Vibration between 50 & 70 mph

[lugz]

Had an interesting email conversation with an engineer at Dynotech this week. He says the yellow paint splot typically marks the heavy part of a rotation, and suggested putting the yellow spot of the pinion yoke 180 degrees from the yellow spot of the driveshaft, so the heavy parts would cancel. What was odd, at least for my stock driveshaft, the yellow spot of the DS was probably 15-20 degrees off from the yellow spot on the pinion. Now, was the factory fine tuning the assembly, or did someone just slap it in that way? Not sure, but I do know the factory assembly was silky smooth.

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[ABS550]

Mine looks very similar. Picture back on post 1773.
www.mustang6g.com/forums/showpost.php?p=1431200&postcount=1773

You can see that they tried to line up the yellow dots to the nearest bolt hole. Mine were off a similar 15 or 20 degrees.
It makes sense that they would mark them and try to line them up. BUT, it would make the most sense if they marked the LIGHT side of one and the HEAVY side of the other one, then try to put the dots close together. (line up the dots)

If they mark the HEAVY side on both, then the dots would need to be on opposite sides which is visually, less practical. (more difficult to do correctly)

Maybe the dots are marked incorrectly on some parts? Maybe some have the dots marked on the light side, when it should have been put on the heavy side etc.

Also if you look at my picture and where I had to add the weight, it was exactly in line with the dot on the pinion side. So maybe when the lined up the dots, they did it to the nearest bolt, but that was not good enough to balance it. If that is the case, then moving to the next bolt hole wouldn't work anyway. As mentioned in an earlier post, it may be possible to place a washer under a bolt, as a counterweight instead of using hose clamps.

If would be great if someone from Ford would chime in to shed some light on the factory assembly and balancing procedure etc.

 

[lugz]

It makes sense that they would mark them and try to line them up. BUT, it would make the most sense if they marked the LIGHT side of one and the HEAVY side of the other one, then try to put the dots close together. (line up the dots)

That's exactly what I was thinking. Short of taking a dynamic measurement of the DS and the pinion, it's anyone's guess which is heavy and which is light, etc. Unless, of course as you suggested, someone from Ford were to chime in here.

work anyway. As mentioned in an earlier post, it may be possible to place a washer under a bolt, as a counterweight instead of using hose clamps.

I like that idea, but doubt a washer would be enough.

Anyway, I'm going to swap out the shaftmasters for the dynotech and go under the assumption that the mark on the factory shaft is the heavy mark, so that's the way I'm going to install the dynotech - yellow to yellow. The shaftmasters shaft really doesn't have a similar splat on it. (There is one, but it looks more for assembly of the slip tube to the main part of the shaft.)

Edit - after looking at the pinion yoke some more, it's kind of obvious what the factory did here - note the balancing holes drilled into the pinion? It's gotta be to counter the heavy side of the DS. Splat to Splat. Look how much more weight they had to take out of your yoke than mine. I'm guessing they've tightened up the tolerance on the DS weight imbalance. And since the DS splat doesn't line up precisely with the yoke splat, that tells me they pre-drill the yoke for a certain amount of imbalance, then line up the DS as close as possible to that spot. If the DS is out of tolerance with the amt of mass taken out of the yoke (either a lot more or a lot less), then your new stang is going to be more like a vibe rider they sell for harleys. The only perfect solution Ford could do would be to remove the *exact* amount of mass at the *exact* right spot of every yoke mated to every DS, and they aren't going to do that on a mass-produced car.

 

[lugz]

A couple more shaps of the factory shaft. Note the balance weights marked in green pencil. .11 at the tail nearest pinion. .13 at the carrier bearing and .02 at the guibo. Dunno why I assumed they were runout numbers, but bet they are balance weights.

I'd be dang curious to see the pinion balance holes/splat on the guys with problems compared to what their DS weights are.

 

[ABS550]

I like that idea, but doubt a washer would be enough.

You would be surprised how little weight it takes to create an imbalance or to balance this assembly. In my case, one hose clamp was too much weight. I had to add a second one and spread them apart (approximately) 150 degrees, which means they almost cancel each other out.

Look at my earlier post 1773. I tried one hose-clamp on the opposite side of the DS in my first balance attempt and took the car out for a drive. Once I got to the highway, I had to slow down and drive with my flashers on because if I went up to highway-speed it felt like I would shake the car apart. I limped home.

That is just one hose-clamp in the wrong location! Not a lot of grams there.

Others in this forum have reported using one or two washers under the correct bolt as a good fix.

