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Thread: 2-3/3-2/reverse clunk
11-03-2009, 05:55 PM #1
Alright. I'm slowly but surely ironing the bugs out of this thing. I eliminated the clunk from the steering wheel by replacing the I-shaft, among other things. Now I need to fix this driveline clunk.....
The symptoms are: When I place it in reverse, it clunks pretty good. But never when placing it in drive. When accelerating from a stop, it makes a slight popping noise from somewhere but it's hard to isolate the location. 1-2 shift is good. 2-3 causes a pretty good clunk that can be heard and felt. The 3-2 downshift when slowing down also makes a good clunk.....
I did a quick check of the u-joints and they seemed to be OK but I'm no expert. Could this be the slip yoke? If someone could explain to me how to isolate this clunk, it would be greatly appreciated. I need to find out if it's something serious enough (ie, a bad rear end or t-case) to make the 70 mile trek back to the dealer I bought it from. Thanks!!
Last edited by TJbear; 11-03-2009 at 05:57 PM.
11-04-2009, 04:35 PM #2
- Join Date
- Sep 2009
Good question.........my 93 Suburban has a similar thing going on. When standing at a light with the brakes on, as I lift off the brake there's a thump in the driveline like there's slop in it somewhere. Almost feels kinda like the rear brakes are hanging up then releasing. U joints seem to be ok and don't think there's a problem with the rear end. Could it be the driveshaft slipping in and out of the trans. tail housing? And if so, should I worry about it or is this normal?Lee
1993 GMC Suburban C1500 (my cream puff)
2003 S10 Blazer 4x4 auto (the wife's wheels)
11-15-2009, 12:31 PM #3
Alright, I ended up greasing the slip yoke and it didn't help at all. I had the wife keep putting it into and out of reverse while I felt and listened for the source of the clunk and it seems to be coming from the transfer case. The 2-3 and 3-2 clunk persists. Tranfer case shot at 70K miles?? Or is it a transmission problem causing it to engage into reverse too harshly? Never does it in when shifting into drive, though. Might just take it to a Chevy dealer and pay the diagnositic fee so i have something to show the used car dealer that sold me this thing...
11-19-2009, 10:53 AM #4
Decided to just take it to a local dealer and they found the transfer case has "excessive lash". Lovely...... They wanted a rediculous amount of money to remove the t-case and take it apart to "see what's going on inside". I said no thanks, ate the initial diagnostic fee and took it home.......
Aside from the clunking, they also said the "humming" noise/feeling I've been getting from the front end is also due to the t-case. Is this possible? I swear it's coming from the left front of the truck but could the t-case be "transmitting" this sound to the front somehow?
At this point, what are my options? Used? Rebuilt? New? Its not something I have to fix right this instant but I'd like to take care of it eventually.
11-19-2009, 11:00 AM #5
As far as the T case i would get a new or remanned one if they even sell them like that, im about to do the same thing. Treat it like you would treat a tranny issue, thats what is basically is... spend the extra money to get it as good as you can so you know it will be good and no further issues for a long time. trust me you wont regret it, I have seen people just try and fix it a cheaper way and never stopped having issues. keep me updated i am right behind you with this issue...1997 K1500 Silverado 4X4. Black Exterior, grey/black interior. 35X12.50X15 wheels and rubber, ProComp 6inch lift 6 shocks in the front 2 in the rear, 3 inch body lift, a few cosmetic mods. Nothing major. Custom leather interior, and stereo upgrade is the future mods.
11-21-2009, 06:31 PM #6
Anyone have any experience with rebuilt t-cases?? List price for rebuilt unit from GM is around 1400 bucks. On rockauto.com, they have em for about 900 bucks minus the encoder motor. The rock auto units are remanned units by "Retech"........
Anyone know the going rate for having a trans shop rebuild them?
12-06-2009, 11:37 AM #7
I've had this truck for 2 months now nad have driven it enough to start noticing some patterns. The humming noise from the front seems to be most pronounced between 50-55mph. Loudest at 55, then drops off as I go faster. I can also hear a rumble or hum under light acceleration right after it shifts into o/d, like something is resonating from it "bogging" at low speeds in o/d.
Another pattern I've noticed is the clunking and the hum seem much worse in cold weather. The warmer it is outside or the longer I drive it, the better it gets.
So I ended up dropping the front drive shaft to try and isolate this humming sound. With it removed, the noise went away. However, a new humming noise appeared around 20-40 mph but much more quiet. With the shaft reinstalled, the new noise went away and the old one came back. I took the shaft to my local shop to check the original u-joints and he said they're fine.
I also noticed the "clunk" when shifting into reverse and 2-3/3-2 was much more muted with the front shaft off....
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