Gearbox knackered
Discussion
Looks like I'm going to be replacing my gearbox in the 400SX.
On a drive to Tring it suddenly let go on the dual carriageway - well just as I pulled off at the sliproad. Managed to crawl it to my destination and had it recovered back home the next day.
Symptoms are rattling like a bag of spanners in 4th and 5th. When it was still hot it wouldn't go into the low gears but it was manoeuverable in 1st and reverse when cold.
I just checked the oil - what oil? It seems to have lost virtually all oil, so it's amazing it lasted as long as it did, must have been the Mobil and moly doing their job right to the bitter end. I'm not sure how it all fell out, as the drain plug was done up tight. Maybe the internal pump pumps it up to the bearings and if the seals leak then it gets out that way?
The moral is: do occasionally check your gearbox level with a clean dipper in the filler plug!
So - time to swap over to my spare box.
Given my situation - taking some time over it in the garage and not having a hoist - I'm going to try the box out with engine in method (for the first time). I gather that means raking the bellhousing off the box? I think I saw a post about it but couldn't find it yesterday.
On a drive to Tring it suddenly let go on the dual carriageway - well just as I pulled off at the sliproad. Managed to crawl it to my destination and had it recovered back home the next day.
Symptoms are rattling like a bag of spanners in 4th and 5th. When it was still hot it wouldn't go into the low gears but it was manoeuverable in 1st and reverse when cold.
I just checked the oil - what oil? It seems to have lost virtually all oil, so it's amazing it lasted as long as it did, must have been the Mobil and moly doing their job right to the bitter end. I'm not sure how it all fell out, as the drain plug was done up tight. Maybe the internal pump pumps it up to the bearings and if the seals leak then it gets out that way?
The moral is: do occasionally check your gearbox level with a clean dipper in the filler plug!
So - time to swap over to my spare box.
Given my situation - taking some time over it in the garage and not having a hoist - I'm going to try the box out with engine in method (for the first time). I gather that means raking the bellhousing off the box? I think I saw a post about it but couldn't find it yesterday.
Well I'm thinking I'll give it a go and if it won't come out I can still pull the engine and get it out quick, then whack the replacement back.
At least it will be mostly ready to come out.
But I did see a post saying it can be done, just need to find the technique.
Another possibility is to use an engine winch - I did put up a crossbeam in the garage and winched my engine up once.
At least it will be mostly ready to come out.
But I did see a post saying it can be done, just need to find the technique.
Another possibility is to use an engine winch - I did put up a crossbeam in the garage and winched my engine up once.
Well I've already done the first bit of that (done for the clutch - twice) so I'll carry on with that suggested sequence - presumably it's the manifold with the longer leg that needs to come off? Or will either do (as the offside one is much easier on mine)?
I looked into winches only £20 on the flea for a 2 tonne one, much cheaper than a hoist hire and I have it forever.
I looked into winches only £20 on the flea for a 2 tonne one, much cheaper than a hoist hire and I have it forever.
I'd better get cracking then. Yet more of my amazing powers of recall have just been demonstrated...
I just had a read of SH Bible prior to getting started, and it says "Adam Quantrill told me to move the engine forward" and it's possible drop the gearbox out.
So - if Steve says it, and it's printed in a book, then it must be true! ;^)
I just had a read of SH Bible prior to getting started, and it says "Adam Quantrill told me to move the engine forward" and it's possible drop the gearbox out.
So - if Steve says it, and it's printed in a book, then it must be true! ;^)
Well my winch arrived yesterday - absolute bargin off the flea.
The frame I put up a while back still loos nice and strong so I reckon winching up by the back lifting eyes will do the trick, it will naturally swing the required 7 or 8 inches forward due to the position if the support.
Then I can let it down onto a front support while I remove the box backwards, down and out.
I also had a check of the replacement if's a C suffix so not ideal but it will do, at least some improvement on an A or B.
All gears seem nice and smooth - no rattling (unlike what it's replacing!)
The frame I put up a while back still loos nice and strong so I reckon winching up by the back lifting eyes will do the trick, it will naturally swing the required 7 or 8 inches forward due to the position if the support.
Then I can let it down onto a front support while I remove the box backwards, down and out.
I also had a check of the replacement if's a C suffix so not ideal but it will do, at least some improvement on an A or B.
All gears seem nice and smooth - no rattling (unlike what it's replacing!)
Yeah I know what they are and probably have some on a spare engine. But I have to strip more stuff off to get them on, more time spent.
Anyhow the box is split off the engine today and offside exhaust manifold removed to make space. Just need to get the engine about 3" further and I reckon the easiest way is to remove the offside mounting from the block so it can clear that funny hoop thing in the chassis - I wonder why that is on there, there isn't one on the other side...
Anyhow the box is split off the engine today and offside exhaust manifold removed to make space. Just need to get the engine about 3" further and I reckon the easiest way is to remove the offside mounting from the block so it can clear that funny hoop thing in the chassis - I wonder why that is on there, there isn't one on the other side...
OK mount is off and that's made all the difference I can get the engine right forward to the front crossmember and now the box is fully off without having to touch the clutch.
The mount bolts did give some resistance though glad the front one moved the easiest as there's hardly any access.
The bearing for the box input shaft seems, well, shafted as it moves around a bit. Up and down and left and right.
Bellhousing off next then there should be enough space to extract the box and stick the replacement in. Must not forget to change over the speedo drive worm gear.
The mount bolts did give some resistance though glad the front one moved the easiest as there's hardly any access.
The bearing for the box input shaft seems, well, shafted as it moves around a bit. Up and down and left and right.
Bellhousing off next then there should be enough space to extract the box and stick the replacement in. Must not forget to change over the speedo drive worm gear.
Some progress today. Put some planks of wood under the engine sump (on the chassis rails) so it can't drop more than 2 inches if any lifting stuff fails. Old box completely out, the ancilllaries swapped to the replacement, and made sure the remote bushes are all solid.
Also I noticed the clutch pivot mushroom thing was a different length so that is swapped over too.
The replacement has ATF in it so that will be flushed and replaced.
Replacement box is in place under the car ready for the lift and reattachment of the gearstick (which had to come off to extract the old one) this part might be a total pain in the arse. It's hard enough to put back on with the box on the floor!
I will be using my old trick of a plank of wood across the doors and a rope through the gearstick hole to make the llfting easier - tried lifting with the trolley jack but it's like a wriggly thing balancing on a pinhead!
Also I noticed the clutch pivot mushroom thing was a different length so that is swapped over too.
The replacement has ATF in it so that will be flushed and replaced.
Replacement box is in place under the car ready for the lift and reattachment of the gearstick (which had to come off to extract the old one) this part might be a total pain in the arse. It's hard enough to put back on with the box on the floor!
I will be using my old trick of a plank of wood across the doors and a rope through the gearstick hole to make the llfting easier - tried lifting with the trolley jack but it's like a wriggly thing balancing on a pinhead!
Reasonable progress today, although I had a few setbacks.
First one was trying to get the stick back on the box after getting it in place. Couldn't get the nylon detent thingy back in, had to give up on that and the box will go back in with the handle on, it's just really tight and you have to get the front up as high as possible.
Second came later I had to laugh - wondered why the engine wouldn't lower and I had forgotten to remove the planks of wood on the chassis rails - D'oh! At least they work.
So the box went onto the splines nice and easy - probably because I hadn't touched the clutch - and is now bolted back to the engine. The heavy stuff is done just bits and pieces to fettle and reconnect now.Oh and I'll weld a few holes up in the manifold while I've got it off.
First one was trying to get the stick back on the box after getting it in place. Couldn't get the nylon detent thingy back in, had to give up on that and the box will go back in with the handle on, it's just really tight and you have to get the front up as high as possible.
Second came later I had to laugh - wondered why the engine wouldn't lower and I had forgotten to remove the planks of wood on the chassis rails - D'oh! At least they work.
So the box went onto the splines nice and easy - probably because I hadn't touched the clutch - and is now bolted back to the engine. The heavy stuff is done just bits and pieces to fettle and reconnect now.Oh and I'll weld a few holes up in the manifold while I've got it off.
Don't worry it went OK, made a few more holes and ended up with a patch of weld over an inch long.
Irritating putting it back on though - it didn't want to go on and I had to remove the engine mount again and put it in from the top.
Just have a few bits and pieces left to connect up and fettle.
Irritating putting it back on though - it didn't want to go on and I had to remove the engine mount again and put it in from the top.
Just have a few bits and pieces left to connect up and fettle.
Hmm while it's fresh in my mind... might be good for me to refer to for the next time - I always seem to forget stuff!
For refitting - as the Haynes manual says - follow the same procedure in reverse.
you will need to lift and move the engine a fair amount. So make sure there's around 5-6 inches between the frontmost part of the engine and the front glassfibre crossmember.
You can lift the engine on the sump (if it's sound, with a load spreading plate) but for this I used a winch from a beam in the garage, the winching point was about 6-8" in front of the centre point of the plenum.
