Installing a clutch and gearbox

[Adam]

The time had come for my clutch to be replaced on the rally Gemini. Prior to this photo being taken at the Caltex Airport Starmart rally I performed all the work described below to get the new clutch in.



The previous clutch (supposed heavy duty) was not wearing well and causing a little bit of slippage. As you can see when I taken out, I found that it had been scoring the face. I did not take a picture of the clutch plate, but needless to say it and the diaphragm face did not look good.



First things first.

Get the car into an under cover area or on a flat piece of ground. It took 2 weeks to get the clutch from the supplier due to their work load, so you will need an area that is not highly trafficked, cause once it’s on blocks you don’t want to move it.

Look at what you have to do and plan. If you have a manual, this will help, and if you have a friend or 2 even better. Get some Ice cream containers or other suitable containers to hold parts / nuts bolts etc.

Check bolt sizes and get the correct spanners, sockets etc. Have a spare container to collect oil if it spills from the rear gearbox seal when you go to remove the drive shaft. Get some rags or such to place under the car just in case.


Time to enter the car.

You may have to remove the gear lever surround if one is installed. This is held on by 4 screws that screw into mounting points which are bolted to the transmission tunnel. 2 at the front in the foot well, and two at the rear near the seats. Unscrew the gear knob and untie the lever boot, if it is tied. If not, then you should be able to slide it out over the gear lever. Place the 4 screws you removed into this and the gear knob and put it aside. There are two plastic boots to remove now. The first stops the mud and crud from entering the passenger compartment. Remove this and take it over the gear lever. The second protects the gearbox from crud. Remove this and twist it around so as to get access to the three bolts holding in the gear lever on a late model box or 2 on an early box. It will not fit up and over the gear lever if it is not split. Put the car into neutral and then remove the bolts holding the gear lever in. Be warned as there is a spring inside. Remove the gear lever and put the bolts with the gear lever on a work bench, or in a rag. Plug the hole with a rag so as not to let dirt in, or oil out if it falls over.

Open the bonnet and undo the bolts that hold the clutch cable against the firewall. There are 2 of them at 17mm. You can mark where both are with a marker before undoing them, and this will help when you reinstall. Disconnect the Clutch return spring, and place it in one of your containers. Also remove the now loose clutch cable from the pivot arm, and push it through the guides towards the front of the engine. Also disconnect the Speedo cable. It is not too hard, but may require a large jaw set of pliers to get it started. Be careful not to loose the plastic washer that is inside the housing. Place this washer in the container with the spring. Also undo the wires that connect to the gear box. One is the reverse lamp wire, and the other if you have it on a 5 speed is the overdrive switch. This has something to do with emissions. The wires are red and black.



Now mark the drive shaft where it meets the rear yolk. This will enable you to line it up, when you go to install it. It will also mean that if both the yolk and shafts have mated and become slightly out you will not upset them when reinstalled. Note the score marks on the drive shaft plate and the yolk. They are shiny and look like they are reflecting the flash. These were made with a piece of hacksaw blade. I have a permanent mark here, and just clean it when I do the removal.



As you can see the bolts are removed already. These are 12mm if memory serves me right. Put these bolts in another container that stays at the rear of the vehicle.

You can at this point also remove the drive shaft and get ready with speshell tool No. 12598. It is a cut down drive shaft, and acts as a plug.

Prise the drive shaft away from the yolk with a large screw driver. It is hard, as the spring that is in the drive shaft end that enters the rear of the gear box inside the spline is pushing it out.

Before pulling the drive shaft out of the gearbox, ensure you have your speshell tool in hand, as well as you oil catching container. In one swift manoeuvre, take out the drive shaft and install the tool. Note if the spring has come out with the drive shaft and keep it with the drive shaft. Any oil spilled will be caught by the container or drip onto the rags you have under the car. Note that oil may well be inside the spline housing, so be careful. Oh and yes Diff and gear oil stink. I like the smell, but it is hard to get both the smell out of your hands and clothes if you spill it on yourself. You can drain the box at this time. It contains about 2 litres of oil. Be careful of the sump bolt, as it threads into alloy and you do not want to stuff the thread.


