825LTRGT

After almost a year and 10k miles, my CS has developed some minor issues. I've tried to read up on these issues but there's so much.

1. Drivers window goes up really SLOWWW. Sometimes it stops on the way up. Much slower than
the pass side.

2. Notice a slight metallic sound between 2 and 3k in second gear at WOT. Heat shield?

3. A WUB-WUB sound from the rear. Might be a rear brake, a bearing, or a bad tire.

4. Twice the Shaker 500 has mysteriously turned on by itself with no volume.

5. A clunk when shifting light or unloading the clutch quickly. UCA or LCA maybe?

Any tips? I'm off starting next week. Maybe I can get it in then.

Thanks

Dixie_Flatline

#2 is commonly from a thin metal shield between the bellhousing and transmission mount. That's what it was with me, none of my heat sheilds were loose or even close to hitting anything and the exhaust was all good. Heard from someone that the plate betweent he bellhousing and tranny could do this, took a while to convince the dealer that was the issue (service rep had bad hearing). But when they looked at it, they fixed it and it's been fine since.

#5 is either the stock two piece driveshaft or the UCA if you've got an aftermarket UCA. When there's no engine power turning the driveshaft, there's a little bit of play, hit the gas and the play gets worked out with a thunk. That's natural for the stock two piece driveshafts. There's a custom steel driveshaft manufacturer in Villa Park, IL that can hook you up with a good one-piece steel driveshaft (same benefits as the aluminum without vibration issues...).

If you upgrade your UCA, you may have to either upgrade the UCA mount or Steeda sells a washer to take up the difference between the UCA shaft and the hole diameter of the mount. For whatever reason, Ford made the hole diameter on the UCA mount a different size than the UCA's shaft. If you upgrade the UCA and don't address that size discrepency, you'll get a clunck like that.

#3: Brakes are easy to diagnose if they're at fault: put it on jackstands, take the wheel off and look at it. Get the tires checked out at a local tire place to narrow down the cause?

I have no clue on the others, though my driver side window will sometimes reverse itself if it's going up for no reason. Maybe there's excess pressure in the opening?

825LTRGT

DixieFlatline,

Thanks for the reply.

My car has stock UCA's and stock drive shaft. The sounds seems like a UCA.

The bellhousing cover..have to check that out.

Brakes maybe. Axle shaft bearing..hope not.

I'm going to take it in and have Ford look at it since it's under warranty.

Dixie_Flatline

It's not the bellhousing cover... there's a plate sandwhiched between the bellhousing and the transmission. That has been known to flex and vibrate kinda annoyingly at times.

It's the stock driveshaft that can have the clunk sound, too. That's why it's hard to tell. Although... how many miles do you have? You're right, it may be the UCA or LCA bushings too. The suspension bushings on our cars are wear items and some people get 40k out of them, some more, but some less too.

Good luck!

825LTRGT

I'll have to take a look. Sounds like a PITA!!!

10K. Would urethane bushings do any good? I had an '83 GT many years ago and they would pop form time to time. I suppose a pop would be better than a clunk. Someone posted somewhere that the ID of the mount is too large and the bushing OD too small on the UCA. Does that sound right?

Dixie_Flatline

Ok, that's not from worn bushings then. Urethane bushings need to be replaced eventually too, but they wear a bit longer and you generally get them on upgraded suspension components, so it's like a two-for-one anyway (LCA, UCA, A-Arms, et cetera). If bushings pop, the part they're on aren't tightened to torque.

That is right about the UCA, but typically those that get the UCA clunk only get it after moving to an aftermarket UCA with a urethane bushing. That's why if you're stock on the UCA, you're probably hearing the stock driveshaft. Seriously, take a look at how those things look, there is a mechanical joint a third of the way back, and when torque is applied and the car starts to move as well as engaging the suspension geometry, the driveshaft will move in ways other than around it's axis before it starts spinning. Thus the clunk.

Try this, next time you're driving on dry roads (ha, good luck this week ) when you're at speed try accelerating in two ways: (1) take your foot completely off the gas then hit the gas pedal. That should initiate the clunk. (2) doing pretty much the same thing as in one, but don't actually take your foot off the gas to begin with, instead keep very light feather on the gas (go by the tach showing a little movement, not so much your feet on the gas pedal as there's an issue with the gas pedal drive-by-wire on our cars where the first few millilmeters of travel on the pedal don't actually engage anythign) then mash the pedal.

