GTI 6th gear into 6MT R transmission?

[DarkArrow]

My transmission needs to come out, so I had a random idea of the possibility of putting in a GTI 6th gear to lower cruising RPM. Is this even possible? Is it a bigger job than it's worth? How stupid of an idea is this?

I'm guessing there will be issues, since the computer uses RPM and speed to determine what gear it's in. Has anyone done this? Or custom gearing in general? Any idea of what faults it might cause? Can these be remedied by OBDEleven or VCDS coding?

 

[gingercabrio]

You could do this and it would cause you absolutely no problems whatsoever, because 6th is the same ratio between the Mk7 GTI and Golf R (0.91). It's the final drive that's different.

Regardless, you can't swap out individual gear sets in these transmissions because they have two output shafts meshed to a common input shaft. I think if you wanted to do this you'd basically have to replace all of the internal parts of the transmission, or the whole transmission, and all of your gearing would change.

 

[DarkArrow]

Got it, thanks for the input. I saw 0.74 on this post, so I thought the 6th gear would be different. So that idea is out.

Trying to learn more about the two output shafts you mention, I see 5th and 6th gear share a final drive that's different from 1-4 gears. A quick google search shows the R final drive has a 3.27 for 5th and 6th gear, while the GTI has 2.62. So, in a similar fashion of trying to lower cruising RPM, would it be possible to put the GTI output shaft in the R? Or, when you say meshed, do you mean they're all linked together and would only work as a complete package?
Thanks for the help and dealing with my lack of knowledge on this.

 

[gingercabrio]

Got it, thanks for the input. I saw 0.74 on this post, so I thought the 6th gear would be different. So that idea is out.

Trying to learn more about the two output shafts you mention, I see 5th and 6th gear share a final drive that's different from 1-4 gears. A quick google search shows the R final drive has a 3.27 for 5th and 6th gear, while the GTI has 2.62. So, in a similar fashion of trying to lower cruising RPM, would it be possible to put the GTI output shaft in the R? Or, when you say meshed, do you mean they're all linked together and would only work as a complete package?
Thanks for the help and dealing with my lack of knowledge on this.

Remember the number associated with the gear is a ratio between the input and output gear. E.g., a 0.74 gear has some number of teeth, and the ratio of it to its input gear yields 0.74. A numerically lower (taller) output gear is physically smaller than a higher (shorter) gear if the pitch of the teeth is the same. If you put a GTI TW2 shaft with longer gears into the R transmission, it wouldn't touch (mesh with) anything (other than the differential, which would be too large for the TW2 pinion gear). You would need the corresponding input shaft, whose gears would be too large for your existing TW1 shaft, so then you need the GTI TW1 shaft, and also the differential/final drive ring gear. At which point you just have an AWD GTI transmission. Transmissions are complicated. VWs are complicated. VW transmissions are ridiculously complicated.

 

[DarkArrow]

Understood. Makes sense you can't have a gear with less (or more) teeth to have the same spacing without being physically smaller (or larger). Once again, thanks for the explanation.

 

[gingercabrio]

Understood. Makes sense you can't have a gear with less (or more) teeth to have the same spacing without being physically smaller (or larger). Once again, thanks for the explanation.

I recommend you Google SSP 205 if you want to learn more about these transmissions.

VW has used this basic 6 speed design for nearly twenty years and as far as I know, nobody has managed to get a longer sixth gear on it. I know some people have swapped the guts (all 3 shafts and differential gear) out with other whole 6 speeds. It's not worth the effort frankly...With the 5 speeds you could just remove the end cap and swap fifth gear, which is why this idea persists in the community.