Transfer Case Chain

mhorgan · November 24, 2010

Ive got an 02 Z71 with the electric shift 246 transfer case and Im pretty sure Im in need of either a rebuild or a new case. Ive had a bump in my driveline that Ive posted about before. In spite of my effort in throwing cheap parts at it in hopes of getting it fixed (trans mount, U-joints), Im getting nowhere. Every time I come to a stop and then take my foot off the brake, I get a big kick in the back of the seat as the TCC clutch engages and I get ready to accelerate. Im to the point now where I slow to a near stop, then feather the brake and let off to take up the slack in the driveline, then press the brake again to make a full stop. That was my original problem I was chasing. I replaced the tranny mount first, nothing. Then I replaced the U-joints, ruined a socket, and thought I might have had it, wrong again . The latest and greatest noise is the hollow rattle I hear when Im at a slow coast- around 25mph. It sounds like the noise you'd hear when you tap on a loose center cap, which is what I thought it was. I cant tell though. Its intermittent but becoming more frequent. The noise sounds like its right behind the cab but its hard to tell when you drive.

Given the symptoms, Im pretty sure I have a stretched chain in the T-case and the rattle is the chain is rubbing the housing when the truck is coasting. Its a miled up work truck (206K) with the original driveline. The engine and tranny are still smooth so Im counting on this truck to last. Ive heard of people changing the chain but for a $200 dollar chain and God knows what else, is it worth throwing a salvage part in there and calling it a day? Is there any kind of a band aid for this? Im also holding out hope that someone might have another idea but Im fairly sure Im SOL. Any light that can be shed will be appreciated.

gmtech4 · November 24, 2010

first , the clunk while accelerating is the slip yoke lube thing that goes in to the t case

the stretched chain is diag'd by doing a brake stand in 4wd ,,when it skips you WILL know it because the truck feels/sounds like it is coming apart,

why have you not gone for an estimate and a road test with a tech?????????

do not cheap out ,you WILL get screwed ,happens all the time to people who are "saving a buck"

my 2 cents,,good luck

ChevyTech77 · November 24, 2010

Remove rear propshaft, clean slip yoke (the part that goes into the transfer case) splines with brake clean and compressed air, add a thin amount of high quality, high temperature grease to the splines in the slip yoke, cycle

the yoke on the transfer case output shaft splines, reassemble and enjoy.

mhorgan · November 24, 2010

Remove rear propshaft, clean slip yoke (the part that goes into the transfer case) splines with brake clean and compressed air, add a thin amount of high quality, high temperature grease to the splines in the slip yoke, cycle
the yoke on the transfer case output shaft splines, reassemble and enjoy.

Interesting. That may or may not explain the fact that the rattle didnt come along until after I swapped the u-joints and reinstalled the driveshaft. I did try the 4wd brakestand and nothing seemed to pop. I ran it up to about 3 grand and the drivetrain held. I used to be a service writer in a past life and remember the V8 AWD Cadillac SRX with it's myriad of t-case issues. Everything sounded okay in mine.

Let me see if Im understanding this right. I took another peek at the diagram and what you're saying about removing the rear propshaft would involve breaking the case, removing the chain and drive sprockets, and the clutch assembly to service the far side of the propshaft? Or is simply a matter of removing the rear case half and cleaning/greasing the splines on the propshaft where the driveshaft yoke slides over it and slapping it all back together? I only know enough to get INTO trouble, not to get out of it in most cases without having a meltdown. Popping the case open seems feasible and easy enough to do, and I assume I could keep the case in the truck. Doing R and R on the case and blowing it apart is what I find intimidating. Aside from thinking I can self diag in most cases (which Im finding I cant), making the mere mention of the word t-case in a repair shop almost always accompanies the word, "teardown" which I cant afford. That usually keeps me from road testing with a tech. Most of my freinds from dealerships have gotten out of the business and my buddy who does help me is over an hour away. If I can fix this joker on my own with a tube of grease I'll name my next kid after you.

ChevyTech77 · November 24, 2010

Remove rear propshaft, clean slip yoke (the part that goes into the transfer case) splines with brake clean and compressed air, add a thin amount of high quality, high temperature grease to the splines in the slip yoke, cycle
the yoke on the transfer case output shaft splines, reassemble and enjoy.

Interesting. That may or may not explain the fact that the rattle didnt come along until after I swapped the u-joints and reinstalled the driveshaft. I did try the 4wd brakestand and nothing seemed to pop. I ran it up to about 3 grand and the drivetrain held. I used to be a service writer in a past life and remember the V8 AWD Cadillac SRX with it's myriad of t-case issues. Everything sounded okay in mine.

