Higher Ratio 5th Gear??

[BKR33]

I own a 4D56 powered L300 2.5TD. I've given it 2 years of hard service and it is still going strong. My only problem/criticism is being a 5 speed manual it revs its guts out at highway speeds. Where possible on the long desert runs i like to sit on 120 or so kph. But the poor mongrel is sitting on nearly 4000rpm at this speed. Bit over 3000rpm at 100kph.
Now my question is has any body heard or know of a higher 5th gear ratio for these vehicles. I assume they run a similar/same gear box to the triton/pajero family. The one I heard of dropped the revs by 750rpm at 100kph. It was over a year ago I read about it on another forum but I'm now stuffed if I can find it back. Any help you guys can offer would be greatly appreciated.
Regards Brett

[South]

There are overdrive units that sit between the box and the tailshaft that will lower the final drive gear when engaged. Like you, I have forgotten who makes the unit, I'm not even sure if they are suitable for the mitsu or not.

I wouldnt mind having one, as I know its not necessary to pull 3000rpm at 110 in our Pajero, a drop of 300+ rpm would improve economy no end. There is one downside, and that would be approaching hills where you would have to turn off overdrive and then switch it back on after a hill (im talking HILL though, not a pissy incline)

[BKR33]

Yeah thanks I know what you're talking about there.
Though the one I was reading about was actually replacing some of the gear set in the gear box. It only changed the ratio of 5th gear and none of the others. He even had pictures of his tacho and speedo of before and after. Its got me stuffed.

[mki]

Hi there! I had the same problem in my pajero, 3500 rpm @ 100km/h, I Tryed to find a set of gears to the box but I haven't found any.... In my case the problem want away by a set of 33" tires, but then the "crawling" speed is to fast most of time. There's one person in a fin forum who's making a 1:4 gear rate to his transfercase.... but he sais that it's pretty tricky..... so it should be possible to make them to the 5th gear, after all they are man made

[hairy one]

Can any one confirm that the Sigma 5th gear is a lower ratio for the 2.5tdi manuals.

Have been told this is an easy swap over but do want to have another horse tell me that.

[mki]

The Sigmas box type is F5M33-2, and the 5th gear ratio is 0,741

[-Scott-]

The Sigmas box type is F5M33-2, and the 5th gear ratio is 0,741

Interesting. Can you post some more info about these Sigmas? Age, market, engines etc? Pictures would be nice, too.

In Australia, the Sigma was produced from late 1977 through to 1987. It came with four different engines: 1600 Saturn (4G32) 1850 Astron (4G51?) 2000 Astron (4G52) or 2600 Astron (4G54 - like the Pajero's.) The 1850 was dropped by about 1980, and a locally turbocharged 4G52 was produced around 1982 - I think only 500 were built.

The base models came with a 4 speed gearbox, either KM110 or KM130. Higher spec models came with a 5 speed, originally a Borg Warner unit (junk ) then a Mitsubishi box, KM132. The KM132 5th gear is 0.856:1. 1st is 3.369, reverse 3.635.

[mki]

Well I don't know very much about the Sigmas tech, but I asked around in The Finlands mitsubishi owner club(forum) and I got that info out....
Here's a picture of the car we know as Mitsu Sigma


And a review from England

Specs from a independent fin car database

It's been at the fin market from 1991 - 1995, and there's a 6G72 (12 and/or 24 valve??) under the hood, with a automatic or manual (F5M33-2)transmision.....

as I said don't know very much about it, sorry

[-Scott-]

No apologies - it's nice to learn what's happening in other parts of the world.

That looks like what the Japanese called a Diamante, and Mitsubishi Motors Australia built them (wider than the Japanese version) as a Magna. As a Magna, we had the 6G72 also, but I don't know about the transmissions.

Dragging this thread even further off-topic, I think this was the era where Mitsubishi's "corporate look" looked at it's best. Just a personal opinion.

Cheers,

Scott

[BKR33]

I found the thread but the link to the pictures doen't work any more.
From memory the pics showed the speedo on 100kph and the taco showing aprox. 2200 rpm

http://www.mdocuk.co.uk/forums/viewtopi ... highlight=

He doesn't seem to be active on this site anymore
He is apparently in Taiwan
Cheers Brett

[PHIL]

From memory the pics showed the speedo on 100kph and the taco showing aprox. 2200 rpm

Interesting stuff here... agreed on the corporate look of the diamante... I liked those days too...

Anyway back ontopic, 33s also brought my revs down, but I do almost 200kms per day in my commute so a little lower still would be nice... I wonder if this new fifth would put the revs too low... If they were down in the low 2000s, wouldn't 5th be practically useless on all but the flatest roads with a tailwind?

[mki]

I have to agree with 33" a lower gear ratio would make the 5th gear useless, and too low rpm gives poor lubrication to the bearings.... But more ontopic... 33" are probably too big for a delica, so using 10% lower gear ratio would make a delica move in a better rpm range , and the Sigma/ Diamante /Magna's gears would just do that.....if they fit

[hairy one]

K Following on with the history of the Mits motors.
The 2.5 Deisel motor is based on the 2.6 petrol motor. If what I'm told is correct then the basic design & dimensions are the same.

If that's also the case with the gear boxes then the gears may be interchangable between the engine sizes.

Ta for the ratios guys.