5 or 6 speed auto transmission Conversion?

[Big D]

As I comute to work daily, and usually at a steady pace of 80-85mph. I look at my rpm guage and the needle is pinned at 2500-2700 RPM, it sounds like its screaming down the road. I always think to myself if I only had one more gear this truck wouldnt be working so hard to get me to work.

yea yea I know I could throw in a 5 speed manual, but manuals suck when your in traffic, and thats daily.


Is there a 5 or 6 speed auto transmission that would work?

 

[cjman250]

I'm sure there's a way to swap a 6l60e in from a new truck. Would not be cheap though

 

[Big D]

this looks like a direct bolt on, but the price...........ugh!

http://www.transmissioncenter.net/4l80e.htm


although, might make up for it in gas down the road since I have no plans to sell this truck....ever!

 

[cjman250]

Yeah that's a big price tag

 

[highspeed]

You could have a nice gmt for that price. That trans is cool as hell though

 

[someotherguy]

You wanna keep the RPM's above 2K anyway or you may find yourself lugging the engine down the road.

You've corrected the speedo for your tire change? What gears you running? Truck probably came with 3.42's I'm guessing or did you swap to 3.73? Is your torque converter lockup working?

I'm guessing at all your specs but those tires look like at least 31's and maybe larger, so:

31" tire with 3.42 gears in 4th gear (0.7:1 OD) at 2700 RPM you should be going about 105 MPH.
31" tire with 3.73 gears in 4th gear (0.7:1 OD) at 2700 RPM you should be going about 95 MPH.

Richard

 

[Big D]

4.10's on 35's

speedo is exactly 5 mph off. so if the speedo says 70mph im going 75 mph.

 

[someotherguy]

OK, so I definitely underestimated the tire size and I see you've upgraded gears to match, not something most bother with.

So the numbers make a little more sense now but still off:

35" tire with 4.10 gears in 4th gear (0.7:1 OD) at 2700 RPM you should be going about 99 MPH. If you're 5 MPH slow on the speedometer, then that should look like 94 MPH to you, not the 85 you stated earlier.

35's doesn't necessarily mean they actually measure 35" but not enough variance in there to explain the difference.

That or the Apex Garage calculator is busted...

Richard

 

[dangileri]

Might be cheaper to regear to lower your rpms at 80- like drop down to 3.73s. First and second gear will suffer slightly but then you just add more power to compensate

 

[Big D]

OK, so I definitely underestimated the tire size and I see you've upgraded gears to match, not something most bother with.

So the numbers make a little more sense now but still off:

35" tire with 4.10 gears in 4th gear (0.7:1 OD) at 2700 RPM you should be going about 99 MPH. If you're 5 MPH slow on the speedometer, then that should look like 94 MPH to you, not the 85 you stated earlier.

35's doesn't necessarily mean they actually measure 35" but not enough variance in there to explain the difference.

That or the Apex Garage calculator is busted...

Richard

I think your calculator is busted......What rpms does your calculator say I should be doing at 80mph? I remember a thread a little bit ago about what gears to use with 35's, and people were sharing rpms at hwy speeds, the RPM levels were closer to my levels then your apex garage calculator.