Transmission / Axle Combo?

Hello all I have a rookie question. Our truck has a 13 speed and 3.70 rears on our 89 International 9300. It’s almost impossible to get going in Low when loaded on any kind of slight uphill incline. The truck is a 3406B and has tons of power, but it’s just hard to get started, even when going in reverse.

What’s the best way to fix this? Swap out for rears like 4:10 or something similar? Someone said all transmissions are the same. A 13 speed is a 13 speed, an 18 is an 18 etc and they don’t have different ratios. Is that true? Also should mention this has the horseshoe shift pattern, 3rd and 4th are opposite if that says anything?

I’ve drove a lot of trucks but this 9300 is the most difficult truck I have ever drove. I see road trucks for sale with 3:55 rears and they are hauling 80-90,000 lbs and have no issues getting going from a dead stop on a hill. I just don’t understand.

Thanks

 

Also, were cruising about 60-65 mph at 1800 rpms. We still have 3rd and 4th gear on the high side untouched.... Its an agriculture truck but used to be a fuel and lube truck before it got to us.

 

I took model number off transmission.

RTLO-14713A

Thanks for any and all help

 

Hi everyone thanks for all the repsonses.

So no, I dont know for sure if the transmission and ratio are all correct. I am just going by the steel stamped tags on the housings. It does say Reman, as well. I did a little research last night and found each ratio for each gear for that transmission. Then, I found a calculator for tire size, rear end ratio, RPM and transmission ratio. From my calculations those ratios are correct when I used my GPS to track my speed this monring.

Attached is my chart. Each colored area is a gear, with that transmission ratio, and calculated MPH. The first set of numbers is with our 3.70 axles, then I did one if we had 4.11, or 4.88. Just wanted to compare speeds. The highest gear we get to now is high side 2nd, or 6th, with the red splitter forward. Ratio of 1.38 at 48-49 mph. (Our spedo was off when I mentioned it in my previous post).

Tire size is 700x40x22.5. 46.1" tall tire I believe. Flotation tires.


As far as the clutch, linkage, and engine mounts I have read before that mounts could be bad. Whats best way of checking all these? Good diesel mechanic? When I accelerate after each shift, I can hear the RPM's increase followed by something finally engaging. Its usually about a 1/2 second delay. Also it usually lurches or lunges ahead. Extremely annoying! Also, at a dead stop when empty, you really have to concentrate to let RPMs out slowly to get truck to go ahead smoothly. I feel like its the first time I've ever used a clutch each time I drive it. Also, the shifter lever does no lunge at all during acceleration.

Thanks alot really hoping to get this thing figured out!

 

Well I have been looking a little more into it. I used an 18 speed for an example ( RTLO-18918B) as well with my 3.70 rears. In Low gear splitter back at 1800 RPMs Id be traveling a speed of 4.63 MPH, 0.79 MPH slower than my current set up. We are trying to price out what is cheaper, just change out tandems or go with different transmission.

I'm pretty confident engine mounts are good, shifter does not move at all during acceleration. Since we only travel 65 tops with the truck seems like we should just throw a set of 4.88 in the back. I found some about 5 hours away for $2,500 full lockers. Is that a good price?

Still looking for any insight on slop I feel after each shift, most likely it would be ring and pinion or similar in there.

Thanks