Vibration between 50 & 70 mph

GT Pony · Mar 29, 2017

GTP said:
If the rear of the car squats, the diff raises relative to the rest of the car, and the driveshaft angle changes in a favorable way. But only very slightly.

The differential is mounted at 4 points into the rear subframe, and the subframe is mounted to the chassis of the car. I think the only movement of the differential pinion angle would only occur from torque twist under lots of power due to the soft mounting bushings, but it shouldn't move the pinion angle if the trunk is just loaded with weight. That would only work on a live axle design.

Gurjit · Mar 29, 2017

GTP said:
If the rear of the car squats, the diff raises relative to the rest of the car, and the driveshaft angle changes in a favorable way. But only very slightly. I don't think it will help at all. However, if the chassis was redesigned, theoretically the diff could be rotated about the rear axle so as to reduce the DS angle.

Our vehicles's differentials are bolted to the rear subframe/irs

If you raise or lower the rear 5 feet it makes no tranny to diff angle difference

Shimming the tranny down does make a difference

BMR Tech · Mar 29, 2017

Glad to see my shimming recommendation has been used and helped so many people!

I am seeing this mentioned everywhere now, and I am happy to know I could be of help to those with this issue.

Enjoy your S550s fellas, I LOVE both of mine!

GTP · Mar 29, 2017

Yeah, I got it wrong.
[MENTION=9985]BMR Tech[/MENTION] what is the link for the shim thread?

markw24 · Mar 29, 2017

Dominant1 said:
Try this experiment. Put 150lbs of weight in the trunk of your car, go out for a drive and if the vibrations subside or are reduced then you know its a pinion angle issue which can be fixed with transmission crossmember shims on the crossmember bolts to improve your pinion angle! If you read this entire thread guys have done this and it fixed vibration issue! No where in this thread did anyone put an aftermarket ds in and it fixed it by itself! Good luck!

So with that said I have a question about the Pinion angle. The angle's from the trans yoke to the pinion input are somewhat fixed. adding weight will change those angles how may I ask. Adding weight to the trunk will change the half shaft angles. Which are CV joints not u joints. CV joint angles can change greatly with in reason before introducing a VIB. adding washers in the cross member with change an already fixed angle, That could increase or decrease a VIB.

markw24 · Mar 29, 2017

markw24 said:
So with that said I have a question about the Pinion angle. The angle's from the trans yoke to the pinion input are somewhat fixed. adding weight will change those angles how may I ask. Adding weight to the trunk will change the half shaft angles. Which are CV joints not u joints. CV joint angles can change greatly with in reason before introducing a VIB. adding washers in the cross member with change an already fixed angle, That could increase or decrease a VIB.

SORRY GUYS AND GALS. I SEE THAT WAS ALREADY BROUGHT UP.

Mustg3 · Mar 29, 2017

So whatta you saying "Domiant" when the camaros ect. outsell the mustang then Ford will fix the problem. I don't think so. Mustang outsells the competition because the overall sell price is less.

Dominant1 · Mar 29, 2017

Mustg3 said:
So whatta you saying "Domiant" when the camaros ect. outsell the mustang then Ford will fix the problem. I don't think so. Mustang outsells the competition because the overall sell price is less.

From Ford's standpoint Only a small percentage of stangs have this issue, dont let this thread mislead you into thinking they all do. They'll do something about it when the s-650 comes out! Mustangs outsell camaros and challengers/ chargers for the price yes but mostly because folks just like the overall car styling and feel of the car! My car never vibrated when it was stock and still doesn't after my n/a build with my dynotech ds! Im in the car business for work and i drive alot of different cars and i still have not found a car that matches or exceeds the overall feel and drivability as my current stang. after having 3 previous stangs before this and many other different cars, i'm convinced this is the best car I've ever had!

Alan2955 · Mar 30, 2017

Dominant1 said:
From Ford's standpoint Only a small percentage of stangs have this issue, dont let this thread mislead you into thinking they all do. They'll do something about it when the s-650 comes out! Mustangs outsell camaros and challengers/ chargers for the price yes but mostly because folks just like the overall car styling and feel of the car! My car never vibrated when it was stock and still doesn't after my n/a build with my dynotech ds! Im in the car business for work and i drive alot of different cars and i still have not found a car that matches or exceeds the overall feel and drivability as my current stang. after having 3 previous stangs before this and many other different cars, i'm convinced this is the best car I've ever had!

