Big hole against the dash - flipped gears13 speed

You can get an extra lower gear if you know how. The low side is like this: low--1--2--3--4--shift range 5 low--5 hi---ect.....

The way to get an extra gear on the low side is to shift in the low side up to third, example: 1--2--3--shift range to high, move shifter from 3 to the low position DIRECT (all the way toward you and back), this gear is the same ratio as 4 in the low side. You use this gear just like 4, except when you reach top rpm, split it to the high side, the when needed shift to 5 low--5 hi, ect. This will give you one extra gear in the lower end without any harm at all to the transmission.

 

I have a 13spd with 3:36 rears and full size 24.5's and it runs about 1350 at 65mph in high gear. Not sure what the difference would be with 22.5's but for me it's perfect. Anything below 65mph and I just use 12th.

 

What you are doing is turning 8th and 9th around to make a double over 13. With 3.55's and 22.5 tires you will pick up speed at lower RPM's. With today low RPM engines 3.55's or 3.70's and a double over 13 would out pull 3.36's all day long. Changing from 22.5 tires to 24.5 tires would cost big bucks, and besides 22.5 tires are the same hight as 24.5 low pros. At the speed your are wanting to run I would say a double over 13 would work but you may be in 12th gear more so than 13th.

Also a poster said using the LOW gear in the high range with a 13 speed...that will work, but it will burn up a tranny as the oil pump is not working while in that gear...READ THE WARNINGS. Never move the shift lever to the LO speed gear position while operating in HI range. I believe only with 18 speeds that gear can be used like that.

Also you can make a 13 speed in to a 18 speed, a slip bearing has to be put in and the gear shifter knob changed.

To the postersaid that his buddy claims his doubleover 18 is faster than a doubleover 13...he is nuts. An 18 speed is a 13 with 5 deep reduction low gears, much like a 10 speed vs a 15 speed, same tranny only the 15 has 5 low hole gears.

 

i did that to a 13 once big mistake to high of gearing not enough motor 3406B putting about 580 to the ground dont do it reratio rears leave trans the way it is.

 

Your way off! A 18 dose not have 5 deep reduction. ITs the same as a 13 only you split all 9 not just the top 4. The only ratio differance is the lowest gear in an 18 is lower than a 13. 14.40 18. 12.31 13. As far as making a13 an 18 ive only herd this done with a mack trans. Their 13 and 18 are actually the same trans. with the shift knob locking the splitter out in the low side. Change the 13 shift knob to an 18, you got an 18. Not saying you cant do it with a roadranger but I never herd of it before.

 

Why don't you like tall 24.5's?

 

The only people who ought to dislike tall 24.5s is the guys that get paid by weight. I on the other hand work in the oil patch and need the extra ground clearence, be it only 2 inches or so.

 

I get paid by weight and wouldn't want anything else on my truck.

 

I guess its a matter of indivedual prefferance. I currently have 24.5s but my last few trucks all had 22.5. I think the 22.5 look beter but that just my oppinion. I see little or no differance in how long they last. The 22.5s are a few dollars cheeper but when your paying thousands to replace 8 drives at a time thats not much of a concern either. As far as ground clearance I agree if you do any off road and I do. A 24.5 in theory should all so get more traction because they have a slightly larger contact patch on the ground but I never noticed a differance. The large OTR companies all run the low pro 22.5 for several reasons. Cost both new when they buy the truck and replacement cost are slightly lower. Not a big deal with one truck but times that buy thousands and they save money. Weight. They are definetly lighter. I know I do alot of my own tire work. Would much rather wrestle a 22.5. Rolling resistance. Thet get slightly better fuel milage.Again with one truck probibly not enough to worrie about, but with thousands they save money. The truck also sits 2 inches lower. Less drag through the air. I also Know guys with 11r 24.5s that their 5th wheel is to high to pull a standard van trailer buy an inch or two. If I were to only run the highways hauling freight I would chose 22.5s. Hauling bulk with a dump bucket at 107,000lbs 20% off road I guess the 24.5 are good. Still think the next ones gona have 22.5s again. Just my oppinion.