T5 Shifting "Issue"

Synchros shot? Weird noises while shifting? Not sure what needs to be replaced?
Puchrider
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T5 Shifting "Issue"

Postby Puchrider » Sun Sep 11, 2016 5:46 pm

I have a 1986 Thunderbird Turbo Coupe equipped with a T5 transmission. It shifts great when you shift quickly. However, if you shift very slowly, it has a slight bumpy feel reminiscent of a grind but smooth and completely silent. I'm curious to whether or not this is typical? Clutch seems to disengage all the way and I have never seen the transmission leak fluid. I'm guessing that this is happening because a quicker shift with more force is the proper way to get the synchro to ride up onto the cone and either speed up or slow down to the correct speed. I guess the ultimate question is if this is a sign of clutch-drag. The car shifts into gear normally when sitting still, so I think that rules it out. Thanks!
"If you're out of gear, you're out of control" - Johnny Mock

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theholycow
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Re: T5 Shifting "Issue"

Postby theholycow » Sun Sep 11, 2016 9:37 pm

1980s car, T5? Now we're in cow territory!

That description could certainly apply to mine, but of course it's impossible to do better than vague and subjective in a forum post about this sort of thing...and mine likely has some clutch drag.

Why would you shift slow? It's a T5, just shove it and dump the clutch/stomp the go-pedal...
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Puchrider
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Re: T5 Shifting "Issue"

Postby Puchrider » Sun Sep 11, 2016 10:06 pm

theholycow wrote:Why would you shift slow? It's a T5, just shove it and dump the clutch/stomp the go-pedal...


Haha, just trying to be easy with it, but the more I think about it, T5s are likely the most abused transmission and I've yet to hear people complain about them on the Ford forums
"If you're out of gear, you're out of control" - Johnny Mock

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Re: T5 Shifting "Issue"

Postby IMBoring25 » Sun Sep 11, 2016 10:16 pm

While the clutch is disengaged and the transmission is out of gear, the input shaft naturally spins down. There is an amount of time for upshifts from disengaging the old gear through engaging the new one for each shift that the natural spin-down of the input shaft coincides precisely with the RPM the new gear is spinning and the synchro doesn't actually have to do anything.

If you take longer than that with the transmission out of gear and don't double-clutch, the input shaft will spin down below the RPM of the new gear and the synchro will have to pull the RPM of the input shaft up (which is harder than pulling it down, since the spin-down is working against it instead of with it). This will be more noticeable if your synchros are a little tired (I'll save you wondering...They are).

This is one of many cases that the car will tell you what it likes. :)


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