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Mk1 L200 gearbox info

 
 
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Rich_C
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Joined: 19 Feb 2012
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PostPosted: Sun Feb 19, 2012 4:07 pm    Post subject: Mk1 L200 gearbox info Reply with quote

Hi there, new to the forum and am looking for a little help. I have a 1992 Mk1 L200 that was originally a 2.0 petrol which I've converted to a 2.5 BMW diesel - But I've got a bit of a problem with the gearing.
It's running the original 5 speed manual 'box, which works nice but is geared a little oddly. 4th and 5th gear are the same ratio? Maybe not quite, if anything 5th is a touch shorter than 4th. It's a little tricky to tell exactly as I've no rev counter installed yet, but flat out the speedo reads 90mph in 4th and 89mph in 5th.
So what i'm asking is, does anybody know why this would be the case?
And if any one could help with some info for what I want to do;
I'd like to end up with a 5th gear that has a normal step up in ratio from 4th.
I think 4th is 1:1, so ideally 5th would be in the 0.85:1 area.
I figure the simplist way would be to use a gearbox that has the 5th I want, but I don't know which models do/don't or whether that's how all the gearboxes from the model are geared? Do maybe the diesel engined versions have a different ratio set? Although I don't even know if they are the same gearbox between the petrol/diesels.
If someone a bit more informed could help me out here that'd be great.
Another option is use the original 'box but swap the 5th gear pair from another gearbox that has compatible internals if the bellhousing etc isn't the same.
Or if there isn't a proper mitsubishi parts bin option then get a pair of gears manufactured and fit them. The problem with this being it's probably quite expensive and I'd probably need another gearbox to strip and measure up, else be with gearboxless truck while it do it.

Any help greatly appreciated,
Cheers,
Rich
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Xpajun
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Joined: 22 Sep 2008
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1988 Mitsubishi Shogun

PostPosted: Mon Feb 20, 2012 12:44 pm    Post subject: Reply with quote

The Mitsubishi box does have the normal progression of gear ratios - wouldn't be any point in having a 5th gear if the ratio was the same as 4th now would it Laughing

The only difference between a diesel and petrol box is on 1st - slightly higher ratio for the diesel, other than that they are the same.

I'd suggest your problem may well be the engine, rather than the gearbox, not being able to produce the power required for 5th gear


You need to get a rev counter fitted - can help you a bit more then
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Rich_C
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Joined: 19 Feb 2012
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PostPosted: Mon Feb 20, 2012 5:16 pm    Post subject: Reply with quote

Thanks for the reply, and yes I'd agree it would seem silly to have a 5 speed 'box with 2 being the same ratio, however I do think it seems to be the case with this particular gearbox.
I appreciate what you're saying regarding engine power, but it doesn't struggle to reach 90mph in 4th, nor in 5th. It is the M51 BMW TDS engine (140bhp 2.5 turbo)
Also when changing between 4/5 there's no noticeable difference in engine tone at a steady speed. Changing up from 4 to 5 it also doesn't feel right, as normally you'd just drop into a higher gear, it feels as though you're dropping down a gear.
Cheers,
Rich
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Xpajun
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1988 Mitsubishi Shogun

PostPosted: Mon Feb 20, 2012 5:48 pm    Post subject: Reply with quote

The ratios for the gearbox for the 4D5 (2.5 diesel) and the 6G7 (3 Petrol) are the same and are as follows:

1st 3.918
2nd 2.261
3rd 1.395
4th 1.000
5th 0.829

Rev 3.925

Output of the 6G7 is 210hp
Output of the 4D5 on the L200 is 104hp
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Rich_C
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PostPosted: Mon Feb 20, 2012 7:07 pm    Post subject: Reply with quote

Are they also the correct ratios for the KM132 gearbox in the Mk1's? I didn't realise they put the 6G7 in the Mk1's?
Cheers,
Rich
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Xpajun
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1988 Mitsubishi Shogun

PostPosted: Mon Feb 20, 2012 8:15 pm    Post subject: Reply with quote

Yes
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Rich_C
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PostPosted: Mon Feb 20, 2012 9:11 pm    Post subject: Reply with quote

Righty, thanks for the info. Box out time and have a look inside to see what's going on then.

