Converting from Automatic to Manual: Manual gearbox rebuild

Does your Mitsubishi L300 make a strange noise? Need wheel alignment specs?
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Growlerbearnz
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Converting from Automatic to Manual: Manual gearbox rebuild

Postby Growlerbearnz » Sat Oct 28, 2017 10:19 pm

Here we go...

You will need:
1 Automatic L300 Delica
1 Manual L300 Delica

From both vehicles remove:
-Driveshafts
-Gearbox/transmission
-Gearbox/transmission mount crossmember
-Clutch/torque converter
-Flywheel/flexplate
-Front and rear differentials
-Clutch slave cylinder and hydraulic line
-Pedal boxes
-Gearlevers and shifter boxes
-Gearshift cables
-Instrument clusters

And that's about as far as I've made it, but I expect installation is the reverse of disassembly? Yeah right.


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Nothing says "poor workmanship" more than wrinkles in the duct tape.

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Growlerbearnz
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Converting from Automatic to Manual

Postby Growlerbearnz » Fri Nov 03, 2017 1:43 pm

Progress continues. The Automatic and Manual bodyshells are identical, so far there's been no drama in swapping the parts. There's even a hole in the floor for the clutch line bulkhead fitting, and a tag on the frame near the bellhousing for the clutch flex line to attach to. Witness the new bulkhead fitting (and the shameful collection of fluff and junk that lives under the carpet:)
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My new gearbox is in pretty good condition, considering it's done 360,000km. The mainshaft retaining nut that holds 5th gear in place was only slightly loose, the staked section had stopped it coming undone (which would have wrecked the gearbox). I'll be using loctite when reassembling.

All gearbox bearings, seals, and synchros are still available, so I've ordered them all (might as well, since it's pulled apart). Selector forks are NLA which is a bit disappointing, since the forks are a bit worn.

So. What to do while waiting for parts to arrive from Japan? Clean and bead blast the gearbox cases:
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Mmm pretty.
Nothing says "poor workmanship" more than wrinkles in the duct tape.

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Growlerbearnz
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Converting from Automatic to Manual

Postby Growlerbearnz » Wed Nov 15, 2017 2:00 pm

Rebuilding the new gearbox mostly entails waiting for parts from Japan. In the meantime I've been researching the gearbox's weak points, and think I have a fairly good handle on what goes wrong and how to prevent it.

The first thing is that the gearbox case can flex under load, which allows the countershaft to move away from the mainshaft, changing how the gear teeth mesh right when they're trying to handle a lot of power. It's not a huge deal, most L300s don't have enough power for this to be a problem, but I'm covering it first because I have the solution right here:
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A cast aluminium lower cover, which replaces the pressed steel cover. Fitted to the Mitsubishi Starion for only two years (1988-89) with original part number MD727553, no longer available, and rare as hell. Starion and 4WD guys have been making their own versions out of alloy plate at enormous expense. (http://projectzerog.com/forum/viewtopic.php?t=1741&sid=e148cdfb4fecd561bf67fb6c461631ff , http://www.starquestclub.com/forum/index.php?showtopic=100703.

...except... they're not rare or unavailable. Mitsubishi put them back into production in 2000, albeit with a different part number.

Part 2502A008. CAD$52. You'll also need the O-ring seal MD727531, CAD$17. Definitely fits a V5M21, should also fit a KM145.

Next post: Input shaft bearing and 5th gear strengthening.
Nothing says "poor workmanship" more than wrinkles in the duct tape.

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Converting from Automatic to Manual

Postby Growlerbearnz » Wed Nov 15, 2017 3:40 pm

The input shaft bearing is a known weak spot- they tend to collect metal particles and fail. Something to do with the flow of oil in the case, I suspect.

Early gearboxes (and cheap rebuild kits) have open bearings, but Mitsubishi upgraded the input bearing to have felt seals, which let the oil in but keep the swarf out. Compare the upgraded bearing to a cheap replacement:
InputBearing.JPG
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Genuine part MD731727 is the snap-ring style input bearing with the fancy seals. (Check that your gearbox uses a snap-ring style bearing first, as some had a flanged bearing.)
Nothing says "poor workmanship" more than wrinkles in the duct tape.

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Converting from Automatic to Manual

Postby Growlerbearnz » Thu Nov 16, 2017 5:05 pm

5th gear failure modes:

KM145 gearboxes (up until about 1990) had a very weak 5th gear. Because the gearbox was originally designed as a 4-speed, Mitsubishi had to make the 5th gear very small to get the desired overdrive ratio, but that didn't leave much metal to hold the gear together. Older 5th gears just broke like this:
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When they revised the gearbox (changing the name to the V5M21) they increased the countershaft gear ratio to enable a larger 5th gear to be used, while reducing all the other gear ratios to keep the overall ratios the same as previous gearboxes. The 5th gear no longer split as often, but now there was another problem: the 5th gear bearing sleeve comes loose. The gearbox I'm currently rebuilding has come loose, but I've caught it just in time to be repairable.

If you remove the transfer case and look inside the gearbox extension casing you'll see the retaining nut holding the thrust washer, keeping the 5th gear and bronze synchro ring against the shifter hub.:
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Inside the 5th gear are caged needle rollers. These let the 5th gear spin freely when it's not being used.
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Those needle rollers run on a sleeve which is clamped in place by the big retaining nut: here's the previous assembly without the 5th gear in place.
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You can see the sleeve just slips over the mainshaft so it's replaceable.
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5th gear begins to fail when the retaining nut comes loose. The mainshaft twists as it transfers torque to the wheels, but the thrust washer and bearing sleeve are more rigid and don't twist as much. Eventually the retaining nut frets into the thrust washer and comes loose. Here you can *just* see the hexagonal marks where the nut has chewed into the thrust washer (I've ground both surfaces back a little before reassembly):
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Once the nut is loose the bearing sleeve is no longer clamped in place, and when you're in any gear but 5th it will spin on the mainshaft (rather than staying still while the bearings rotate around it):
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If the sleeve is free to spin, the needle rollers have no incentive to rotate and tend to rest in one position, brinelling (denting) the sleeve and making the sleeve spin even more.
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Eventually the sleeve chews into the mainshaft, destroys the needle rollers, and breaks 5th gear. A new mainshaft is *not* cheap.

The proper way to prevent this would have been for Mitsubishi to grind a notch in the sleeve which engaged with a peg on the mainshaft, so even if the sleeve came loose it couldn't spin (like they did on the transfer case mainshaft). I guess you could add one by grinding a notch into the sleeve and mainshaft, but that would also create a stress-raiser, and I'm not brave enough to risk it. Instead I'm using retaining compound (Loctite for bearing sleeves) to glue the sleeve to the mainshaft, and regular loctite on the retaining nut.

I'll also be periodically removing the transfer case and checking that the mainshaft nut is still tight.
Nothing says "poor workmanship" more than wrinkles in the duct tape.

Morgonzo
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Converting from Automatic to Manual

Postby Morgonzo » Mon Nov 20, 2017 12:48 pm

Killer post. Very educational and yet paranoia inducing at the same time :-( . Can the nut work itself loose even if you don't use 5th? Our van has started to make a low hum/rumble from the rear end but only in 5th on the hwy. The only way to check for sure is to remove the t-case?
The "Zanimo Wagon" 1988 Mitsu Delica L300 StarWagon P25W 5spd :M
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Converting from Automatic to Manual

Postby Growlerbearnz » Mon Nov 20, 2017 1:38 pm

Morgonzo wrote:Can the nut work itself loose even if you don't use 5th? Our van has started to make a low hum/rumble from the rear end but only in 5th on the hwy. The only way to check for sure is to remove the t-case?


Yes, the nut can come loose in normal use, and is theoretically more likely to come loose while using the lower gears as there's more torque. The mainshaft twists when it transmits torque, which unscrews the threaded part of the nut, while the outer edge of the nut is held in place by the stack of bearing sleeves and gears it's clamping.

Once the nut is loose, driving in any gear *except* 5th causes damage. When you're in 5th, the 5th gear is locked to the mainshaft and so the bearing isn't turning. In any other gear the 5th gear will be turning relative to the mainshaft, which lets the bearing sleeve also turn, which chews into the mainshaft.

A noise in 5th could well be 5th gear being loose (and it's worth checking now because the consequences aren't pleasant), but it could be something else that only shows up when the engine's quiet(er) and speeds are high; U-joints, diff bearings, wheel bearings.

Even if the nut is loose, you can probably repair 5th by taking off the extension housing, saving you from having to remove the whole gearbox. You'd need a new needle roller bearing, sleeve, retaining washer, and nut. Oh and some retaining compound for the new sleeve (presuming the mainshaft isn't too far gone).
Nothing says "poor workmanship" more than wrinkles in the duct tape.

