input shaft bearing

Input Shaft Bearing Replacement

if you are able to remove the gearbox, chances are you have the ability to replace the input shaft bearing. But be warned, as you might notice there are two gearboxes pictured on this page, this is because I snapped a syncro ring rushing the reassembly of the first one. So learn from my stupidity – and take your time. If you’re taking a box apart for the first time, get a spare box and work on that.

here's a picture of what we are starting with, it's an L3 gearbox taken from a UK CRX 1.6 16v, approx 1988. I’m told reliably that the Y1 & Y2 boxes have a similar layout, but I’ve not cracked open my spare Y1 yet. If it’s any different I’ll write a separate page (one day)

note the box is supported on blocks of wood, this is because the input shaft stands slightly proud of the mating face.

obviously to replace anything inside the box, we are going to have to take it apart. strip all the bit and pieces off the box (mounting plates etc) then remove the dozen or so bolts that hold the bell housing on (arrowed)

(I was trying to decide which colour arrows to use here)

next thing to do is to get access to the snap ring. don’t worry if you don’t know what a snap ring is, we’ll soon see it. to get to the snap ring, using a 3/8th’s socket wrench, undo the nut thingy arrowed. it’s usually pretty tight, get a strong friend to help if you are struggling.

underneath the nut, you’ll see the snap ring:

take a look at it (I’ve drawn over it so it stands out) , later you’ll need to expand the snap ring, I did this using a pair of needle nose pliers. but first there’s other things to do:.

before we split the box, we need to remove a bolt (it’s there to lock the shift mechanism).

turn the box on it’s side and look at the end where the input shaft is. you’ll see the allen bolt, (I think it’s 8mm) remove the bolt, it’s usually on pretty tight.

that done, turn the box over so it’s input shaft is facing the ground, making sure it’s on blocks still.

right, so now the only thing holding the bell hosing to the main casing of the box is the snap ring, AND whatever sealant Honda used when they built the box. in general they seem to have used some kinda high strength glue as a sealant. Haynes manuals would probably say something like ‘gently prise the bellhousing from the main casing’. In the real world a cold chisel on the joint and a bloody big hammer will eventually open up a small slit between the bellhousing and the casing. (note if you damage your gearbox casing, it’s your fault. don’t come blaming me if you hit it too hard!)

once you’ve opened up a small slit between the bellhousing and the casing, shove a screwdriver into the slit.

now it’s probably best to go and get a helper at this point. (ask your girlfriend to help, it’ll make her feel wanted.)

get your girlfriend to lever (gently) on the screwdriver to prise the case open, whilst at the same time you are opening up the snap ring. first time I did this it took a good 30 mins! just keep at it.

eventually the bellhousing will just ‘pop’ and lift off the snapring. It will probably only lift about 5-10mm so now you’ll need to lever a bit all round the box, just do it a bit at a time, until the bellhousing can be lifted clear of the main casing.

once the bellhousing is lifted clear, you should see this:

don’t worry, nothing should spring out. now’s a good time to check the magnet (orangey brown arrow) remove it from the box with pliers. expect some oily filings to be stuck to it, but there should be no actual pieces of metal. wipe it clean and refit it to the box

thought it best to explain what each bit is now:

the pink arrow is pointing at the diff / crownwheel assembly, the yellow at the input shaft, the blue the countershaft.


next step in taking the box apart is to remove the brass bolt, it’s just at the end of the pink arrow above. this will release the shifting mechanism, so we can lift out the input & countershafts.

before we can lift them out we need to remove the reverse idler gear, here’s a piccy:

remove the two bolts arrowed yellow. You can then remove the arm assembly. Once the arm is clear lift out the reverse idler gear and shaft (red arrow) note which way the reverse idler gear goes up.

this is now the point where the main shaft’s can be lifted clear, but before you do take a good look at the input shaft, the gears are not bolted onto it and will slide off if you’re not careful. I usually put a couple of zipties over the top of the bearing and looping lower round the shaft so the gears can’t separate at the wrong moment.

okay so we’re ready to lift out the input shaft and countershaft. before we do, lay some clean rags or an old towel down to put them on.

take a good look at the shift mechanism (the bit the brass bolt came out of), make mental notes as to how it is assembled. you’ll need to know this later.


righto, now for the fun bit. both shafts, including the shift forks, will be lifted out together. grip round both shafts and the shift forks and lift them clear of the box.

You should then have a gear assembly, like the left picture, and a box like the right pic:

You can leave the diff assembly in the box, but it gets in the way. I would recommend lifting it out, it seems to be only held in by the viscosity of the oil in the box. Every one I’ve come across can be lifted out with one hand lifting at the centre bearing. If you are gentle will it lift out easily, trying to force it out takes three times as long and risks damaging the box.

Once it’s out it looks like this:

Obviously, it doesn’t take a genius to figure out, you could swap an LSD in at this point.

Okay so the box is stripped, you should have a pretty bare main casing, like mine: