International 4700 Eaton Transmission Swap

I wanted to put an Eaton fuller transmission in my international 4700 because I'm used to the feeling of larger trucks with manuals. I swapped from a spicer 6+1 model eso66-7b to a 9 speed Eaton fuller RTX12609b.

The first step in swapping transmissions was finding one with suitable torque ratings and gear ratios. Most transmissions I found fall into either direct drive or overdrive. In those two groups the top 4 ratios are mostly the same until you get to 13 or more speeds. Eaton has a nice spreadsheet that lists all of their transmissions and specs to help identify suitable transmissions. Anything over 900 lb-ft seems to be oriented toward large trucks. I pulled my transmission from a international 9400 in a salvage yard. I was hoping it would be a mostly straight forward swap. And I needed all the extra parts like the shifter and the boot on the floor.

The second step was figuring out what I had and getting all the parts I needed. The transmission needed a new bellhousing. It had an sae1 on it and it needed sae2 to fit the dt466. A new one at Sadler powertrain was going to be $1500. I found a NOS one on eBay for $300 after looking long enough. When replacing the bellhousing make sure you tighten the bolts on the input bearing cover before tightening the bellhousing bolts. It has a very tight clearance on the input shaft and it will bind if its not perfectly centered. The input shaft was the next issue. It was 2” spline and the truck was 1.75”. The cheap option was getting a new input shaft and front cover. I think it would have been around $150. I would have had to take the transmission apart though. Instead I was able to get a new clutch with disks that had the 2” spline and a 950 lb ft rating. I was going to replace the clutch anyway so I went this route. As a side note. My clutch instructions made it clear the flywheel on the dt466 will need replaced if it needs to be resurfaced or the clutch will interfere with the flywheel bolts. My flywheel was almost perfect so I skipped this. The original pilot bearing was the correct size for the 2” input shaft. The output yoke was my biggest issue. It was 1760 series u joints on the transmission and spl90 on the truck. I could not get an spl90 yoke for the transmission and I couldn’t get a 1760 yoke for my spicer N175 rear end. Union flanges were unavailable as well. I ended up buying a 1760 yoke and having my local machine shop weld it onto the original driveshaft tube for the spl90 driveshafts. The front shaft had to be lengthened by 2” any way so he was able to build a collar to stretch the shaft and adapt it top the bigger yoke. The original spicer transmission was actually longer than the Eaton.

With all the parts swapped over getting the spicer out and putting the Eaton in was pretty straight forward. The Eaton is wider so you will need to make room to roll it under the truck on the transmission jack. It might have been easier if I removed the PTO first but I didn’t want to. The Eaton is shorter though so the air tanks weren’t in the way like they were while removing the spicer. I did have to leave the air tank a little farther back though to make room for the bigger u joint setup on the end of the transmission. The air supply for my transmission was plumbed into the 3/8 npt plug on the rear tank. There’s also ½ plugs on the tank. The 3/8 ones face the frame and they are a bit harder to notice. The air line size is 3/8. I had to cut the hole in the floor farther back to make room for the shift tower. About 2” further back than stock I think. The boot that came with my transmission doesn’t cover the entire hole. I will probably use a sheet of plywood under the shifter boot to cover the hole. The clutch pedal adjustment was a bit difficult. In order to get the input brake to engage I had to pull the arm from the spicer transmission and put it on the Eaton. It was noticeably shorter. Also had to cut the linkage by about an inch and cut more threads. I just kept shortening the linkage from the pedal until the input shaft brake would engage just before the pedal hit the padding on the floor. Then from there I had to adjust the clutch quite a bit to get about 1-1.5 inches of free travel at the top. There’s a bolt on the clutch itself to adjust the pull style clutch. As you adjust the clutch the release bearing will move closer to or further away form the brake. Just make sure the brake isn’t dragging and the the fork that pulls the release bearing isn’t resting against it when the pedal is all the way up.

Driving the truck is nicer with the Eaton. The engine rpm drops faster than bigger trucks though and the engine revs higher than bigger trucks too. It seems to be a little trickier to shift than the big trucks but also faster to shift than with the spicer. The spacing between the gears feels a lot better now too. The lower ratio in reverse will be nice to have when pulling trailers. And it is a lot easier to get the truck into gear when it is stopped now. I have noticed it is a lot quieter when lugging around at lower rpm also.