246 Auto Trac Case= Noisy. Just a PSA
#1
246 Auto Trac Case= Noisy. Just a PSA
So gents, I have an 02 Tahoe that has spent a lot of time in 4wd in her life. She was regeared to 4.10(~5yrs ago), and I had this noise in the front that I thought was diff. Noise started right around late May/early June. You could feel it in the floor, you could "hear" it from the front, you felt it up front. So, I got an OEM 4.10 diff because I thought the diff was the problem after going through the major components like CVs, hubs, output flanges, input bearings, u joints, etc. I was noticing some other problems, like 4hi acting up and the truck didnt want to go forward in 4hi, grinding in reverse, etc. Thought something CAD, or diff related was giving me crap.
Got the 4.10 diff in with some parts mixing and matching and a run to the u pull. No big deal. Our diffs are easy to swap, thanks GM.
Fire the truck up, drives fine, 4wd is fine. But that noise is still there in reverse! like WTH right? Well now I look into it more, front shaft doesnt free wheel in 2wd with the truck on the ground. Do some google, dont find anything I want to read. Had a friend shift the case and I can hear and feel trash inside the case. With your ear next to it, sounds like its chewing on rocks in there. Interesting however is that noise is almost 100% gone in forward. Its bad in reverse, but only under load. Maybe its the clutch. Fluid is still blue even.
So, the PSA here is: dont spend money without checking everything connected with driveshafts. haha. I have a 241 and a manual lever, so not a deal breaker for me at all, but damn I coulda saved a couple hundred on the front diff mixing around since it wasnt the problem!
Verification, noise still exists in reverse with diff de- coupled from driveshaft.
I'll report back in a few weeks/months when I swap the 241 in. I expect everything to be fine then.
Got the 4.10 diff in with some parts mixing and matching and a run to the u pull. No big deal. Our diffs are easy to swap, thanks GM.
Fire the truck up, drives fine, 4wd is fine. But that noise is still there in reverse! like WTH right? Well now I look into it more, front shaft doesnt free wheel in 2wd with the truck on the ground. Do some google, dont find anything I want to read. Had a friend shift the case and I can hear and feel trash inside the case. With your ear next to it, sounds like its chewing on rocks in there. Interesting however is that noise is almost 100% gone in forward. Its bad in reverse, but only under load. Maybe its the clutch. Fluid is still blue even.
So, the PSA here is: dont spend money without checking everything connected with driveshafts. haha. I have a 241 and a manual lever, so not a deal breaker for me at all, but damn I coulda saved a couple hundred on the front diff mixing around since it wasnt the problem!
Verification, noise still exists in reverse with diff de- coupled from driveshaft.
I'll report back in a few weeks/months when I swap the 241 in. I expect everything to be fine then.
#3
Put the Case in 4wd, Leave it in park, stick the front shaft into the splines, and twist back and forth, see how much slop there is. My hunch is the chain is stretched, the noise you hear is the chain slapping the case, grinding away, when you put it in reverse or forward, the chain slop is either on the top or the bottom if that makes any sense. The front shaft does not freewheel on the 99-02 246 cases. The front drive is clutched like an automatic, but its a Mechanical activation by the Decoder motor. The 03 up ones will freewheel so to speak, they have looser clearance and a small return spring.
#4
Thank you guys for the info! I really don't want to mess with the 246. I have a 27 and 32 spline 241 laying around. I will be using a 241 with the 4L80 anyway, so this is a good time to work on the wiring and any tuning changes.
I do swear that I could turn the shaft by hand when I got the truck re-geared. I'm inclined to believe you tho, because that was 5yrs ago and I've only been under there to change fluids and build exhaust since then.
I do swear that I could turn the shaft by hand when I got the truck re-geared. I'm inclined to believe you tho, because that was 5yrs ago and I've only been under there to change fluids and build exhaust since then.
Thread
Thread Starter
Forum
Replies
Last Post
1fastmofo
GM Drivetrain & Suspension
0
10-26-2006 09:51 PM
RobZ71LM7
GM Engine & Exhaust Performance
2
04-01-2002 05:29 PM