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ZF Shifting issues


Joshuam08

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Hey all,

 

I've been noticing a few weird little things with my G6E Turbo and thought here would be a good place to ask about them.

 

My G6E is currently tuned to 280rwkw, so not a lot of power extra but a bit. My ZF is tuned, however I noticed these issues before the tune.

 

Basically, when I am driving in traffic without a lot of acceleration, shifting is perfect and almost unnoticeable. With WOT, shifting is also nice and smooth.

 

The issue I'm having is when I'm on like 40-60% throttle (at a guess, basically putting my foot down a little bit but not hard), sometimes when the car goes to shift, the car jerks and there is a bit of a thunk feeling and it's not smooth at all. I guess it almost feels like the ZF goes to shift, doesn't find a gear straight away so the car looses some momentum, and then it slams into a gear and keeps going causing the jolt/clunk/shunt etc. Sometimes this is also accompanied by a "shift fart" which I don't usually get on shifts if that matters at all. It seems like it mostly occurs in 3rd to 4th shifts but can occur in other gears I believe. It also occurs when I shift manually. 

 

I wanted to see if this was a normal thing, or a common issue that I can get fixed? I found another thread where someone asked the same question but didn't get a response so I don't think I'm the only one.

 

Thanks all!

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  • Member For: 15y 11m 19d
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  • Location: Melbourne

well, the "shift fart" you reference, is the torque reduction in the gearbox tune, which could definitely cause the symptoms of "momentum loss" you describe.

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I used to have the torque reduction as part of the gearbox tune, so I know what that feels like (and loved it). While it does have a little bit of a fart, the jolt I'm feeling isn't the same as what is usually felt by the torque reduction. This one feels a lot more violent and shakes the car a bit.

Edited by Joshuam08
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could be a tailshaft centre bearing or rear bushes issue, too, as the lash in the driveline (and associated mounts) can cause issues like this.

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It's going in for a ZF service soon so I'll get them to take a look at that. I'm also just a bit confused why there is no issue with minor throttle or WOT, and only when in the middle. Thanks for the help mate.

 

Only other thing I thought I'd ask, I did have the shift fart and loved the sound, and I don't have it now. Is there any reason to have shift farts/no shifts farts etc? I think the tuner told me they found that firm shifts prolonged the box but curious if there is a negative to going back to torque reduction being enabled.

Edited by Joshuam08
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  • Member For: 15y 11m 19d
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Yeah, you can tell your gearbox tuner to put the fart back in, if you want it... but like he said, the firmer shifts can prolong the box's life at high power levels... 280rwkw is fine to have the torque reduction remain in the tune.

 

no worries, happy to help :spoton:

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The engine and the trans have to be tuned to compliment each other which is why a generic zf tune is not a great idea.

 

Watching some of the hoontune tuned cars you can see that there is a decent wait while the trans makes the shift in some of them. You can clearly hear a shift fart in a car that ran 9.30 @ 154mph.

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It wasn't a generic tune (it was tuned with the engine at the same time), and it also had the same issue prior to being tuned. Unless I'm misinterpreting what you mean by generic. I was hoping a tune would've fixed it but sadly not so I'm just trying to work out what else would be the cause as I'm pretty sure the ZF and engine are in some kind of harmony. It's just confusing the issue doesn't seem to occur in WOT.

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Just now, Joshuam08 said:

It wasn't a generic tune

 

I didn't mean yours was, I was just making a point that they need to be done together.

 

From your first post it seems that it is shifting with the converter locked, possibly with some other funny stuff going on. Your tuner should be able to fix this if it is the case.

 

As it was there before it might not be able to be fixed with a tune and it could need opening up and inspecting.

 

How are your coils? They can cause transmission dramas.

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