Tailshaft Seal replacement

[silloyd]

I have oil leaking out of the rear end of the gearbox that is particularly noticeable now I've just replaced the oil. According to the previous owner, the gearbox is a recon unit (1098 ribbed) that was installed about 10,000 miles ago and I have no other problems with noises, rattles, gear change, etc., so I'm reluctant to whisk it out unless I really have to.

Having read elsewhere on the forum that the leak could be caused by the seal having failed, I would like people's advice on the following please:

1. How can I tell if it is the seal rather than the bearing that's cream crackered?
   
   Can the seal really be changed without removing the gearbox? (I only have access to trolley jack + axle stands)
   
   If it's the bearing, it sounds like a difficult job that I'm not going to be able to do without facilities to ream the new bearing. Is that a fair assessment?

Any additional points to note or be wary of would be welcome too...

[MarkyB]

From memory, you can change the seal quite easily.
If the brass bush that the end of the prop runs in is too worn it wont last long.
I think you can replace that too by taking the end off the gearbox BUT the new bush needs to be reamed after it has been fitted, and before it is used.

[silloyd]

Thanks.

How would I go about reaming the bearing and could that be done on the car?

[nezza]

I just changed seal on mine and it stopped leak ,so dont think you will have a problem as mine was pouring out.

[nezza]

p.s you will have to take propshaft off ,I did mine by using axle stands on the rear axle and doing it that way so I would certainly try a new seal first before going into any expence.

[MarkyB]

Absolutely, try the seal first but be aware that if the underlying problem is the bush it won't be a lasting fix .
The new bush would need to be reamed off the car as the tail shaft would get in the way of the reamer.
Adjustable reamers are available, but a small engineering firm should only charge beer money for the job.

[silloyd]

Thanks gents, will give the seal a bash first.

[bmcecosse]

Check the prop shaft joints - if they are worn and the prop is flailing about - the seal won't last 5 minutes.

[silloyd]

Check the prop shaft joints - if they are worn and the prop is flailing about - the seal won't last 5 minutes.

...and if there is a lot of play in one or both joints are they relatively straightforward to replace?

[bmcecosse]

It's not a job I have ever done! But I believe it is straightforward enough - according to the Manual!

[silloyd]

Poo, poo and more poo! A chunk of the tail casting came off with the old seal, and I was really trying not to be too enthusiastic I'm going to have to replace it now, as the damage looks too bad.

Can it be done without with the remainder of the gearbox in situ?

Also, can anyone tell me where I can get hold of a replacement, or will I have to get a a whole gearbox?

I guess that as and when I replace the casting, I will have to sort the bush to match the prop as well.

Not a good day

[katy]

How big of a chunk broke off? And from what position?
If it's not too bad you may be able to put the new seal in with some silicone or other sealant to seal up the damaged spot.
A pic would help.

[silloyd]

Thanks for the quick response but I don't think silicone, plastic metal or any other kind of sealant is going to work here.

[frame][/frame]

[bmcecosse]

To me that looks like previous damage - possibly by whoever 'reconditioned' the gearbox. Yes - I would try silicon and a new seal - what's to lose?!

[silloyd]

Thanks for the views.

I know that years ago as an impoverished student that I fixed a cracked sump on a Vauxhall Viva with something called 'Plastic Metal' which was completely successful but not so sure here, particularly as it looks like a bit of the bush is showing through. I guess I could use Evo-stik Hard & Fast Metal Epoxy Putty, which seems to be the current equivalent, to build up thickness and either file back to a fit or only use a thinner layer of silicone.

The new seal assembly will only cover as far as the edge of the missing chunk therefore I need to have confidence in any bodge that I do (today has not been a stunning one - apart from my daughter's ballet demonstration so my confidence is not high). A bad fudge has the potential to fail catastrophically and dump all my gearbox oil (probably very rapidly).

What's to lose - a gearbox through seizure?

[MarkyB]

You wont lose all the oil through the rear seal as it just splashes about in the gearbox.
The seal operates on the surface of the prop so wont be affected by the missing bit at all.

[bmcecosse]

It'll be fine - lots of silicon and tap the new seal on - fix it in place with a couple of small self tappers if you are really worried it could come loose.

[silloyd]

The new seal is a nice tight fit on the prop, so I'm not worried about it leaking there but the rubber back edge of the seal needs to mate against something and, due to the lack of metal now, the only thing left would be silicone. (UJ's seem OK and no particular play in the bush so shouldn't deteriorate rapidly). As you say possibly worth a punt before going to the effort of more extensive work.

Love your optimism and appreciate your experiences!

[nezza]

The rubber seal mates onto the propshaft so I dont think there will be a problem with the chunk missing ,give it a go.

[silloyd]

I'm going to see if I can build it back up with metal epoxy putty and silicone. Wish me luck!