99silverado vibration problem
Purchased 5.3,ext-cab, z71 that developed what
seemed to be a drive train vibration at speeds over
45 mph. After trying to fix problem, GM took truck
back. Other trucks on the lot have same problem.
Am trying to find out how large this problem is, or
is it restricted to a certain lot of trucks.
seemed to be a drive train vibration at speeds over
45 mph. After trying to fix problem, GM took truck
back. Other trucks on the lot have same problem.
Am trying to find out how large this problem is, or
is it restricted to a certain lot of trucks.
0
This discussion has been closed.
Comments
to see if that's the same problem you had.
Also please tell us more of your problem if
you know further info.
THanks,
Tung
seems to occur after accelerating from a stop
right after it shifts into 2nd gear(around 15mph)
and starts to smooth out after 25mph.Makes you want to gun it a bit just to get past the vibes.
I thought it may be anything from a bad U-joint,
to Goodyear tires,transmission,Etc.Maybe I'll
just take some kind of Yoga class so I can just
smile when it happens.
What GM response did you get concerning a possible fix in mid-may?
I doubt a costly transmission problem is likely since thousands of 4L-60E transmissions have been in service before the introduction of '99 Silverado/Sierra. If anything, it's going to be one of those powertrain control module proms getting re-flashed with up-dated codes. Or they will tell us it's normal if it doesn't have an adverse effect on durability.
They never really fixed those rattling exhaust heat shields on the pre-'99's. We don't have that problem so they gave us a new one.
It is POSSIBLE that a code change in the transmission could solve the problem. Maybe the engine and transmission work well for emissions but have this shudder problem. It sounds like too high a gear ratio for engine RPM at the moment.
Just a thought to all of you who have the problem. What is your rear axle ratio? Is there one ratio in common?
Rich
"new calibration to correct harsh 1-2 upshift and driveline growl. may affect fuel economy."
What you can infer is that the "driveline growl" is naturally occurring resonant energy. The fix is to delay the torque converter lock-up. The penalty for doing this is a decrease in fuel economy from running the higher rpms to get beyond the frequency where the noise is centered.
Probably no harm whatsoever with the noise, unless it is severe. My '99 Silverado was afflicted with this too, but with 7000 miles on the odometer, the growl has all but disappeared on it's own. I'm not sure what has changed, but I've been driving on the same stretch of road where I most noticed it before, and I can't seem to discern it now, or if I can, it is very slight or inconsistent.
So after some thinking, I've decided in my case, the risk from changing the transmission calibration isn't worth the certainty of harming fuel economy, so I'm skipping the change for now. But if you don't want to, you can visit
http://calid.gm.com/vci/
, enter your VIN number, and find out if the transmission calibration update is available for your specific truck.
Do you think that the programming change would really affect your mileage much more than a couple of tenths?
Rich
GM bulletin stated that any attempt to correct the problem before a GM response would void the vehicle warranty.
bed; 2wd) for one month today. Have vibration on
takeoff and also occassionally at crusing speed.
Took it in to have tires balanced and vibration
checked. Called me later and gave me a case number
for GM. Said GM engineers are working on a solution for changing angle of driveshaft. Does this sound logical. Will go along. Really like truck.
Said no hard driving and truck will be OK.
So, I'm assuming from your posting that I have nothing to worry about since I have a regular cab 2wd truck and not a 4wd extended cab. Am I correct?
My truck is an 1500 extended cab 2wd 5.3l with 3.42 rear
The trans vibration at 40-42 mph is gone or least
I cannot notice it any more; the rmp seems to be
boosted 200 rpm compared to before the fix.
The throttle response is much better in my opinion. The acceleration is smoother and somehow I feel the truck delivers more power than before.
However, the engine still pings. I hope with more
miles, the run-time parameters will be gradually
updated and the ping will go away.
Had the wheel balance checked by another dealer
(the 4th time!). This dealer said I had 2 bad tires, and they ordered 2 new for me. They'll let
me know when the tires come in.
Bottom line, the software updates seems to be
great to have!
Tung
I have my option list on my homepage:
http://www.neonramp.com/~dbleess/dean/truck/truck.htm
It's quiet at cruise, if I stomp on it for one reason or another, then all I hear is the music of a growling V-8.
Are all the vibration problems on the ext cab short bed auto's?
complain about the vibration/shudder I feel upon
acceleration from a stop. Starts to clear at about
35mph.The customer service rep said GM's techs are aware of this and are trying to come up with a fix.Also it seems this particular problem is with the 2wd trucks.The 4 wd's seem to have a different
problem which occurs at speeds above 40mph.