 

[kh1818]

Another update - I have the car back, dealer has ordered an entire rear assembly from Ford, will arrive in a few weeks. They also test drove some of their own new inventory to benchmark the vibration against my car and discovered that their new ones have the issue, but worse than mine! They also put it up on a lift and noted that the vibration is definitely related to the driveshaft system. They seem willing to do whatever it takes to get to the bottom of it, fingers crossed the new assembly will fix. I'll update in a few weeks

 

[BOBS550]

Another update - I have the car back, dealer has ordered an entire rear assembly from Ford, will arrive in a few weeks. They also test drove some of their own new inventory to benchmark the vibration against my car and discovered that their new ones have the issue, but worse than mine! They also put it up on a lift and noted that the vibration is definitely related to the driveshaft system. They seem willing to do whatever it takes to get to the bottom of it, fingers crossed the new assembly will fix. I'll update in a few weeks

My daughter had her`s replaced and that did the job no more vibration:hail:Good Luck

 

[Dominant1]

Not to put a cloud on your relief, but what surprises me is many folks in this thread thought they had the vibration fixed and it returns later. I say this because mine is back but not nearly as harsh as before... im gonna go the shim route. guys that have done this never had it return!

 

[offroadkarter]

Not to put a cloud on your relief, but what surprises me is many folks in this thread thought they had the vibration fixed and it returns later. I say this because mine is back but not nearly as harsh as before... im gonna go the shim route. guys that have done this never had it return!

Exactly, people who have had the dealer "fix" it, put a few hundred miles on it and come update us later. I made this mistake and thought it was fixed for about 100 miles.

 

[Cobra Jet]

Jumping back in... For those who have read my very detailed posts in this thread, my driveline vibe has been documented throughly (and as others have experienced, fixed too....only to come back time and time again).

So, here I am again - car was brought back to service last week with just 23,xxx miles on it due to a humming noise and the dreaded driveline vibe.

This will now be, if I remember, the 5th time it's been in the shop since I bought it new in Dec 2015 for the SAME issue as experienced by many.

I don't have my current paperwork handy, but the Tech performing the work (same Tech who did the last corrective fix for same issue last November) is SUPER thorough. The Service Center was in touch w/Ford Engineering Team again. They used the listening equipment again. They drove the car distance, everyone has confirmed its a driveline issue and it's been documented that the vibe is directly related to the driveline and has now this time been narrowed down to the rear differential.

The Tech pulled the diff drain plug and noted there are metal particles mixed in with the gear fluid (not good). Also noted that the listening equipment attached to the car this time around recorded excessive hz (I'll update thread tomorrow with the work order info).

The entire rear diff is going to be replaced under warranty Per the Service Center, the new diff is being built at Ford and will be shipped to the Service Center in about 2 weeks, at which time they will call me so I can bring the car back for repair.

----

I suspect my rear diff has been the potential issue since my initial complaint at 1,900 miles and should have been replaced at that time. My guess is that at every interval of a supposed potential fix, the rear gears were wearing into different wear patterns. This may explain why each time the vibe felt like it was fixed - but then resurfaced X,xxx miles later was because after so many miles, the gears wore differently, and the corrective actions have only been "temp" fixes until the diff gears are just totally shot...

There's no reason there should be metal particles in the sealed diff, not at 23k miles.

To those wondering, yes, this is also the first time anyone unplugged the rear diff to check the fluid. Not sure why it was never looked into before though...

Not only is there a hum, a driveline vibe, but also excessive clunking when coming to a stop - as if there is too much slop in the rear diff allowing the driveshaft to clunk as the driveline is winding down when coming to a stop.

The driveline vibe starts at around 48mph and gets excessively worse at 50-55 (bad vibe felt in floor pan, gas pedal, door panels, front seat backs, trans tunnel, steering wheel, etc), remains at 60-65 but this time around does not taper off after 65+ Like it did in the past.

We'll see what happens after the rear is replaced.

 

[Kong76]

Cobra are your vibes harmonic? Do they come and go in waves while your at the crucial speed/s? Can you drive through it? Sorry if already stated. My Jeep had this and it was my pinion angle.

 

[kh1818]

Exactly, people who have had the dealer "fix" it, put a few hundred miles on it and come update us later. I made this mistake and thought it was fixed for about 100 miles.

What did you do after the vibration came back? Any further resolution?

Jumping back in... For those who have read my very detailed posts in this thread, my driveline vibe has been documented throughly (and as others have experienced, fixed too....only to come back time and time again).

So, here I am again - car was brought back to service last week with just 23,xxx miles on it due to a humming noise and the dreaded driveline vibe.

