With a few modifications the 404’s transmission can gain 2 extra forward gears on the low range side. The mod is nothing new and has been well documented in this popular PDF. It does have a few downsides I wasn’t crazy about. First is that you have to add yet another lever to operate in the shifting process. Second is that with the new lever’s location you lose the option of having a PTO. 404 PTOs are like Unicorns, so most don’t care but I’d like to have one someday.
So this is the stock shifting pattern, low gears on the left and high (road) gears on the right:
The white dot in the pic is the Q-Transverse and is not very smooth to shift across in the 404. The go-to method outlined in the PDF above basically blocks off the low side’s shifting gates on the guide plate and uses the higher gear’s H shaped gates for both the high and low gears. The lever you have to add shifts the gate between the high and low side resulting in a shift pattern like this:
So while going from 4th to 5th, you have to throw an additional lever so you don't end up back in 1st .... which the drivetrain wouldn't like.
So I went another route. The biggest advantages, in my book are no extra levers, it keeps the option for a PTO open and uses a more standard shifting pattern like this:
Still have that Q-Transverse in the middle but I think keeping a standard shifting helps make an already complex transmission easier for somebody to jump in and drive or move.
After you remove the shifting levers and top cover from the transmission it exposes the guide plate. You can pull it right up and off of the transmission housing. Take a picture of the top of the plate so when you reassemble you can be sure to have the shifting forks in the same position.
Here are the top and bottom sides of the guide plate.
For reference:
A = Angular Lever – This will be modified.
B= Pivot Bolt – This is an alignment bolt.
C = Latch Lever – No longer be needed.
D = Shifting Slide Plate – This will be modified.
E = Shifting Slide Plate Retainer – No longer needed.
Green numbers 1 – 6 are reference points for top/bottom pics.
Making the Modifications
Guide Plate Modification
In order to add the two gears on the low side you’ll need to cut an additional shifting gate next to the factory 1st to 2nd gate. With that cut, gears 1 & 2 will move to the new gate, and the new 3 & 4 gears will go in their factory spot.
Here is a before and after pic:
I had a bit of a documentation fail here. I don’t have a pic from right after I cut the new gate. That pic from after the mod was from later in the process and shows a modified Shifting Slide Plate sitting over one gate and a few extra pieces to the right of the new gate.
Shifting Slide Plate & Pivot Bolt Modification
With the new gate cut into the guide plate the Shifting Slide Plate will need to slide further to the right to grab those gears. The bolt to the right of plate and the ‘ear’ on the Angular Lever will prevent it from sliding as far as it needs to. To correct this, the areas highlighted in green need to be removed. The single green line in the pic represents a hard edge that needs to be beveled to match the opposite side so the shifter can easily operate at that angle. The dark green area is not for is not for clearance and will be explained later.
Cutting the tab off the plate and beveling the edge is a no brainer. Cutting the Angle out of the top of the Shifting Slide Plate and the edge off the Angular Lever can be tedious. It’s something you want to sneak up on. Cut some, reassemble the assembly and test. This process will go much faster if you marked the factory position of the Pivot Bolt before removal. Here is a pic of the Shifting Slide Plate and Angular Lever reinstalled to get an idea how the plate can move to the new gate unrestricted.
Once you have the Shifting Slide Plate assembly moving freely across all the gates, you’re done modifying the top of the guide plate. Next up is modifying the shifting forks under the guide plate.
So this is the stock shifting pattern, low gears on the left and high (road) gears on the right:
The white dot in the pic is the Q-Transverse and is not very smooth to shift across in the 404. The go-to method outlined in the PDF above basically blocks off the low side’s shifting gates on the guide plate and uses the higher gear’s H shaped gates for both the high and low gears. The lever you have to add shifts the gate between the high and low side resulting in a shift pattern like this:
So while going from 4th to 5th, you have to throw an additional lever so you don't end up back in 1st .... which the drivetrain wouldn't like.
So I went another route. The biggest advantages, in my book are no extra levers, it keeps the option for a PTO open and uses a more standard shifting pattern like this:
Still have that Q-Transverse in the middle but I think keeping a standard shifting helps make an already complex transmission easier for somebody to jump in and drive or move.
After you remove the shifting levers and top cover from the transmission it exposes the guide plate. You can pull it right up and off of the transmission housing. Take a picture of the top of the plate so when you reassemble you can be sure to have the shifting forks in the same position.
Here are the top and bottom sides of the guide plate.
For reference:
A = Angular Lever – This will be modified.
B= Pivot Bolt – This is an alignment bolt.
C = Latch Lever – No longer be needed.
D = Shifting Slide Plate – This will be modified.
E = Shifting Slide Plate Retainer – No longer needed.
Green numbers 1 – 6 are reference points for top/bottom pics.
Making the Modifications
- Remove the Latch Lever (C) by removing the cotter pin & washer. None of these parts will be reused.
- Remove the Shifting Slide Plate (D) by sliding it (left if going by pic above) out from under the rails holding it in place.
- Remove the Pivot Bolt (B) to pull off the Angular Lever (A). IMPORTANT: Turning the Pivot Bolt adjusts the location of A and should be marked for reference before loosening or removing.
- Remove the Shifting Slide Plate Retainer (E) by grinding down the rivets. Once removed, smash the rivets back down to hold in the lower retainers. I was able to get my guide plate into my press to smash these.
Guide Plate Modification
In order to add the two gears on the low side you’ll need to cut an additional shifting gate next to the factory 1st to 2nd gate. With that cut, gears 1 & 2 will move to the new gate, and the new 3 & 4 gears will go in their factory spot.
Here is a before and after pic:
I had a bit of a documentation fail here. I don’t have a pic from right after I cut the new gate. That pic from after the mod was from later in the process and shows a modified Shifting Slide Plate sitting over one gate and a few extra pieces to the right of the new gate.
Shifting Slide Plate & Pivot Bolt Modification
With the new gate cut into the guide plate the Shifting Slide Plate will need to slide further to the right to grab those gears. The bolt to the right of plate and the ‘ear’ on the Angular Lever will prevent it from sliding as far as it needs to. To correct this, the areas highlighted in green need to be removed. The single green line in the pic represents a hard edge that needs to be beveled to match the opposite side so the shifter can easily operate at that angle. The dark green area is not for is not for clearance and will be explained later.
Cutting the tab off the plate and beveling the edge is a no brainer. Cutting the Angle out of the top of the Shifting Slide Plate and the edge off the Angular Lever can be tedious. It’s something you want to sneak up on. Cut some, reassemble the assembly and test. This process will go much faster if you marked the factory position of the Pivot Bolt before removal. Here is a pic of the Shifting Slide Plate and Angular Lever reinstalled to get an idea how the plate can move to the new gate unrestricted.
Once you have the Shifting Slide Plate assembly moving freely across all the gates, you’re done modifying the top of the guide plate. Next up is modifying the shifting forks under the guide plate.
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