First I would like to thank everyone for all the valuable information on this website. I felt I would post my recent experiences with the 4:30 gear change and can try and answer any questions that come up. When I was researching the gear change I found a lot of suggestions from people to others on what gears may work for them but not a lot of actual results.

The Ex we have to start with – 2005 Ex, 6.0l, 6” lift, 35” tires, stock 3.73, SCT tunes, and more (see signature line). The Ex is used for pleasure and towing and is not used for commuting. The truck had a tendency to want to downshift when empty on steeper grades. Despite having the SCT it always felt like it was working the transmission harder than it needed. When towing the trailer we had (9000k lbs) it did well but did not like to hold 5<SUP>th</SUP> gear and would downshift to 4<SUP>th</SUP> at any rise in the road. On a real steep pass we often travel (Stevens pass WA) it would at times even want to downshift to 3<SUP>rd</SUP> and the transmission is then no longer locked. We were on the fence between 4:10 and 4:30 gears. The 4:10s would be at stock rpm levels but considering the extra rolling mass of the 325/65-18 tires and the trailer we were about to purchase which will weight close to 10k loaded we opted for the 4:30 gears.<O

A few weeks ago I gave the new 4:30 gears the first test. I drove 2,200 miles from WA to IN to pick up the new 35’ Sabre travel trailer to then tow the 2,200 miles from IN back to WA. Initial impressions of the gears are that the Ex gets up to speed effortlessly. The transmission just sings through the gears now (wife says sounds like a fine tuned sewing machine). <O

On the 2200 mile trip from WA to IN the Ex pulled all the passes with the speed control on without downshifting holding 5<SUP>th</SUP> gear. RPMs at 65 were 1,950, at 70 were 2,100 and at 75 were 2,250. Fuel mileage may be down slightly at highway speeds (all mpg numbers are hand calculated using the GPS trip computer to establish the distance multiplier for the larger tires – adding the 4:30 gears did not change the odometer readings and they are still 10%low). Running through Montana and climbing a lot of passes running 80mph I was averaging 14.5mpg. When I reached North Dakota I backed the throttle down to 65mph and at times lower (running 55mph in 4x4 on icy roads) and then brought the average up to 17mpg. The next tank was all in 2wd and flatter running 65mph except for the stop and go (more stop than go in Chicago) and averaged 17.8mpg. I think I may have lost 1mpg running empty at speeds above 65mph. At 65mph and lower it is about the same. In town seems to be slightly better and I have yet to see a tank below 13.5mpg this winter. <O

Upon arrival in IN I installed a Propride Hitch on the new trailer and it tracked perfectly. Here is a write up on the hitch if you are interested - RV.Net Open Roads Forum: Travel Trailers: Propride hitch experience <O

Now for the 2,200 mile road trip home from IN to WA with the new trailer (scaled at 8600lbs lightly loaded with 1300lbs tongue). I primarily ran at 65mph with cruise on the trip home. I was in a headwind most of the way from IN to MT. The headwind on the first few tanks was only about 10mph and I was averaging 9.5 to 10.2 mpg. Through South Dakota I had a 20mph headwind which dropped me to a trip low 7.9mpg – ouch. Once further into MT I hit snow, having just fueled up I decided to drop to 58mph in the snow and mountains. This was my best tank coming in at 11.2mpg despite towing in the mountains. Part in the fact that there was no wind, the lower speed and we dropped a little in overall elevation. The last tank was from Spokane, WA to Monroe, WA. I ran this tank at the speed limit 70mph so I could make it home before the kids went to bed. This tank was a good one at 10.1mpg despite the speed and some hard pulls. The biggest factor appears to be the wind. The truck was able to maintain any speed up to the limit on the passes without downshifting lower than 4<SUP>th</SUP>. It was able to pull most hills with the trailer and stay in 5<SUP>th</SUP> gear. <O

Overall, I am extremely satisfied with the gear change. It wasn’t cheap but is a lot cheaper than fixing a transmission. We are seldom on highways with speeds above 65mph here in WA so the loss in mpg will very rarely be seen by us. Adding 0.5-1mpg on the in town will offset any mpg losses at the higher speeds for us. <O

I am done rambling for now. I hope this may help those of you wondering about a gear change. I will do my best to try to answer any questions anyone may have.<O

Thanks.<O

 

Awesome! I really think Ford should bring back the option of ordering trucks with whatever gear ratio you want... or at least give us more options. It doesn't cost any extra R&D for parts, just the right robot picking a different part when configuring your own truck...

 

Great information!!! Reps to ya.

 

Your experience with the 3.73's were exactly like mine when I had my 6.0. I always thought that the X struggled a little more than it should, especially with a load. I now have 4.30's in my V10 and love them. If I still had my 6.0 I would look into this.

 

how much does it cost to re-gear from 3.73 to 4.30?

 

With TrueTrac added as well, it cost me $2300. I did not have limited slip prior. Work was done at Randy Ring and Pinion.

 

Excellent info, reps to you!

 

I was quoted $2,200 plus tax to do the same at my local powertrain shop.

 

Red ex, thank you for taking the time for the detailed post. You brought up a good point about the odometer being off 10%! Im going to check mine with the gps on my next trip

 

Thanks for the reps guys.

My speedo and odomoter are both off with the larger tires. The speedo is off about 8% and the odometer is off 10% per the GPS - go figure that they are off by different amounts. They probably are not very accurate in a stock truck. I have a Kenwood DNX-8120 GPS/radio. I normally just turn on the satellite radio and then change the screen to drive with it set to GPS so I have a accurate speedometer. The best part about the GPS is it shows my actual speed as well as what the posted speed limit is right next to each other in large letters that look like speed limit signs. Really helps you know the speed limits on unfamiliar roads.

 

Reps to Red Ex.....great info. My Ex struggles just as yours did before the swap. Now I have another change to make to mine!

 

Thanks. I noticed in you signature line you are running 305/50-20 tires which are 32". My 325/65-18 tires are 34.8". You would probably be about 200rpm higher with those tires which would be great for towing but may hurt your mpg at higher speeds - more than I noticed. My plan is to stay in the 34.5" to 37" tire range. It all depends on what you use it for and what the conditions you drive in are as to whether it makes sense or not. I did notice you have a TT listed in the signature line as well.

 

Glad you pointed out the tire size difference and effect on RPM. I think the 4.10 gears might give mine similar results to yours with your taller tires and 4.30 gears. I like the idea of reducing torque on the transmission by changing gears. The lower RPM and higher boost is noticeable to me and seems like the engine is working too hard. Someone here on FTE told me about a roof mounted air deflector that he uses on his EX that makes a noticeable difference in MPG towing his TT. It lays flat when not towing and raises for towing, and it looks good too!

Yes I pull a 31 ft Puma TT. It's heavier than most bumper pulls due in part to having 2 separate water systems for the front and rear baths. I also have a custom installed Onan with a 30 gallon gas tank for it. The Gen install is about an extra 600-700 lbs.

Thanks for all the great info.