what is your gears # and tire size ???? - Page 2

Viejo · 03-13-2012, 05:05 PM

I have 4.10 gears on a 7.3 diesel with 315/75-16 tires = 34.5"
It turns 1750rpm at 60
(It also turns 1750 at about 5mph in low range 1st)
I don't tow anything.

carringb · 03-13-2012, 07:45 PM

265's, which are ~32" tall, with 4.56 gears. If I'm not towing, a double OD trans would be nice, since it's overkill for empty cruising. But when I'm moving 22,000 pounds up and down really steep grades, I wish had even lower gears. Or some in-between gears.

This grades got the brakes mighty warm (we were loaded at 22k that trip):

Gnarvan · 03-13-2012, 09:16 PM

Quote:

Originally Posted by carringb

265's, which are ~32" tall, with 4.56 gears. If I'm not towing, a double OD trans would be nice, since it's overkill for empty cruising. But when I'm moving 22,000 pounds up and down really steep grades, I wish had even lower gears. Or some in-between gears.

You seem to be pretty handy. I'm thinking you should figure out a way to put a hi/low splitter on the diff.

rockbender · 03-13-2012, 11:05 PM

Quote:

Originally Posted by Gnarvan

I found a website that does a rpm calculation if you give it final drive ratio of transmission (.78 for the E4OD in overdrive), tire size, diff gear ratio and vehicle speed.

E4OD is actually a .71 overdrive. This is nice because the deep OD gear allows you to run lower gears for towing/big tires/etc and still have a good cruising RPM.

carringb · 03-13-2012, 11:35 PM

Quote:

Originally Posted by Gnarvan

Quote:

Originally Posted by carringb

265's, which are ~32" tall, with 4.56 gears. If I'm not towing, a double OD trans would be nice, since it's overkill for empty cruising. But when I'm moving 22,000 pounds up and down really steep grades, I wish had even lower gears. Or some in-between gears./quote]

You seem to be pretty handy. I'm thinking you should figure out a way to put a hi/low splitter on the diff.

I'm really just waiting for somebody to come out with a stand-alone controller for the new 6R140. It's ratios are perfect for a V10 with low rear-end gears, and is the main reason they were able to bump the F650 V10 up to 33,000 pounds.

I have thought about adding a Gear-Vendors, but it's weak in reverse, and can't do automatic sequential shifts.

Gnarvan · 03-14-2012, 07:56 AM

Quote:

Originally Posted by rockbender

E4OD is actually a .71 overdrive. This is nice because the deep OD gear allows you to run lower gears for towing/big tires/etc and still have a good cruising RPM.

Thanks for the correction. My mistake. I was looking at the gear vendors ratio breakdown for the E4OD and used their 3rd overdrive ratio of .78 not the Ford 4th overdrive final drive ratio.

I recalculated the rpms for the lower final drive ratio and updated my previous post.

Viejo · 03-14-2012, 12:14 PM

A paved highway with a 26% grade?? Where the heck is that monster?

Gnarvan · 03-16-2012, 11:16 AM

It looks like Sonora pass headed eastbound out of Yosemite down to 395.

I've driven Gnarvan for 60 miles now with the new gearing. The first and most noticable change is the power out of the hole. It's a lot perkier off the line. "Perky" is a relative term and you need to factor in I'm talking about a 7500 pound lifted van pulling a parachute when I use the term. The transmission hunting at cruise speed is gone. The increase in RPM's is noticeable and a little annoying. I'm running it with the front hubs locked right now to break in the front ring and pinion so it will be a while before I get a feel for any change in fuel useage.

I'm dying to test the Truetracs but the guy at the shop said to be gentle with it for the first 500 miles while things are breaking in. No four wheel drive smokey burnouts for a while.

**daveb** · 03-16-2012, 01:43 PM

Actually Tioga (Ca-120) is out of Yosemite but neighboring Sonora pass (Ca-108) is the steepest pass in the Sierra Nevada range and it does have a grade of 26% in a few spots. I'm running 285's with 4:10's and cross it with no problems in my 6.0 SMB that weighs about 11.5K while also pulling my SMB trailer. The turbo gets too hot and I usually have to pull over along one spot above Kennedy Meadows and when going down a few sections there are spots where I shift into low range.

Gnarvan · 03-16-2012, 06:39 PM

I did a few more test drives today with the new gearing. I noticed I had a slight vibration so I started the day at Les Shawab getting the tires balanced. That fixed most of the vibration but I still feel a vey faint buzz. If it starts to bother me I'll go in and have the driveline balanced.

The more I drive it the more I'm liking the change. Hard to put a finger on it but it just feels better mannered than before. The real test will be when I start pulling my boat around. I was thinking about going out tomorrow but I think I'll stick with the break in procedure and try and get as close to the 500 mile recommended break in as I can before I tow. I was pleasantly surprised when I compared the speedometer with a gps driven app on my I-phone. It looks like the two are within 1/2 mph or so of each other.

Correct me if I'm wrong here but since I didn't change the speedometer calibration and it's reading accurate wouldn't that mean the change in gearing has offset the larger tires? That should also put the transmission back into it's designed rpm shift pattern. That may not be such a good thing since I still haven't compensated for the weight and aerodynamic drag of the van.