Try this a bunch of times in a row until you're pretty sure you were consistent in both and listen for the clunk, you should also slightly feel it.

If you hear the clunk with (1) and not with (2), then you've reasonably ruled out suspension noises, and it's likely nothing more than the stock driveshaft behaving in the way it mysteriously does. If you get the clunk with both (1) and (2) and you're really sure you never let off the rpms before mashing the gas, then I'd either inspect your rear suspension or have the dealer do so. With only 10k miles, there isn't anything it's more likely to be than anything else, and it doesn't sound like you've got aftermarket suspension parts that need torquing down (torque wrenchs are your friend!), so maybe the dealer can look for TSBs.

Again, good luck!


As for the plate between the bellhousing and the tranny, if you can get under there with your front up on ramps, it should be easy to spot the gap. The dealer will have an easier time of it with a lift, but the guy who clued me in on where the noise was coming from said some people just use a silicone gasketing sealer on both sides of the plate and that works real well.

825LTRGT

The WUB-WUB sound was the front tires. Drove a few miles during the TPMS saga with the other rims and the sound was gone. I put those back on the rear. The tires looked like they were out of round when I spun them while they were still on the car.

The clunk seems to be the driveshaft but I'll have the dealer check it out.

Thanks for the tips!!

cdynaco

Here's some notes I saved about the S197 drive shaft and rear end clunk. s197_guy is with Ford and used to post some engineering insights into the Bullitt design on another site:

Poster?
I spoke with an engineer with Ford SVT back when I had my 2007 Kenne Bell GT500 and at the time they flew out from Michigan to check out a clutch issue. I asked him, while the car was up in the air on the lift, why didnt Ford put a 1 piece driveshaft on the 2005+ Mustangs. He told me there were two reasons. #1. NVH could be reduced with the two piece and #2. In all the crash testing that Ford did on the new body, a rear impact crash on a 2005+ Mustang with a 1 piece driveshaft resulted in a punctured fuel tank the majority of the time so the design had to be changed! Oh well, I guess I figured if I ever got rear ended, I'd get the hell out asap!


s197_guy 2 piece drive shaft
The 2-piece driveshaft is required to meet internal engineering requirements for safe operation at max vehicle speed. Basically, it is designed to provide a driveline system resonance well above what the speed limiter will allow you to operate at. If you put your driveline into resonance, bad things may happen! I've seen what it does to a car and it isn't pretty.

The driveshaft CV joints are required components on this type of driveshaft when combined with a live axle. If the rear suspension were IRS, simple flex couplings would be used (look at the new Camaro, Challenger, etc...) and would make for a lighter driveshaft.

The driveshaft also has an internal torsional damper (ITD) which is soley there to attenuate axle whine. If package allowed, the ITD would be mounted on the exterior of the driveshaft as a much lighter ring design. Since the equivalent inertia is required out of the smaller diameter part when installed inside the driveshaft, the mass has to increase. So, you get a heavier ITD vs a lightweight ETD.

A single piece steel or aluminum 1-piece would have to be larger in diameter than the current package allows. Basically, you would have contact with the fuel tank at full rear suspension jounce. 1-piece carbon fiber was explored at one time...

Hope this helps.

s197_guy
I do know about the 2-piece in the factory car. It is a fairly robust piece. Vibration is not an issue unless the centerbearing shims are not installed properly, the shaft has a balance issue or the pinion angle is off. These would be quality issues (that I'm not aware of having in production), not design. The 2-pc has no roll in whether or not you have a random vibration. U-joint angles, run-out (flange or shaft), balance and system modal (resonance) response govern vibration.

s197_guy
Clunk is driven by total driveline lash, dominated by the gear sets and clutch tuning/capability. The 3.73 amplifies this a bit compared to the 3.31 and 3.55 axles. The 2-piece driveshaft is not the cause of the clunk noise. The Bullitt will have higher levels of clunk compared to the base GT. The base GT throttle response is a bit softer than the Bullitt's. The increased throttle response makes the clunk a bit easier to get. It is a trade-off - improved performance feel vs clunk.

825LTRGT

Thanks! Interesting.

So I guess that is the nature of the beast. I'll still have them check it out to make sure it's nothing else.

825LTRGT

Got the car back from the dealership today.

Clunk is "normal" Nothing "abnormal" Tightened the UCAs and LCAs. We'll see.

Windows are better. Reprogrammed and no issues. But they ordered a new door seal.