6xStang

I'm noticing something strange on my 2006 GT 5 spd convertible.

When decelerating while in gear (engine braking), when the engine get around 200o rpm or so (though most noticable in second gear), I am noticing a vibration that almost feels like the tires are running over a series of small bumps. Pressing in the clutch does not seem to immediately make it go away. It is not engine lugging. For the life of me I can't figure it out. At first I thought it was just bumps in the road, but it is not. Subtle, but noticable.

Does anyone else notice anything similar? I'm not going to take it in to the dealer for this....I'll wait till I have other items. But I am trying to figure out if this is "normal" in some abnormal way.

rhein

Sounds like something that happened to me and a Celica (Early Rear Wheel drive version) in college. Turns out the the carrier? bearing in the third member was going out. Since it does it clutch in, and clutch out, it's something farther down the chain, so it would be driveshaft, diff, wheels or tires. It's hard to diagnose because the car would only do it on decel, accelleration was fine.

From what you describe, if you were to go out on a straight deserted road, and just put the car in neutral, and coasted, as the speed drops you will get a speed at which the shudder will start, and at some lower speed (or a stop) it will go away. Is this correct? If it is, I would think that something in the rear end is the most likely culprit.

Hope this helps.

austijc

Yes, I have the same ride, and I have noticed that. I figured it was a product of how the computer cuts off the fuel supply during deceleration to keep it from running rich and then starts feeding it again as the revs get lower. It's still a lot smoother reving down than my Wrangler ever was.

6xStang

Well this is funny. My technical analysis was leading me to a conclusion along the lines that Rhein described. My hope is that it is something like what austicj described.

What I will do to troubleshoot it further is let the car roll in neutral to see if it will do it, just as Rhein suggested. It seems.....wierd. I'll post more when I learn more. (though I just washed the car and we are due for rain so it might be a couple of days; I want to keep it clean as it goes in for a clear bra on Monday).

austijc

Actually, I didn't read that close and didn't notice the clutch in part. That would cancel out it coming from engine control. Next time it happens I'll try clutching and see what it does.

MikeVistaBlue06

Mine is doing it at around 25mph during decel (I have an automatic).

It started doing it after I had the first set of 3.73s installed. They had not phased the driveshaft right.

I had a 2nd set of gears installed and it is still doing it. I am going to get Manny to look at it again when my "0" plugs come in. I think the driveshafts on these things are a mite touchy!!!

Has anyone done any gear work on yours? If not, take it back to the dealer and raise hell!

There is also a vibration TSB out under: TSB 06-04-01

Hope this helps.

Mike

2006GT

Mine does it too. Sounds more engine related than driveline. I just thought it was the charge motion plates closing. DOn't they open up around that RPM under acceleration?

__________________
2006 GT
Lots o' Mods

6xStang

update: I've done some testing with coasting vs engine braking on smooth roads. It does only occur when the clutch is in. I'll have to drive a couple of others to see if this is "normal." Doesn't seem like a big issue, but it does seem wierd.

D