Orion gearbox

[Matchless?58]

Hi all
Well I finally found time to drop out the gearbox oil . My god I have never seen anything like it ! The old oil is thick , glutinous and a light toffee colour coming out in great big blobs ! It is pretty obvious that I will have to flush the gearbox with something . paraffin would be my favourite but its a bit hard to get hold of now not like years ago when every corner shop sold it .
I think petrol would be a bit too risky so does anyone have any suggestions of what I can flush out the gearbox with ?
I left the gearbox to drain overnight but I think it will still take a couple of flushes to clean it . Unbelievable but it works perfectly
with every gear easily obtainable .
Also I think the output seal is leaking.
I won't be able to do it right now as I need to use the dumper ATM but is it a really awkward job ?
All advice gratefully received .
Cheers Chris

[essexpete]

Better the oil like that than a milky emulsion!

[Matchless?58]

Hi Pete
Yeah I guess so . Have to be honest I was expecting loads of water to drain out .

[cobbadog]

I always use diesel to flush the gearboxes out as it is safe to do so. With our Cropmaster it was contaminated with water and was milky in colour so I drained it for a couple of days then filled it with diesel and slowly drove it around the yard hitting the brakes hard and that too really got it sloshing around and then drained that out. Amazing how much this removed so I did it a second time and it was good enough to drain and fill with fresh oil. This cleaned everything out thoroughly and was safe in doing so. Diesel is not as expensive as kerosine or any other petroleum product but glad you did not use petrol as it is flamable and a spark would not be too good around that.
Use the correct grade oil for your local climate and all should be good. Buy a new rubber boot to put over the gear lever/s as this is how water got in and will again if it doesn't get sealed properly. Many tractor rubber boots would fit the size of your lever at the base and seal over the hump in the top of the gearbox where the lever enters.

[Matchless?58]

Hi cobba
I didn't give diesel a thought but I guess that would shift most of the muck . I have already filled it with old engine oil then added an engine oil flush product . My plan was to drive it for a day then drain and refill with clean oil . However a new problem has popped up now . The drive chain was very loose so much that it was dragging on the guard . The noise was what made me look to see what it was . I have had to remove a link to shorten it as it was beyond the limit of adjustment I am beginning to think it may have been the wrong chain fitted by a previous owner. I am assuming that you have to move the gearbox over left or right to tension the chain properly which is going to be another problem as the clamping bolts are rusted solid I think it might be easier to grind them off and fit new bolts can't shift them ATM and access is a bit awkward . Left them soaking in WD 40 and will try a bit of heat tomorrow . Who would have thought a simple gearbox oil change would have opened this can of worms .
Now I've got it apart I might just check the clutch while I'm there as there seems to be a rubbing noise ..............
Cheers Chris

[cobbadog]

Always best to check what you can while your inside these areas. The diesel works a real treat and a David Brown field serviceman told me about this and they did it all the time. I found it does work very well and now with fresh oil and a pair of rubber boots in place there is no milky oil any more.

[Matchless?58]

Hi all
Just an update on the Orion gearbox . I managed to flush all the crud out of it by using old engine oil with an engine flush added . Ran it for a while then refilled with ep 90 gearbox oil all good now .
I have just got round to sorting out the drive chain . I was unable to get the correct tension because the bolts holding the gearbox were rusted solid so I couldn't undo them to slide the gearbox across . Access is very difficult had a job to even remove the chain guard as those bolts were rusted too ! In the end I had to grind the heads of the bolts off and punch them through the holes in the base of the gearbox . Once the bolts were out I put a block of wood against the bottom of the gearbox and used a car jack to break the seal , after that I was able to slide the gearbox easily to get chain adjustment . Replaced the bolts with stainless steel bolts and nuts and put everything back together . First test run tonight and goes great again with smooth gear changes .
Let's wait and see now what breaks next .
Cheers Chris

[essexpete]

Sounds good

[Bolton]

Maybe I should just take the dodgy gearbox off the Thwaites but as mentioned yesterday I'll post up a few more pictures as new to this

Here is my spare 40M gearbox:





This is the chain assembly, clutch on RHS at rear of engine:




This is the label on the current gearbox:




This is the layout (Matchless - I guess you know this model anyway)





HTH thanks again in advance on any more thoughts..

[Matchless?58]

Hi I will have a look at mine tomorrow morning . I'm not very techno minded so I won't be able to upload a picture of my gearbox . I will just have to take a picture on my phone and see if my gearbox matches the picture you posted . It looks like it but can't quite recall all the details . What gearbox do you have in your dumper ATM ?
To be honest it's not a massive job to remove the gearbox worst problem will be rusted nuts and bolts looking at your picture they all seem to be like that .
You will have to remove chain/clutch guard . Remove chain Via the split link don't forget to make a note of direction of rotation for replacement . Undo the 4 gearbox retaining nuts/bolts . Drop the drive shaft off . Gearbox can then be removed .
With the weather we have now should be more pleasant , I did mine in the middle of a muddy field and it kept pi@#£g down on me !
Hope this helps . If the old gearbox is knackered it won't do any harm to remove it and offer your 40 m up anyway .
Cheers Chris