In no particular order, you need to undo:
- disconnect the battery earth
- the exhaust joints at the back ends of the manifolds [1/2"]
- drop the exhaust centre box (undo the bobbins) [1/2"]
- the propshaft [9/16"]
- speedo cable at the g/b [10mm]
- earth strap from g/b to chassis [10mm]
- undo gearbox mount nuts [1/2"]
- gear knob - then put the box in 4th
- support the engine
- engine mount bolts (the ones that point fore/aft) [1/2"]
- remove offside spark leads
- undo the drivers side manifold top bolts [9/16"]
- remove drivers side engine mount (if you can) [17mm & 1/2"]
- remove the manifold
- remove top and bottom main cooling hoses - catch the water to put back in. [8mm]
- if fitted, undo the oil htermostat [1/2"]
- undo the remote filter mounting bracket [1/2"]
- remove the rear alternator bolt that holds the cable loop [1/2"]
- most of the other loom connections will stretch but do keep an eye on them while lifting the engine in case they are getting tight and need removing.
- depending on the air inlet layour disconnect the inlet hose at the most convenient point (if you have an SX, that's at the inlet to the throttle body)
- lift the engine a few inches and swing forward.
- lif the gearbox on a small jack so it's clear of the mount slots
- remove all bellhousiing bolts
- remove the clutch slave but not the pipe
- remove the bottom flywheel cover
- split the engine from the gearbox - I usually use a jack handle between the bellhousing and the flywheel while jiggling the gearbox around and shoving it backwards.
- lift the engine a few more inches and swing forward.
- get the g/b input shaft clear of the clutch
- jack up the rear of the box an point the bellhousing down
- remove the bellhousing [17mm ?]
- lift the engine a few more inches and swing forward.
- jack up the front of the box and pull the output flange clear of the crossmember at the back
- jiggle the gearstlick free of the hole - it may need a bit of force
- box should now come out
- have a cup of tea
Please also see the notes above here for other tips.
Let me know if I missed anything. Spanner/socket sizes are in square brackets. Have a selectoin of sockets, ring spanners both flat and offset, and open spanners to hand.
For refitting - as the Haynes manual says - follow the same procedure in reverse.
Changing the gearbox with the engine still in the car.
Preparation
you will need to lift and move the engine a fair amount. So make sure there's around 5-6 inches between the frontmost part of the engine and the front glassfibre crossmember.
You can lift the engine on the sump (if it's sound, with a load spreading plate) but for this I used a winch from a beam in the garage, the winching point was about 6-8" in front of the centre point of the plenum.
Disconnecting
In no particular order, you need to undo:
- disconnect the battery earth
- the exhaust joints at the back ends of the manifolds [1/2"]
- drop the exhaust centre box (undo the bobbins) [1/2"]
- the propshaft [9/16"]
- speedo cable at the g/b [10mm]
- earth strap from g/b to chassis [10mm]
- undo gearbox mount nuts [1/2"]
- gear knob - then put the box in 4th
- support the engine
- engine mount bolts (the ones that point fore/aft) [1/2"]
- remove offside spark leads
- undo the drivers side manifold top bolts [9/16"]
- remove drivers side engine mount (if you can) [17mm & 1/2"]
- remove the manifold
- remove top and bottom main cooling hoses - catch the water to put back in. [8mm]
- if fitted, undo the oil htermostat [1/2"]
- undo the remote filter mounting bracket [1/2"]
- remove the rear alternator bolt that holds the cable loop [1/2"]
- most of the other loom connections will stretch but do keep an eye on them while lifting the engine in case they are getting tight and need removing.
- depending on the air inlet layour disconnect the inlet hose at the most convenient point (if you have an SX, that's at the inlet to the throttle body)
Box removal
- lift the engine a few inches and swing forward.
- lif the gearbox on a small jack so it's clear of the mount slots
- remove all bellhousiing bolts
- remove the clutch slave but not the pipe
- remove the bottom flywheel cover
- split the engine from the gearbox - I usually use a jack handle between the bellhousing and the flywheel while jiggling the gearbox around and shoving it backwards.
- lift the engine a few more inches and swing forward.
- get the g/b input shaft clear of the clutch
- jack up the rear of the box an point the bellhousing down
- remove the bellhousing [17mm ?]
- lift the engine a few more inches and swing forward.
- jack up the front of the box and pull the output flange clear of the crossmember at the back
- jiggle the gearstlick free of the hole - it may need a bit of force
- box should now come out
- have a cup of tea
Please also see the notes above here for other tips.
Let me know if I missed anything. Spanner/socket sizes are in square brackets. Have a selectoin of sockets, ring spanners both flat and offset, and open spanners to hand.
Edited by adam quantrill on Tuesday 18th April 22:09
Yes! It moves on its own wheels. I had a bit of a strange one when flushing the gearbox - it would only run for a few seconds and then cut out. It felt like petrol (which was reading low) so I stuck another gallon in and leveled the car off.
Finally twigged I had forgotten to reconnect the air meter - d'oh!
Finally twigged I had forgotten to reconnect the air meter - d'oh!
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