I don't think it's a small number. I've test driven 2, and rented 3, and only one of the five didn't vibrate badly, and even it vibrated a bit. I have a 2014 with no such issues, so I'm not holding these to a luxury car standard. It's a disgrace that Ford is putting out this crap, and seems unable to fix it. As for outselling competitors, I see tons of Mustangs on rental lots, and very few Challengers and Camaros. I'm sure that accounts for a good deal of the sales lead the Mustang holds. I'm hoping Ford eventually sorts this out, as I'd love a newer Mustang in the next couple years.

HoosierDaddy · Mar 30, 2017

Alan2955 said:
I don't think it's a small number. I've test driven 2, and rented 3, and only one of the five didn't vibrate badly, and even it vibrated a bit.

And someone can flip a coin 5 times and get heads all 5 times. Not doubting your experience but your sample is far too small to predict the odds of any particular car having it.

There was a guy on another car forum I moderate that had an engine blow and get replaced under warranty. The replacement engine blew almost right away. The engine in the loaner they gave him while the second engine was being replaced blew up before he got home. He was convinced that all the engines would blow up and I can't blame him, but he was wrong.

speedfrk · Mar 31, 2017

HoosierDaddy said:
And someone can flip a coin 5 times and get heads all 5 times. Not doubting your experience but your sample is far too small to predict the odds of any particular car having it.

There was a guy on another car forum I moderate that had an engine blow and get replaced under warranty. The replacement engine blew almost right away. The engine in the loaner they gave him while the second engine was being replaced blew up before he got home. He was convinced that all the engines would blow up and I can't blame him, but he was wrong.

Nah, he's right. Even the Ford FSE who rode with me in my car said they all do it to some degree. He said he has had 2 GT's as company cars and they both did it. He and I are both engineers and knew what we were looking for. He said most people just don't notice it unless it is quite bad. I bet the 17's are somewhat better due to production changes but the fact that the 18's have drive line changes suggests a problem.

GT Pony · Mar 31, 2017

speedfrk said:
I bet the 17's are somewhat better due to production changes but the fact that the 18's have drive line changes suggests a problem.

What's the changes in the drive line for the 2018s?

Alan2955 · Mar 31, 2017

speedfrk said:
Nah, he's right. Even the Ford FSE who rode with me in my car said they all do it to some degree. He said he has had 2 GT's as company cars and they both did it. He and I are both engineers and knew what we were looking for. He said most people just don't notice it unless it is quite bad. I bet the 17's are somewhat better due to production changes but the fact that the 18's have drive line changes suggests a problem.

Exactly! The odds that I would randomly drive 5 of these from 2 model years that all vibrated would be pretty slim if this was a rare issue. I've never driven any other vehicle that vibrated like these do, and I'm 61 years old and I've driven a bunch! Lol. I'd bet the non vibrating ones are the unusual ones, and the vast majority suffer mild to bad vibrations. Ford gets by with it because the majority of owners either don't notice it, or it doesn't bother them enough to battle with the dealer getting it fixed. Let's hope 2018 models actually have some serious improvements!

Cobra Jet · Mar 31, 2017

GT Pony said:
What's the changes in the drive line for the 2018s?

Yes, I'd like to know about the above as well - seen this mentioned a few times in different threads on this site, but no other facts or what exactly has been noted as production changes??

Dominant1 · Mar 31, 2017

You guys trying to tell me i'm in the minority never having this issue in my auto car. Maybe its just a mt-82 issue.... never seen anyone with a gt-350 that has a vibration issue, i find that interesting as well!!!

Vibration between 50 & 70 mph

Do you experience vibration and rumbling between 50 and 70 mph?

No

Yes - V8/MT

Yes - V8/AT

Yes - V6/MT

Yes - V6/AT

Yes - EB/MT

Yes - EB/AT

GT Pony

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BMR Tech

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GTP

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markw24

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speedfrk

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GT Pony

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