FwyFlyr Posted December 17, 2003 Report Share Posted December 17, 2003 I'm now at 12k miles and this has been present since day 1. Doesnt seem to matter what gear I'm in (3rd or od) Only happens while on throttle, the harder, the worse it gets. It's as if the front driveshaft is out of line with the T-case and front diff. This scares my feet. ( if the d-shaft let loose, bye bye feet. ). Dealer says all dimensions are within spec. Anyone got ideas? Know of a 4 wheel dyno in chicago area? Link to comment Share on other sites More sharing options...
cerbomark Posted December 17, 2003 Report Share Posted December 17, 2003 I d park it in there showroom ( if you know what I mean). My Benz had similair problems at 90 MPH and although the dealer wouldn t drive the vehicle at those speeds the tech offered to ride with me to get a feel for the problem. Not that it s the same problem but they put a spacer back in the wrong spot on the rear diff causing a driveshaft allignment problem like you stated. Did anyone ever remove anything from those areas? Rear end repairs? How about a driveshaft balance problem. Good Luck, I don t know how you put up with that for so long. Link to comment Share on other sites More sharing options...
marc_w Posted December 17, 2003 Report Share Posted December 17, 2003 Mine does this too. Definitely not a wheel. Definitely a driveshaft or two. I get a slight shudder at 70 at times, but when I put my foot in it, I usually get the bad vibes. I've been meaning to get under the truck to check things out myself - maybe bump one driveshaft at a time, 180*. Something like that. If that don't work, it'll have to go to service to get the shafts balanced. Link to comment Share on other sites More sharing options...
FwyFlyr Posted December 18, 2003 Author Report Share Posted December 18, 2003 Nothing has been taken apart or worked on. I really think something is out of balance, but the vibration goes away when I let off. I thought I'd pull the front d-shaft and make a run but, from what I read somewhere, I could damage the T-case. Did someone say something about front axles & being in or out of phase? The axles seem to be perfectly straight & level. Tempted yes, but I have'nt even turned the torsion bolts. Lowering would seem to straighten the d-shaft but, would then put angle in the axles. The front shaft just bugs me because it does'nt seem to have any free play front to back. I wonder if under hard load the tranny moves just enough to cause a bind? I guess I should start balancing things to the extreme degree. Thanks for your imput. Link to comment Share on other sites More sharing options...
deezel Posted December 18, 2003 Report Share Posted December 18, 2003 I don't know if this is the same thing, but I have twice experienced a disturbing "rumbling" sound/slight vibration when accelerating at high speeds (over 80mph). Disappeared when I let off the throttle... I logged one of these events with EFILive and observed that the computer was dumping in more fuel than normal when this happened. I suspect that this was the COT (catalyst over temp) protection function of the PCM. Apparently the PCM adds fuel when it thinks the cats are getting too hot. If this makes the mixture too rich it could cause the engine to stutter... This happened before I had Edit. Now I can turn off the COT function... but I haven't tested this theory yet. Link to comment Share on other sites More sharing options...
FwyFlyr Posted December 19, 2003 Author Report Share Posted December 19, 2003 Good one deezel but, [/u] (for me anyway!!) Goodyear says my tires are o.k. But it was a cheesy balance. Got appt. sat. for a "Road Force" balance on sat. ( ouch! $125. ) Hey all in the name of performance, right! Wrong about d-shaft angle / stays the same. Link to comment Share on other sites More sharing options...
FalconPilot Posted December 20, 2003 Report Share Posted December 20, 2003 My truck has the same noise a 80 to 100. Past 100 it goes away. It sounds like a harmonic of some sort in the drive line. Because the noise goes away when the load is taken off, I tend to think it is in the front diff. Anyone know the speed limit in Montana? will you get a ticket for 80? If not, there is the reason to have it fixed. Chad Link to comment Share on other sites More sharing options...
FwyFlyr Posted December 20, 2003 Author Report Share Posted December 20, 2003 Update; The "Road Force" balance took 85% of the bad vibes out!! Best $125. spent in a long time. 1 Tire was way off the other 3. Link to comment Share on other sites More sharing options...
Plwtwo Posted December 23, 2003 Report Share Posted December 23, 2003 You guys need to find someone who Speed Balances on the Truck...... I've had to have it done in the past with strange vibrations. Tires and wheels can sometime balance on the machine but when they are on the Hub they are out of Balance.. "On Car Speed Balances" will balance the wheel on the hub at speeds up to tire speed rating.....its a little costly but it works!!!! Link to comment Share on other sites More sharing options...
detjoe Posted January 3, 2004 Report Share Posted January 3, 2004 I have the same sound. When hauling aSS, there is a low growl. Step on it more and it goes away or the exhaust comes up, one of the two, or both Might this have to do with the TSB about the frond drive axels??? When in my other SS @80 you can go and go some more but in the SSS @80 you can feel bogged down, more gas, not the same pull as the Impala...could this be fixed with LS! edit?? Not the grinding sound the bogging probably just keeping informed joe Link to comment Share on other sites More sharing options...
FwyFlyr Posted January 4, 2004 Author Report Share Posted January 4, 2004 Been advised by a tranny guy that mine is probably the rear d-shaft. Road force balance took most of it away, but not all. Haven't had a chance to pull the shaft and send it out. marcwsaid he would try to set one 180 off to see if it was harmonics. Don't know? Link to comment Share on other sites More sharing options...
MustBBrent Posted January 4, 2004 Report Share Posted January 4, 2004 Just to chime in. I have the problem above ~95mph. It does feel like the drive shaft as it is in my feet on the floor board. Dunno what to say. The dealership definitely does not want to help me on this one. Link to comment Share on other sites More sharing options...
ledfootss Posted January 4, 2004 Report Share Posted January 4, 2004 have you guys had these problems from the start or did they just show up? Link to comment Share on other sites More sharing options...
MustBBrent Posted January 4, 2004 Report Share Posted January 4, 2004 have you guys had these problems from the start or did they just show up? I never took it over that speed until my nelson performance tune 2 weeks ago. It has made the vibration every time I get the truck up to the speed which 4 times so far. Link to comment Share on other sites More sharing options...
whitebowtie Posted January 4, 2004 Report Share Posted January 4, 2004 Yeah i feel a shudder on mine, but after a certain point, it goes away. it felt also that it would happen high up in the RPM's, and i kind of felt it before the 2-3 shift. im not worried about it. i dont often drive over 90, and if something does happen, provided i am uninjured, ill be happy because i get a brand new SS, and if i do get hurt, i can sue chevrolet for more money. Link to comment Share on other sites More sharing options...
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