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Old 04-01-18
Jase3444 Jase3444 is offline
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Default How to replace clutch in Pajero NS - NW

Hi Guys,
I've just replaced the clutch in my Pajero NS at home. Prior to having a crack at this, I did a fair bit of digging around on Pajero forums and couldn't find any decent advice on this job. I did find though, a lot of misconceptions about removing Pajero Gen 4 gearboxes and clutch replacement, i.e.:
  • always take the job to a mechanic
  • the job is too difficult to do at home (on the garage floor) because the gearbox/transfer case is too heavy, unbalanced and needs many hands to remove and replace
  • mis-aligning the clutch will cause shudders (this cannot happen as the clutch must be aligned to get the gearbox back in!)
There are certainly some challenges having a go at this job yourself as the Pajero gearbox is tightly fitted to the firewall and getting the gearbox back in requires at bit of dicking around with the engine block/car angles. Regardless, this job is no more difficult than any other 4wd that I've played with, and I thought I would write up my experience to help others who may be looking to do a clutch replacement down the track.

The following instructions are just based on my experience, I'm sure there's more efficient/better ways to do this job. Note: it's critical that you have access to a workshop manual to obtain the bolt torque settings etc.

Apologies if this topic has already been covered.

Cheers
Jase

Last edited by Jase3444; 04-01-18 at 09:09 AM.
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Old 04-01-18
Jase3444 Jase3444 is offline
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REMOVING THE GEARBOX

The first thing to do is to remove the driveshafts. You need to do this job while the car is on the ground as you will need to roll the car forwards/backwards to access the bolts on the driveshaft connections to the diffs. Make sure that you mark the drive shaft connections/flanges so that they go back in the same position.

Rear driveshaft - empty the transfer case oil before removing the driveshaft as it will bleed out through the shaft.

AC604828AB00ENG.png

Front driveshaft - you will need to lower the rear cross strut under the motor to remove this driveshaft. Place a trolley jack under the strut and remove the bolts at either end (two at each end). Lower the strut with the jack and remove the driveshaft. Reconnect the strut - I just stuck some smaller bolts back in to hold it in place as it will need to be lowered again to re-install the driveshaft.

After removing the driveshafts, I lifted the car onto blocks using two 70mm pine sleepers under each wheel. This gave me plenty of space under the car to work (plus the suspension is already lifted by 40mm).

Remove the two exhaust sections under the gearbox - easy.

Remove the gear lever assembly from inside the cabin - I first removed the drivers seat as this gave me easy access - 5 min job. Remove the gear lever knobs - screw them off. Then access the center console cover attachment screws by removing the cup holder (gently prise up with a flat screwdriver). Remove the console center cover (over the gear levers), unplug the electrical connections on the 4wd selector, remove bolts and remove selector unit. Remove bolts from gear lever shroud, peel back rubber boot on connection to the gearbox, remove the circlip and remove gear lever assembly - easy.

Detach the clutch slave cylinder from the LHS front side of the gearbox and tie onto chassis. Disconnect the water hose mount plate on the RHS front side of the gearbox.

Disconnect the clutch release bearing from the clutch cover:
- remove the bell housing access boot on the RHS
- insert a flat head screwdriver into the gap between the clutch release bearing and the clutch cover
- twist the screwdriver whilst the clutch bearing is tight against the clutch cover. This should separate the two.
Note: I didn't need to do this step as the clutch release bearing had already separated from the clutch cover (disintegrated is probably a better description). There's a stack of information on disconnecting 'pull type' clutch release bearings on the internet, so hit Google if you need more help on this task.

Disconnect the cable (between the transfer case and chassis) at the LH rear of the transfer case. Disconnect the earth strap connected to the transfer case.

Place a trolley jack under the transfer case. I used a standard jack with a block of wood. Disconnect the gearbox cross strut from the chassis - two bolts on either side. Lower the gearbox down approx. 5-6 inches. Disconnect the electrical connections on the gearbox/transfer case and the two wiring loom connecting brackets (12 mm bolt heads on top left). Cable tie the loom to the chassis to keep it out of the way.

While the gearbox is lowered, remove the top four bell housing-engine block mounting bolts. These are easy to access via the top of the gearbox using extension bars (tI used a couple of long ones to get to the bolts ~ 1.3 m). Remove the lower mounting bolts (x4).

Place another trolley jack under the bell housing to support the gearbox. I used a block of wood on top of the jack.

