gearbox

[monninkyla]

Hi,
Unfortunately the gearbox on a silver century has seized (there is some movement but very stiff). It was filled with grease at some time!
Has any one any experience of dismantling one . Do I need special tools ets ?
Thanks in advance

[rosbullterier]

Probably every contributor to this forum has some experience with the gearbox.

I would not deign to think my answer would be as helpful as others. However, just as a start off - is the box completely removed and without its drive shaft?

This is to question whether firstly the water pump impellor is at at fault, although this is not likely.
If the gearbox is very tight then possibly the old reason is corrosion if not just solid grease. If this is so,then the bolts holding the box to the water pump housing will possibly need heating to turn. Use butane torch. These are the two at the top, unfortunately only the back one can be seen in the pic. Tap off this top part.
The only other two are set screws holding the back plate on. Heat might again be needed.
Remove this round back plate, look inside inside, report back.
Remember original bolts are all Whitworth. These spanners and heat are neccessary.

[Charles uk]

Remember all these bolts are BSF thread pattern but take the same size spanners as Whitworth

[Horsley-Anarak]

Remember original bolts are all B.S.F.

H-A

[rosbullterier]

When you have reassembled your box with its now sparkling innards you will be wanting to retain its tip top running performance.

That quaint old firm, Seagull, recommended 140 grade oil. I used to use this in my Series 1 Landrover steering box. Which I should think revolved a lot less than an outboard gearbox.
No, I don't use a Seagull for extended trips, however I feel GL5 90 grade is perfectly thick enough to rob the little power endowed to this humble engine. I fill my 102 boxes with 90 grade and it doesn't run out.
Not being either a farmer or Seagull outboard user, I do check the levels annually.

When enjoying the next outing with the trusty Seagull, dip the old fingers in the briney and test the temperature. That cold water is is super cooling your gearbox filled with treacle.

[rosbullterier]

No one likes a smart ass. Hope you die.
Horribly.

[charlesp]

I believe there ius a strong possibility that the seizure could be in the pinion bearing. Insufficient lubrication or the wrong type of lubrication over the years could have started the pinion shaft rusting.

So why not try copious amounts of thin lubricant (diesel, WD40,three-in-one etc.), and heat around the 'neck' of the gearbox casting. Then rotate the shaft by hand at first, followed by a bit of powered rotation using a hefty electric drill, all thge while continuing to pour lubricant into the bearing. Afetr a while it'll free up.

Thgat's what they would have tried at the factory. Naturally they would have shifted all the grease as well.

[Waggles]

Is it my old eyes ( or even the fact I am sober ) but in that cut away pic isn't the water pipe incorrectly fitted?

[monninkyla]

Thamks everyone , tis is really fascinating. This is my first visit to the workings of a gearbox so the information and advise is really helpful.

[John@sos]

Well spotted Waggles, it is wrong!

I have not got round to stripping and rebuilding it correctly, you are the first to notice!

Now what does that make you??? Observant or smart ass!

cheers,
John
SOS

[Waggles]

Oh definitely 'smart ass'!! just ask H.I.D. !!

[timberman2004]

yup she confirmed it .....

with a few of her own comments about Waggles and his 'water pipe'