Manual Trans. Thud when shifting

[D3adch1ld]

Yup. Every time I grab 1st quickly after pressing the clutch in (like half second after pedal hits the floor), it thuds. The clutch disk will carry quite a bit of rotational inertia, so the input shaft is still spinning at engine speed or slightly slower until the synchro cones slow it down or the synchros engage generating a "thump." Even FWD cars make these kinds of noises, you just have to have the window down to hear them, and they don't feed back into the body so easily because most of them have cable shifters. The difference is that a FWD trans is in front of the firewall (thick steel) and insulation, the RWD trans is in a tunnel, right about calf-muscle position. It's like an amphitheater.

Couldn't put it better.

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[D3adch1ld]

Ok, this is great to know, and is a quick work around for the 1st gear input.
What about from 1st to 2nd gear when driving slowly, like in a parking lot, or heavy traffic. That's probably the thing that annoys me more.

Is an aftermarket shifter or trans mount going to help dampen this, or will it make matters worse. I'd be ok if it was a little less of a thud, mine is pretty loud.

The return spring mod will probably take this away. Its all in the modulation of the clutch, for some reason the spring really makes modulating the clutch unpredictable and guessing it feels wrong, but if play with the clutch as you enter 2nd it softens it up.

 

[Ruby305GT]

If it's synchros then why is it not happening on all gears?


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[aeropaul]

:shrug: Without examining the design differences between the synchro hub assemblies, I won't even begin to formulate a theory as to why it doesn't do it in all gears.

 

[Ruby305GT]

:shrug: Without examining the design differences between the synchro hub assemblies, I won't even begin to formulate a theory as to why it doesn't do it in all gears.

I hope someone would take the trans apart, just to see what's in there. Some shop has to have done this or planning to, I would only hope.


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[D3adch1ld]

If it's synchros then why is it not happening on all gears?


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Its been established, once the car is moving the drivetrain is already in motion and thus the input shaft doesn't stop, it simply drops to the speed of the rest of the driveline.

 

[Ruby305GT]

Its been established, once the car is moving the drivetrain is already in motion and thus the input shaft doesn't stop, it simply drops to the speed of the rest of the driveline.

I understand that but why is it then happening between 1-2 since the drivetrain and input shaft are already moving.

 

[D3adch1ld]

I understand that but why is it then happening between 1-2 since the drivetrain and input shaft are already moving.

The shunt I feel on 2nd is because of the clutch engagement, if you easy the clutch into second it disappears. The higher the gears the easier engagement you'll experience. Personally, I'll be trying the "return spring mod" which should allow me to better modulate the travel/engagement of the clutch rather than the artificial feel we get with the spring on.

The only real problem I have experienced with the trans is the notchy feeling entering 2 and 3, specially when cold. This, however, I attribute to the oil used by Ford. I don't want to change it just yet so they don't have any reason to deny any repairs under warranty, but my preference would be Redline Lightweight Shockproof. I won't get into the details, but that's the only oil that has worked for me on other platforms under severe cold and hot temps without any problems.

 

[Ruby305GT]

The shunt I feel on 2nd is because of the clutch engagement, if you easy the clutch into second it disappears. The higher the gears the easier engagement you'll experience. Personally, I'll be trying the "return spring mod" which should allow me to better modulate the travel/engagement of the clutch rather than the artificial feel we get with the spring on.

The only real problem I have experienced with the trans is the notchy feeling entering 2 and 3, specially when cold. This, however, I attribute to the oil used by Ford. I don't want to change it just yet so they don't have any reason to deny any repairs under warranty, but my preference would be Redline Lightweight Shockproof. I won't get into the details, but that's the only oil that has worked for me on other platforms under severe cold and hot temps without any problems.

Got it, makes sense. You can always change fluids if you feel it's best and you noticed from personal experience it actually works.

 

[D3adch1ld]

Got it, makes sense. You can always change fluids if you feel it's best and you noticed from personal experience it actually works.

I'll be trying some things before going there, but yes, what Ford doesn't know, doesn't hurt me. lol :gossip:

 

[Ruby305GT]

I'll be trying some things before going there, but yes, what Ford doesn't know, doesn't hurt me. lol :gossip:

Cool, keep us updated if you find any breakthroughs. Anything is helpful as many are experiencing these issues. I am just getting ready to deal with mine if issues do come up, always good to have a plan B.

 

[D3adch1ld]

Cool, keep us updated if you find any breakthroughs. Anything is helpful as many are experiencing these issues. I am just getting ready to deal with mine if issues do come up, always good to have a plan B.

Will do. Keep an eye out for the review on the Whiteline Insert. Ill be putting it on next week.

 

[Ruby305GT]

Will do. Keep an eye out for the review on the Whiteline Insert. Ill be putting it on next week.

Awesome! I was waitng for DemonCoyotes review but it hasn't come up yet. He also mentioned he was changing fluids, but I am very interested in the whiteline insert review. Hopefully it will be like magic and make everything disappear!

 

[D3adch1ld]

Awesome! I was waitng for DemonCoyotes review but it hasn't come up yet. He also mentioned he was changing fluids, but I am very interested in the whiteline insert review. Hopefully it will be like magic and make everything disappear!

Im also hoping for some positive outcome from the change, should be interesting!

 

[SilverSpoon09]

So with my recent trip to the dealer for my other trans related noises, I also grazed across this topic as well. The tech seemed to be extremely knowledgeable about the mt-82 and the mustang in general. He claimed that the thud is due to the driveshaft backlash. While you guys are correct with the engagements within the trans; the thud is caused by driveshaft backlash. He claimed that ford greatly increased the amount of backlash in the 2015's driveshaft. It is supposed to increase longevity of the drivetrain. So be happy about it? Smiley wink wink??

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