What's the lowest speed you can cruise in 6 gear, MT6

[CJJon]

I pay more attention to the tach than I do the speedo. Well, I pay attention to the engine sound...same thing.

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[m3incorp]

Based on those 3 charts, what is the reason you are changing to 4.09 gears?

One could guess, I assume as there are different reasons for the change. Many want them for more low-end get-up and go...OP might want them to be able to use 6th at a lower gear.

The 18-20 version of GT MT82 (D4) - with 3.55 gears and 275/40/19 tires:

r

Same setup with 4.09 gears:

15-17 GT MT82 with 3.73 (PP) gears:

That's why I'll be adding 4.09 gears to my '19 base GT

 

[MikeMr305]

I got the 3.55 ratio and comfortably cruise in 6th at just over 43mph. Its unnecessary, but it works

 

[Nuked]

I have 3.73 with a 325/30/19, so shorter than stock. Works out to be almost 3.90 ratio with that tire IIRC. On a 15-17 I don't think I would want any more gear, sometimes I feel like it is too much as is. I use 6th regularly when cruising around 55-60. Any hill or need for acceleration and down to 5th.

 

[KeyLime]

Flat ground, not accelerating I'll cruise in 6th at 48-50 (3.55). If it's not lugging I don't worry about it.

But let me ask the obvious question. If you have the A10, what gear does it select when cruising?

 

[CJJon]

Flat ground, not accelerating I'll cruise in 6th at 48-50 (3.55). If it's not lugging I don't worry about it.

But let me ask the obvious question. If you have the A10, what gear does it select when cruising?

It hit's 10th often.

 

[ctandc72]

Based on those 3 charts, what is the reason you are changing to 4.09 gears?

One could guess, I assume as there are different reasons for the change. Many want them for more low-end get-up and go...OP might want them to be able to use 6th at a lower gear.

Essentially, putting 4.09 gears in a 18+ MT82 makes it very close to a 3.73 gears 15-17 MT82 car.

We tend to forget that manufacturers make a lot of compromises to appease CAFE standards. Remember it's essentially "theoretical" fuel economy. It doesn't take into account lugging or real world driving conditions.

75mph in my 3.55 geared 19 GT is right at 2K RPM. Try accelerating to pass or avoid something in 6th at that low of an RPM....

Me personally, I like doing me best to put an engine where it's most efficient in the RPM range I use the most when driving. With 4.09 gears, my car would be right at 2500 RPM in 6th gear going 75mph.

The mechanical advantage in acceleration, especially in lower gears, wouldn't be unwelcome either.

 

[sotek2345]

I have a bad habit of shifting to a higher gear too early when just cruising around - this usually lead me to be in 6th at 30 to 35mph around town (and then downshifting whenever I hit a significant hill or needed to accelerate). I am better about that in the GT350 if only because the exhaust valves shut when shifting into 6th (so I stay in 5th). But 6th around town in my '14 GT and '11 GT500 was very normal. Can will run fine in a straight line at ~800 rpms

 

[gadgtfreek]

I go based on RPM, won't even use 6th unless I'm on the hi-way and rpm is minimum 2,000. Otherwise, it just feels like the engine's lugging.

Yep!

45 mph I generally stay in 4th, if thing are cruising well I may move into 5th, unless there is a stoplight every 200 feet. I only touch 6th if I am setting cruise at beyond 60mph. Running 50-55 in 5th, the car isn't lugging and gets good mileage (for a 5.0 with 3.73's).

 

[Norm Peterson]

Curious if anyone has mods that allow them to cruise around in 6th gear at lower speeds then stock. I really can't get into 6th until about 55. Lot of areas where it'd be nice to hit it around 45 or so. Thinking the 409 gears may allow this?

Stock GT MT6 perf pack

Why the desire to use 6th at speeds where 5th is already the gear to be in?

Just drive in the gear that will give you adequate throttle response for the conditions of the moment and don't worry about which gear that might have to be. That's part of why cars today give you 6 forward gears to choose from.

Back in my 3-speed MT days, yeah, you wanted to get up into top gear because even 2nd was too short to be useful except in slow-moving traffic. That was then . . .


Norm

 

[m3incorp]

That's a good explanation.

Essentially, putting 4.09 gears in a 18+ MT82 makes it very close to a 3.73 gears 15-17 MT82 car.

We tend to forget that manufacturers make a lot of compromises to appease CAFE standards. Remember it's essentially "theoretical" fuel economy. It doesn't take into account lugging or real world driving conditions.

75mph in my 3.55 geared 19 GT is right at 2K RPM. Try accelerating to pass or avoid something in 6th at that low of an RPM....

Me personally, I like doing me best to put an engine where it's most efficient in the RPM range I use the most when driving. With 4.09 gears, my car would be right at 2500 RPM in 6th gear going 75mph.

The mechanical advantage in acceleration, especially in lower gears, wouldn't be unwelcome either.

 

[NoVaGT]

.....Back in my 3-speed MT days.....

Oh....look at you all high & mighty with your three gears. Shifting from 1st to 2nd, and then into 3rd........

One word; Dynaflow.

 

[Norm Peterson]

Oh....look at you all high & mighty with your three gears. Shifting from 1st to 2nd, and then into 3rd........

Three wasn't the fewest - my folks had one car (that I did get to drive) that only had two speeds (think Powerflite). But that was a full-on automatic, even though I normally just pushed either the button marked '1' or the button marked '2' when going forward. A non-lockup 2A compared to today's 10R80/10L90.

One word; Dynaflow.

One more word: ugh.

Buick's Dynaflow had to have been about the softest-shifting manual-shift-only transmission configuration to ever make it to market. Probably closest in feeling to a CVT in either of its fixed reductions, and likely deserving a share of the blame for automatics picking up the derogatory 'slushbox' tag.


Norm

 

[Ebm]

I got the 3.55 ratio and comfortably cruise in 6th at just over 43mph. Its unnecessary, but it works

I have 4.10s and can cruise around in 6th gear at around 45 mph. Any lower and you are in bog territory. No way in hell you can drive in 6th gear with a 3.55 rear end at 43 mph.

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