HD swap? Real benefits?

[curtis73]

My M5R1 in my 94 B4000 is just not shifting right. It only has 97k on it. I have tried three different fluids (MercV, RP Synchromax, PZ Synchromesh) and no matter what I do, the first and second synchros just aren't doing their jobs. I have fully ruled out the clutch. Not only is it a brand new clutch, master, and slave, it did this before the clutch replacement, and it also is working correctly. If I'm at a stop light (neutral, clutch out) then push in the clutch and go for first, it won't go without really pushing hard. Once it is in, I can take it back out and leave the clutch in and it goes straight back in with no click, even after a few minutes, so I know the clutch is disengaging and not creeping. Shifts from 1-2 require equally large effort and it takes forever. Third is a little better, and 4th/5th are fine. I thought about going one step thicker than the Synchromesh with something like RedLine, but the fact that the three fluids I tried had no effect on it makes me think it's just time for more drastic measures.

The first thought is to just rebuild mine, but wanted opinions on the HD swap.

Other than the higher 1st and 2nd ratios, is there anything else internal that makes it an "improvement", or is it just the increased torque capacity from the higher ratios? Good sources for some possible lower ratios while I'm in there? Specifically reverse. I'm Ok with 1-5, but reverse sucks with a trailer.

 

[RonD]

A 4.0l M5OD-R1 or R1HD have the same gear ratios, the M5OD-R1 from 3.0l or 4cyl had the different ratios for 1st, 2nd and 3rd

The "HD" was added because of the extra bolt hole in bellhousing and different shifter used, so they are different, and have a different model number

No real benefit for use, an M5OD-R1HD will be newer(2001 and up) so lower miles hopefully, that in itself is a benefit
Make sure to get complete M5R1HD as your shifter parts will not work on an HD model

And any trans swap needs to match 2WD or 4x4 not easily interchangeable, but can be done on manual transmission

 

[curtis73]

Gotcha. I found the ratios in the tech section. Not sure I want to worry about 3.72 first vs 3.40. Not much of a difference, and first isn't my gripe, it's reverse. I swapped to manual hubs up front, so I can at least back the trailer in 2-lo without fighting the steering, but it's a bit of a pain. Somewhere around 4.50:1 would be swell. Good job, Fordzda. Give a truck a tall reverse ratio.

I think my key here is to find a good core and go through it and swap it on a weekend so I don't have the big downtime. Is there a big torque capacity difference with the 3.72 first in the 3.0L version? I'm certain my OHV 4.0 doesn't make enough torque to do any damage, but I'm also known for not keeping my engines stock. I also tow about 4000 lbs occasionally