Gear Recomendation Discussion for 37s

[Desertrat83]

If the calculation I did is correct - in third gear with 37" tires and 4.10 @ 6000rpm will go 106mph and with 4.88 @ 6000rpm you will go 89mph





Here is a chart for the rev change

Nice chart Glo. I have a few questions though. What gear does this chart relate to? (4,5,6) What is the speed this chart relates to? (65,70,75,80) mph.

 

[Glo]

Nice chart Glo. I have a few questions though. What gear does this chart relate to? (4,5,6) What is the speed this chart relates to? (65,70,75,80) mph.

Good question - I shouldn't have cut the info off the pic. Irrc it was 1:1 at 60mph or 65mph. Let me see if I can find the site again and link it here. But I think its a good reference point to what you can expect.


I calculated the speed/revs using this calculator:
Gear Ratio Speed Calculator

EDIT: I couldn't find the link for the chart anymore - but I am pretty positive it was 1:1 @ 65mph

 

[Desertrat83]

Good question - I shouldn't have cut the info off the pic. Irrc it was 1:1 at 60mph or 65mph. Let me see if I can find the site again and link it here. But I think its a good reference point to what you can expect.


I calculated the speed/revs using this calculator:
Gear Ratio Speed Calculator

EDIT: I couldn't find the link for the chart anymore - but I am pretty positive it was 1:1 @ 65mph

Well that helps. Now another question not just for you but anybody. What are the gear ratios 1-6 for our trucks? I tried the Internet but you can't always trust that

 

[Glo]

What are the gear ratios 1-6 for our trucks? I tried the Internet but you can't always trust that

Ford.com

 

[tbone]

I'm pretty sure those are off because i can't get to 100 in 3rd gear on 37's 89 seems like the near top end for 3rd normally

 

[Glo]

These calculations are bound to be off a bit as I used 37" as the tire diameter and most 37" tires really are a bit less. Especially when worn. Did you adjust your speedo to match your larger tires? Would show lower speed when not adjusted. Also I do not know where the shift-points from 3rd to 4th are - might not be at the 6000rpm redline which I used for the calculator.

 

[factive]

I paid a little more attention to the 2-3 shift when I was out in the desert this last weekend. If you're #1 goal is really off road performance, I would go with the 5.13 gears. There was a couple 2-3 shifts that definitely left me outside the powerband. You could also look into a custom tune.

Just so you know, I was running 91 gas in offroad mode, tc off, and rear diff locked.... affected mods are 37s, 4.88 gears, SVC tune, SW LT headers, Corsa Sport exhaust and Corsa CAI.

 

[Glo]

I paid a little more attention to the 2-3 shift when I was out in the desert this last weekend. If you're #1 goal is really off road performance, I would go with the 5.13 gears. There was a couple 2-3 shifts that definitely left me outside the powerband. You could also look into a custom tune.

Just so you know, I was running 91 gas in offroad mode, tc off, and rear diff locked.... affected mods are 37s, 4.88 gears, SVC tune, SW LT headers, Corsa Sport exhaust and Corsa CAI.

Thanks so much for the feedback! Just what I was hoping for! Do you happen to have any thoughts on the low gear range being too short with 5.16?
I do have a 5* Star 91 mail order tune and CAI. SW headers will be put on any day now and then going with a custom dyno tune. But not expecting tune to have too much impact on the 2-3 power hole. Was contemplating building the motor, but for now I am hoping that the gearing will give me enough punch that I can hold off dropping too much on the motor.

 

[Glo]

I'm pretty sure those are off because i can't get to 100 in 3rd gear on 37's 89 seems like the near top end for 3rd normally

Just saw this video:

Big Bill - FORD RAPTOR FORUM on Vimeo[/QUOTE]


Looks like on stock tires his shift point was @92mph. Don't have my raptor at the moment...daughter stole it a couple of days ago otherwise I'd check myself what my actual speed is with 37s!

EDIT: With 37s ( that are almost bald) I was able to hit about 105mph gps - my speedo is off a tiny bit too. So Calclations are pretty close to real world!

 

[Dv8tor]

Im going to ask again since no one answered my question from earlier.
So it seems like there's kits to change the rear diffs out but what about matching the front diffs gear ratios? Or do these kits come with both front and rear diff ring and pinions?