The time has now come to undo the bolts that hold the gearbox to the engine. What I have found to be good is when taking them out, number where you took it from with a texta or marker, and then wrap some masking tape around the nut and bolt and write the corresponding number on it. When you go to put them back it makes the task so much easier. Travel around the tunnel in any direction undoing the bolts, but do the numbering. Once all the bolts are out, be prepared for the starter motor to fall from where it is. You can get an old wire coat hanger cut up to produce a hook and hang it out of the way in the engine bay. You must also undo the exhaust from the manifold or remove the manifold and push the exhaust to the passenger side. If you do not do this, then the gear box will not come out easily.

Now with you trusty jack, you can get under the car and place it as a support under the gearbox. You can now undo the four bolts 14mm that hold the rear of the box to the transmission tunnel and place them in one of your containers.



With the help of you friends you can now start moving the gear box back from the engine. Be very careful not to drop the gearbox down on an angle, until it is out of the clutch and rear end of the engine or you could bend the input shaft.

You will then have it out and standing on the jack hopefully. Be patient, cause some times they are a pain in the arse to get out. Note the board under the jack. This enables the jack to move more smoothly on and around the floor. You can also see the speshell tool No. 12598 installed. Be careful not to let it fall as gear oil will go every where.



You can now move the gear box from under the car to the bin or another car if it is a 4 speed and bring in the 5 speed or Diesel box. You can see the new thrust bearing installed, and all the crap which is normally inside the box, has been cleared out.



The early models had an old fashioned design gearbox that had a separate layshaft with loose needle roller bearings. This gearbox can be easily identified because it has a bolt on cover plate on top of the main case. The later type gearbox has the gear shafts assembled on a centre plate which is sandwiched between the main case and the rear extension housing. There are no cover plates. This type of design is much more modern and the separate pressed on ball race bearings give much more reliable performance than the old design.

Both design gearboxes are interchangeable, but some of the late model gearboxes have fine spline output shafts – you would need to get the tailshaft as well if fitting one of these gearboxes.

Tis now time to unbolt the clutch.

There are six bolts holding the clutch and plate to the flywheel. You can undo all 6 without fear of the plate landing on you, as there are 3 aligning lugs. Now remove the clutch from the fly wheel and toss it, or return it to get your money back on the exchange system most clutch places seem to have.

You are now ready to remove the flywheel. Most places will not guarantee your new clutch if you do not re-face the flywheel. I cannot remember the size of the six bolts that hold the flywheel. To undo these bolts, you can utilize the gear teeth of the wheel as a brace. Get a square barrel screw driver, and line up one of the bolt holes from the gearbox with the gear teeth and this will not allow it to move. This then allows you to undo the bolts without the fly wheel turning. Make sure you undo any spacer or lock washer tabs before undoing the bolts. Place these bolts in your container.



Time to put the new bits in. These bits were obtained from Race Brakes in Sydney. Pretty red, petty you don’t see it when it is installed.

You also now have your machined flywheel and are prepared for the install. With all bits in hand you should clean out the threaded areas on the flywheel, as well as the rear end of the crank. Use WD-40 and squirt it in. Clean it out with a rag and repeat till reasonably clean. Also clean the clutch and flywheel bolts as well. It means everything will mate up easier and stay in place also. You can use a small drop of clean oil on the threads when you do up the bolts. Do up the bolts as specified in the manual and to the correct torque settings.

You should also replace the spigot bearing at this stage. About $3 if I remember.

On goes the flywheel. This one is a special made for circuit racing. Quicker spin up time, and seriously lightened. It is mated up to an auto flex plate so it can still be started.



