Seeking Help With Dead JDM V5MT1 Mystery

[ARDOR]

I'm updating this as I work through this issue to provide a record in hopes of offering some guidance to anyone who may find themselves venturing down this path at some point in the future.

Further research has shown that the input shafts of V5MT1s found mated to petrol 3.0/V6 6G72's are not only larger diameter, but also have a different spline count than the input shafts of V5MT1s found mated to diesel 2.5/2.3 4D55t/4D56t/D4BF's.


Petrol 3.0/V6 6G72 V5MT1 input shafts (ME581629/ME581628):
+/- 29mm diameter
14 spline




Diesel 2.5/2.3 4D55t/4D56t/D4BF V5MT1 input shafts (ME580758):
+/- 25mm diameter
23 spline




Based on comparisons of several different V5MT1 parts diagrams, from various markets, models, and configurations, I'm fairly confident, and very hopeful, the diesel input shaft, ME580758, can be swapped into the petrol V5MT1 w/o issue.

It seems all of the directly associated bearings, snap rings, synchro, and counter shaft share the same, or at least compatible, part numbers, so I've ordered a Hyundai made ME580758 input shaft and will update this thread once it arrives and I've been able to try rebuilding my V5MT1 w/it and new bearings/synchros; if there are other differences and/or issues, I'll report them as well.

 

[plh]

Diesel 2.5/2.3 4D55t/4D56t/D4BF V5MT1 input shafts (ME580758):
+/- 25mm diameter
23 spline
View attachment 603096
View attachment 603097

Interesting that the shaft diameter and spline count of the diesel version of the V5MT1 is the same as the KM145

 

[ARDOR]

Interesting that the shaft diameter and spline count of the diesel version of the V5MT1 is the same as the KM145

I agree, it's odd they went to the hassle of offering two separate input shafts for the V5MT1, but I would hypothesize they already had a clutch engineered for the 5G5x/4D5x motors, which came mated to the KM/FM series transmissions, and it was easier/cheaper for them to alter the input shaft and bell housing rather than contend with developing a unique diesel clutch with the 6G7x engines' spine/input shaft diameter spec.

I know many(all?) of the non turbo 4D5x vehicles were mated to KM/FM series transmissions, seemingly only the 4x4 turbo 4D56s were mated to the V5MT1.

What I find especially bizarre is that the diesel input shaft is +/- 4mm narrower, which should make it weaker, yet it has 23 splines, vs the 14 found on the 6G7x input shaft, with increased spline counts typically indicating greater strength.

The hp/torque specs of the 4D56t vs 6G72 don't seem that far off to warrant such substantial differences in input shaft specs, but I suppose both blocks, especially the 6G7x, was further developed for significantly greater power and the input shafts were likely designed with those higher limits in mind.

 

[YogaSlackerSam]

What is the difference between the V5MT1 and the V5M21?

 

[ARDOR]

As far as I've been able to determine, the V5M21is a further refinement of the KM145; aluminum case with integrated bell housing and not considered to be especially robust. I don't think it was offered in any North American vehicles.

The V5MT1 is an entirely different unit with a removable bell housing, cast iron case, and generally considered to be pretty stout. In the US it was found behind 3.0/V6(6G72) Gen 1 & 2 Monteros, Gen 2 MM/D50s, and '97-'99 Montero Sports. The very early versions had paper lined synchros, which were upgraded in later years, by the early 90s I've read, to brass synchros. This article about the V5MT1, linked to in the 4th posting of this thread, claims [emphasis added]:

"Mitsubishi has a passion for alpha-numeric codes for transmission identification, but if you understand the codes it makes perfect sense. The first letter V identifies the type of drivetrain, V is the code for 4WD based rear-wheel-drive. The second digit is the number of forward speeds, in this case 5. The third digit is either A for an automatic or M for a manual transmission. The fourth digit stands for the manufacturer of the unit. If the fourth digit is a number, it means that the unit was designed by the passenger-car engineering division of Mitsubishi Motor Corp. The letter T in this unit means it was produced by the truck and bus division of Mitsubishi. The 5th digit is the development order. The second design is denoted by a 6th digit, as in the 1992 version V5MT1-3." - http://tcase.rsgear.com/articles/1997_06.pdf

 

[B-Line Performance]

How did this turn out? Where you able to swap input shafts and get back on the road?

 

[airbats801]

Interesting. I was assuming a 4d56 v5mt1 bell housing would bolt to the usdm v5mt1, I picked one up with my 4m40 trans that im having shipped over from the uk. So you are saying the bell housing actually houses the input shaft seal or bearing?

 

[ARDOR]

The US V5MT1, which was only ever found behind 3.0 V6's, uses a +/- 29mm diameter / 14 spline input shaft (ME581629/ME581628).

In the rest of the world, when paired to a 2.5/2.3 4D55t/4D56t/D4BF, the V5MT1 uses a +/- 25mm diameter / 23 spline input shaft (ME580758).

The differences can be seen here on this Russian forum:

https://translate.google.com/transl...bs/phpBB2/viewtopic.php?f=31&t=77456&start=60

[/URL]

The larger V6 (+/- 29mm diameter / 14 spline) input shaft won't fit through the 4D56t > V5MT1 bellhousing and the wall thickness of the sleeve the throw out bearing runs on doesn't appear to have sufficient material to safely/reliably bore it out.

If the thicker input shaft could be made to fit the 4D56t > V5MT1 bellhousing, it would still necessitate a custom clutch to mate the 4D56t clutch to the 14 spline shaft.

As I posted above, I ordered a Hyundai input shaft (ME580758) and will swap it out when I rebuild my V5MT1 in the coming weeks.

 

[Aetro]

Did this ever get tested out?
Has anyone ever tested out the M5UR1 transmission from the kia sorento?
I found torque ratings for it from 282lbft(32kgfm) to 330lbft. Starion guys say its big, so the main/countershaft spacing is likely wide meaning it should be strong