405 Gearbox Rebuild and Clutch Change

evilally · Post by **evilally** » 09 May 2010, 14:22

spider wrote:Assuming the cable is OK (probably self adjusting yes?) , its likely to be the springs in the cover (the 'fingers') , possibly someone changed the actual clutch disc itself but not the cover plate (a bad practise, should always change all three parts for best results)

Spot on, there's a big crack in the pressure plate!

evilally · Post by **evilally** » 09 May 2010, 14:31

Progress today.....

I started stripping down my gearbox. The first thing I noticed straight away is that the oil is like mud, and also smells distinctly different from the donner box. The oil in the donner box was spanking clean. The insides of this one are covered in black sludge.

A bit further, absolutley filthy:

A slight worry was that one of the casing bolts was non-standard. It was a hex and far too long for the job, it protruded a lot from the casing. Has someone been in here before?

Here's the shaft I'm hoping to swap, they look identical (donner on the top, mine at the bottom):

I'm confused about the synchro hub. Thye both look the same. How do I tell a worn one from a good one?

Gammy leg · Post by **Gammy leg** » 09 May 2010, 18:13

evilally wrote: I'm confused about the synchro hub. Thye both look the same. How do I tell a worn one from a good one?

I'd like to know this as well. I've got the 1st& 2nd hub from my Synergy ML5T box in the garage but can't honestly see what is wrong with it.

Gammy

Post by **CitroJim** » 09 May 2010, 18:53

Well done Ally

That's excellent progress. The fact the old oil is rough indicates it might be a little overheated. It should smell sickly sweet and with overtones of cat's pee.

Now, to tell if the hubs are worn. Ideally you need the hubs apart. Look firstly at the bit (the hub) in the centre of the picture below and look for the surface of the soft alloy being really shiny and possibly warped. On a good hub it should be possible to make out radial lines on the surface.

The second test is to check the mesh of the hub cone into the corresponding pinion. It should not push fully home and should grip the pinion very strongly. If it goes right in below the outer surface and does not effectively grip, it is well worn.

In use, the hub cone is pushed into the pinion to spin it up to speed so the dogs can engage easily. If the cone is so worn that it cannot effectively spin up the pinion before the dogs engage, you will hear a crunch.

You may also see "blueing" on the pinion where the hub has been slipping badly, leading to overheating.

Check too the "C" spring around the hub. this sometinmes breaks and results in a crunch.

The hub in the picture above is worn and your lower one looks worn to me.

Does that make sense. Hope that helps for the ML5 too Gammy. I've nit been inside an ML5 yet but I'd expect it to be similar.

evilally · Post by **evilally** » 09 May 2010, 19:22

Cheers Jim, I thought it smelled very strongly like old socks....perhaps we're thinking of the same smell. I'm thinking once rebuilt and everything's working again (touch wood), I'll run the box for 500 miles on new oil then change it in the hopes of cleaning it out.

I'll get out this evening and take another look at the hubs. I'll maybe post a close up for your expert opinion! Otherwise, do you think I can be lazy and just use the whole shaft from the newer box?

evilally · Post by **evilally** » 09 May 2010, 20:12

Ok, closer pictures of the hubs:

Am I looking at the bit I've indicated in the first picture? That one is smooth, and the one from the doner box has lines round it.

Post by **CitroJim** » 09 May 2010, 20:16

Old socks? Umm...

Then old oil might also have been black and sludgy due to having a good bit of the synchro cones ground up in it!

You should be Ok to use the new shaft compete provided the tooth count on the pinions are exactly the same. You'll have to check the bearing pre-load is right though and that's something I don't cover on my website. If you do use the new shaft complete, tell me and I'll tell you how to check the preload.

If you disassemble the shaft and reassemble it with a new synchro hub and use the same bearings, the preload issue does not arise. Trouble is, you do really need a press for this.

evilally · Post by **evilally** » 10 May 2010, 01:12

Advice on checking the preload would be much appreciated!

Post by **CitroJim** » 10 May 2010, 12:34

I'm sorry Ally, I missed your pictures a couple of posts up

Now, looking at the top one, Look to the left of your red arrow to the tapered part that disappears inside the pinion plate. You can see some radial lines on the surface and this is an indication that side is unworn. However the opposite side looks smoother and shinier.

Can you get a photo of the right-nad tapered part. It needs to be in sharp focus...

jgra1 · Post by **jgra1** » 10 May 2010, 14:28

good stuff Evilally.. hadn't seen this post till now.

does your camera have a macro setting? symbol looks like a tulip / flower? if it does, try taking a pic about 2 feet away from both shafts, should help.. sorry if this is all granmas and egg sucking

Post by **myglaren** » 10 May 2010, 17:53

jgra1 wrote:good stuff Evilally.. hadn't seen this post till now.

does your camera have a macro setting? symbol looks like a tulip / flower? if it does, try taking a pic about 2 feet away from both shafts, should help.. sorry if this is all granmas and egg sucking

With some cameras focus on the Macro setting is extremely limited, you have to focus by moving the camera in relation to the subject.

evilally · Post by **evilally** » 10 May 2010, 20:46

Ok, better pictures!

This is the shaft from my gearbox:

Shaft from doner box:

They both look ok to me

addo · Post by **addo** » 10 May 2010, 23:52

I feel the contact faces of the second gearset look far better condition. It could be the light, however.

evilally · Post by **evilally** » 12 May 2010, 18:58

If only Jim were about, maybe he could say for sure

Post by **CitroJim** » 12 May 2010, 19:40

I am here

Sorry

I thought I'd replied. Adam, you are correct!

Yes, if you look at the second and third pictures, you can see the radial lines on the soft alloy hubs and this usually indicates they are unworn but the acid test is how far they go inside the pinion cups. If they go right in but don't grip well then they will work poorly. They should, even when pushed hard in, have a tiny bit of the taper face still visible. Compare with the fifth gear assembly, which should be unworn.

A bad hub will be shiny smooth on the face and maybe warped too.

This is the full guide to checking a BE gearbox from an old 205 BoL. It is based on the BE1 but this is the same 'box apart from the lift-up reverse by first gear.

It is a big file and will take a couple of years to download on my slow link but it covers well the preload check and so on. You may find it useful but be patient!

can you put up pictures comparing old with new Ally?