JMono

My manual transmission Mustang GT has 11K miles.

My transmission squeals on deceleration at low speeds (less than 30mph). It only squeals on deceleration and only from speeds under 20-30 mph. It sounds like a squealing motor belt, but it’s definitely coming from the transmission. The noise does not change with clutch position or gear engagement. The noise only appears if the car is warmed up. It sounds like the noise is linked to trans. fluid temperature and deceleration for some reason.

To sum it up:
1) If I slow down squeal noise will appear around 20-30 mph. and go away at the last few feet of coming to a complete stop.
2) If I slow down a bit at high speed, no noise.
3) If I accelerate from a dead stop, no noise.
4) If I push the clutch pedal in during the squeal, the noise persists.
5) If I let the clutch pedal out during the squeal, the noise persists.
6) If I turn the motor off during the squeal and coast, the noise persists.

I wonder if this is an input shaft or slave cylinder issue? It’s odd that the noise only appears on decel at low speeds. Clearly, something inside the trans. is spinning and making the squeal. As the slow down, the squeal slows down, but it’s still there until about 5 mph and then it goes away completely.

Any tests that I can perform on my own to narrow it down further?

I just want an idea before I take it into Ford.

jwog666

the way you describe the noise, it seems to me that it is a rear axle or direveshaft noise. maybe the driveshaft center bearing.

JMono

Does the driveshaft move forward during deceleration? I would assume it does move forward and thereby placing pressure on the bearing on the front of the driveshaft. I’m sure it’s a sealed bearing, but perhaps the it’s gone bad.

jwog666

any forward/rearward movement is minimal. but the load on the bearing would change. and if the bearing is bad that could cause the noise to change.

CincyGT2009

Hey all, it's a pleaseure to join the forum! Just bought my 2009 GT last Wed. Now has all of 200 miles on it! Have heard this on mine too... Wondering what the resolution was...

Thanks in advance from a Taurus Car Club of America "brother"!

fgmz727

The design on the transmission gears on the mustang are a delta type end. this allows for less friction but the trade in is that they may make a slight whinning sound when decelerating or accelerating.
Is this what you are getting? If it is, it is totally normal. There is no way of getting rid of it. It's inherent with the type of design of the gears in the Mustang.

REDBOSS1

I have 4.10's now but even when I had 3.55's my car did the same thing. If I down shift and let the clutch out very slow it reduces it alot but if I just slam into a down shift to accel the whole car shakes and the sound is very loud. I just had a new clutch pack installed (Ford tried to deny me a warranty because I had 4.10's but they are FRPP and installed a Ford dealer so they warranted them after hours of complaining) and I still get the sound that you are talking about. To me it's not a big deal it's nothing that is going to break the car.