the two apart. Where does one find one of these couplers if I find that is the problem. Are they something I can get at a NAPA or do I gotta go somewheres special? __________________ 1969 4x4 Nothing beats a good rock drill and some dynamite

10-02-2011, 09:54 AM	#8
hugger6933 Registered User Join Date: Oct 2008 Location: Marianna Arkansas Posts: 7,280	Re: Tranny went bang Just throwing this out there probably not it because of the 3-4 noise but Iwould check the center of the clutch to is if the center has broken out. That might be you next cheapest hope next to the trans coupler

10-02-2011, 11:44 AM	#9
odog Registered User Join Date: Oct 2007 Location: Wendell, Idaho Posts: 608	Re: Tranny went bang Thank you all for the info, I will try to get it pulled out today. I will post what I find. __________________ 1969 4x4 Nothing beats a good rock drill and some dynamite

10-02-2011, 12:16 PM	#10
Jack_71C10 Shortbed club member Join Date: Jan 2008 Location: Halethorpe, MD Posts: 439	Re: Tranny went bang I had the samething happen to a '89 camaro. thought is was tranny, turned out to be clutch. But I was driving it pretty hard when it happened. __________________ 71 custom/10 6.0/4L80E SWB ece 4/6 72 custom camper 350/3 spd 2020 Chevy Express 3500 2023 Hyundai Tuscon 1986 GMC 3500 Bucket Truck Sent from my Rotary Phone via 14.4kb/s modem.



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