Given the size of the gearbox (and all the online commentary about its weight and balance), I used a portable engine hoist and heavy duty strap through the drivers door to support the center section of the gearbox, and to have a backup in case it flipped/fell when removed. In hindsight, this wasn't really necessary. I also placed a stack of wooden blocks on either side of the gearbox cross strut to support it if it tilted/dropped to one side (most likely the LH side)

Hoist.jpg
Support.jpg

Place a wooden chock between the engine block and the rear cross strut to support the engine when the gearbox is removed. This involves raising the transfer case end a little, chocking the engine and then lowering the jack to rest the engine on the strut.

Strut chock.jpg

Remove the remaining mounting bolts from the bell housing. Gently 'crack' the gearbox from the engine block using a screwdriver/jemmy bar. Lower the gearbox when the bell housing has cleared the clutch assembly.

Gearbox disconnected.jpg

I used a hand winch to pull the gearbox back towards the rear of the car - you don't need to do this but I found it to be useful working solo.

Winch attachment.jpg

Observations - the gearbox nicely balanced on the two trolley jacks. It didn't end up tilting to one side (as I had expected). Once on the floor, I supported the gearbox with blocks.

More to follow..

Last edited by Jase3444; 05-01-18 at 09:54 AM.
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Old 04-01-18
Jase3444 Jase3444 is offline
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REMOVING THE CLUTCH ASSEMBLY (INCLUDING FLYWHEEL & REAR MAIN SEAL)

I ended up moving the gearbox about 60cm to the rear of the vehicle so that I could sit and work comfortably in front of the clutch assembly.

Gap between gearbox.jpg

Remove the clutch cover bolts. You should be able to do this without locking the crankshaft. Remove the clutch cover and disc. The clutch cover may be 'stuck' on the guide pins so a screwdriver may be needed to lever it off.

Old clutch cover.jpg

Next the flywheel needed to be removed as I was swapping out the dual mass flywheel to a single mass flywheel. The flywheel mounting bolts can be a pain to remove on some vehicles and it is often necessary to lock the crankshaft to prevent it from turning whilst removing the bolts. I used an air impact gun to remove the bolts - they came out easy without locking up the crackshaft which was great. I've had a lot of trouble in the past removing these bolts on other vehicles and I've found that using a single hex impact socket is generally better to avoid rounding off the bolt heads.

The flywheel didn't take a lot of persuasion to remove. Its heavy and I recommend placing a pad either on your legs or the floor prior to removing the last bolt in case it drops like mine did (placing another chip in the concrete floor).

Once removed, it was fairly easy to tell that the clutch assembly and flywheel were knackered. The flywheel was covered blue blotches indicating where it had overheated and it was noticeably loose (dual mass). I suspect it was probably the original DM flywheel.

Old clutch.jpg

I had tossed around the idea of replacing the rear main seal whilst the flywheel was removed. Mine wasn't leaking however I wasn't sure it was the original one or not, and with 240,000 kms on the clock, it would be sure to leak if I didn't replace it. Advice from local mechanics ranged from 'don't touch it if it's not leaking' to 'you would be a fool not to replace it'. In end I decided that I'd change it over. I'm not fussed about using genuine seals vs off market ones, so for $30 it was a no brainer from my local spare parts guy.

The seal was removed by carefully wedging a flat headed screwdriver around the edges and gently prising the seal out. Being a large seal, it came out reasonably easy.

Last edited by Jase3444; 05-01-18 at 09:58 AM.
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Old 04-01-18
Jase3444 Jase3444 is offline
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INSTALLING THE REAR MAIN SEAL, FLYWHEEL AND CLUTCH ASSEMBLY

Clean the rear main seal retainer and crankshaft prior to installing the seal. Also check the surface of the crankshaft as this can get scored by the seal as it gets harder over time.

Crank.jpg
Lip.jpg

Thankfully, the surface of the crankshaft was smooth so no worries. I've encountered 'grooving' in other vehicles which necessitated mounting the rear main seal either slightly further in or out of the mount to avoid the groove.

Wet the inner edge of the seal with engine oil and place it into position. I used a piece of pine to gradually knock it in. Care must be taken to avoid damaging the seal, particularly the inner lip. The seating position is fairly obvious as the seal is mounted more or less flush with the engine block surface.

Seal installed.jpg
Wooden block.jpg

Clean the surfaces of both the flywheel and clutch cover to remove any protective films that may have been placed there to prevent rust etc. For this, I used oil and wax remover (a fair bit of crap come off the surfaces).

