Manual Trans. Thud when shifting

[DivineStrike]

AeroPaul thanks for the explanation. That makes a lot of sense. I'd be willing to bet you are right, as your explanation explains the thud when stationary and while moving.

A different "issue" I have is shifting quickly into fourth after reaching the top of third WOT, it seemed to not want to go in a couple times. I will have to play around more and see if this really is an issue. I also had one time where the 6th gear synchro let out a"yelp"lol however it has only occurred once, if it's an issue in the future I'm sure it will get worse before the warranty is up.

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[Demon Coyote]

My dealer ordered the friction modifier for the transmission and the diff, hopefully this helps with the problem. I will also be installing the whiteline transmission insert on the car next week so with all those things combined I'm hoping the transmission is smoother than butter.

 

[RedBaron777]

I have experienced the same "thud" from the time the car was delivered but it doesn't seem to happen all the time. What I have found was if when stopped, you "ease" it into first, there has been no noise. Try it and see what happens. That might make it easier to diagnose if there is a problem.

 

[dwaleke]

My dealer ordered the friction modifier for the transmission and the diff, hopefully this helps with the problem. I will also be installing the whiteline transmission insert on the car next week so with all those things combined I'm hoping the transmission is smoother than butter.

Rumor is the friction modifier is already in the transmission. Do you have confirmation from Ford that it is not?

Friction modifier in the diff will have no impact on the thud.

The trans mount is probably the best bet. Keep us posted on that.

 

[robb]

My dealer ordered the friction modifier for the transmission and the diff, hopefully this helps with the problem. I will also be installing the whiteline transmission insert on the car next week so with all those things combined I'm hoping the transmission is smoother than butter.

Please give a us a full review after you install the whiteline transmission insert. THANKS!!!

 

[svoguy2000]

Mine does it from time to time also. It's a non issue. I've heard it many times before in other cars.


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[Patrick S]

I heard it from my car for the first time today shifting into first at a stop light. the car was not cold as i was 30 minutes into my trip already. It was a toasty 38º outside, so, no ice either. It happened just as i was passing the threshold where the stick usually gives into first gear. i have 1300 miles on the car.

im not going to stress a whole lot yet, unless we see anyone coming into major problems in the transmission, as everything is under warranty for another 28700 miles.

 

[Loki]

Mine also does this when shifting into 1st while stopped.

 

[souprmage]

At idle, there isn't any pressure pushing fluid through the trans, it's a lubrication bath.

The clutch may be fully disengaged, but input shaft of the transmission may still spin in neutral until a mechanical resistance is applied (shifting into first) due to aerodynamic forces inside the clutch mechanism. If it's in neutral with the clutch out, then you push the clutch in, the input shaft will still spin for a time because it carries some rotational inertia, until you slam it into first.

During all of this, one half of the synchronizer assembly is spinning at idle RPM (or slightly lower since you pushed the clutch in a half-second ago), and the other is stationary.

When shifting while the car is moving forward, one half of the synchro assy is moving at engine speed, the other is moving at wheel speed X Rear gear ratio.

The whole thud-while-shifting is not a transmission internal component issue, it has more to do with the stiffness of the transmission mount and shifter mount to the body of the car transmitting feedback from the synchro units back into the body and cabin.

Google "transmission synchronizer" to see the details of how these work. If someone has a better theory, feel free to put it forward. If you're having grinding, hard-to-engage gears, or missing shifts, then you have a problem. This is just a NVH issue inherent with the remote shifter design as far as I'm concerned. More likely a by-product of beefing up the shifter mounting design due to issues with the 11-14 cars. I also read somewhere that Ford had Getrag beef up the synchros for the '15, so there "shouldn't" be an issue there anymore.

I've never watched videos on how transmissions really worked before. But now that it makes sense, I think you're absolutely right.

The sychnronizer is really just a brake, and the momentum of the countershaft and the gears is probably pretty high if it doesn't sit for long in neutral, so when the synchronizer locks down on the moving parts, that energy gets absorbed and we hear a clunk.

