Got my 5.13 gears in the rear axle, did some break in miles today and the truck barely felt any different. It feels a little more responsive but not what I was expecting. Obviously I wasn't driving hard since I'm still in the break in period but I thought it would make enough of a difference to feel in the butt dyno. I definitely don't think it's going to make enough difference to help when climbing hills with the trailer behind it. Oh well...it's just money right?!

 

If going from 3.73s to 5.13s doesn't register on your butt-dyno then something is wrong with either your EX or your dyno, seriously. My EX with the 4.88s and 32" tires felt like a hotrod around town compared to it with the stock 3.73s.

 

Agreed. There is something wrong with your butt dyno.

 

Your butt dyno is out of whack! I think once you wind it up you will feel a difference. the V-10 loves to rev, so if you are just putting around right now you may not feel it. You should feel it shifting sooner!

 

Yep, Butt Dyno malfunction. You need to go get that thing calibrated. (Don't ask me for the calibration tool!!!!)

Seriously, though, An Excursion, even with the V-10 and 3.73's, when rolling around town without a decent load is overpowered. With the 3.73, you normally use only a small percentage of that power. As you said, you've been taking it easy and staying in that small power use area. The difference will be most obvious once your break in is done, and you pull out onto a highway at full throttle to get up to speed with traffic. Your butt dyno will be well calibrated during that maneuver when you realize that several seconds have been shaved off your 0 to 75 speed run.
Then try to take it unloaded up a long steep hill and step on it.. There are a few in Kentucky I hear. We will probably be able to hear your 'WOW' for 500 miles in any direction.

5.13 gears are stump puller ratios. Go much higher and you will need to take off the Ford emblems and put on ones that say "Massey Ferguson". They are putting 37.5% more power to the wheels vs 3.73. You will feel it when you need it.

All I said above goes even better when towing. You will find yourself with less sweat on the brow knowing how MUCH more power you can put to the wheels when you need it.

Of course, all of the above is totally useless information if you are doing something crazy like running 40" + tires.

 

Yeah I agree with the above posters.

Both my Ex's have 3.73 gears. One was the stock 265 75 16 tire size and my current truck is 285 75 16, I can easily tell the difference in power between them.

I've also had the pleasure of driving Tom's(WE3ZS) truck when I visited him at his splendid residence. His truck with 4.88's felt MUCH MUCH quicker/torquier than either of my Ex's. I think we were into 4th gear(OD) around 40mph? As soon as the converter locked up you could really feel the gear and the torque multiplication it provides.

The fact that you're having trouble feeling your newly installed 5.13's is really strange.

 

I too find it weird that you dont feel a difference. I had a Jeep regear from 3.73s to 4.88s and although the initial "take off was not horribly different... Holding speed and gears on hills was very noticable.
Hopefully... once you hitch the trailer up and do some pulling you will notice a big difference.
Please update when that happens. I too believe that your $$ will be worth it at that point.

 

I was going to mention that both you and Twitch could attest that my V-10 with only an effective 4.30 ratio is no slouch.

 

I guess we'll see when I get on the freeway. I'm doing the slow speed 15-20 minute drives right now with 20 min. cool down time. I"m only on 32.6" tires so it should certainly be noticeable! We definitely have plenty of steep hills around here especially going to the local off road park where I haul my toys.

Maybe I was expecting the tires to burn off with light throttle just pulling out on the street. I have to get these break in miles done so I can hook the trailer up to it. I hate to waste 500 miles of fuel just joy riding though haha... I have a company car for daily use so my tow rig sits in the garage every day normally.

 

It definitely gets into the next gear a lot faster than it did before.

 

 

haha, ok. The only time I ever went full throttle on it before was going up a hill with the trailer. I kind of drive like a grandma these days.

 

 

Try a 4Lo session and see if there is a difference.

confirm the correct gears were installed. Rear driveshaft should rotate 5ish times for each tire revolution.

be careful, because if someone screwed up and put wrong gears in rear and the right gears in front than it will bind your driveline.

something is wrong if you cannot feel the difference. Maybe your rear axle wrap is so bad it's soaking up the seat of pants dyno.

 

Front gears aren't in yet so I can't do that!
I did the install, you can see the pinion gear difference, it's huge. They were stamped with 5.13 as well.
I know they're in there because RPMS are way higher than they were at the same speeds prior. I was just expecting neck snapping torque at even partial throttle upon take offs. I was expecting it to be hard to prevent wheelspin pulling out of a side street. I can tell a difference now after a few more miles but just not as dramatic as expected.