Manual Trans. Thud when shifting

[Kong76]

Its mostly related to the PP diff in the cars. My 17 doesnt have it. I also didnt buy a PP. Ive still yet to read any non pp owners complain. Ive also told you that this isnt an uncommom thing on IRS equipped vehicles. I also dont see any autos complaining about it either. You just want to complain, in my opinion.

Well I have a base 2016 GT and mine has been doing this from day 1 as well. Noticed you straightened up your attitude when Tony responded. Why do you have to be such a prick? I've seen other threads where you respond the same.

Whats your problem? Napolean complex? No girlfriend? Not big enough? Gotta be something... tell us...

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[Draklia]

I've had the thud since day one on my base '16 too. I am not convinced it's a problem in the fact that it will cause damage.
I thought it was just the backlash in the ring and pinion along with a pretty hefty drive shaft, that and the transmission doesn't really have anything in it to quiet it. But just guessing on that. It is annoying though, but life goes on (hopefully).

 

[Asharus]

I've had it since day one. 27k miles and over 2 years later, not concerned at all. I've had several other manual trans cars (all Getrag trannies).

 

[EXP Jawa]

People talk about it being a driveshaft issue, a rear end issue, a transmission issue. And you see some situations of replacing a part and it going away for one guy, but not another. Here's my best guess / theory.

The root cause may be there's some amount of drag across the clutch, even when disengaged. This causes the input shaft of the transmission to spin slightly when in neutral, but being in gear obviously provides enough resistance to stop it. When you're in neutral and move into gear, the inertia of the input shaft transfers to the transmission output. Depending on how much backlash is in all of the downstream components, you'll get a thud of varying degree as that inertia is transferred down the drivetrain and all of that lash is used up, forcing the input shaft to stall. More combined lash means more thudding.

So, if you have low lash in the axle, but a bit in the 2-piece prop shaft, putting in a 1-piece shaft reduces the lash - and the inertial movement - enough to make the thud less noticeable. But if there's also excessive lash in the axle, then you don't make enough reduction in system lash to change how the thud feels. It might be more noticeable off the bat in PP cars because 1) the 3.73:1 gears multiply the axle back lash more than the taller gearsets do, and 2) the Torsen lacks a preload spring, which masks the differential gearing lash in the clutch plate diffs. So, more perceived lash comes from the axle. But you can get it in other axle combinations if the prop shaft or transmission system lash is also high enough. You don't get it in A/T cars because the transmission obviously sidesteps the issue.

I could be completely off base on this, I'm just an axle guy. But this is the only thing I've been able to come up with that addresses all the facts as I understand them. You can chase various aspects of drivetrain back lash and improve the situation, but I'd bet that if the clutch could be set up so the clutch disc more fully disengages the pressure plate, the problem would disappear. At least that's my thinking...

 

[wildcatgoal]

The point is, it's a 2015 MY car... there is no excuse for this. Not one single manual transmission vehicle I've driven or owned prior (Subaru, VW, BMW, Nissan Versa, Toyota Scion, '94 Honda Accord) have done the same. It's pitiful. But... you get used to it.

 

[Tony Alonso]

I could be completely off base on this, I'm just an axle guy. But this is the only thing I've been able to come up with that addresses all the facts as I understand them. You can chase various aspects of drivetrain back lash and improve the situation, but I'd bet that if the clutch could be set up so the clutch disc more fully disengages the pressure plate, the problem would disappear. At least that's my thinking...

What do you think about the change in the '18 GT to twin-disc clutch and new dual mass flywheel? Purely for higher torque output?

 

[EXP Jawa]

What do you think about the change in the '18 GT to twin-disc clutch and new dual mass flywheel? Purely for higher torque output?

I'd expect that the main reason for doing that is increased torque capacity. I doubt it would be done as a thud improvement. In fact, I'd think that with dual-discs, there is an added level of complexity to getting it set up right. One disc might still drag and the other not.

 

[mustang_guy]

Well I have a base 2016 GT and mine has been doing this from day 1 as well. Noticed you straightened up your attitude when Tony responded. Why do you have to be such a prick? I've seen other threads where you respond the same.

Whats your problem? Napolean complex? No girlfriend? Not big enough? Gotta be something... tell us...

My attitude has zero influence based on his presence. Ill say what i want to say regardless. Im a bit too old to fear being banned on a forum. Maybe you should stop adding tone to text. Couldnt care less what your opinion of me is.

The point is, it's a 2015 MY car... there is no excuse for this. Not one single manual transmission vehicle I've driven or owned prior (Subaru, VW, BMW, Nissan Versa, Toyota Scion, '94 Honda Accord) have done the same. It's pitiful. But... you get used to it.

Wrx and sti most definitely thud if shifted hard. Their issue is with their diff bushings.

 

[skytop1]

I've decided to purchase a new 2018 Vette instead of the new 18' Mustang. I am tired of fighting with Ford.

 

[5LITER]

My previous car of 10 years was a mazdaspeed6. It also has a getrag transmission and makes the same thuds as my 16 gt. 120k miles later and it was fine until i sold it. I truly believe its a getrag thing.

 

[Dave2017GT]

My 2017 GT PP does this as well. Car only has 420 miles on it. From everything i read this is just a normal sound. Very unfortunate considering this is the first new car ive ever bought. Anyway, taking to the dealer next week to have a busted tail light (lol not joking) replaced. Also, my emergency brake is also really loose. Hopefully they can tighten it up.

 

[ZanarkO]

3500 miles 2017 mustang gt base 6 speed does this as well. Also the shifter seems randomly notchy in 2nd and 5th gear some times, no syncro issues I dont think just maybe a fluid change? Anyway its annoying and it seems like sometimes the transmission shifts great other times it shifts like crap at random.

 

[keltymd]

Mine did it as well I did the BG fluid change and it is almost gone. I say almost because the notchyness is gone but on occasion it does thud just not as bad as it was.

 

[isedawishy]

My 2017 GT PP does this as well. Car only has 420 miles on it. From everything i read this is just a normal sound. Very unfortunate considering this is the first new car ive ever bought. Anyway, taking to the dealer next week to have a busted tail light (lol not joking) replaced. Also, my emergency brake is also really loose. Hopefully they can tighten it up.

Reported the parking brake issue when I got my 15 and they said they'd need to keep it at least over night. Just tightened it myself...

It helped some, but it's still loose... seems like a bad design. My Focus parking brake feels much better which is sad.

 

[wireeater]

16 PP with 14k on it now. I have the thud too. Mostly when the car is cold and shifting into first. I haven't really noticed it through any other gears. I was aware of this and just figured I'd have to live with it while I owned the car. I've had it since owning the car with 12 miles.

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