 

[Demon Coyote]

Rumor is the friction modifier is already in the transmission. Do you have confirmation from Ford that it is not?

Friction modifier in the diff will have no impact on the thud.

The trans mount is probably the best bet. Keep us posted on that.

It could be that they didn't add enough or didn't lubricate the parts properly during assembly. The friction modifier in the diff is actually for the noise that's coming from the diff, what feels like diff binding when I'm taking a slow turn from a dead stop. XL-18 for the trans and XL-3 for the diff.

I will be working on everything together next weekend once the fluids and everything come in and will install the trans mount then. I will keep y'all posted.

Please give a us a full review after you install the whiteline transmission insert. THANKS!!!

Will do boss!

 

[dwaleke]

It could be that they didn't add enough or didn't lubricate the parts properly during assembly. The friction modifier in the diff is actually for the noise that's coming from the diff, what feels like diff binding when I'm taking a slow turn from a dead stop. XL-18 for the trans and XL-3 for the diff.

Ok. You have more issues than what everyone is reporting here. I thought you were referring to the thud only.

Let us know how it turns out.

 

[Demon Coyote]

Ok. You have more issues than what everyone is reporting here. I thought you were referring to the thud only.

Let us know how it turns out.

Yessir, sorry for the confusion. The diff noise is light but happens only when I stop and make a slow turn. Happens only once unless I'm interpreting the noise incorrectly. Once the fluids have been added with the additives in the trans and diff and I have installed the Whiteline trans insert I will inform everyone about it.

 

[minicobra]

I have the GT factory thud package, I mean performance package.
I just picked the car up yesterday, and noticed it immediately after driving off the lot. I know some people don't seam to be concerned about it, but I personal think it is a flaw in design or engineering. Mine is very apparent, and totally takes the enjoyment out of driving this car for me.
I traded In my 47k mile thudless shifting 2012 GT500 for this car, I know different transmissions, but just goes to show that it can be engineered out.
Not to mention I didn't experience this in my 370z, 335i, older 91 5.0, and even my 1970 boss 302. I mean, come on, after 40 years of transmison and engineering advancements, Getrag or Ford can't figure this out.

If there is an aftermarket shifter or part that will fix this, please manufacturers chime in, I only have 90 miles on my car, but will install it tomorrow.

Otherwise, Ford should come up with a solution and issue a TSB.

It just boggles my mind that with all the testing done before a new model car is released, that some engineer heard/felt the thud and thought that this was normal or acceptable in 2015.

All they would need to do is drive any number of other manufacturers rw drive manual cars for the past 40 years.

 

[minicobra]

Any aftermarket shifting companies have a solution for this ???
MGW, Steeda, etc.

 

[aeropaul]

After seeing the shifter disassembled, I'm inclined to believe the thud is more related to slack in the ridiculous amounts of play and the absurd range of motion in the stock shifter.

Well, this is a huge exaggeration. There is no ridiculous amount of play in the shifter, and the range of motion is just fine

Mechanically, the way gears in a transmission are cut, once slotted the gears will mesh together and pull each other together. I am guessing that the slack in the shifter (there to reduce NVH and promote 'smoothness' in arm articulation) are the thud when the slack is being pulled out in the shifter arm in lieu of direct gear placement from a solid shifter arm. This would also explain why it seems random for some folks and doesn't happen to others - depending on which way the articulation in the arm is laying in the unit, it will either place the gear smoothly (no sound) or only catch the gears and cause the transmission rotation to 'pull' the rest of the gear into place and take the slack out.
.

Gears don't work that way, especially helical cut gears. In fact, helical cut gears want to separate themselves along their axis of revolution. When you shift, you aren't moving gears, you're moving synchronizer cones. See my post a few pages back about why you're hearing noise. The thud is feedback from the synchros engaging being transmitted back up through the shifter and into the body because it's attached to the body.

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