Cheers,

Rich
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Rich_C
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PostPosted: Tue Feb 21, 2012 6:53 am    Post subject: Reply with quote

Are they also the correct ratios for the KM132 gearbox in the Mk1's? I didn't realise they put the 6G7 in the Mk1's?
Cheers,
Rich
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kerrynzl
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PostPosted: Mon Feb 27, 2012 2:35 am    Post subject: Reply with quote

I'll chime in here [ this is my 1st post ]
The Alloy case Mitsy box has 2 variants

The common KM-145 [ KM-132 ] and the later updated V5M-21

The KM series has a "weak as ****" 5th gear that would split , because to get the overdrive ratio Mitsubishi had to make the gear quite small.

What Mitsubishi did to remedy this on the V5M-21 was make the driven gear larger which effectively lowered the 5th ratio.
Then they corrected the overdrive ratio by gearing up the countershaft [ cluster ] drive ratio and also lowered the 1st, 2nd,and 3rd ratios because the countershaft is now spinning faster [ giving the same corrected ratios for both gearboxes ]

The KM-145 and the later updated V5M-21 5th gears are totally interchangeable

The most probable scenario is your KM-145 has split 5th gear sometime in the past and been replaced with the larger V5M-21 5th gearset so 4th and 5th will appear to be almost the same ratio.

You can pull gearsets out of normal 2WD Mitsy L200's they are totally interchangeable , Only the mainshaft and tailhousing are different
When ever you pull one of these apart , ALWAYS replace the input bearing [ They also always fail ]

Cheers Kerry
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Rich_C
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PostPosted: Mon Feb 27, 2012 8:41 pm    Post subject: Reply with quote

Kerry, thanks, that is an awesome reply! So to achieve what I want (longer 5th) I'd need to swap in the later counter shaft cluster? Which would bring 5th to the right point, but then I'd guess I'd also need to swap 1-3 to bring those down?
I suppose the best option is to source a later gearbox complete. Do you know what sort of vehicles it was fitted to? Is it just the later models of the L200's?
Again, thanks for the information.
Cheers,
Rich
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kerrynzl
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PostPosted: Tue Feb 28, 2012 8:17 am    Post subject: Reply with quote

Hey Rich,

The easiest way to correct this is to swap the 5th gears in from an early box [ KM-145 ] All you do is split off the transfer box an the 5th and Rev gears are external
but doing this does give you the weaker 5th so DON'T TOW in 5th.


Swapping the counter shaft cluster isn't quite as easy as you think, you also need to swap the matching input shaft.

Then the 1st, 2nd , & 3rd also need to be swapped as well [ because the drive gears are lower ratio to correct the higher counter shaft speeds ]

By the time you do all this you might as well buy a new gearbox.[or a 2wd Donor box ]
The V5M-21 is a 4WD version of the R5M-21 it is only the bolt on tailhousing and output shaft that is different.

On most Jap Mitsy's all the gearbox & axle codes are on the firewall tag so it is easy to scout around breaker yards to find what you want!


Another tip: The clutch on most diesel mitsy's have weak springs and are expensive to replace but a English Mk4 or Mk5 Cortina 2.0 SOHC clutch is a bolt in swap, even the pilot ID is identical and way cheaper
[I used an old cortina input to line up the clutch on my pajero ]

Cheers from NZ
Kerry
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Rich_C
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Joined: 19 Feb 2012
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PostPosted: Mon Mar 05, 2012 11:10 pm    Post subject: Reply with quote

Hi Kerry, excellent information again, thanks very much!
I've got hold of another 'box which has the right 5th ratio, but I'm unsure of whether it's a KM145 or V5M - I can't see any markings/numbers on the casing (if there are any) and as I've not seen the different 5th gear sets side by side I'm still not which it is. I don't suppose you know the diameters of the different gear sets do you?
I only ask as it makes the choice on which way i get the right 5th in the truck. If it's a KM145 brill, I can just swap the 5th into the existing 'box.
If it's a V5M, I'll have to spend some time modifying the bell housing of the 'new' 'box to fit the BMW engine (Which isn't the end of the world, but a bit time consuming)
Thanks again,
Rich
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kerrynzl
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PostPosted: Tue Mar 06, 2012 10:38 am    Post subject: Reply with quote

The V5M-21 gearbox has helical cut reverse gears but the KM-145 has straight cut reverse gears is the easiest way to tell.
You need teo split the transfer box to see this.

The codes on the side of the box can be decyphered by any Mitsy service dept.
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