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"Snap" when driving??


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Hey all,

 

with the nice weather lately I have been driving my truck around with the windows down and have noticed an interesting noise. My truck is an 03 Z71 -

 

The best way to describe it is it sounds like a "snap" - it is very abbreviated and sounds the same every time. From inside the truck it almost sounds like something electrical is arcing under the cab. It usually only "snaps" once or sometimes twice and I only notice it when I first put the truck in gear or give it gas to get rolling. Ever once in a while I may notice it driving around town if I give it some gas and the tranny downshifts.

 

Another observation - it doesn't always make the snap sound when the gear changes. I put the truck in D and R last night back and forth and it didn't always make the snap sound, and sometimes it wouldn't do it until I held the brakes and gave it a little gas.

 

I bought this truck last fall and haven't really drove it around much w/ the windows down until now so I don't know if this noise would be considered "normal" or just recently begun.

 

Anybody else experience this? Any ideas??

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I know! :cheers: Hello, mine as done this since new, not U-joints as the sound never changes and I bet your truck has done this since new. The dealership says it is just the end of the driveshaft rubbing. The told me something about it is a two piece shaft (inner and outer tube, not two separate shafts) and if the weld was not compressed at the end enough it rubs and when you shift as you describe, it "snaps" (look at the end of the shaft, it is welded, this is the area they told me about, there are two tubes (one you see one you cannot because it is inside that area...I think, it has been a while since I had this converation) and if the guy who builds it does not compress those wels just enough, the power/torque will cause the snap noise, like when you shift fro P to D and R...I guess it is as simple as that). Mine behaves EXACTLY as yours does...I saw a post (see below) and the GM-Tech said this happens to trailblazers (just read the GM-Tech reply the guy who posted sounds as if he has another issue)...they just replace the shaft (and sometimes the sound goes away for a while then comes back), but it is no big deal at all. I took mine in when I bought her last summer, the service manager called Chevy Tech support...they said what I descibed earlier, and said it was up to me to replace, but it would never cause a problem, even towing, just a noise...I never bothered since they were on backorder (even though warranty would cover it...it is an 800$ shaft)...You are right, always sounds exaclty the same, sometimes once sometimes twice...that is simply the area flexing back to the original position, sort of like a quick "snap-snap" all in about 1 second, sound familiar??, sort of like a pneumatic air gun going off real quick or snapping your fingers (only more tinny and metallic)...sometimes you hear it sometimes you do not, exactly as you state! I PM'd the GM-Tech, he says the TSB is only for trailblazers...has not seen one for Silverados, but a dealership around here has had this on some SSR's and some silverados, they gave me the oppurotunity to switch it out but I never bothered cause the part was on backorder and as I said, Chevy and multiple dealerships told me they have heard it, it is not a new problem, has happened in the past with various models and they have never had any issues with them. I actually listened carefully to some trucks at the dealership and heard a couple more do it...the service manager said most people do not ever pay that much attention...as did the GM-Tech...it is just a tinny, metallic snap from the shaft, that is all...cannot hear it with the windows up unless it is quiet and you are listening for it...is this right, usually when you shift from P to D or R (you are right you can go back and forth and it usually only does it the first time...) and then sometimes when you take off, depending on how much gas you give, right? Sounds exactly like what I hear...has not increased or decreased in frequency over the last 10 months (I would say I hear it frequently but not nearly everytime I shift from P to D or R...just once in a while and if I have the windows down or am listening with no radio/AC/heater on), always sounds the same, not louder then softer etc...just as you observe. Chevy told the guy if we wanted to prove this to ourselves we could drill a tiny hole at the end of the shaft a squirt some oil in there...the noise will stop for a while...we did not do this, but I guess tells you they know what we are talking about, and it is just a characteristic of the particular shaft when they built the truck. I told them as long as it will never affect anything I do not mind becuase it is not really noticable unless the windows are down or you are listening for it. Arcing..that is a new desricption I had not thought of! Anyway, hope this helps, later, :cheers::mad::cheers:

 

http://www.gm-trucks.com/forums/index.php?showtopic=40746

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Thanks - that's great info biochemist! :cheers:

 

I don't notice my truck doing this ALL the time when the window is down either - just as you state - but enough that it is mildly bothersome to me.

 

Biochemist, you mentioned that the dealership would have warrantied your driveshaft for this issue, is that correct? Would a dealership actually warranty the driveshaft even though it is admittedly just an annoyance type issue? What do you suppose my chances would be of getting a replacement driveshaft warrantied just to get rid of this noise?

 

Also, you mentioned that the shafts were on backorder when you spoke with the dealer about it, how long ago was this? Just curious if they may still be on backorder.

 

My warranty is going to runout in a couple thousand miles so I am kinda getting paranoid about any little noise, tick, shudder, etc. and want to get anything that may be or become a problem fixed under warranty before it expires, if possible.

 

Thanks :mad:

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Thanks - that's great info biochemist!  :cheers:

 

I don't notice my truck doing this ALL the time when the window is down either - just as you state - but enough that it is mildly bothersome to me.

 

Biochemist, you mentioned that the dealership would have warrantied your driveshaft for this issue, is that correct?  Would a dealership actually warranty the driveshaft even though it is admittedly just an annoyance type issue?  What do you suppose my chances would be of getting a replacement driveshaft warrantied just to get rid of this noise? 

 

Also, you mentioned that the shafts were on backorder when you spoke with the dealer about it, how long ago was this?  Just curious if they may still be on backorder.

 

My warranty is going to runout in a couple thousand miles so I am kinda getting paranoid about any little noise, tick, shudder, etc.  and want to get anything that may be or become a problem fixed under warranty before it expires, if possible. 

 

Thanks  :cheers:

 

 

 

Sure, they told me they would order one if I wanted, but it may take time to come in...this was last Sept. They will replace it under warranty if asked to do so...but as we say (and Chevy), it is just an annoyance...they will replace it though if you want them too. Up to you, read the GM-Tech post for the trailblazer...this is the same issue (happens with the EXT version...longer shaft I guess). As long as they document the noise, they will replace in the future...not to worry, just talk to your service department, reproduce the noise...no big deal. I am with you though, I pay attention to everything...just anal I guess. I figure though it is much better to take real good care of our trucks (that is why we read this great forum! :D ) than to (like most other people it seems) just treat as a point A to B object and have some odd look when something happens. Have not seen you here before, what other mods do you have on your truck, any pics, plans? Anyway, hope this helps, later, :D:mad::cheers:

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Thanks again biochemist!

 

Looks like I'll be scheduling a trip to the dealer soon.

 

I just put a pic of my truck in the General Pic Post, not many mods yet but way more plans than money right now - isn't that how it usually goes?

 

Just a pic of my truck

 

Later

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