Vibration at 40-55 mph

Hello-
I have a 2006 Tahoe 2wd. Lately there has been some vibration around 40-55 mph when driving, it is intermittent and hard to explain. It kind feels like I hitting bumps in the road but it doesn't seem to be suspension related and not comming through the steering. It's not happening all the time but when I throw it in neutral it seems to go away. I found a random article online about varnish building up on the TC causing this problem. Has anyone else experienced this? I just got the tires rotated and re balanced yesterday and I am getting an alignment this afternoon to see if that helps. Other than that there are no sounds , codes or anything else happening.

**I forgot to add I have checked the front end for any looseness in the steering or wheel area and found nothing.

So I had this same problem about 6 months ago on my '05 Tahoe. It felt like I was driving over the drunk bumps on the side of the road. I took mine to a local shop and they ran some sort of cleaner through the transmission and it fixed it. I may not be totally accurate on the terms, but he called it the "steppers"...something mechanically between the trans and torque converter.

Someone else may be able to provide more detail. Hope this helps because I was trying EVERYTHING from driveshaft, trans, wheel balancing, front end, etc..

I think it is the TC as well or related. I took it to my mechanic and they said my rim was bent. This doesn't make sense to me as everything is smooth except when i get between 40 and 57 it starts to shudder. Did they flush the transmission or just use a cleaner?

GangstaCowboy said:

I think it is the TC as well or related. I took it to my mechanic and they said my rim was bent. This doesn't make sense to me as everything is smooth except when i get between 40 and 57 it starts to shudder. Did they flush the transmission or just use a cleaner?

Click to expand...

They actually flushed it and cleaned it. I also had the intake cleaned and and all the plugs and plug wires replaced, tire R&B, new front shocks, oil change and a new drive shaft. Pretty much a full tune up a week PRIOR to the flush and cleaning. But once we did the flush and clean it was gone.

When mine began to vibrate I would punch it out of O/D and it would stop vibrating - someone told me that was a way to tell if it was the TC. So every time I got in I would take it out of O/D to drive it and from time to time (just as before when driving in O/D) it would still vibrate - so that told me it didn't matter if it was O/D or not.

This is a PAIN to track down but luckily the shop owner I use knew exactly what to do.

sometimes what will happen is if the transmission dip stick inst locked/latched water off the wiper blades cowl/cover funnels water right into the dip stick tube and the water contamination will cause the vibration also its rare but if the integrated trans cooler will internally leak and get contaminated with coolant 2006 Chevrolet Tahoe - 2WD | Avalanche, Escalade, Suburban, Tahoe, Yukon VIN C/K Service Manual | Document ID: 1766073
#05-07-30-017B: 4L60-E/4L65-E/4L70-E Automatic Transmission/Torque Converter Clutch (TCC) Shudder, Water in Transmission (Repair Transmission and Seal Cowl Area) - (Feb 17, 2006)
Subject: 4L60-E/4L65-E/4L70-E Automatic Transmission/Torque Converter Clutch (TCC) Shudder, Water In Transmission (Repair Transmission and Seal Cowl Area)

Models: 2004–2006 Cadillac Escalade Models
2004–2006 Chevrolet Avalanche, Silverado, Suburban, Tahoe Models
2004–2006 GMC Sierra, Yukon Models
with 4L60-E (RPO M30), 4L65-E (RPO M32) or 4L70-E (RPO M70) Automatic Transmission
This bulletin is being revised to add additional model years, the 4L70-E transmission and clarify usage of Labor Operation B9758. Please discard Corporate Bulletin Number 05-07-30-017A (Section 07 — Transmission/Transaxle).

Condition
Some customers may comment on a shudder condition at approximately 64-80 km/h (40-50 mph) when the TCC engages.

Cause
This condition may be caused by water in the automatic transmission fluid (ATF). Water may enter the transmission by dripping from the cowl area onto the handle of the transmission fluid level indicator.

Indications of water in the ATF may include:
Visible water in the oil pan
A milky white substance inside the pan area
Spacer plate gaskets that appear to be glued to the spacer plate, valve body or case
Rust on internal transmission iron/steel components
Important: For vehicles suspected of having a leaking transmission oil cooler that would cause contamination of the transmission fluid with coolant, the following check should be performed before deciding to replace the radiator.