This will now be, if I remember, the 5th time it's been in the shop since I bought it new in Dec 2015 for the SAME issue as experienced by many.

I don't have my current paperwork handy, but the Tech performing the work (same Tech who did the last corrective fix for same issue last November) is SUPER thorough. The Service Center was in touch w/Ford Engineering Team again. They used the listening equipment again. They drove the car distance, everyone has confirmed its a driveline issue and it's been documented that the vibe is directly related to the driveline and has now this time been narrowed down to the rear differential.

The Tech pulled the diff drain plug and noted there are metal particles mixed in with the gear fluid (not good). Also noted that the listening equipment attached to the car this time around recorded excessive hz (I'll update thread tomorrow with the work order info).

The entire rear diff is going to be replaced under warranty Per the Service Center, the new diff is being built at Ford and will be shipped to the Service Center in about 2 weeks, at which time they will call me so I can bring the car back for repair.

----

I suspect my rear diff has been the potential issue since my initial complaint at 1,900 miles and should have been replaced at that time. My guess is that at every interval of a supposed potential fix, the rear gears were wearing into different wear patterns. This may explain why each time the vibe felt like it was fixed - but then resurfaced X,xxx miles later was because after so many miles, the gears wore differently, and the corrective actions have only been "temp" fixes until the diff gears are just totally shot...

There's no reason there should be metal particles in the sealed diff, not at 23k miles.

To those wondering, yes, this is also the first time anyone unplugged the rear diff to check the fluid. Not sure why it was never looked into before though...

Not only is there a hum, a driveline vibe, but also excessive clunking when coming to a stop - as if there is too much slop in the rear diff allowing the driveshaft to clunk as the driveline is winding down when coming to a stop.

The driveline vibe starts at around 48mph and gets excessively worse at 50-55 (bad vibe felt in floor pan, gas pedal, door panels, front seat backs, trans tunnel, steering wheel, etc), remains at 60-65 but this time around does not taper off after 65+ Like it did in the past.

We'll see what happens after the rear is replaced.

Sorry to hear it re-emerged for you. My car has 800 miles on it, and they are replacing the rear diff along with the rest of the rear assembly - hoping that knocks it out for good. Do you suspect that replacing the rear diff will fix your vibration issue?

 

[Dominant1]

The fix is pinion angle adjustment with cross member shims guys. its easy to do and very inexpensive! Dont know why more folks aren't doing it. Kelly at BMR has confirmed it works on his own cars!!

Read this thread Kelly has some great info here:

http://www.mustang6g.com/forums/showthread.php?t=74783&highlight=Crossmember+shims

 

[SoulTea]

Very technical thread. I took my car to the dealer last thurs for first service and oil change and asked them to check out the vibration as it had a constant vibration above 80 km/h. They replaced the driveshaft, I had to leave it overnight so they could get the part in. So far I've put maybe another 200km on it since it was done and it is 95% gone. It seems to have shifted the vibration up to a higher speed if anything, more like above 120km/h but it's nowhere close to as bad as before either. Could just be the stock pirelli all seasons too, not sure. Either way I'm happy and if it stays like this I'm fine with it.

Another positive I've noticed is that the 1-2 shift has seen worlds of improvement. The car would always buck and I'd hear the driveline basically shit itself if I shifted at 2k, it would only be ok if I shifted at 2.5k or above. Now with the new driveshaft it shifts like butter even at 1.5k 1-2 if I really want to be a turtle from the stoplight. Very happy with that improvement as it is something that plagued me all the time.

Here what was written on the invoice for the technical specs I've seen talked about in here

COMPLAINT: VEHICLE VIBRATES AT HIGH WAY SPEEDS - ANYTHING OVER 80KM/H
REAR VIEW MIRROR SHAKES DUE TO VIBRATION
CAUSE: VERIFIED CONCERN LOUD HUM NOISE AT HIGHWAY SPPEDS CHECK
OASIS FOUND SSM 45938
CORRECTION: CHECKED DRIVE SHAFT RUN OUT RUN EXCEEDED .6MM ACCESS AND
REPLACED DRIVESHAFT RE CHECKED RUN OUT RUN NOW WITHIN SPEC
ROAD TEST WITH SHOP FOREMAN CONCERN NO LONGER PRESENT

 

[offroadkarter]

We'll see what happens after the rear is replaced.

Keep us up to date

What did you do after the vibration came back? Any further resolution?

Nothing yet, however I'm tempted to go back to the dealer and see if I can get a new diff put in. It might not fix this issue, but maybe it'll fix the hilariously bad gear lash I have.

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