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Discussion Starter #1
i have a 01 ECSB 5.3 z71. my tranny makes some crazy cluncking sounds when shifted into all the gears it sound worst with the tow/haul on. i was wondering if hypertech would help at all? also with hypertech i know you can put the truck back to stock for when it gets serviced but wont the dealer know that i used it? or would it say it had an error or something?
btw my trcuk has 45565 miles


thanks

Mark
 

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03 Tahoe
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If the trans is making odd noised and not shifting correct than modifying it won't do any good. I'd check the fluid level, maybe do a fluid and filter change, and/or take it to the dealer and have it checked out.

Cameron
 

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The clunk could also be the slip yoke. Also, check u-joints for play.

here is some slip yoke info:

QI have a 2000 GMC Sierra. When I slow down and then accelerate there is a clunk in the driveshaft. The dealer, under warranty, greased the driveshaft on the transmission splines, and it worked for a while. I found there has been acontinuing problem with GM trucks for several years. I spoke with two GM mechanics and they tell me that there is a replacement part that fixes the problem. I asked the dealer, but he said he knows nothing about it. Do you know if there is a fix and what it is? My resources are tapped, and now my truck has 39,000 miles, so it's my problem to solve.

AThis clunk is caused by the splines on the driveshaft yoke binding on the splined output shaft of the transmission/transfer case. When you reverse the drive loads, as in braking to a stop and then accelerating, the yoke tends to bind as the splines try to slide a bit as the driveshaft changes length. Since the transmission and transfer case are mounted to the chassis and the rear axle housing is located by trailing arms and moves up and down on the springs, the driveshaft must change length as the rear axle moves through its range of travel. That's why the yoke and output shaft are splined, and this is what binds as you try to accelerate. It finally "pops" free and slides, creating the noise. It's not harmful, but it sure is annoying. For years, the first fix was to remove the yoke and lubricate the splines with a special molybdemum disulfide grease. Just as you described, this stopped the binding and clunking for a while, but the noise tended to come back eventually.

The latest issue of ALLDATA says GM now has a permanent fix available. For 1500 series trucks from '99 to '02, it's a nickel-plated driveshaft slip yoke, part number 12277702. If it's a 2500 series truck, the part number is 1247704. The nickel plating provides a slippery surface, and should prevent the binding that causes the clunk.

This upgrade is described in TSB No. 01-04-17-004 dated October 2001. Ask your dealer about it, and if you originally brought the vehicle in to fix this problem while it was still under warranty, ask the dealer to petition GM for a customer goodwill adjustment to help with the cost of the repair.
 

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Discussion Starter #4
i set an appointment at my dealer to look at my truck (tues next week). also today my driverside window motor died and my window is stuck half way up and it is raining right now but luckily my truck is in the garage.

thanks for the help
 

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jebx said:
The clunk could also be the slip yoke. Also, check u-joints for play.

here is some slip yoke info:

QI have a 2000 GMC Sierra. When I slow down and then accelerate there is a clunk in the driveshaft. The dealer, under warranty, greased the driveshaft on the transmission splines, and it worked for a while. I found there has been acontinuing problem with GM trucks for several years. I spoke with two GM mechanics and they tell me that there is a replacement part that fixes the problem. I asked the dealer, but he said he knows nothing about it. Do you know if there is a fix and what it is? My resources are tapped, and now my truck has 39,000 miles, so it's my problem to solve.

AThis clunk is caused by the splines on the driveshaft yoke binding on the splined output shaft of the transmission/transfer case. When you reverse the drive loads, as in braking to a stop and then accelerating, the yoke tends to bind as the splines try to slide a bit as the driveshaft changes length. Since the transmission and transfer case are mounted to the chassis and the rear axle housing is located by trailing arms and moves up and down on the springs, the driveshaft must change length as the rear axle moves through its range of travel. That's why the yoke and output shaft are splined, and this is what binds as you try to accelerate. It finally "pops" free and slides, creating the noise. It's not harmful, but it sure is annoying. For years, the first fix was to remove the yoke and lubricate the splines with a special molybdemum disulfide grease. Just as you described, this stopped the binding and clunking for a while, but the noise tended to come back eventually.

The latest issue of ALLDATA says GM now has a permanent fix available. For 1500 series trucks from '99 to '02, it's a nickel-plated driveshaft slip yoke, part number 12277702. If it's a 2500 series truck, the part number is 1247704. The nickel plating provides a slippery surface, and should prevent the binding that causes the clunk.

This upgrade is described in TSB No. 01-04-17-004 dated October 2001. Ask your dealer about it, and if you originally brought the vehicle in to fix this problem while it was still under warranty, ask the dealer to petition GM for a customer goodwill adjustment to help with the cost of the repair.
Did you ever get this fixed? What was the fix?

thanks
 
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