Tremec 3650 Noise - Not the classic throwout or 1-2-3 problem... Tailshaft bearing?

[racerock]

Thanks for taking the time to read the following in an attempt to troubleshoot this vehicle.
Vehicle:
06 Mustang GT, 12,000 Miles (yes, 12K), bone stock when the noise started
Tremec 3650 manual 5 spd
Noise started with original fluid, original driveshaft

This trans shifts fine from 1 - 2, 2 - 3, 3 - 4, 4 - 5 and into Reverse - has none of the typical Tremec 3650 shift problems

This trans makes no noise when vehicle is stationary - clutch in or out, in gear with clutch depressed, or at slower speed (say up to 10..., but not 100% on that...seems to need vehicle speed to occur)


General Noise description - Marbles/pebbles in a can - sort of like a throwout bearing going bad if the vehicle was stationary and clutch depressed - but I don't necessarily want to steer in this direction (yet)

Vehicle condition when noise appears:
- It must be cold out, vehicle sitting overnight or at least 4 hours if it is very cold (say low - mid 30's)
- Vehicle must be moving at least say 30 MPH
- Vehicle under at least a slight load (after a cold soak overnight or during a very cold day in the 20's)
- Vehicle under a moderate to heavier load - acceleration (after an overnight soak of 30's)
- Will occur in 3rd, 4th, 5th at all high speeds - High speed increases probability of occurring

- With the console/rear seat removed - noise seems to appear from the front of the driveshaft or more forward to the back of the engine (say throwout bearing/bellhousing to the front u-joint)

- When it is cold, first gear seems to not make the noise at all, will confirm this as well as second gear...


What makes the noise go away?

1. Driving down the road, say you are in 5th, put a load on and the noise appears, then:
-- Clutch in
-- Shift into neutral (Noise continues as long as the clutch is engaged (pedal down)
-- Let clutch out (coast)
-- Count to 2 or 3 (like clockwork) - Noise goes away
-- Put back into 5th - noise does not re-appear... unitl... you put another load on it.

Similar situation with 4th, 3rd gears

2. Warming up.
-- The longer/colder the soak is, the longer it takes for the noise to disappear entirely

3. Diagnostics/Action Taken thus far:

- Does not appear to be coming from the rear
- Does not appear to be an exhaust noise

3a. Early diagnostic when temps started to go down - sounded like the front joing on the two piece driveshaft - classic driveshaft/CV noise as if a slight load was getting it twisted up
SO - Aluminum driveshaft that is sitting on the shelf waiting to go in - went in.
NO CHANGE... Bummer

3b. Original Fluid - maybe it was low (did not check before draining - UGGH)
Royal Purple MAX ATF went in - no change
Changed to Royal Purple Synchromax - Noise still there, but it does sound/feel nicer at low speeds... At speed - absoluetly no change

4b. - Shifter Change (again, it was in the queue for mods - installed... Just to see...
No change


Of late, it seems that there is a slight noise change at speed when the clutch is depressed

There is also a secondary noise starting to appear - that sounds similar to pinging. slightly higher pitch than the base noise.

Once warmed up and on the higway (water temp up, sort of feel that the gear box fluid is warming - noise starts to gradually go away, and takes about 20 - 25 minutes to fully go away

Of late, we are wondering if it may be:

Throwout bearing (but it does not make the classic noise)
Internal trans bearing

Any suggestions?

I have put a multi channel stethescope on it and it sounds like it is coming from the tailshaft. I had them on everything from the motor to the rear. Rear was amazingly quiet, motor very quiet. SO, I just reconfigured the clip on sensors to focus on the bellhousing to the tailshaft of the trans.

Has anyone had to change the bearing in the tailshaft area?

 

[Hatchman]

Uhh.............. I got nuthin.

 

[sheizasosay]

I let my car warm up to temp before I drive it. There is a dust shield that will annoy me if I don't and the car shifts like crap. Once at temps I'm all good. That dust shield is generally the culprit for noise making in the tranny in cold wieather. I don't remember it sounding like marbles in a can though.

I would not bother with diagnosing before the car is completely warm.

 

[racerock]

I let my car warm up to temp before I drive it. There is a dust shield that will annoy me if I don't and the car shifts like crap. Once at temps I'm all good. That dust shield is generally the culprit for noise making in the tranny in cold wieather. I don't remember it sounding like marbles in a can though.

I would not bother with diagnosing before the car is completely warm.

This happens when the car is warmed up, but it is cold out - gearbox cold. The latest data I hear from the multi channel stethescope is that it is from the gearbox itself - soundling like a bearing in the tailshaft housing.

The colder it is outside, the longer it takes to go away. Around 15 - 20 F outside and it takes about 1/2 hour of driving...

If it is say over 40 degrees - might not happen at all.

 

[sheizasosay]

I probably wouldn't sweat it then.

I don't do transmission work, but replacing a tail shaft seal is fast (1/2 hr to 1 hr labor) I don't know about the bearing and what replacing it requires. I'm all out of help for you.


Sent from my iPhone using Tapatalk

 

[ummduh]

Stock driveshaft?

How about the Center bearing on the driveshaft? Mine makes a ton of noise while it is warming up. Doesn't do it stone cold, and won't do it once the bearing is nice and hot, but right in between it makes all sorts of noise, and seems to fit your description.


Edit: never mind, see that you put a one piece in to diagnose.

 

[Fullboogie]

My first thoughts were U joint, mid driveshaft bearing, TO bearing, pilot bearing, and tranny bearing. Ruled out U joints and mid driveshaft bearing due to new driveshaft; and tranny bearing (and possibly pilot bearing) due to low mileage. That leaves TO bearing and maybe pilot bearing.

Keep in mind that the noise could be originating from anywhere between the engine and rearend, and anyplace in between. You're just hearing it up near the bellhousing. Tough thing to figure out.

 

[racerock]

My first thoughts were U joint, mid driveshaft bearing, TO bearing, pilot bearing, and tranny bearing. Ruled out U joints and mid driveshaft bearing due to new driveshaft; and tranny bearing (and possibly pilot bearing) due to low mileage. That leaves TO bearing and maybe pilot bearing.

Keep in mind that the noise could be originating from anywhere between the engine and rearend, and anyplace in between. You're just hearing it up near the bellhousing. Tough thing to figure out.

Absolutely it can be from anywhere which is why I threw on a 6 channel stethescope - really cool tool - clip on 6 individual clip on acoustic sensors - goes to a switchbox with a selector and volume control for your earbud!

- Engine - sounds sweet
- Rear - extremely quiet (nice surprise here!)
- tailshaft - sounds like the place
- bellhousing - sort of picking it up - can hear the changes with TO bearing in/out.

SO, I have moved all 6 to various portions of the trans - now just waiting for a chance to drive it.

This tool is really cool - better than any mechanics stethescope I've used for troubleshooting chassis/drivetrain noises. Cruise down the highway and listen to the the key components (almost said heartbeat there but that would be pretty bad - Chebby like...)

 

[racerock]

In case anyone runs across this - the 6 channel stethescope is leaning towards a bearing in the tailshaft housing.

Sides of the gearbox sound normal.

SOme of the sound coming from the bellhousing and operation of the clutch make it seem like the TO bearing is normal.