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From 3.73 to 4.30s Is it worth the cost

 
  #1  
Old 04-12-2014, 07:24 PM
muddyforeman
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From 3.73 to 4.30s Is it worth the cost

OK so I'm a long time lurker, short time poster. I like to take in more than I talk LOL. I have an 03 supercab 4x4 V10. I have an sct from 5star (best investment EVER for towing). I'm running 265/75/16s and plan on going to a 285 soon. The rear axle is on it's way out so I'm contemplating going to 4.30s. It seems the 4.30s are considerably more money compared to staying with a 3.73. I tow a 30' bumper pull camper that hits 11k fully loaded for vacation.

My questions for those who have 4.30s,
How much fuel economy did you lose (if you daily drive as I do) with this switch?
Does it really pull THAT MUCH better as I've read?
Do I need to get with Mike to get the tunes changed after a gear swap?
Detroit tru trac, Auburn, Full Detroit? (my TJ had a Detroit in the back, and after a learning curve wasn't a bad DD, I've heard they aren't as noticable in a longer wheelbase vehicle)

Where to buy it all from? Is there a site sponsor that you'd recommend?

Thanks for taking to the time to read my rant, sorry if I'm asking questions that have already been answered, but this is a BIG investment for me so I want to make sure I spend my monies wisely as I don't get clearance from the board of directors (aka wife ) too often for a purchase like this.
 
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Old 04-13-2014, 01:02 PM
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The short answer is "Yes", going from 3.73 t0 4.30 will make a huge difference in towing.

I had a 1999 F-250 V-10 that I first towed an 8000# travel trailer, and later an 11,000# fifth wheel. It towed the travel trailer ok, but did not handle the fiver well at all. I has d the rear end gears swapped from 3.73 to 4.30 and it made all of the difference in the world. Better performance and better mileage. And the mileage was essentially the same when unloaded, so there was no downside beyond to cost of the gear swap.

I noticed when I ordered my 2010 F-350 V-10 that they didn't even offer the 3.73 gears any more, so I guess that the jury was in by then.

I had a 2WD truck so only had to pay for one gear set. I went to a shop that only does differentials (Pyle Brothers, Baytown, Texas) and they used Yukon brand gears for the swap. Set-up of the gears is key, so choose a shop that works with differentials exclusively, or at least extensively.

Mark
 
  #3  
Old 04-17-2014, 09:48 AM
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To start have an 03' F250 Crew Cab Short Box F250 V10. It's a dedicated tow and hunting vehicle and currently has 71k miles on the ticker. It's also my baby even though my daily driver is an 11' F150 Ecoboost. I had the F250 since 2004 so I know this truck well. I've installed a modified Y pipe, a Five Star Tuned SCT tuner, rebuilt the trans about 5k miles ago and beef'd it up a bit and also switch my gearing from 3.73s to 4.56s. I've owned and pulled 4 different Campers with this truck ranging from a light weight (6500lbs) 26' bumper hitch Wilderness to my current 39' Cedar Creek Fifth wheel that tips the scales at nearly 15k lbs. I also Run 285/75/16 sized tires

I will start with saying, if you going to go up to 285s in tire size, then change the gears to 4.56s. You'll essentially be just a touch deeper geared than a stock truck with 4.30s.

Does it pull better, ABSOLUTELY. There is no question that if you want to make it a towing beast that the gear change is the most significant improvement you can make. The tuner helped, the gear change made is what made the difference between me buying a new diesel or keeping what I have.

As far as fuel mileage, you'll lose a little economy when empty and gain economy when loaded because it will pull that much easier. Honestly it might have change by +-1.5 mpg. These aren't fuel misers to start with so this would be the least of my concerns.

As it sits, I'm now at the point that if I towed anything more substantial I'd simply want more truck, probably a dually. The single rear wheel F250 is at the upper end of its capability with a 15k lb fifth wheel. This isn't because of a lack of power, this is more of a handling issue. My previous camper and with my boat in tandem, my scaled weight was between 21k-22k lbs. I pulled this combination for 2 seasons with 3.73s before making the switch. What I can tell you is that combination with 3.73s could not be ran on OD and I often found my self down in 2nd gear with any adverse conditions. After the switch to 4.56s, I now can tow in OD about 50% of the time at 2,400 rpm toolin down the highway. With a headwind or hills, a quick downshift to 3rd (or drive) takes the rpms up to around 3,000-3,200 and it's as happy as the day is long. 2nd gear is now an awfully rare occurrence.