New flywheel.jpg
New clutch cover.jpg

To fit the flywheel, use two of the old bolts to attach it to the end of the crankshaft. I made a retaining bracket out of some spare strap iron. This was attached to the one of the clutch cover mounting holes on the edge of the flywheel and to one of the gearbox mounting holes on the engine block. The bracket prevents the crankshaft from turning whilst torquing up the flywheel mounting bolts.

Flywheel bracket2.jpg

The flywheel came with new mounting bolts. The tips of the bolts were covered with a red film. I assumed that this was probably some kind of retaining compound however I decided to coat them with Loctite thread retainer just to be on the safe side.

New bolt.jpg

There's a couple of options for the Loctite thread retainer compound - blue vs red. I decided to use the blue as it's apparently less permanent than the red one. It's a matter of personal preference - worth doing your homework.

Loctite.jpg

Tighten the flywheel bolts to specification using a torque wrench - note: they need to be done up very tight.

Attach the clutch assembly - cover and disc. Make sure that you mount the clutch disc the right way round. Best to double check the workshop manual to ensure the correct direction. NOTE: test fit the clutch disc to the main drive shaft on the gearbox to confirm that you have the correct disc. At this point, it would be worthwhile greasing the drive shaft spline (refer to my comments in the next post).

Loosely fit the clutch assembly using the mounting bolts. I used a dab of Loctite on these as well. Using a clutch aligning tool, align the clutch disc with the spigot bearing (bearing in the middle of the flywheel). I understand that some clutch kits come with an alignment tool, but I already had an alignment kit to suit various spigot bearing diameters.

Alignment.jpg
Alignment2.jpg

Taking extreme care to align the clutch disc, tighten the clutch cover bolts to lock the clutch disc in place. Tighten the clutch cover bolts to specification using a torque wrench.

Clutch cover.jpg

The clutch assembly is now ready for mating to the gearbox.

Ready.jpg
Attached Images
File Type: jpg New seal.jpg (88.4 KB, 33 views)

Last edited by Jase3444; 05-01-18 at 10:03 AM.
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  #5  
Old 04-01-18
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Silver Bullet Silver Bullet is offline
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This is absolute gold! Thank you Jase for taking the time to document this.

I know you’re still part way through posting this but I’m keen to know how long each of the steps took to complete.
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Old 04-01-18
Jase3444 Jase3444 is offline
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Hi Silver Bullet,
Thanks for the positive feedback. It took a few days to sort out as I have been distracted by the Xmas break. I'd say no more than 4 hrs to knock the gearbox out - stuffed around with the front strut trying to remove the front driveshaft but then easy going. Maybe 2.5hrs mucking around with removing and installing the clutch assembly, flywheel and rear seal. Then came the fun, getting the gearbox back in probably another 5hrs - mainly due to access issues as I'll outline in my final post. It would have been much quicker had I known more about the engine vs gearbox alignment. If I were to do it all again, one day max.
Cheers
Jase
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Old 04-01-18
Jase3444 Jase3444 is offline
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GEARBOX INSTALLATION

OK - here's where the fun started! This is where my experience might help others with the gearbox re-installation.

Replace clutch release bearing:
- remove bolt holding in the clutch release fork shaft
- knock out the sealing cap (welch plug - RHS of bell housing) from the inside using a rod and hammer. This can be re-used if you are careful.
- slide the clutch release fork shaft out
- slide the clutch release bearing forward with the release fork and remove
- clean them up, grease the fork shaft and re-install with new clutch release bearing
- re-install the sealing cap using a socket and hammer (there's a cut edge around the hole which will guide the installation depth

Clutch fork.jpg

Greasing the main drive shaft splines - there's a lot of debate about whether to grease the main drive shaft splines (shaft coming out of the gearbox). Too much grease and it could fling into the clutch assembly and give you major grief. Some guys dont worry about grease at all. The factory manual recommends lightly greasing the splines. I applied a light coating of grease. Using a toothbrush, I wiped it up and down the splines then used a rag to lightly wipe the excess off paying attention to the ends. Ideally, this step should be done prior to fitting the clutch disc. Moving the disc over the splines will collect any excess grease which can be removed.

Aligning the gearbox with the engine - clearly both ends need to be 100% aligned for the gearbox main drive shaft splines to mate with the clutch disc splines. This is where the Pajero set up makes life difficult. If the vehicle is perfectly flat (i.e. all four wheels are sitting at the same height), then the rear of the engine block needs to be angled down to allow the bell housing to fit in under the firewall. This means that the gearbox needs to be moving backwards and upwards at the same time to slide it into the clutch assembly. This is where four blokes standing under an engine hoist come into their own, however if you are like me, and working from the garage floor, it is impossible to achieve.

The solution! The rear of the vehicle needs to be elevated at the rear end. This means removing the blocks from under the front wheel wheels and placing them under the rear wheels so that the rear of the vehicle is approximately 30cm off the ground.

Elevation1.jpg
Elevation2.jpg

Level the engine block so that the face of the clutch assembly is 100% vertical (using a level). This is done by jacking the engine block and placing spacers (e.g. wooden blocks) between the engine block and rear cross strut. This took a little time to get right but it is critical to get the motor level if you are to slide the gearbox on.

Engine chocks.jpg

Place the trolley jacks back under the front and rear sections of the gearbox and slide it forward until the front of the gearbox is almost level with the face of the clutch assembly. At this point, the gearbox can be carefully raised to be level with the engine block. It may be worth placing wooden blocks under the gearbox cross strut just in case it decides to come off one of the jacks.

Supporting the front.jpg
Supporting the rear.jpg
Matching gearbox.jpg

Once the gearbox is level with the engine block, very carefully move it forward (5cm max) so that the front of the gearbox main drive shaft is level with or just penetrating through the hole in the middle of the clutch cover but not touching the clutch disc. You can view the position of the drive shaft through the release fork opening on the LHS and the access port on the RHS of the bell housing using a torch.

When the drive shaft is roughly centered though the hole, check the gap between the bell housing and clutch assembly to ensure that there is an even gap - re-center the drive shaft/gearbox if the gap is not even.

Measure the gap between the mating faces of the engine block and bell housing. This will indicate whether the gearbox needs to be moved L or R at the rear, or up and down from the rear (using the trolley jack).

When all of the gaps are even and the drive shaft appears to be correctly centered, move the gearbox forward slowly. To do this, I got under the rear of the car and pushed on the transfer case with my feet.

If you are extremely lucky, the splines might match and the gearbox will slide forward. If you are like the rest of us, the gearbox splines will be mis-matched or the gearbox mis-aligned.

Patience! The first thing to do is to check whether the drive shaft splines are aligned with the clutch disc splines. For this, I used a telescopic mirror placed into the bell housing through one of the openings and shot a torch onto the mirror to illuminate the splines. With some patience, you will be able to see the splines and whether they are matching. If they are not matching but the drive shaft is centered, carefully rotate the main drive shaft and align the splines using a long screwdriver (taking care not to damage the splines).

Once the splines are aligned (confirmed via visual inspection via the mirror), re-check the gaps between the engine block and bell housing. At this point, the gearbox should slide forward with minimal effort. If this doesnt work, go back and verify the alignment of the main drive shaft, spline alignment and gaps between the engine block and bell housing. I must re-emphasize that having both the engine block and gearbox perfectly level is the key to matching them back together.

Back together.jpg

Once the gearbox is back on the engine block, replace the mounting bolts on the lower half of the gearbox. Lift the gearbox slightly, remove the chocks under the rear of the engine block, lower the gearbox slightly and replace the top mounting bolts using the extension bars. Re-fit the electrical connections on top of the gearbox/transfer case while it is lowered. Raise the gearbox (from the rear) and re-connected the gearbox cross strut to the chassis. At this point, the rear jack can be removed.

Re-install the clutch slave cylinder, front and rear drive shafts, rear engine cross strut, gear levers, exhaust sections, top up the transfer case oil and you are away!

Observations - I discovered by trial and error that the rear of the car must be elevated to enable the engine to be leveled and for sufficient space to be left to fit the gearbox bell housing between the engine block and the fire wall. Had I been aware of this from the onset, re-uniting the gearbox with the motor would have been a breeze.

I sincerely hope that my post is useful and that removing and re-installing the Gen 4 Pajero gearbox at home is definitely a feasible task.

All the best! Jase

Last edited by Jase3444; 05-01-18 at 10:11 AM.
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Old 04-01-18
NJV6 NJV6 is offline
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Good job. I have done my gen 2 twice (same gearbox) replacing noisey throw out bearings and can do it in an afternoon when all goes well. Both times I have had difficulty getting the pin out that the clutch fork rotates in, being partially siezed in place. I have a couple of ‘Mitsubishi service tools’ that I have made to help with the job.
I also have a garage pit so makes moving the gearbox easy. With the gen 2 there is a permanent crossmember the torsion bars are mounted into that are useful as a rest for the gearbox when you pull it back.
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Old 04-01-18
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Great job

Fantastic resource for our members - well done.
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Old 04-01-18
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Jase: Thank you for that writeup. I sincerely hope that I never have to do this, but should the occasion arise, I have noted the writeup and will refer to it extensively
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