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Why Regear Your Axles When You Can Regear Your Tranny?

Posted in How To: Transmission Drivetrain on October 30, 2017
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When we added a 4-inch Superlift suspension and 33-inch-tall Cooper MTP tires to our 2001 Ford Ranger, we gained ground clearance and traction. The tradeoff, however, was decreased fuel mileage and a perceived loss of power with the larger tires. This is a project truck, and regearing the axles is on the to-do list, but it fell way behind things like replacing the three timing chains (thanks Ford) and rebuilding the transmission in the 200,000-mile Ranger.

When we were exploring rebuilt transmissions to replace the noisy M5OD-R1HD five-speed, we came across some interesting information. These Mazda-designed transmissions have been used in everything from the Aerostar to V-8 F-150s and Broncos, but not all used the same gear ratios. We asked our buddy Aaron Lechner from Axleline if he thought swapping a transmission from a 3.0L Ranger into our 4.0L truck was possible. “Let’s find out!” he replied. He had already changed the gears in a ZF transmission for our big-block–powered F-150 so we knew we were talking to the right guy.

Lechner was able to replace the gears inside our original housing with gears, bearings, and synchros that came out of a remanufactured transmission for a 3.0L-powered Ranger. The total effort and expense was comparable to rebuilding the existing transmission, and the lower gear ratios compensate for our larger tires. This is of particular use on the Ranger platform, where the lowest gear ratio offered for the front Dana 35 axle is 4.56. If you are looking for improved crawl ratio out of your Ranger or Explorer, there are options other than the differentials. Or a regeared transmission could be combined with lower axle gears to compensate for even larger tires.

The dropped torsion bar brackets from Superlift use a crossmember that can be unbolted to allow the transfer case and transmission to be removed without having to touch the torsion bars.
We had to remove the driveshafts, exhaust, and transfer case to get the transmission out. You could do all of this in the driveway with jackstands and a floor jack, but having access to a four-post lift made it much safer and easier.
The M5OD uses a hydraulic master cylinder and internal hydraulic throw-out bearing. The factory disconnect makes transmission removal easy, and when the transmission is out we recommend replacing the slave cylinder at the same time.
Note that the M5OD does not use a removable bellhousing. Instead, the entire transmission case is one piece of aluminum. This required the guts of the new transmission to be swapped into our existing case.
The 3.0L V-6 engine used a different bellhousing bolt pattern (left) than our 4.0L V-6 engine. The transmission internals are different as well; however, they are interchangeable between the M5OD-R1 and the M5OD-R1HD transmission cases.
Both transmissions use 1-inch, 23-spline input shafts so it would be possible to change gears on the shaft, but we used the entire new assembly from the donor transmission. The common spline count means that both transmissions also use the same clutch part number.
While the bellhousing bolt pattern is different, the tailhousing extensions are the same. All Rangers with the M5OD transmission used the same Borg Warner transfer case, although they were available with both electronic and manual linkages. Note that some M5OD transmission cases do not have the bosses for the manual linkage.
The shift towers looked the same between the two transmissions, but we found that the location of the shifter varied between them. We recommend using the shift tower that matches your original transmission.
The input and counter shafts install in the back of the transmission. This is not necessarily an “in the driveway with handtools” kind of swap, but Axleline offers M5OD transmissions with lower gears installed that can be shipped to your doorstep.
When installing the new transmission we recommend replacing the clutch and resurfacing the flywheel. In the big scheme of things these steps are not very expensive or time consuming, and they will prevent you from having to drop the transmission again the future.
The M5OD calls for automatic transmission fluid. We used Lucas Multi-Vehicle ATF, and the transmission is quiet and cool and shifts smoothly. The BW1354 also uses ATF for lubrication, but they are not shared between the two boxes.
The stub at the bottom of the shifter is different between the two transmissions, with the flat mating surface at a 90-degree difference between the two. We did not originally realize that and had an issue using our original shifter with the new tower. Sourcing the correct shifter remedied the problem.
The lower gears in the new transmission are well matched to the 33-inch Cooper MTP tires on our Ranger. We gained back acceleration on the street and crawl ratio on the trail.

M50D Applications

All of the M5OD transmissions use an aluminum case with an integral bellhousing that is a top-loader style with lid over the main case containing the shift rails. The easiest way to differentiate an R1 from an R2 is by the position of the shifter on the lid. For the R1, the shifter is near the rear of the lid; for the R2, near the middle. While there are differences in gear ratios, the main shaft size is the same, suggesting that there is little strength difference between the various models. Maximum input torque is rated at 330 lb-ft.

M5OD-R1
First 3.72; Second 2.20; Third 1.50; Fourth 1.00; Fifth 0.79; Reverse 3.40
1988-2011 Ranger (with 2.3L I-4, 2.5L I-4, 3.0L V-6, and 4.0L OHC V-6 engines)
1988-1990 Bronco II
1988-1995 Aerostar
1991-1996 Explorer

M5OD-R1HD
First 3.40; Second 2.05; Third 1.31; Fourth 1.00; Fifth 0.79; Reverse 3.40
1997-2001 Explorer (with 4.0L SOHC V-6 engine)
2001-2003 Explorer Sport (with 4.0L SOHC V-6 engine)
2001-2011 Ranger (with 4.0L SOHC V-6 engine)

M5OD-R2
First 3.90; Second 2.25; Third 1.49; Fourth 1.00; Fifth 0.80; Reverse 3.39
1988-1996 F-150 (with 4.9L I-6 and 5.0 L V-8 engines)
1987-1996 Bronco (with 4.9L I-6 and 5.0 L V-8 engines)
1997-2008 F-150 (with 4.2L V-6 and 4.6 L V-8 engines)

Sources

Lucas Oil
Corona, CA 92880
800-342-2512
www.lucasoil.com
Axleline
775-870-9585
http://Axleline

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