Hello, i am looking to swap the 4 spd NP435 in my 1984 F-150 for the M5R2 5 spd out of a 1989 F-150. Has anyone done this before? I am having a hard time finding information about which parts are interchangeable, which parts need swapped, and what needs customized.
Both trucks are 2wd, long beds, with 4.9 I6. The bigger issue is the clutch hydraulics as the NP435 has an external slave cylinder and the M5R2 has an internal slave cylinder. I was told I might need to swap out the clutch and brake pedal bracket, but would that also affect my brake master cylinder?

 

I have never done this before, but I can give you some possible alternatives.

You might want to check the length of the rod coming off the clutch pedals that goes to the clutch master cyl of both to see how much difference there is., if any.

If the amount of travel is the same , the other consideration would be the size of the bores of both clutch master cyls. If they are equal you should be getting the same amount of fluid to the slave when depressing the clutch, and that should be acceptable. Let us know how you make out with this, thanks.

 

That is what i was thinking, if fluid displacement is the same between the two clutches, they should be interchangeable. I am trying to find the specs on both master cylinders, but haven’t yet.

 

That might be a little difficult , unless you can actually compare the internal bores and the travel of the push rod.

 

The bore dimension is listed on several parts websites, and as far as I can tell, both Master Cylinders use a 7/8” diameter piston, i am just unsure of the stroke length.