Remove the surge tank cap and examine the coolant for signs of contamination with transmission fluid (the coolant will have a milky, not clear appearance).
If the coolant has a normal, clear appearance, the radiator should not be replaced.
The cooler can also be tested by following the Coolant System Leak Test procedure. Do NOT replace a radiator without verifying that the transmission oil cooler is leaking.
Correction
Two steps are required to repair the vehicle. First, repair the transmission and second, seal the cowl area to prevent repeat water contamination of the ATF. This bulletin is focused on repairing the second step.

Transmission Repair
Important: If water or coolant is found in the transmission, the following steps must be performed:
Remove the transmission. Refer to the appropriate SI procedure.
Disassemble and inspect the transmission. Refer to Unit Repair Automatic Transmission - 4L60-E/4L65-E or 4L70-E.
Important: If water or coolant is found in the transmission, the following components MUST be replaced.

Replace all of the rubber type seals.
Replace all of the composition-faced clutch plate assemblies including the band.
Replace all of the nylon parts.
Replace the torque converter.
Thoroughly clean and rebuild the transmission, using new gaskets and oil filter.
Flush and flow check the transmission oil cooler using J 45096. Refer to Corporate Bulletin Number 02-07-30-052D or newer – Automatic Transmission Oil Cooler Flush and Flow Test Essential Tool J 45096 TransFlow .
Seal the Cowl
Open the hood and install fender covers.
Object ID: 334315Click here for detailed picture of the image.
Remove both air inlet grille caps by pulling up on the caps.
Loosen the sheet metal screws, one on each end of the air inlet grille panel.
Object ID: 348546Click here for detailed picture of the image.
Remove the four attaching clips running along the edges of the center air inlet grille panel.
Measure and cut a piece of 7/64 inch hose, P/N 14033569 or equivalent, 1.27 meters (50 inch) long.
With an appropriate sharp cutting tool, cut down the center of the hose, splitting the hose into a C shape, allowing the hose to be installed over the cowl seam.
Apply a thin layer of Weather-strip Adhesive, P/N 12345097 (in Canada use 10953479) or equivalent, into the center of the cut hose.
Lift up on the air inlet grille panel in order to expose the cowl area metal edge.
Object ID: 1662820Click here for detailed picture of the image.
Place the 7/64 inch hose over the cowl metal edge between the two inner fender brace bolts. Make sure that the hose is long enough to be retained by the two most outer air inlet retaining clips.
Push back, towards the windshield, on the air inlet grille and install the four retaining clips.
Push back, towards the windshield, on the air inlet grille and tighten the end screws.
Tighten
Tighten the sheet metal screws to 2 Y (18 lb in).
Install the two air inlet grille end caps.
Close the hood.
Place the vehicle in an area that a water test can be performed.
Turn OFF the vehicle.
Open the hood.
Place a shop rag over the top of the transmission dipstick.
Close the hood.
Spray and/or run water over the windshield and cowl area for three minutes.
Open the hood.
Inspect the shop rag for signs of water leaking on top of the transmission dipstick area.
If NO water is present, close the hood and NO additional repairs are required.
If water IS present, repeat steps 1-20.
Warranty Information
Important:

Thanks for the great information. After trying to diagnosis myself and through my normal mechanic I broke down and took it to the dealer. They charge 90 bucks to figure out the problem and I will go form there. I hope this does not need a transmission rebuild as it just started happening 2 weeks ago.

what did they tell you at the stealership?

Update* Dealer is saying its something with the wheels, like my previous mechanic diagnosed. I am still not sure this could be possible. Would a bent rim only cause vibration at certain speeds and not all the time? They have had the Tahoe for 2 weeks so far, they gave me a 2015 loaner to drive. They said they have checked everything and the transmission tech checked it out and said no problems there. They are road testing the tires today and will let me know.

Update- Took it back to discount and they took the tires off inspected them and remounted and balanced. Still had vibrations just at different MPH. Took it back yesterday and took off the Good Years and put on BFG's and immediately noticed a difference over all in ride quality. So far the vibration seems to be gone, I tried multiple times to make it happen on the way home and this morning and it was smooth. I guess problem solved. Last time I get Good for years.

After driving for a week it became apparent the tires did not fix my problem. Took it back to the dealer and rode with the head transmission tech. Tc was slipping. Got referred to a transmission shop b my general mechanic. My radiator and trans cooler were leaking into each other so there was water in my transmission just like the tsb stated. 2200 for rebuild and new radiator.