What is the difference gen III 3.55 to 3.73 towing capacity?

Looking at the charts that one of you kind gentleman supplied, the towing capacity for a 2WD 4.0 Gen III with a 3.55 is 3260 lbs with a CGVW of 7700. By contrast the capacities of a 3.73 equipped vehicle are 5780 with a CGVW of 10,240. 7000lbs more lbs just because of a 3.73 LSD (and a built in trailer brake controller)? Is that all there is? Springs or brakes upgraded?

Theoretically one can change a class II to a Class III with a hitch, LSD, and a brake controller?

Don

 

[FordLover]

Looking at the charts that one of you kind gentleman supplied, the towing capacity for a 2WD 4.0 Gen III with a 3.55 is 3260 lbs with a CGVW of 7700. By contrast the capacities of a 3.73 equipped vehicle are 5780 with a CGVW of 10,240. 7000lbs more lbs just because of a 3.73 LSD (and a built in trailer brake controller)? Is that all there is? Springs or brakes upgraded?

Theoretically one can change a class II to a Class III with a hitch, LSD, and a brake controller?

Don

Brakes are the same, but the spring rates are different to handle more tongue weight. The brake controler is only an aftermarket item, but the wiring is provided on the vehicle, at least with the tow package it is. There is also a question of oil cooler, transmission cooler, etc.

Not sure where the 7,000 lbs. more number you stated is coming from, however.

 

[donstevens]

Tow package bits

Thanks for the reply Fordlover,

My math was wrong. I was referring to CGVW. 10240-7700 = 2540 more CGVW. I subtracted the 3260 form the 10240 to come up with the 7000 (actually 6980) number.

Anyway - Can you advise what the difference is in spring rates?

I drove a V8 4x4 with the calss III towing package the other day and it did seem stiffer that the 4.0 class two 2wd. I did not know if was just because of the V8, 4WD, or the class III package.

Both the lighter 4.0 and the 4.6 4WD seemed pretty wimpy in the brakes department.

Don

 

[jrford]

Anyway - Can you advise what the difference is in spring rates?
Both the lighter 4.0 and the 4.6 4WD seemed pretty wimpy in the brakes department.
Don

i might want to clarify, but i pretty sure the springs are the same. Check on replacement springs, there is do differentiation between tow and non-tow, same part no.

If difference between 3.55's and 3.73's are about 200rpm's and 2,000lbs more capacity.

shock's seem to wear out and its hard to tell when they do, no typicall noise dive or such they just turn soft. New shock's/struts are really stiff, so you might have just driven one with that was a little wore out.

Brakes can be improved significantly with decent stuff.

 

[donstevens]

iBrakes can be improved significantly with decent stuff.

Examples - Pads? SS Lines? Higher temp Fluid?

Don

 

[jrford]

Just the simple stuff, good pads and rotors do wonders.
EBC 6000 Green's, Raybestos Adv Metal Rotors - stops great no fade, might be a little soft but they work well, much better than factory.

 

[FordLover]

i might want to clarify, but i pretty sure the springs are the same. Check on replacement springs, there is do differentiation between tow and non-tow, same part no.

I respectfully dissagree. Springs are computer selected during manufacture, and which spring is selected to go on the truck depends on which options are selected (basically what the truck is going to weigh when it's done) and packages like towing, 3rd seat and rear a/c, etc.

My Explorer doesn't squat nearly as much as my uncles does when the same trailer is hooked up, and they are both the same year. Mine has the tow package, his doesn't.

You can see what your spring code is by looking on the door sticker, or on the spring itself if the tag is still intact. If you go buy new springs from Ford, they will want to know what your spring code is so they can 'order by code'. Autozone, car quest, etc. will only carry one spring, and who knows what it's rated for.

 

[jrford]

i stand corrected,. . . I was just going off the ready struts, AZ . .
ford parts direct website does list a note 'order by code' and they do list 3rd row non-3rd row springs.