If I was going to replace my 3.73 gears with 4.30s what all would need to be changed? I know I woul have to do the front and rear end 4x4 but would anything else need to be changed like the transfer case, computer reprogrammed or maybe shift times? I have an auto tranny.
Im just trying to figure out the cost of doing this so if any one has any input or has done this your input would be of big help!
Thanks in advance
Jason Trucks

 

I had my rear end gears swapped from 3.73 to 4.30 about two years ago. I have a 2WD so can't help with the transfer case question, but for mine there were no additional mods necessary. The computer senses vehicle speed off of a sensor on the rear end, so the gear change will be transparent to it. I have an automatic trans. and it too worked fine after the swap.

 

How much did they charge you to make the swap? I'm going from 3.73 to 4.56, but haven't made up my mind as to whether or not I want to tackle it myself.

 

Generally, nothing but the gears need to be changed, but the computer has to be told about the gear swap to get everything right. Otherwise, the computer will throw a code for the tranny, blinking the O/D light.

Edit: on the other hand, maybe it doesn't need any reprogramming, I was thinking about tire sizes...

art k.

 

My gear swap ran right at $850.00. I'd hoped to get out for about $600.00, but once they pulled the gears out we decided that the bearings needed to be replaced as well. My truck had about 40k miles on it, and there was some noticable pitting of the races and rollers on the bearings.

The shop that did the work (Pyle Brothers in Baytown, Texas) works only on differentials, from street rods to HD trucks and right on through custom rear-ends for race cars. They noted that they'd seen more bearing problems on factory trucks with synthetic lube that with conventional, and they put conventional back in with instructions to change it every 30k miles. I'm going with that since they really seemed honest and knowledgable.

Remember, I only changed one axle, so your's will be more!

 

I only have one (2WD) as well. Did $850 include the gearset? I live near Beaumont, so Baytown is not too far for me to go to get a quality job done.

 

I had a 96 Bronco and had gears in both axles changed (with rebuild kits) for 1100 at a 4x4 shop that mostly deals with lifts oand off-roading. 850 for one sounds a bit high.

 

MPTJELGIN-

What was your need to change gears? Tires or towing? Did you notice a different in MPG?

 

I had this swap done on an 1993 F-350 crew cab 7.3 non turbo diesel when I went to 36" tires. I know the biggest expense is labor, and a good rear-end set-up man is worth his weight in gold, so don't go cheap there. The gears are relatively inexpensive, getting them out and in isn't very hard or expensive either. It's setting up the correct backlash that makes the difference. Too tight and there's not enough space for lubricant, too loose and the gears wear prematurely. And the gears have to mesh perfectly in the middle of the ring and the pinion for best performance and wear. I had to go to 4:56 gears to get that big dog of a non-turbo diesel to move with those Buckshot mudders. But my brother who had the same truck and went with 40" tires didn't swap gearsets and towed approximately the same size travel trailer, until he replaced 2 tranny's. So it's worth the expense.

 

Sorry for the slow reply, but I've been out for a week. The price did include the gearset. I absolutely agree with Ken04 that the key to getting this done right is finding a good shop to set them up. I live near Austin and couldn't find anyone that really seemed to want to mess with it, or that did very many rear-ends at all. So I drove all the way to Baytown because that is all that Pyle Brothers does! They can answer questions, give you reams of past history and experience, and they really wanted to do the work. Imagine!

Igotoneforya - I changed gears because I went from a 6000 lb travel trailer to a 10,000 lb fifth wheel. I just didn't like the way it pulled with the 3.73 gear. It is night and day with the 4.30's. I get about 1/2 mpg less when unloaded, but about 1/2 mpg better when pulling the trailer. It will pull in OD almost all of the time now, where as previously I was in-and-out of OD quite a bit.

As for the cost, I'd imagine that it will be less than twice as much for 4WD than I paid for 2WD, since some of the cost is simply getting the truck in and on the lift. Whether or not you need bearings will also be a big factor.

 

Thanks for all input guys !! I think I am going to see how she works pulling my 26 ft TT for the summer and see if I can live with it but after reading all the posts on this topic I got concerned. I am a real junky for power and being able to pass anything on the road and also my fried has a cummins and he pull a 5er and his boat at the same time and told me he woul pull bolth of them up the same hill as me with just my camper and smoke me so their is a little ego involved also
TakeCare
JasonTrucks

 

Bing, bing, bing, red flag!! That makes no sense, I think I would have found another shop to do it. Synthetic is far superior than conventional oil.

 

I tow with 3.73's, I'd like 4.10's or 4.30's but since I have nothing to compare it to, I can only speculate at any benefits. It SEEMS like they would keep the engine more in the higher horsepower rpm band at slower speeds, so instead of towing at 70 I could comfortably tow at 55 or 60. If you have stock diameter tires you will be very happy towing your 26' TT. I'd take that bet with your buddy and the Cummins, I pass alot of them going up the hills. Sure I'm running 3500-5000 rpm, but so what ? This motor, it's been said, will run at it's rev limiter all day. That Cummins is a whale of a motor, granted, but it is a 6 cylinder, highly boosted diesel running 20+ lbs of boost and even though it's an oil burner that makes LOTS of torque down low, you still have to spin it to keep going. That V-10 will make big power, it's up to you to keep your foot buried to the floor, it's goes against my inner being to hold an engine at that rpm for that long, but again, everyone says the engine will take it easily. So you hook up that travel trailer and let your pal hook up his 5'er and his boat, but make sure he pays his debt when it's all over. Good luck !

 

More than likely, they put Timken bearings in it, and they will last forever anyway. Plus, Ford's synthetic may not be all you expect...

Front pinion bearing on a bunch of 8.8"s (stock) I've worked on were NTN or some other brand, while the rest of the unit had Timken. Guess what? Even though the front pinion bearing usually doesn't wear much, it was the one bearing in the entire unit that was almost fried, EVERYTIME.

If the rebuilder puts in Timken all-around, you'll be better off than stock, even without synthetic...

One note to ken04 with 3.73's, the 4.30's will give 14% more torque to the back wheels. Period. That's a BIG difference. I personally have an '01 V10 auto with the 3.73 - I don't tow much, but when I do, it's obviously under-geared...

 

Thanks for the input Ken! I pulled the camper to the lake this last weekend and was loaded to the hilt with all the gear, dogs, people, and supplies I was around 14k to 15k and the truck performed just like I had hoped Up hill Down hill all the same! I had to kick it in the a$$ a couple of times going up a few hills but never lost speed. I told my buddie that it was on for the trip home and he decided against it and probably a good thing because we bolth had the wifes and kids with and I think the truck could have done it but Im not shure I could have But this trip assured me that for the load I am working with this truck with the 3:73s will work for me!! I also feel a little funny about running the RPMs up to 4000 and above it just dont sound good but it did it fine the couple of times I did!
Thanks everyone
JasonTrucks
Keepin the 3:73s for now