5th gear vibration/noise

Army Ranger · **Posted:** Thu May 01, 2014 1:41 am

I have the GDE Standard Eco Tune. Everything else is stock.
When accelerating gently as soon as I get to 50 MPH the transmission shifts to 5th gear. As soon as the shift occurs I get a slight vibration/noise from what I can only suspect to be the transmission. The day I noticed the vibration I checked the transmission fluid immediately. It was the typical red color, sweet smell, no visible dirt/grit, no feel of dirt/grit and it was at the correct level.
*This is different from torque converter shudder*
I am very familiar with shudder, 5th gear lock-up, up hill, heavy acceleration = loud, harsh vibration like driving over multiple sets of train tracks but vanishes with lift of the throttle.
The 5th gear vibration is constant, occurs every time I shift into 5th, flat ground, no wind, slowest acceleration possible, it's always there. The frequency of the vibration does seem to change with MPH, for example, at 65-70 MPH it is smoother, and is a fading in and out low pitch humming.
Other Info:
I know that if you have a GDE tune and stock torque converter it is recommended that you do not tow. I had to tow a U Haul trailer on a short trip across town, highways only, not stop and go traffic. This was 10 days prior to noticing the vibration. Went slow and easy, OD off the whole time. Temps were steady and normal.

Other than the 5th gear vibration/noise the transmission is exactly the same as it has always been. It pulls hard off the line through the gears, shifts smooth and quiet, with no hesitation.

Please help in any way you can, Thanks

thermorex · **Posted:** Thu May 01, 2014 7:10 am

I am pretty sure it is the torque converter. At 50 it gets to 4th and 60 (or 61) switches to 5th. Both 4th and 5th have the tc locked, and at low rpm, at about 1700-1800, the shudder occurs, correct? I had the same issue when I had the old torque converter with a tune chip (not gde). Since the engine has more torque, and torque converter is garbage from factory, these are typical symptoms. The fix consists in replacing the torque converter with the euro (good) or Suncoast (best).

Till you replace it, try to either accelerate harder prior to switching in 4th or 5th,so when it switches gears engine would be at about 1900rpm, either accelerate very gently once the shift occurred.

CATCRD · **Posted:** Thu May 01, 2014 6:18 pm

I'm betting it's your u-joints on the rear driveshaft. Have to take the shaft off to feel them all for free movement. You can't tell if it still bolted in.

Army Ranger · **Posted:** Sat May 03, 2014 7:42 pm

I am afraid it is the torque converter more everyday I drive it. It is becoming increasingly obvious every time I get to 50 MPH. The sudden drone as soon as the torque converter starts to engage at 48-50 MPH is growing louder and louder.
Now my concern is: can I harm the rest of my transmission by continuing to drive it in this condition?

I will still check my rear drive shaft u-joints regardless. They are more than likely the originals with 175K miles and should be swapped for new ones.

woodtick · **Posted:** Sun May 04, 2014 1:18 pm

If it is a cyclical vibration at higher speeds (one you can hear and feel) that varies and is more pronounced the higher the speed, it could be the driveshaft out of balance. This very well could be u-joints are junk and not keeping the shaft perfectly aligned, thus putting it out of balance. I'd chock the wheels and pull the shaft to check the joints. 15 minutes or so to rule it out.

50 mph +/- is where I have noticed this occur on other vehicles.

My :2cents:

DOC4444 · **Posted:** Sun May 04, 2014 8:00 pm

TC "shudder" is VERY specific. It occurs when you are under throttle at about 58 MPH and the TC tries to lock up in 5th. Usually, it is easy to "drive around" the problem by letting off or nailing it unless you are towing. Shudder is rather dramatic. On ours, my vision was blurred by it. Cured by a "euro" TC.

Yes, driving with frequent shudder will put a lot of debris in the ATF which can damage the trans. You need to stop this "problem" from happening right away in order to protect your transmission by either avoiding it or actually fixing it.

Good luck!

DOC

woodtick · **Posted:** Sun May 04, 2014 8:08 pm

I just reread your first post. If I was a gamblin' man, I'd bet on the rear most U-joint. I would also check to see if the weight used to balance the shaft is still attached.

racertracer · **Posted:** Sun May 04, 2014 8:15 pm

It sounds like what I had, I cured the noise and vibration with a good cleaning of the rear differential and then replacing the gear oil with new.

Don't be afraid to stick your hand in there to remove all the caked on muddy muck sitting at the bottom.

Wear rubber gloves.

While your at it, I would attack the front differential and the transfer case too.

Army Ranger · **Posted:** Sun May 04, 2014 8:38 pm

It seems like more and more people joining the u-joint/drive shaft crowd. I hope you all are right, u-joints are MUCH cheaper and easier than a new torque converter. Well like I said I won't turn away good advice, I will definitely go ahead and buy a couple u-joints and put them in. I am sure they need to be replaced after 175K miles either way.

And I will double check the rear diff Racer. The diff oil, front, rear, and transfer case oil, was all changed right before I purchased the vehicle. It also doesn't have the limited slip so no worries of worn clutch material ruining my carrier/pinion bearings (been there, replaced ALL that a time or two). So not to worry I am certainly not afraid! But for anyone else, you will want way more than rubber gloves for diff work. I would say wearing old clothes you don't mind throwing away/burning when you are done is a must. Old gear oil is the worst! You will never get rid of that smell!

racertracer wrote:

It sounds like what I had, I cured the noise and vibration with a good cleaning of the rear differential and then replacing the gear oil with new.

Don't be afraid to stick your hand in there to remove all the caked on muddy muck sitting at the bottom.

Wear rubber gloves.

While your at it, I would attack the front differential and the transfer case too while your at it.

5th gear vibration/noise

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