6th gear swap (MT) possibility?

[troyguitar]

Has anyone figured out a better 6th gear to put in the GTI for highway cruising? I'd really like to see 2k rpm at 70 mph - is it even possible?

Having to keep it at 55-65 to get great mileage is annoying, I'd much rather move that range to 70-80 and just use 5th gear more often on things like 45mph roads.

 

[thatspsychotic]

You're probably better off looking around for a final drive swap... that topic has come up before, but I'm not sure if anything came out of it.

 

[Chris@Revo USA]

These transmissions are a dual output shaft with dual pinions for a single ring gear. While there are options and you can swap bits around finding the combination that would actually work correctly will be very difficult if not impossible.

 

[troyguitar]

I know final drive would be easier but that would drastically change performance in 1st-5th gears. My goal is to just increase highway mileage without changing anything else. I suppose it might also increase top speed but that is not really relevant with no Autobahn in this country :lol:

 

[aw6141]

Do 6mt A3's or TSI Passts have different ratios?

 

[socal87]

Why is it every time I brought this up, someone has to be RAAAARGGGGH Y U NO BUY TDI??!!!

I thought the whole point of this forum is to swap ideas and mods and such.

OP: I've been looking around for a similar solution...personally I would like a taller final drive because I don't like how close the gears are, but knowing that would kill acceleration, I agree that a 6th gear swap would be the best option. I wonder if the TDI 6mt is parts compatible?

 

[DSMconvert1]

I would love to run a lower RPM in sixth, kinda silly to run 3k at 70 mph

 

[Chris@Revo USA]

I know final drive would be easier but that would drastically change performance in 1st-5th gears. My goal is to just increase highway mileage without changing anything else. I suppose it might also increase top speed but that is not really relevant with no Autobahn in this country :lol:

No it wouldn't change 1-5

This is a DUAL output shaft car with TWO pinions..

1-4 are on one final drive
5-6 are on another

It is maybe possible to just change the 5/6 but then your 4-5 jump may be huge.

the cost would also be well above anything you would ever possibly recoup in increased fuel economy.

A whole TDI box could be used but the gearing would suck for the 2.0t.

 

[Chris@Revo USA]

I would love to run a lower RPM in sixth, kinda silly to run 3k at 70 mph

Keeps the car in the area of peak torque in the cruising gear, makes a lot of sense actually.

 

[troyguitar]

No it wouldn't change 1-5

This is a DUAL output shaft car with TWO pinions..

1-4 are on one final drive
5-6 are on another

It is maybe possible to just change the 5/6 but then your 4-5 jump may be huge.

the cost would also be well above anything you would ever possibly recoup in increased fuel economy.

A whole TDI box could be used but the gearing would suck for the 2.0t.

Just the 5/6 might not be a bad idea. The cost is hard for me to say without really knowing more details, but if I could get an extra 5 or so mpg (I currently get ~32 at 70 mph and ~39 at 60 mph so it's a reasonable assumption) for 40000 miles at $4/gal we're talking around $800 which isn't much. Add in the time factor of all of additional fillups and I'd call it something like a $1000 cost difference over 40k miles or $2000 over 80k miles. Probably not worth doing but it's interesting to think about.

My biggest concern would be whether or not I'd need to use 5th gear on any race tracks (road course, not 1/4 mile or autoX).

 

[Chris@Revo USA]

It is most likely well over a grand before labor which with removal of the trans and tearing it down would be another grand possibly.

I don't see you doing a swap for less than about 2k

Also your math isn't entirely accurate because that assumes you'd be getting 5mpg better 100% of those miles so you wouldn't be.


Not know exactly what options are out there for gearing I know the tdi stuff could be way way too tall requiring you do downshift a lot. We used a TDI box when we set the land speed record with Skoda UK, that got us over 220mph in 6th gear on a 2.0t running little over 8grand (not sure of tire height). Thats really tall to expect to be able to roll on the throttle and pass in 6th gear

 

[Chris@Revo USA]

did the math real quick..

using the .72 6th from a tdi box assuming there was possibly a way to use it with the 2.0t final you'd go from 2800 rpm at 70 to 2100 rpm (using a 24" tire in the calcs).

You'd really have to downshift to pass in 6th now

If you used the whole TDI box with the 2.76 final you'd be at 1950 rpm at 70mph, that is really not idea for that engine to be cruising at as it is well too below peak torque. It could actually in theory reduce fuel economy if the load on the engine that would be required to maintain that speed was too high.


I just don't see it being beneficial financial due to the cost of parts vs the possible fuel savings, nor do i see it being pleasant to drive.

 

[crew219]

did the math real quick..

using the .72 6th from a tdi box assuming there was possibly a way to use it with the 2.0t final you'd go from 2800 rpm at 70 to 2100 rpm (using a 24" tire in the calcs).

You'd really have to downshift to pass in 6th now

If you used the whole TDI box with the 2.76 final you'd be at 1950 rpm at 70mph, that is really not idea for that engine to be cruising at as it is well too below peak torque. It could actually in theory reduce fuel economy if the load on the engine that would be required to maintain that speed was too high.


I just don't see it being beneficial financial due to the cost of parts vs the possible fuel savings, nor do i see it being pleasant to drive.

GTI uses a 25" tire if that makes any difference.

 

[Chris@Revo USA]

GTI uses a 25" tire if that makes any difference.

Thanks and it does, I didn't rework all of the scenarios but going from a 24" tire to a 25" tire at 70mph with the TDI final and 6th gear would drop rpms from 1950 to about 1850. TDI box would make the 25" tire cruise it probably way too low of an rpm.


They did actually change the ratios on the TDIs between 10 and 11 I think( don't recall exactly) The gearing i'm using is based on VWs current listed ratios for 2012 models. In theory there may be another combo that would put you between the TDI and GTI ratios i'm using, still not entirely sure the cost is worth it.

 

[troyguitar]

I actually prefer downshifting to accelerate anyway, if there was a way to use only the 6th gear from a TDI box that would be pretty cool I think. Basically treat the car as a 5-speed with a cruising gear.

I do unfortunately drive 90-95% of my miles on the interstate with cruise control so there is a chance that it could be worth doing in the long run. Being able to go 500+ miles on a tank at 70 mph in a car that is still decently quick would just be plain cool. At that low of an RPM I could probably still get about the same result even if upgraded to a k04, giving me the ultimate all-around car. 350+ hp with decent track performance plus huge cargo capacity and 35+ highway mpg? Sure it might not be cost-effective but it would be badass :lol: