Ford GT - Transaxle Repair?

[Intervention302]

The clutch rollover sound is very distinctive - some have compared to a box of rocks. It is caused by natural engine harmonics causing vibration sounds in the unloaded gears of the transmission. The Ricardo is pretty well known for this. That said, it is NOT a squealing sound. I do hope it is the rollover noise.

I've heard of a customer with a similar but much more pronounced screaching noise. As he describes, it was very bad. It was caused by one of the clutch discs being installed backwards. This is quite easy to do if you are not paying very attention to the explicit markings on the discs themselves.

Thanks for the reply, I sent you a PM with my cell phone as well.

Here is a video of the sound:

Here's what we know.

A. Car got a brand new transaxle, clutch assembly, firewall from Ford. Transaxle came filled with fluid, clutch had a new TOB pre-installed.

1. This was after 4 drive cycles, it was fine before.

2. This sound happens parked, is not generally rpm dependant (hard to hear)

3. This sound happens in all 7 gears while parked.

4. This sound ONLY happens when the clutch is 100% hard to the floor. If you pull out to 90% pedal, the sound goes away nearly completely.

5. The sound dissappears slowly after lifting the pedal. Moving the shifter changes the tone.

6. When I was driving back to the shop, the car was hard to shift from a dead stop. Smooth on highway.


My guess is the clutch is somehow over disengaging. My mechanic thinks it's possible I bent the pedal assembly bracket. At the moment, we are considering a rubber grommet as a pedal stop.

If the clutch pulls out too far, the clutch fingers will rub and potentially keep the input shaft spinning. That's the theory

 

[nota4re]

Interesting. I don't think it is normal to have a different sound if you are 100% clutch depressed versus 90%. Maybe others can chime in on their experience. Clutch rollover noise occurs when the clutch is disengaged - and let's assume that has occurred by ~70% of clutch in?

I don't necessarily subscribe to the theory of over-disengagement. The throw-out bearing in the GT is hydraulic (just like in the Mustang and many other modern manual transmissions). It has a finite amount of movement and *I think* impossible to over-extend it. (If it over-extended it would pop apart.)

 

[PeteK]

Make sure the clutch slave cylinder is completely bled and free of bubbles. Do it in accordance with the instructions in the manual. I'm not sure that will fix the noise, but it's something to check before you entertain ideas of removing the transaxle again. .

 

[69b302]

I would bleed the clutch again. Since it drove ok at first, probably not a clutch disk installed backwards. There are two bleeders, one on the firewall, and one down on the transaxle. The one on the firewall can be accessed from top driver side. Very important to do both bleeders, when you are having shifting issues. Hard going into gear, when stopped, is a sign of the clutch not fully disengaging.

 

[2112]

Personally, I have been through more GT transmissions on the race car probably than anyone on this forum. I can honestly tell you, just purchase a new one from Ford and you will be much happier and only have to do the job once. If you are interested in selling the "core" for more than Ford will give you, let me know I might be interested since i stockpile them at my shop. Most times when dealerships take them in, they sale them as well so if you core, let me know the dealership and I can reach out to them. Trust me on getting a new transmission, its the best route to go.

Mark Heidaker
M2K Motorsports, LLC
281-346-8114

Mark, have you ever found problems with one of your new, over the counter transaxles?

 

[nota4re]

Guys, think about what OP is saying. Clutch dis-engagement is occurring just fine. If there was an issue with dis-engagement (more "throw" is needed) then I would agree with the add'l bleeding comments. But that's not what he's been describing. As FYI - we've been working on these for almost 20-years and never once have we even touched the bleed nipple by the firewall.

I'm 99.5% certain that it is physically impossible to achieve too much throw. Specifically, no one is going to engineer the hydraulic throwout bearing so that it has the capability to move too far... far enough that strange sounds and/or physical contact within the clutch assembly could occur. Imagine if this was possible as then it would be up to installers to get just the right amount of "bleed" in the system. Too much air and the clutch won't fully disengage and too good of a bleed results in too much throw. Nope, that's not gonna happen.

I'm sympathetic for the shop that installed this as it is admittedly a bit of a head-scratcher but having thought about it, I think it is an assembly problem and my guess would be a clutch disc that's not facing the right way.

 

[Intervention302]

Guys, think about what OP is saying. Clutch dis-engagement is occurring just fine. If there was an issue with dis-engagement (more "throw" is needed) then I would agree with the add'l bleeding comments. But that's not what he's been describing. As FYI - we've been working on these for almost 20-years and never once have we even touched the bleed nipple by the firewall.

I'm 99.5% certain that it is physically impossible to achieve too much throw. Specifically, no one is going to engineer the hydraulic throwout bearing so that it has the capability to move too far... far enough that strange sounds and/or physical contact within the clutch assembly could occur. Imagine if this was possible as then it would be up to installers to get just the right amount of "bleed" in the system. Too much air and the clutch won't fully disengage and too good of a bleed results in too much throw. Nope, that's not gonna happen.