Next is to install the clutch and plate. You will need an aligning tool. The manual tells you how too make one, and that can be seen in the next photo. The clutch and plate will only go on one way, as the aligning spurs are setup this way to match the clutch.



You are now ready to put the box back in.

Installation is the reverse of removal, and taking it out gives you an idea of how to put it back in. You should jack up under the front of the engine to give it a slight lean towards the rear of the car. This helps the install a great deal.

Be very careful again when putting the box in so as not to rest the spigot shaft on the clutch. Be careful also not to crush the fuel and brake lines when pushing up the box.

When you have it mated up, you can use G clamps to pull the two pieces together, as illustrated.



You are now installed. You just have to put the ancillaries back on, the reverse and fifth gear wires, the Speedo cable, not forgetting the plastic washer and the clutch cable.

Get ready with the drive shaft install. If you have changed from a four to a five speed, check the lengths of the drive shafts, and use the shorter one if there is a difference in length.

Install the exhaust again, and re-attach the clutch cable. It would not hurt to install a new one, unless you know how long the old one has been there.

If you drained the oil from your box, you will need to fill it now. I have filled it through the gear lever hole in the past. People have advised not to do this. I cannot fathom out why. You now need to put the gear lever back in as well as the boots, and then the lower console.

All that done you should be able to fire it up and set the clutch properly.

Best of luck.

[martin]

I would really like to see the photos from this if they are available?

[Steven]

Alternative to stopping rotation is to bolt a length of chain between gearbox mounting hole on block and diaghram locating hole in flywheel. Also, remember to disconnect battery before undoing starter.

[Thirsty]

The photo of the 'G' clamp is not as described... All the clamp is doing is holding the bolt not holding the housing against the block?!!!!!But it is a good article nontheless.
Thirsty

[GEMGEM]

Do u have any more information on the custom flywheel! From what I can see the auto flex plate is used and a new face is machined to adapt to the flex plate, Ie: Do u have ne drawings of the adaptor part at all, how much in machining time were u up for! Thsnks for sa great post!
I'll remember that G Clamp Idea!

[rodeo bob]

when removing the gear stick you could just undo the four bolts straight onto the gearbox and leave the spring loaded part all together. its easy enough to do just ensure to put a rag in there (or better still the remote selector off a shuttle) to keep the crusties out. get the gearbox warm and drain the oil first over night gear oil is shit stuff when its cold. lining up the clutch for reassembly is easy enough to do by eye. assemble it all up and do the bolts on the pressure plate up just enough to hold the friction plate and get a screw driver and slide the plate around untill it looks nice and central. if u were real worried about it not lining up a dummy shaft can be made up easy enough out of wood in a lathe (u dont need the splines) or aluminium if u got the gear. just make one end a good firm fit in the spigot and the other a close fit in the clutch plate. ive done it the above three ways on various small to med trucks and cars. a 70kg twin plate semi clutch now thats the bugger u need a tool for.

[rodeo bob]

i should have mentioned last time before i trick someone into getting all up side down under their car peering into the little dark hole use the outside of the pressure and clutch plates as your guide then check the centre. 99.9% of stock clutches have the same diameters on the outside of the clutch and pressure plates. as i found out yesterday that the only factory 1.8 & 2L in the rodeos were the G180 & G200 (not 4Z motors) in theory u would think the rodeo clutch a bit beefeier and it should fit in a gemini. can any one confirm this??????? ive one here in altona (melb)if some one has a gem one and would care to come over and investigate. im here to help the cause.

[Poida]

I see everyone mentioning GEAR OIL in the Gemini box...

Gears stiff to shift????

When you refill it, try using SAE-40 ENGINE oil instead of that smelly gear oil! I use Penrite HPR30 and it shifts as smoothly as one can expect a 20+ year old box to shift.

Yep the correct oil to use in these Isuzu MSG gearboxes is engine oil, NOT gear oil. Read your glovebox user manual or workshop manual.
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