1956 G80S fork dissasembly

Information relating to the Matchless G80 or AJS Model 18 500cc Heavyweight.
Spanielsam
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1956 G80S fork dissasembly

Post by Spanielsam »

Hello
I am just after a bit if advice before I start working on my 1956 G80S forks and get stuck !

I want to replace the fork inner tubes (stanchion ?) springs and seals - tube kit has been ordered from the spares shop and springs from another owner

When I first got the bike a couple of years ago I stripped the forks apart and only replaced the seals but found that the springs were different lengths and the tubes were very badly rusted with a split in one of them at the top where it goes into the yolk , lack of funds precented me carrying out more work at the time
I did not take the damper tube out as I remember but I might be wrong

My question is , do you need any special tools to replace the inner tubes ? The workshop manual talks about "articulated clamp" tool and a special spanner etc I cannot see any reference to , it also states Dealer Service Only which alarms me a bit

Thanks in advance

Trevor
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Janet
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Re: 1956 G80S fork dissasembly

Post by Janet »

The spares scheme has fork dismantling tool listed but I don't know if that's what the manual describes as an articulated clamp.
Regarding the spanner, I think you'd need to know where it was being used to know whether one is available. I suppose you'll find that out when you discover you don't have anything that fits.
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clive
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Re: 1956 G80S fork dissasembly

Post by clive »

You will need a 1/4 whitworth box spanner or thin walled 3/8 drive socket for the damper tube bolt inside the bottom of the sliders. A fork puller to get the stanchions fully home in the top yolk on replacement but it also helps when removing them. In my experience a blow torch or hot air gun to carefully warm the slider to get the seal out. My trick is to warm it up, clamp the slider just above the upper mudguard bolt point in a workmate, and then stand on the side of the workmate and pull the stanchion sharply upwards a couple of times. This results in a shower of oil but the thing is apart. The only other tool needed maybe a strap wrench to get the cover which screws into the slider off. Again gentle heat helps. Obviously this needs to come off before trying to remove the seal. Original versions of the screwed cover I have seen have got a small hole up where the outer cover hides it, the special tool could involve a c spanner or clamp to help remove this as the steel can corrode with the ally over time. Not in my view a dealer task as I have done it many times as described and without any tool bar a strap wrench or a pair of leather gloves for grip for undoing that screwed cover.
clive
if it ain't broke don't fix
Spanielsam
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Re: 1956 G80S fork dissasembly

Post by Spanielsam »

Thanks for your replies, it is much appreciated, I only have limited garage space and once I start it I need to finish it quite quickly

When I replaced the seals the main problem I had was getting the fork legs back into the yolks, the holes in the top and bottom yokes nearly aligned but not quite which made getting the two fork legs in a bit of a challenge
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clive
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Re: 1956 G80S fork dissasembly

Post by clive »

That's why you need the puller makes life a whole heap easier, I think you did well to get it together without last time. The club spares sell the fork pullers although I see both types (yours ought to be 1 1/4 if forks are correct for the bike) are on "limited availability ring before ordering". I have a universal type which has bolt on inserts for different types so will cover both AMC sizes, triumph BSA etc. Works fine so long as you check the bolt is done up firmly before you start. It's possible to make one if you have the skill/equipment and a spare top bolt for the inner stanchion.
clive
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clanger9
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Re: 1956 G80S fork dissasembly

Post by clanger9 »

clive wrote:That's why you need the puller makes life a whole heap easier, I think you did well to get it together without last time.
I second that: it's a really difficult job to get the forks back in without a puller!

If you've got a spare fork top, you can make one by cutting the hex part off (leaving just the threaded bit), drill a hole through the middle and then stick a long bolt through. Here's mine:
IMG_0908.jpg
If the forks are tight in the bottom yoke, you can replace the bolt with a length of threaded rod to pull the fork leg in over a longer distance.
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Spanielsam
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Re: 1956 G80S fork dissasembly

Post by Spanielsam »

I think it was my trying to get the tube into the top yolk that caused it to start splitting, I got the tube nearly in place but then starting pulling it up using the top big fork nut which did not feel right

From your excellent replies I presume that you screw the screwed insert into the fork tube and then pull it into the yolk ? I have seen Fork tube pullers on e bay but not really known what they are for as they look long

All is becoming clearer now

Thanks Again :-)
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clanger9
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Re: 1956 G80S fork dissasembly

Post by clanger9 »

Spanielsam wrote:I presume that you screw the screwed insert into the fork tube and then pull it into the yoke?
Yep, that's right. It should usually just pull straight in.
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56G80S
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Re: 1956 G80S fork dissasembly

Post by 56G80S »

I made up something similar to Clanger 9 but using a longer length of threaded rod from farmers merchant and I drilled the old top/cap bolt and put a split pin through it as well as the nut underneath.

It makes the whole thing easier; takes only minutes to pull the tubes up, fish the damper rods out and lock them onto the bottom of the nice new shiny cap bolts.

Johnny B
Spanielsam
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Re: 1956 G80S fork dissasembly

Post by Spanielsam »

Thanks for all your advice

I made up a fork puller from a piece of box section , threaded rod and modified fork top screw, worked a treat, so much easier than trying to man handle the thing back in

Also replaced the steering bearings so hopefully the front end is now sorted

My only question now is How do you get fork oil out of my clothes, the work jacket that was hanging up behind me and the garage roof , it certainly goes everywhere when the fork leg comes off :-)
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