I'm sympathetic for the shop that installed this as it is admittedly a bit of a head-scratcher but having thought about it, I think it is an assembly problem and my guess would be a clutch disc that's not facing the right way.

Helpful, but if the clutch was wrong... I don't think it would have driven perfectly for 20 miles with two seperate drivers.

Mechanic also does not think bleeding will fix

 

[Intervention302]

This video isn't great, but here it is.

The sound isn't as audible in the cabin as I first thought it was. You can hear the noise "spin up" as a gear is selected, and then "slow down" as it goes back to neutral.

No noise happens if you push the clutch 90% instead of 100%

 

[nota4re]

Helpful, but if the clutch was wrong... I don't think it would have driven perfectly for 20 miles with two seperate drivers.

Doesn't it drive perfectly now as well? Sounds like you want to say that the noise anomaly wasn't there at first, but now it is? I'm asking if it is possible this anomaly was there the entire time but you didn't really "notice" it until after the drive? Perhaps a moot point? If you elect to have the transaxle removed again, I'd make darn sure you were there when they remove the clutch pack. Together, I think you want to inspect the clutch spring (fingers) and then each disc for any manufacturing anomalies or possible incorrect assembly. Sorry you are having to go through this...

 

[Intervention302]

Doesn't it drive perfectly now as well? Sounds like you want to say that the noise anomaly wasn't there at first, but now it is? I'm asking if it is possible this anomaly was there the entire time but you didn't really "notice" it until after the drive? Perhaps a moot point? If you elect to have the transaxle removed again, I'd make darn sure you were there when they remove the clutch pack. Together, I think you want to inspect the clutch spring (fingers) and then each disc for any manufacturing anomalies or possible incorrect assembly. Sorry you are having to go through this...

Sorry I was a little unclear.

I BELIEVE it drives mostly good as is, as long as you don't stand on the clutch pedal like I was personally doing on my short drive.

I was in my work parking lot, and initially it wouldn't go into gear that easily, so I pressed really hard on the clutch thinking that would have helped. It then immediately made the noise. It sounds like you're trying to shift a vehicle without using the clutch. Feel it in the shifter and hear the whininess

We only drove right back to the shop. I haven't had any more time in the car since.

It is possible that the noise was apparent from the get go, but wasn't perceived. I'm younger and have better hearing, and of course the car being so loud doesn't help.

Mechanic taking a fresh look at it on Monday.

 

[GT@50]

Look at your old bellhousing. It better not have a dowel pin in it.
I haven't done a clutch on one yet
It sounds like PP finger to TO bearing noise but,
There's usually a plate between engine and trans that aligns the starter on Fords. If the starter wasn't in the hole properly when tightened it may bend it(plate), and a tad more clutch push may get it to hit. Hmmm, plate get left out?
Check crank endplay.

 

[nota4re]

Update?

 

[Intervention302]

Update?

Sure thing...

It went back to the mechanic that night to be studied. They listened with to the transaxle with a stethoscope and determined the noise is up front by the clutch, and not the transaxle itself.

It was at that time the noise was determined to only happen with the clutch fully depressed hard to the floor.

They then discovered that the pedal assembly bracket that holds the clutch neutral safety switch was bent. My interpretation of it at least. They did mention that earlier that day, they thought the neutral safety was acting up when trying to start the vehicle.

We fashioned a temporary very thin pedal stop at the bottom of the clutch pedal with some delrin bushing stock. Pushing hard to the floor now makes zero noise.

My father took delivery of the vehicle and has made multiple cruise nights out with my mom, maybe 150 miles. Zero issues or noises.

My dad does believe he needs to relearn the clutch as it's now releasing mid stroke, as opposed at the very tippity top like before.

After 500 miles, the mechanic wants to see the vehicle again to see if the pedal stop is still needed after the clutch breaks in.

Of course, I think it's still remotely possible that the clutch assembly/TOB from Ford is defective and that we will need to restart the whole process. But for now, my dad is out and enjoying the car at 74. Happy for him

 

[HighHP]

My dad does believe he needs to relearn the clutch as it's now releasing mid stroke, as opposed at the very tippity top like before.

Interesting comment. This would mean that the clutch slave cylinder and thus clutch pressure plate are not being displaced as much as before. Hummm...........

You also mention that it is harder to put in gear (than normal?) when stopped and easy when driving.

Both the above indicate that the clutch is possibly not releasing completely.

 

[Intervention302]

Interesting comment. This would mean that the clutch slave cylinder and thus clutch pressure plate are not being displaced as much as before. Hummm...........

You also mention that it is harder to put in gear (than normal?) when stopped and easy when driving.

Both the above indicate that the clutch is possibly not releasing completely.

I can't confirm how its driving now, after the pedal assembly adjustment. The hard to get in gear was only after I smashed the pedal to the floor and potentially put something out of adjustment

I'll get some seat time soon.