4.10 and 3.55 comparison.

[ocnorb]

Mabye this is just a noob question but wouldnt a 3.73 be a good in the middle ratio?

3.73 is also a good choice because it has the largest pinion gear and is stronger than other ratios (Both higher and lower). The further away from 3.73 your gearset gets, the weaker it gets.

This is a shot of the 4.56 gears being installed in place of some 3.73's:

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I just swapped 4.30's inot my wife's '49 Willys and even that small step had a shocking size difference.

 

[Goofyexponent]

475 kilometers on 62 liters = 7.66 kilometers per liter.

OR...

295 miles on 13.65 IMPERIAL gallons = 21.6 miles per IMPERIAL gallon.

...which boils down for you Americans to..

295 miles on 16.4 US gallons = 17.98 miles per US gallon

 

[Cincinnati Guy]

Chris what was you getting before the swap? Im on the hunt for a set for my sterling and 60!

 

[Goofyexponent]

Depending how I drove it, I could get 17 MPG and I could even eek out up to 19 mpg at 55 MPH.

All the stats I posted with the 3.55's were at 65 MPH. So better mileage at a greater speed.

To put this in perspective....and this is all with stock tire sizes, this is what I come up with for DS rotations per mile.

With the 3.55's the DS makes 2 327.73 rotations per mile.

and with the 4.10's it makes 2 688.37 rotations per mile.

Over the course of a trip to and from work (a HAIR over55 miles), the 3.55's spins 130 121.55 times

And the 4.10's lets the driveshaft spin 150 281.55 times.

You are saving 20 160 rotations over a 55 mile trip.

That saves a lot more than fuel. Driveline parts will last longer, your engine is brought down in it's rpm's and will last longer and even through you are told to change oil every 3000 miles, with the 3.55's the engine oil will have less wear on it....as the engine turns less RPM's.

 

[GOOSE]

475 kilometers on 62 liters = 7.66 kilometers per liter.

OR...

295 miles on 13.65 IMPERIAL gallons = 21.6 miles per IMPERIAL gallon.

...which boils down for you Americans to..

295 miles on 16.4 US gallons = 17.98 miles per US gallon

That is very good numbers for any full size truck, half ton through one ton, gas, diesel, what ever. I would say that the rest of your truck is kept up pretty good to support these numbers.

 

[TLBREWER]

I just completed a lift on my wife's truck, which included going from 285's to 315's (33's to 35's ?). It has 3.54 gears and the drop in RPM's was very noticable. At 65 it now turns about 1800 RPM which should greatly increase gas mileage, if she can keep her foot out of it. The trade-off is acceleration, which isn't that noticable on the flats, but it is on the hills. I have been considering re-gearing to 4.11's, but I think I'm just going to do some more tweaking on the IP and wastegate for more power instead. Since she doesn't pay any attention to the gauges, I have it slightly de-tuned so no accidental damage occurs.

Tom

 

[rjjp]

Hey Goofy, hows it tow with the 3.55, I've been contemplating installing my wide ratio ZF and a set of 3.55's.

 

[Goofyexponent]

Hey Goofy, hows it tow with the 3.55, I've been contemplating installing my wide ratio ZF and a set of 3.55's.

I didn't mind the 3.55's for towing....however I haven't hooked up to anything considerable with the ZF installed. I do have the 5.71:1 ffirst gear though, so I should about be able to get any load started about anywheres I am sitting.

Everything you see here I hauled with 3.55's and the E4OD.

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The bed of this truck was LOADED with tires...and I mean LOADED!!!

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This load....not so heavy!

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That camper weighs a TON...Nothing I EVER hooked to sagged my truck down, and it's sitting like a bulldog in these pics!!!!

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I hauled that bronco ON the trailer as well as the one BEHIND the trailer for BigRigTech.

My first real load with the ZF will be to haul my crew cab home in the comin weeks. I wish I could have gone down for her today, but I have to go into work to weld a new floor in one dump truck and patch up a tailgate on another dump truck.

 

[f-two-fiddy]

Depending how I drove it, I could get 17 MPG and I could even eek out up to 19 mpg at 55 MPH.

All the stats I posted with the 3.55's were at 65 MPH. So better mileage at a greater speed.

FWIW: I ended up with pretty much the same results as Goofy when I did the 4.10/3.55 swap.

Dropped about 500RPM at cruise, gained about 4 MPG @ 70 MPH. That's with the lumber rack loaded with 800+LBs. (lotsa drag up there)

Another thing about My trucks. ALL of the speedometers read LOWER than stated MPH. Compared to GPS. I bought the GPS after doing the swap. Started driving the speed indicated by the GPS. So when I had the 4.10's. I was only driving 66/67 mph, when the speedometer was showing 70 mph. Now I'm actually cruising @ 70 MPH, (speedometer showing 74mph) and getting 4 MPG better fuel mileage.

 

[fields_mj]

Didn't I read you have a later model ZF with a lower 1st gear? My Dad's PSD is a 97 and 1st is fairly useless in his, but I always use 1st in mine unless I'm headed down hill. I have to ride the clutch too much for a 2nd start from stopped. I have 4.10 rear too, as does my Dad.

I thought that those ZF trannys were a 6 speed, which was essentially the ZF5 with a granny gear on the front. I could be mistaken though.

I started off with 4.10 gears and had about the same results. I was thinking that 3 grand got me to about 85 mph. 60 mph was about 2200 rpm if I remmember right. Not much use for first gear.

I've switched to 3.55 gears and it increased my milage by about 10%. Now I'm running almost 65 at two grand. If I've got a load of firewood on, or pulling a trailer, I just run it up a little more between shifts.

4.10 gears would be fantastic for a farm truck, or for a lot of hauling, but I like the 3.55 gears for driving too and from work, and doing the limited haulnig that I do.

Just my 2 bits,
Mark