4:10 questions

[CPman]

Hi all,
Can anyone tell me what RPM @70 MPH they are turning in 5th gear with 4:10's(manual trans) and also when you had the gears installed, would the car run good enough for the installer to test drive it without it going into limp mode. I have an XCAL and would rather do the computer work myself.
Thanks

 

[Emay]

I have 4.10's i could only guess my 70 mph rpm range so I won't answer that, but in regards to the limp mode, I drove mine for just over 500 miles before recalibrating the speedo and it never went into any type of limp mode. It ran perfectly just with a way inaccurate speedo.

 

[Grabber07GT]

The car will run fine without updating the computer. The only reason that the computer needs to know about the new gears is to accurately reflect the mileage and speed. On the old 5.0's all you had to do was change a little gear. Now, everything's electronic. Hope that helps. Oh yeah, on a 2004 the RPM's were around 2400 or so @ 70 mph with 4.10 gears. I'm not sure what they are on an '05+. I imagine that it's pretty close to that, though.

 

[Rock36]

I forgot to bring my Xcal2 with me when a buddy installed my 4.10s and drove 2 hours home with out adjusting the speedometer and no problems.

After adjusting my speedo, I run about 2800 rpm @ 80 mph and still can get 23.3 mpg on the highway. 70mph should run around 2400-2500 rpm

 

[anthony05gt]

I'm at around 2700 rpm's @ 80mph with 4.10's. When my car was an auto it was 3000rpm's @ 80mph.

Shift points would be screwed up with an automatic transmission among other possibilities.

 

[MBDiagMan]

It's very simple to determine the relative RPM for ANY gear change.

Simply divide the projected gear ratio by the current gear ratio such as 4.10 / 3.55 = 1.15149. Now multiply that number by the RPM at the speed of your choice. An example would be if you now turn 2300 RPM at 60MPH X 1.1549 = 2,656 RPM.

 

[JonW]

I'm at around 2700 rpm's @ 80mph with 4.10's. When my car was an auto it was 3000rpm's @ 80mph.

Shift points would be screwed up with an automatic transmission among other possibilities.

So you can't put 4.10s in an auto-equipped car?

 

[bigcat]

you need to adjust for the new gears. i believe he was referring to if you only installed gears. the speedo and the tranny would be off, instead of just the speedo as in a manual transmision car.

 

[anthony05gt]

So you can't put 4.10s in an auto-equipped car?

Yes, you can put 4.10 gears in an auto equipped car. The computer would need to be flashed for the the gears though because the transmission will want to shift at the wrong points. Not a problem with a manual tranny because you shift it yourself. You can easily adjust the computer for gear changes with an aftermarket hand tuner. Both trannys would have the speedo off so all gear changes should have the computer aware of what gears are in the car so it can correct the speedo for you.