Let me see if Im understanding this right. I took another peek at the diagram and what you're saying about removing the rear propshaft would involve breaking the case, removing the chain and drive sprockets, and the clutch assembly to service the far side of the propshaft? Or is simply a matter of removing the rear case half and cleaning/greasing the splines on the propshaft where the driveshaft yoke slides over it and slapping it all back together? I only know enough to get INTO trouble, not to get out of it in most cases without having a meltdown. Popping the case open seems feasible and easy enough to do, and I assume I could keep the case in the truck. Doing R and R on the case and blowing it apart is what I find intimidating. Aside from thinking I can self diag in most cases (which Im finding I cant), making the mere mention of the word t-case in a repair shop almost always accompanies the word, "teardown" which I cant afford. That usually keeps me from road testing with a tech. Most of my freinds from dealerships have gotten out of the business and my buddy who does help me is over an hour away. If I can fix this joker on my own with a tube of grease I'll name my next kid after you.

Propshaft = Rear driveshaft.

mhorgan · November 24, 2010

Remove rear propshaft, clean slip yoke (the part that goes into the transfer case) splines with brake clean and compressed air, add a thin amount of high quality, high temperature grease to the splines in the slip yoke, cycle
the yoke on the transfer case output shaft splines, reassemble and enjoy.

Interesting. That may or may not explain the fact that the rattle didnt come along until after I swapped the u-joints and reinstalled the driveshaft. I did try the 4wd brakestand and nothing seemed to pop. I ran it up to about 3 grand and the drivetrain held. I used to be a service writer in a past life and remember the V8 AWD Cadillac SRX with it's myriad of t-case issues. Everything sounded okay in mine.

Let me see if Im understanding this right. I took another peek at the diagram and what you're saying about removing the rear propshaft would involve breaking the case, removing the chain and drive sprockets, and the clutch assembly to service the far side of the propshaft? Or is simply a matter of removing the rear case half and cleaning/greasing the splines on the propshaft where the driveshaft yoke slides over it and slapping it all back together? I only know enough to get INTO trouble, not to get out of it in most cases without having a meltdown. Popping the case open seems feasible and easy enough to do, and I assume I could keep the case in the truck. Doing R and R on the case and blowing it apart is what I find intimidating. Aside from thinking I can self diag in most cases (which Im finding I cant), making the mere mention of the word t-case in a repair shop almost always accompanies the word, "teardown" which I cant afford. That usually keeps me from road testing with a tech. Most of my freinds from dealerships have gotten out of the business and my buddy who does help me is over an hour away. If I can fix this joker on my own with a tube of grease I'll name my next kid after you.

Propshaft = Rear driveshaft.

Geez, Im gonna stop and feel dumb for a second longer. My wife is gonna hate that we have to name our first kid Chevy Tech77 but a deal is a deal. I guess propshaft is the correct technical term but my brain has been fixated on thinking about t case internals for so long it flew right over my head. We're a little simpler down here in Georgia. We dont use fancy terms like propshaft. Im off to get some grease and a can of brake clean. Fotunately we do call grease grease but brake clean doubles as mouthwash depending on who you ask...

ChevyTech77 · November 24, 2010

Geez, Im gonna stop and feel dumb for a second longer. My wife is gonna hate that we have to name our first kid Chevy Tech77 but a deal is a deal. I guess propshaft is the correct technical term but my brain has been fixated on thinking about t case internals for so long it flew right over my head. We're a little simpler down here in Georgia. We dont use fancy terms like propshaft. Im off to get some grease and a can of brake clean. Fotunately we do call grease grease but brake clean doubles as mouthwash depending on who you ask...

Works great for cleaning out cuts on your hands too. Finish up with some super glue and black tape.

Now as for the whole pop and soda debate, we'll just let that one slide.

mhorgan · November 24, 2010

Geez, Im gonna stop and feel dumb for a second longer. My wife is gonna hate that we have to name our first kid Chevy Tech77 but a deal is a deal. I guess propshaft is the correct technical term but my brain has been fixated on thinking about t case internals for so long it flew right over my head. We're a little simpler down here in Georgia. We dont use fancy terms like propshaft. Im off to get some grease and a can of brake clean. Fotunately we do call grease grease but brake clean doubles as mouthwash depending on who you ask...

Works great for cleaning out cuts on your hands too. Finish up with some super glue and black tape.

Now as for the whole pop and soda debate, we'll just let that one slide.

I grew up in California so my loyalty is to soda, I dont know what the hell a pop is. My old roommate was from some podunk town in Oklahoma and he called it pop so just an FYI on what kind of company you're keeping. Further, this wasnt a college roommate, this was in the Marine Corps otherwise known as Uncle Sam's Misguided Children.

Here's one more for you. In Georgia, theres a third contender- doesnt matter what it is, its a Coke. Period.