I did have Mike switch my tunes slightly which he was happy to do. I don't know that it would make much difference other than adjusting a few shift points.

I kept my Stock Limited slip and did full master rebuilds with all new bearings, seals and gears. I believe the ones installed were Yukon but I don't recall anymore. If your doing it your self I would call Randy's Ring and Pinion and they'll set you up with what you need. Best of Luck.
 
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Old 04-19-2014, 05:52 PM
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I would say the 4.56 would be a better bet as well. Plus if you price gear sets the 4.30s are way more $ than 4.10 or 4.56. Dunno why.
 
  #5  
Old 04-19-2014, 07:25 PM
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Well, I've decided to stay with 265's (long story). I have new 4.30s, and a rear tru trac otw from Randy's. We'll know how she does soon enough.!
 
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Old 04-19-2014, 10:35 PM
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What kind of cost is involved in doing this swap? What does everyone think about just changing to a set of differentials with 4.30s already in them?
 
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Old 04-20-2014, 12:51 PM
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I got what I consider a heck of a deal at 1500 for Yukon gears, master kits and tru trac. Main reason I did this instead of a used set of axles, was the fact that I wanted the piece of mind knowing everything was new in a 150k mile truck.
 
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Old 04-20-2014, 01:31 PM
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Originally Posted by fordboy2 View Post
What kind of cost is involved in doing this swap? What does everyone think about just changing to a set of differentials with 4.30s already in them?
That is what I am doing. My 2005 V10 came with 4.11's, but I bought a 2001 Excursion rear axle with 4.30's for $385!

I am swapping to 295-65-18" (33"s) and the 4.30's will put me about back to where it was.
At some point I might like to go to 325-65-18 (about 35"s) with 4.56's, but that will be well into the future. My 33"s are brand new, And shops want $900 just for a rear re-gear!
 
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Old 04-20-2014, 01:39 PM
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Originally Posted by muddyforeman View Post
I got what I consider a heck of a deal at 1500 for Yukon gears, master kits and tru trac. Main reason I did this instead of a used set of axles, was the fact that I wanted the piece of mind knowing everything was new in a 150k mile truck.
Yeah you are the oppisite of me. I went used mainly for the piece of mind that the that the gears are set-up right from Ford.
I have had nothing but problems from every set of gears a shop set up!

And when I swap in my Eaton Truetrac, I will do it myself! Even if it is wrong, at least I wont be paying money for it to be done wrong.
 
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Old 04-20-2014, 02:26 PM
muddyforeman
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I understand your mentality there. I've ordered 3 used axles in the last little bit for customers. 2 out of the 3 were worse than what was being replaced. It's a royal pain in the rump to get LKQ to pick up a return. 4.30 axles aren't too prevalent for me either so here I am. I may regret it in the long run,,, I sure hope not
 
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Old 04-20-2014, 07:00 PM
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Hope you don't regret it too. I have delt with LKQ many times as well, about 80% of it has been positive.
Infact the 2010 3.55 rear axle I put in my Excursion came from LKQ, as did the 2001 4.30 axle I put under the V10 F250. They gave me a deal on the 4.30 axle because they said it was the rarest optioned and in low demand.
 
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Old 05-18-2014, 06:59 PM
muddyforeman
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Just a quick update, Hope to have it back up and running tomorrow or Tuesday as time allows. Got it tore down Thursday night only to discover we were sent the wrong master kit for the rear. 10.5 housing with 10.25 gears needs a 10.25 master kit Either way, correct parts are here, now I just need that precious time that one never seems to have enough of.

PS
Hope to have a set of Thorley headers in the mail next week. Prepping for our first good towing trip camping on Father's day wknd!
 
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Old 05-18-2014, 08:50 PM
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Be sure to keep us posted here. Swapping up from my factory 3.73s to 4.88s with 35" tires for an effective ratio of 4.39 was the best mod I have done for my EX that is our tow rig. Solo running MPG dropped by 1 MPG and towing mileage went up by 1.5 to 2 MPG, trailer is a 41' 11k travel trailer.
 
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Old 05-24-2014, 05:49 PM
muddyforeman
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Just, Got it back Wednesday night, Have yet to tow with it, We'll be towing of father's day weekend. Gonna try and get some headers in and on first,,, Wish me luck
 
 
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