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Discussion Starter #1
I wonder how this supposed to be normal, or maybe there some mechanical problem to look at.
I have almost no way to upshift when revs above 5k. Shifting become or no go… or cranchy hard to push through. Yea, there way to hold clutch for couple of seconds and as soon revs bit down shift the gear. But it quite a waste of time when trying to get speed up to be honest..
I know one NC Miata experienced mechanic, so he might have some idea, but I believe there some changes were made by Fiat when they convert NC gearbox to 124, I saw some NC folks wrote about adjusting clutch, is this option available in 124?

Anyway hope somebody could give me some hints.. Thanks in advance!
 

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I just broke the engine in but I’ll try to do some high rev shifts and let you know
 

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Not sure I understand the question...
But I know for a fact, I've had no problem shifting into second whilst bouncing off the rev limiter...
:ROFLMAO:
 

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Discussion Starter #4
Pretty much it, I can't do it. I wonder is it any how tune related...
 

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There is a clutch pedal adjustment with the NC transmission. Is your clutch engaging with the pedal too close to the floor?

Also, there is an adjustment that sets the 3rd/4th gear throw. It's on the side of the transmission . You can find a description and photos here: NC 6-Speed Transmission Adjustment Procedure DIY

Notice that this fixes problems with balky- or no-shifting at high rpm's. It's not a DIY adjustment, but it's likely that Fiat techs will not know about it. Mazda techs mostly don't know about it, either, so the photos will be useful.

I'd try the pedal adjustment first; then take it in to a dealer or your NC mechanic for the throw adjustment if that doesn't work. Makes sure you bring the photos from the link above.
 

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Discussion Starter #6
There is a clutch pedal adjustment with the NC transmission. Is your clutch engaging with the pedal too close to the floor?

Also, there is an adjustment that sets the 3rd/4th gear throw. It's on the side of the transmission . You can find a description and photos here: NC 6-Speed Transmission Adjustment Procedure DIY

Notice that this fixes problems with balky- or no-shifting at high rpm's. It's not a DIY adjustment, but it's likely that Fiat techs will not know about it. Mazda techs mostly don't know about it as it's still not in the Mazda service manual - so the photos will be useful.

I'd try the pedal adjustment first; then take it in to a dealer or your NC mechanic for the throw adjustment if that doesn't work. Makes sure you bring the photos from the link above.
Thanks!! I hope Fiat's clutch pedal is adjustable as Miata's. I don't think clutch engaged too late. My problem really that no shifting on high rpm's..
Knowing local Fiat service quality I would rather pay someone decent instead dealership doing messy work for free)))
 

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The input shaft of your transmission has a lot of rotational momentum and needs time to slow down to the rpm of the next gear before meshing. If you force the tranny into the next gear without waiting, it will grind. Even though the gears have synchronizers helping out, your input shaft is still not going to jump to the correct speed instantaneously; synchronizers can be overloaded too if you overpower them.

However, for me the wait time between shifts at redline never exceeds 1 second, even for 1st to 2nd or 2nd to 3rd where the jump in gear ratio large, not several seconds like you mentioned. If you really have to wait that long, then something could be wrong. Either your clutch is not separating like it should (clutch drag), or your synchros are not happy. If you can shift through all your gears at all, I don't think gear throw is the problem.

I would rule out clutch drag first. If you park your car on level ground, go to first gear, clutch in, handbrake down, then rev to redline, and your car starts moving, you have clutch drag and clutch adjustment is needed. If it doesn't, you clutch is fine, don't fix it if it ain't broke!

If clutch drag is not the problem then it's very likely down to the synchros or the transmission fluid. What fluid are you using btw?
 

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OEM fluid, should I try something different?
No, OEM is fine. A bad aftermarket fluid can cause problems but OEM is adequate. A more premium fluid might help reduce minimum shift time but we're talking maybe milliseconds of difference on a transmission that's working properly.
 

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Discussion Starter #10
I really want now to test with default tune. Shifting is pretty ok as far it just above 5K, I remember it was easy to shift when I bought spider, but sometimes might change since the tune was added.
 

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I really want now to test with default tune. Shifting is pretty ok as far it just above 5K, I remember it was easy to shift when I bought spider, but sometimes might change since the tune was added.
An ECU tune does not alter a manual transmission in any way; the tranny is not even hooked up to the ECU except maybe that one wire that checks what gear you’re in. The only thing that could remotely affect the transmission is if you’re making more torque at 5k rpm. Not saying don’t try what you want to try though, it won’t hurt anything.
 
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