I wonder if it has to do with the combination of 255R70-16 and 3.42 axle?
Or could it be a driveshaft out of balance?
Good luck, and keep us posted!
In reponse. Been there, done that. The dealer replaced the drive shaft from one that they had in stock. Could be that this one may be out-of-balance also. Will have set up an appointment with them any have them recheck it. Both the Generals and Michelins didn't solve the problem. From reading posting on other Edmunds topics and other GM Silverado/Sierra message boards, I'm not the only one with this problem. Just hope that GM finds a solution soon. Later.
If it's a "natural occurrence," I wonder if changing to a different gear ratio could help?
So far, I believe everyone reporting this problem has the 3.42 gear. One said he had a 3.73, but his dealer later diagnosed his problem as a noisy exhaust system. Not saying there is anything wrong with the 3.42 or any individual system, but when they interact together in combination, you get the vibration.
I know it doesn't count for much, but my prediction is that the first owner to solve this problem will be the one who gets his dealer to change the gear, and recalibrate the speedometer.
That theory may not be popular, but due to the vibration getting amplified to its maximum, in most cases near 70 mph, this is consistent.
The drive shaft afterall, runs right underneath the cab and is supported by the frame. It gets input from the engine and transmission. It transmits output through axles and wheels to the ground. It's all connected, so to speak.
Changing the speed that it rotates at 70 mph will move its component into a different, less offensive frequency range.
If I'm wrong, then you should be able to make the vibration go away at 70 mph by shifting the transmission into a different gear (3). But if you change gears this way, and the vibration remains, it is because at 70 mph, the driveshaft always turns the same rpm, no matter what transmission gear you have selected.
I hope I'm wrong, but then you all have exhausted the other possibilities, tires, balance, etc.
I agree with with what you say. The only thing that I can think of that would counteract the resonant or harmonic frequency, would be to have some sort of a counterbalance or floating counterweight placed somewhere in the drive line. However, I personally do not think GM will do this (to costly and complex). As an A&P Mechanic, I have worked on Teledyne Continental engines. Years ago, (because of the nature of a pancake 6 cylinder engine) they had a problem with an uneven firing order impulse setting up a 5th order frequency which was breaking crankshafts in their 6 cylinder engines at 100/150 hours. To solve the problem, they came up with a floating counterweight on the crankshaft cheek of the #5 connecting rod journal. This dampens out the vibration by displacing the shock to the floating counterweight and thus absorbing it. When you shut the engine off, they sure makes a clacking sound when during the last few revolutions they come to rest. Later.
I forgot to mention in my last post, that I did try what you had said about the transmission gear selection not changing a thing. About a week ago I had the transmission in third gear (by accident) and the shimmy remained the same, shifted to overdrive same thing, so I guess you are right on this one.
As a follow up. One of the guys I work who has the same shimmy problem with his 99 Silverado. He took his back to the dealer the for the umpteenth time for the shimmy. The dealer he bought his truck from now has a new type of electronic tire machine that can simulate loads and speeds to measure lateral and radial run out (like running a your vehicle on a set of rollers). By preloading and rotating a tire at various speeds they found one of his General tires had a lateral run out and shimmied when it was under load at 68 mph, even though it had been balanced with no apparent runout (the other three were within spec). The whole process he said took almost four hours to complete for all his tires. He now has a replacement tire on order and it should be here in a few days. If this has indeed cured his shinny, I may just take my GMC to his Chevy dealer (45 miles away) and have mine checked (if they'll do it). If this did or didn't cure the shimmy, I'll post it. It would be nice to for once drive a truck that didn't shake at highway speeds.
the dealer 3 times. They are ordering 2 new tires
for me and hope that might fix the problem.
I was thinking about using the spare tire, but my truck had all 4 wheels out of balance when I got it! I had no faith that the spare tire might be well balanced. Besides, I'm not sure which of the tires was the problemed one.
Just a thought.
Tung
I got the straight scoop on that tire balancer for you. I call my friends Chevy dealer and talked to the service manager to find out about it. It does exist. He told me that it is a Hunter GSP9700 Road Force Measurement System. He also told me it rotates the tire at a slow speed (not at a high speed as previous been lead to believe). That may explain way it took almost 4 hours to do 4 tires. The cost is $10,000 to $12,000 depending on options and other equipment. Here is the link: www.hunter.com/pub/product/balancer/4159T/4159t.htm I hope this helps. Later.