What are the differences? Is the HD mean heavy duty to handle the horsepower of the SOHC motor?

 

Hmmm....i'm curious too.

I know only the 4.0L SOHC got the HD models. Maybe they just upgraded the synchros. ??? No clue. I know Mr. Bob will reply. I'll be watching this thread.

 

the only difference in the R1 and R1HD is the R1HD has a lower 1st gear ratio......

 

There is very little info out there but here's what I have been able to find out from the shop manual and other sources:

• Throughout the 90's and up through 2000, all Ranger manuals were M5OD-R1 made by Mazda, regardless of engine displacement. Besides internal ratios, the only other difference was in the outer cases which were different to match the individual engine bolt patterns (these transmissions have a bell housing that is integral to the transmission case casting).
  
  
• In 2001, an upgraded Mazda trans called the M5OD-R1HD was introduced for use only with the 4.0L SOHC. The shop manual shows that the synchronizer blocking rings for first and second are different. The first gear ring is larger in OD and ID and the second gear ring is of a different construction. It stands to reason that the shift fork, synchronizer sleeves and the cones on the matching gears would be different to match the uprated rings.
  
  Going only by the shop manual, it appears that the rest of the M5OD-R1HD transmission uses the same construction as the M5OD-R1. It would take a trip to a dealer parts counter to verify that all other internal part numbers are actually the same.
  
  
• 2001+ 2.3/2.5/3.0 continue to use the original style M5OD-R1 as in earlier years.
  
  
• All 4.0L use a closer ratio gearset as compared to the 2.3/2.5/3.0 engines. It doesn't matter whether you're talking about 4.0L OHV or 4.0L SOHC, R1 or R1HD.
  
  3.40 / 2.05 / 1.31 / 1.00 / 0.79 (4.0L Engines)
  3.72 / 2.20 / 1.50 / 1.00 / 0.79 (All Other Engines)
  
  

 

The reason I was asking was because I found an extension housing and the description says its for a M5OD-R1. There is no picture so I can't tell if it has the hole for the VSS but it does have the to bosses for manual shift linkage. I'm going to ask for a picture to see if its the right one.

 

if it doesn't have the holes for the VSS, let me know and I will aquire it

 

Sure.

 

I'd bet my own money that the 4x4 extension housing is the same whether the trans is an R1 or R1HD. Then all you need to worry about is the linkage bosses and the OSS sensor port. The OSS is just about dead center in this photo.

 

I hope its there. Its cheap.

 

WOAH! Bob got a new avatar. This is weird seeing a different avatar for ya bob. It's about dang time! lol.


Hey Bob...do you happen to know if there were any internal gear changes(ratio changes) in the HD models?? The reason I ask...is that my new '05 trans seems to have alot different ratios compaired to my '01 trans.