I have an '03 Silverado 4X4 with the 4.8L engine. It has about 64,000 miles. I just bought it a couple months ago and noticed if i don't ease into the throttle when coming out of corners or just rolling and then getting back into the throttle, it sounds like the rearend is clunking into gear and the throttle response seems very mushy, just before it bangs/clunks into gear. Its not in neutral or anything, it just seems like the throttle response isn't there, just prior to clunking. I tried dropping it down in 2nd gear to see if its clearance in the rearend between ring and pinion, or whatever the 2 gears are. I get going like 20 mph in 2nd then goose it and then let right off completely, but no clunking noise, either giving it some or letting off the throttle. It seems to shift smoothly otherwise. If i feather or ease into the throttle slowly, it seems to fix / help the problem. A friend of mine has the same truck and he said his does the same thing and his dealer told him, the '03's had some kind of limited slip / semi locker rearend come standard equipment, and the noise are the clutches or something. I was wondering if the torque management could have something to do with it? Is there any adjustment on throttle response, where theres no throttle cable? I'm used to vehicles with a throttle cable. The only mod i have done is a K&N FIPK. First thing when the truck is started, it seems like it stays in low gear longer than normal. I have checked the universals on the driveshaft and etc and where the driveshaft goes into the tranny i believe, it is leaking slightly, as the seal is wet, not soaked tho, but i don't believe that would cause my problem / concern. Oh yeah, and NO CODES in the dash, and my dealership hooked it up to the OBD and they checked " all " the computers. Ok, enuf of me, now, i'd like to hear from some of you gurus out there, and yes, that includes you "Argon". Thanx, Jim


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I used to have this issue as well, and here was the problem. When slowing down, if you don't come to a complete stop the tranny will be between 1st and2nd. The clunk is when you hit the gas it jumps into gear. If it is slow, you went to 2nd, if it takes off then you are in 1st. You can confirm this by slowing down at a light then right before the truck stops completely, hit the gas (not real hard) and you will feel it. There is no fix that I can find, but if you ease into the gas at that time it won't do it.

 

Its taking off in second,I think..I've seen em do that...its a calibration issue.A dealer needs to update the pcm,most likely

 

1. Chevy trans always clunk. Every one I ever had did it when it got around 50k to 60k. Make sure you flush trans and replace the filter every 60K (thats what the owners manual says).
2. If it sounds like it is coming from the rear axle and not the trans, it wouldn't hurt to have it looked at. My buddy has a 99' with a limited slip (Z71 option) with 120K and his rear end blew out because a little $3 pin shfted out of place and the differential came apart. Not sayin this will happen to you but if all else fails, it won't hurt.

 

I disagree about the trannys chevy makes. My last tranny went 283,000 miles before giving any trouble and I treated it like crap. Also when the performance trucks look at a tranny swap they always get a chevy tranny.

 

Hey Argon, whats it cost to calibrate the PCM ? Is it something GM will do as like a recall or update issue or not? My dealers supposed to be taking it for a spin and see if they can find out just what exactly is happenin. I drove it all weekend and eased into the throttle, and it was fine. Almost like the RPM's are dropping too fast and the tranny cant keep up or something. I hope its an inexpensive fix to my annoying problem. Will let ya know what they tell me, thanx, Jim


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How long did it sit before you drove it? My '01 did the same thing, but only when the bed was empty. When the suspension is unloaded it has a different angle to the driveshaft than when it is loaded. In an unloaded P/U the rear axle can change pitch (angle) rapidly and in turn pushes the driveshaft into the back of the tranny. The aluminum driveshaft causes the sound to appear to come from different places.

 

The dealership can give you a temp fix for about $80,Greasing the yoke

 

Well everyone,I droppedmy truck oGMff at the dealership this morning, and the service manager and the guy that does all the GM tranny work, took my truck out to see what i was talking about. Bottom line.......... theres nothing wrong with my truck. They hooked the truck up to the computer, all the updates have already been done, they checked the DCM, and its shifting correctly, clutches are engaging correctly, and etc. They checked the backlash in the rearend gears, andtheyhadlike .003 - .005 play, which was fine.They told me, not to worry about breaking anything, and the tranny guy was actually very impressed with the truck. I guess its the nature of the beast.......... They told me to check with them like every 6 mos or so, as GM udates their hardware quite frequently. Thanx everyone for your input, Jim


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