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Converting from Automatic to Manual: Manual gearbox rebuild

Postby Morgonzo » Mon Nov 20, 2017 5:54 pm

Thanks for the info GBNZ. I'm going to look into this asap. So the rework of the needle roller bearing and the sleeve and all that can be done with the trans in the van? Do the KM145 and the V5M21 share the same housing? just different ratios in the case? One could be swapped for the other?
not that one is easier to find than the other here......
The "Zanimo Wagon" 1988 Mitsu Delica L300 StarWagon P25W 5spd :M
"Zowie Zow!" :-D

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Converting from Automatic to Manual: Manual gearbox rebuild

Postby Growlerbearnz » Tue Nov 21, 2017 2:58 am

Morgonzo wrote:So the rework of the needle roller bearing and the sleeve and all that can be done with the trans in the van? Do the KM145 and the V5M21 share the same housing? just different ratios in the case? One could be swapped for the other?
not that one is easier to find than the other here......


All the 5th gear work can be done with the gearbox in the van. If you have a KM145 consider removing the gearbox and replacing the input shaft bearing too, as they can be troublesome.

The housings are identical, as far as I can tell. The gearbox model number is stamped at the top of the bellhousing, where it collects dirt and is almost impossible to see. The entire gearboxes could certainly be swapped. Swapping only a few internal parts might be tricky, as some of the bearings changed.
Nothing says "poor workmanship" more than wrinkles in the duct tape.

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Converting from Automatic to Manual: Manual gearbox rebuild

Postby Growlerbearnz » Fri Nov 24, 2017 12:26 am

Some more notes on converting from one to the other:

Gearbox wiring. I kept my existing automatic wiring. I had to connect the two large black wires together (black/yellow and black/white) to bypass the start inhibitor. I connected the manual gearbox's reverse switch to the blue and red/blue stripe wires. Because the manual gearbox is a bit shorter than the auto, I had to unwrap the wiring loom between the front fuel tank and the transfer case switches and re-wrap it to make it a bit shorter.

Speedometer cable: the auto's speedo cable is longer than a manual's. I thought about swapping to the shorter cable, but it's a nightmare to remove. In the end I re-routed my existing cable around the outside of the front fuel tank (above the side step brackets), which used up the excess cable length and kept any bends in the cable nice and smooth.

Instrument cluster: there are a vast number of different instrument clusters available. My old cluster was for an automatic, diesel, 4wd, with hub lock light. The parts van was a manual, petrol (wrong rev counter), 4wd, without hub lock light.
In the end I bought a 2wd manual diesel cluster from the wreckers which gave me the correct rev counter face. I swapped the gauge face onto my old instrument panel and simply removed all the PRNDL bulbs. The circuit board on the back needs to match your wiring if you want all your existing features to keep working...

First impressions: the automatic's torque converter did a *really* good job of hiding the epic turbo lag. There's *nothing* below 1500rpm. First gear is rather short so if you don't wind it out to 3500rpm before shifting to 2nd the engine just falls flat on its face. With the automatic traffic light drag races were fun (which means I'd surprise people- up to 60kph) but I don't think that's going to happen much any more. I'll try adding more fuel at low revs to get the turbo working sooner, but I'm not optimistic.

The van feels really truck-like with a manual. Vrooooooomm... (pause, shift)... vrooooomm... I'm sure I'll get the hang of it, and not having to worry about breaking the transmission is nice, but right now it feels like a bit of a step backwards. My advice: keep your automatic if you can, just don't tow in overdrive. Especially if you've done silly things to your engine.

One final observation: my van only just clears the door to my workshop. After removing the automatic transmission (and associated fluid-cooling accessories) the van was so high it wouldn't fit out the door again. I had to let the tyres down. Reliability plus less weight plus suspension lift? I guess that's a win.
Nothing says "poor workmanship" more than wrinkles in the duct tape.

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Converting from Automatic to Manual: Manual gearbox rebuild

Postby lrp374 » Fri Nov 24, 2017 10:14 am

Looking @ what you had do do reminded me I forgot to ask if you swapped the upgraded turbo when you changed engines?
( Wrong post I know but this works better than my short memory!)

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Converting from Automatic to Manual: Manual gearbox rebuild

Postby Growlerbearnz » Fri Nov 24, 2017 12:35 pm

No, I kept the new engine's standard turbo as it's water cooled. It seems to do just fine up to 17psi.
Nothing says "poor workmanship" more than wrinkles in the duct tape.


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