11screw50

OK, saw this in another thread:

https://www.fleet.ford.com/truckbbas...0Raptor_SB.pdf

and have seen similar for 2012 and 2011 (I think I have them saved on my computer at work). It appears that there are three different axles (page 96), the 8.8 rated for 3800# and two 9.75's rated for 4100# and 4800#.

Pages 92 and 93 list max GAWR for front and rear with a note that the listed value is determined by the weakest component (axle, spring, wheels or tires).

So, in the case of a 5.0L, 4x4 SCrew 145" wb, the rating is 3850. The axle would thus be the one rated for 4100#, wheel rating (page 100, say, 18x7.5 chrome clad aluminum) is 2025# each or 4050#, tires Goodyear Wrangler SR-A in 275/65-18 which have a max load of 2601# leaving the springs as the limiting factor (would have to be the 3850# springs).

Realizing that there is no way to change the yellow sticker on the door, it appears that swapping the 3850# springs listed on page 99 to either of the 4220# springs would change the limiting factor to the wheels at 4050#.

Oddly, the 3.5L w/ Max Tow has a RAWR of 4050# (limited by the wheels?) which is a 200# difference from non-max-tow, I thought max tow added 500# to payload (which is the part I thought was odd...add 500# payload but only 200# to axle ratings?)

Platinum_Sean

Enough to drive one nuts, huh???? I read the same stuff 3 years ago and came to the same conclusions, and, questions.

800 ASK FORD was no help either.

Fx4_5.0Man

iTrader: (1)

Overly complicated and shouldn't be..

11screw50

I was not saying that it was complicated, it makes sense to me that the RAWR would be based on the lowest rate component and that one would have to consider tires, wheels, springs and axle in determining what the weakest link is.

I just looked at the 2011 and 2012 pdfs and the axle ratings were 3800, 4000 and 4800. The SCrew max tow is still rated 4050# RAWR so it must have had the 4800# axle though the rear spring tables show nothing above 3850# so who knows. I thought I had it figured out but apparently not. The 2013 pdf makes sense, the other two do not.

Platinum_Sean

[MENTION=57554]11screw50[/MENTION]- I totally follow you, and did the same research myself. The GAWR is indeed based on the lowest of all the components involved- like a chain, it is only rated on the weakest link in that chain as that is 1 part that will fail first, in theory.

So does that means upping the springs (add, or Superspring) increases the GAWR (assuming the springs were the lowest rated amoung all the other inputs??)?

I did call Ford, they were non committal, probably due to legal reasons.

Good digging though. Not conclusive info from Ford

Fx4_5.0Man

iTrader: (1)

My grandads 2005/2006 f150 regular cab 4x4 long bed with the 4.6 4 speed and 8.8 diff has the same RAWR as my 2011 FX4 5.5 bed Crew with the 9.75..

So that's definitely saying something. The 9.75 is a big step over the 8.8.