Gearbox knackered

Gearbox knackered

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Discussion

adam quantrill

Original Poster:

11,535 posts

241 months

Tuesday 28th March 2017
quotequote all
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.

ElvisWedgeman

2,714 posts

164 months

Tuesday 28th March 2017
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adam quantrill said:
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.
Doing this on the floor, on ramps, is going to be a very difficult job. If I were you I would hire a hydraulic hoist and take the engine and box out together. I'm sure it'll be a lot easier. I've never done this on a wedge but I have done it on a Lotus and even then I had two people helping me, especially when putting it back.

Tony. TCB.

adam quantrill

Original Poster:

11,535 posts

241 months

Tuesday 28th March 2017
quotequote all
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.

ElvisWedgeman

2,714 posts

164 months

Tuesday 28th March 2017
quotequote all
An engine winch works but the hydraulic hoist on wheels is much easier to manoeuvre. It's almost a one man job because it's so easy to use. You will still need assistance in putting it all back though, otherwise you risk damaging something like the body etc.

PS. Maybe we should recall everyone using moly slip and mobil 1 and convert to silverhook fully synthetic biggrin

Tony. TCB.

Edited by ElvisWedgeman on Tuesday 28th March 23:37

adam quantrill

Original Poster:

11,535 posts

241 months

Wednesday 29th March 2017
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Nah I'm saying it's very good - the problem was the oil dropped out!

KKson

3,395 posts

124 months

Wednesday 29th March 2017
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Flushed and refilled the 390 'box with Mobil 1 and Moly last month and the 'box now is as smooth as...... Just luvvvelly.

gmw9666

2,734 posts

199 months

Wednesday 29th March 2017
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Mine did that last year. Here is the sound it made https://www.youtube.com/watch?v=q7Di_vMG5hk

My box was full of oil but when rebuilt the chap said at some point in the cars history it had ran low on oil (I guess they can tell)

Adam is right, go check your levels, all those drips over time do reduce levels

350zwelgje

1,818 posts

260 months

Wednesday 29th March 2017
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It is unfortunately due to the design (play can get outside tolerances quickly) of the gearbox and low on oil or internal pump not working it only takes a few hundred miles and it has damaged another bearing and is starting to grind the gears to destruction. Think it is the end-shaft bearings, especially the lay shaft and had a box go on a SD1 (lay shaft bearing gone and it starts to take the rest out). Then only fourth is still working as it is a prise-direct and gets you home...
Fifth is an add-on (original four gear design box) and not allowed to pull heavy loads on the original Rover cars it was used in.
So always worried when I hear noises in the lt77 box as that is the first sign that it is going to end. TVR is still fine on the original box and over 180.000km.
Fluid level is key, but is no guarantee...

Rob

mrzigazaga

18,534 posts

164 months

Wednesday 29th March 2017
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Oh dear Adam.....

My gearbox has a slight leak and so does the diff so I get mine checked and topped up if needed every four months, Including the diff oil..UJ's and door hinges.

Apparently the ATF degrades the gearbox top seal...

Hope you sort it soon.

Ziga

v8s4me

7,234 posts

218 months

Wednesday 29th March 2017
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mrzigazaga said:
....Apparently the ATF degrades the gearbox top seal...
If you have an LT77 my advice (for what it's worth) is to get that muck out as quickly as possible and refill with Difflock. This oil transformed my gearbox making changes smoother and quieter, even when cold. It is a bit thicker than ATF so any leaks won't be as bad. I've tried ATF and got it out as quickly as I could. I didn't know about Difflock at the time so the ATF was replaced with semi-synthetic gear oil. This was a huge improvement on the ATF but the Difflock is on another level again.

mrzigazaga

18,534 posts

164 months

Wednesday 29th March 2017
quotequote all
v8s4me said:
mrzigazaga said:
....Apparently the ATF degrades the gearbox top seal...
If you have an LT77 my advice (for what it's worth) is to get that muck out as quickly as possible and refill with Difflock. This oil transformed my gearbox making changes smoother and quieter, even when cold. It is a bit thicker than ATF so any leaks won't be as bad. I've tried ATF and got it out as quickly as I could. I didn't know about Difflock at the time so the ATF was replaced with semi-synthetic gear oil. This was a huge improvement on the ATF but the Difflock is on another level again.
Sounds good mate...Thanks for the info...smile

stevoj

798 posts

160 months

Wednesday 29th March 2017
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I put difflock in mine, not that I had any problems but just a matter of course. Not cheap but certainly does what it says on the tin (or bottle) and made for the box.

pk500

1,973 posts

211 months

Wednesday 29th March 2017
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Adam if you change the engine mount bolts for longer ones you can pull engine forward enough to get box out you have to remove one exhaust manifold pull gearbox back and remove clutch and flywheel take bell housing off box and you can get box out ok I've done a few like that

adam quantrill

Original Poster:

11,535 posts

241 months

Wednesday 29th March 2017
quotequote all
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.

pk500

1,973 posts

211 months

Wednesday 29th March 2017
quotequote all
adam quantrill said:
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.
You can remove either it is only done so you can get bell housing out

adam quantrill

Original Poster:

11,535 posts

241 months

Wednesday 29th March 2017
quotequote all
Thanks Paul.

I'll try and write up the procedure.

KKson

3,395 posts

124 months

Wednesday 29th March 2017
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Yes please and a copy of the bruises and cut fingers accident book entry.

pk500

1,973 posts

211 months

Thursday 30th March 2017
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adam quantrill said:
Thanks Paul.

I'll try and write up the procedure.
One other thing to take off is the flange for the propshaft it gets in the way !

stevoj

798 posts

160 months

Thursday 30th March 2017
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Adam, sounds like Paul knows exactly what he is doing - just give it to him. idea

pk500

1,973 posts

211 months

Thursday 30th March 2017
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Line up got jim's to sort next weekend