4.09 gears

[K4fxd]

Anyone running these on the street with a 6R80?

Is it too steep in first to launch?

is the RPM too high for the freeway?

I've got 27.5 tires currently but am going to put 29 inchers on it when these wear out.

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[WildHorse]

Will be shifting outta first at around 33 mph w/ 4.09 with 27". 35 mph with 29".

 

[LxMike]

First gear with the 6r80 is 4.17. The auto trans don't need as much gear help as the mt82 does. The taller tire will help but it'll still be shifting out of first quickly unless you hold it manually

 

[K4fxd]

I have 3.31's and hate the lack of torque at street speeds. Am debating 3.73 and 4.09.

4,09 puts me at 70 in 6th at 2500 RPM..

4.09 has me trapping at 6500 in 4th. 1/4 mile At my current power level
3.73 has me trapping at 5900, 2250 is 70 in 5th

The above with 27's

I am mostly wondering if I will get any traction in 1st or if I would have to launch in 2nd. Also how does the car feel on the street. Right now it feels like a full size pick up with a V6 till I get over 4500.

 

[WildHorse]

4.09 has me trapping at 6500 in 4th. 1/4 mile At my current power level

So like 112 mph, what was your ET? Don't worry about launching in first unless your running big boy power.

 

[K4fxd]

It consistently runs 13.1 at 112

No real plans to increase power. At least in the near term

Edit for fat fingers.

 

[K4fxd]

I do test and tune grudge racing a couple of times a month, but really want the gears so I can stay with corvettes on the twisties.

 

[K4fxd]

I've decided to go with the 4.09 (or 4.11 if I can find cheaper) Can any forum sponsors help a poor boy out?

 

[TeeLew]

I've decided to go with the 4.09 (or 4.11 if I can find cheaper) Can any forum sponsors help a poor boy out?

You know, 3.90's exist if you want to split the difference.

 

[Vstang2]

You know, 3.90's exist if you want to split the difference.

Do 3.90's exist for the 18+? I hear everyone talk about 4.09 and 3.73 but never 3.90s

 

[K4fxd]

Yes, there are 3.91's

It's not an easy thing to decide. The 3.91 will work better with the 27 inch tires and if I add power.

With the 29 inch tire and current power the 4.09 looks like it wins.

Scratches head and wishes it had an old school 9 inch.

 

[TeeLew]

Yes, there are 3.91's

It's not an easy thing to decide. The 3.91 will work better with the 27 inch tires and if I add power.

With the 29 inch tire and current power the 4.09 looks like it wins.

Scratches head and wishes it had an old school 9 inch.

In general, you'll ET better with the shorter gear as long as you can hook up even if you touch the rev limiter for a half second at the end. Mph will, of course, be artificially limited by the gear.

Can you bump your rev limiter up 100 rpm?

 

[K4fxd]

I can set the rev limiter where ever I want. I think it is at 7800

 

[TeeLew]

I can set the rev limiter where ever I want. I think it is at 7800

You might not be making power there, depending on how the engine is set up, but if it allows you to run the shorter gear, you might think about letting it overrev a little in top gear. You can't shift & you'd probably rather not lift. It's an option to consider.

 

[K4fxd]

I've pretty much talked myself into the 4.09. I raised the limiter so I wouldn't hit it LOL

6 feet of chain plus oil pump gears.....

When it was stock limit I banged it a few times

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