Gears

[Canadian Expy]

So I might finally get a set of gears for the Expy , with new bigger boat and the 35" it's a little tough on hills, I don't think the trans likes it!

So 4.56 or 4.88? Anyone here running either of these?

I'm going to try and run 40" but it might be 37-38" in the end$$$$
Anyways in the winter I'll go back down to 35"
Thoughts ??

 

[toms89]

Heres a easy to follow chart.
http://auto.howstuffworks.com/auto-...wing/maneuvers/gear-ratio-tire-size-chart.htm

Heres a website that has extensive calculators which you may find helpful. Scroll down a bit and look on the right for gears.
http://www.wallaceracing.com/Calculators.htm

 

[toms89]

Gear ratios for 4R100 is:

1st 2.71 to 1
2nd 1.54 to 1
3rd 1 to 1
O/D .71 to 1

Now you can calculate what rpms you will see at any given speed with X size tire and rear gear ratio.
Zero slip with converter locked up.

 

[Thermo]

canadian, I am running 4.56 gears with 37" tires. This is essentially the same as running the stock tires with 3.73 gears. I think it is a good combination of highway gearing with towing ability for hills.

yes, your tranny will not like having 35's, stock gears and towing a decent boat.

If you are truely set on getting 40's, then 4.88's would be better, if not 5.13's. But, you will also take a decent hit if you step back to 35's for the winter. Personally, with that large of a tire, if you go with a good mud tire, it will do wonders in the snow too. I Love my TRXUS tires in the snow. Drove most of the way across the US on the backside of a blizzard. Not a problem. Granted, the people behind me had to wonder since I had "Hawaii" license plates on the truck at the time.

 

[toms89]

60 mph in O/D. All figures are rounded off:

Stock 255/70 -16 = 30" diameter

3.55's and 30" tires = 1700 rpms
3.73's and 30" tires = 1800 rpms
4.56's and 35" tires = 1870 rpms
4.56's and 40" tires = 1650 rpms

4.56's sound like a good compromise if your trying for near stock ratio.... well about as good as your going to get with such a large difference between 35" and 40" tires.

 

[TRTLSLO]

Ran 4.88's in a 97 F150. Winter tires were 35's, summer she wore 38.5's. I was concerned at first but after running them it was the perfect gearing for me. YMMV. Don't forget when stepping up in tire size you are adding a bunch of extra tire weight and the shorter gearing helps make up the weight difference

 

[Canadian Expy]

60 mph in O/D. All figures are rounded off:

Stock 255/70 -16 = 30" diameter

3.55's and 30" tires = 1700 rpms
3.73's and 30" tires = 1800 rpms
4.56's and 35" tires = 1870 rpms
4.56's and 40" tires = 1650 rpms

4.56's sound like a good compromise if your trying for near stock ratio.... well about as good as your going to get with such a large difference between 35" and 40" tires.

Thanks Tom...I have actually 3.73's in mine and stock 17" rim before, my worry with 38-40" tire in the summer and pulling the boat is 4.56 won't be enough??

 

[Canadian Expy]

Ran 4.88's in a 97 F150. Winter tires were 35's, summer she wore 38.5's. I was concerned at first but after running them it was the perfect gearing for me. YMMV. Don't forget when stepping up in tire size you are adding a bunch of extra tire weight and the shorter gearing helps make up the weight difference

Did you find in the Winter the motor was reving to high on the highway?

 

[Canadian Expy]

canadian, I am running 4.56 gears with 37" tires. This is essentially the same as running the stock tires with 3.73 gears. I think it is a good combination of highway gearing with towing ability for hills.

yes, your tranny will not like having 35's, stock gears and towing a decent boat.

If you are truely set on getting 40's, then 4.88's would be better, if not 5.13's. But, you will also take a decent hit if you step back to 35's for the winter. Personally, with that large of a tire, if you go with a good mud tire, it will do wonders in the snow too. I Love my TRXUS tires in the snow. Drove most of the way across the US on the backside of a blizzard. Not a problem. Granted, the people behind me had to wonder since I had "Hawaii" license plates on the truck at the time.

I though of going with one tire setup but chrome and salt don't mix,
Also where I go snowboarding in the winter always has lots of ice so I want a good ice tire.

 

[TRTLSLO]

Did you find in the Winter the motor was reving to high on the highway?

I never minded the added rpm's. Always thought 4.10's should have been available from the factory for these tanks. Towed in the summer with the 35's and they were GREAT for that. In the winter, with the snow/ice conditions here in MI, most highway driving was done in the 50-60mph range so it wasn't a huge isssue for me. I'm planning on 4.88's for the Expy with the 35's I have on now (stock 3.55 gearing sucks with them, lol). Food for thought, You could get a 5.4 Super Duty with factory 4.10's... if you use the calc that Tom linked, stock tire w/4.10 is 74mph, the 35/4.88 combo is 70, both at 2300rpm

 

[Canadian Expy]

So I bought 4.56 gears only because the 4.88 with 35" and highway driving at 80 didn't make sense, hopefully I'll be happy with the set-up.
I had 4.56 and 39" in a F150 but that was with a C6 and it was a nice set-up.
Now to get them installed.

 

[Razor]

How did the install go? I'm looking at running the same. Which gears did you choose to go with and how is the gear whine?


Razor