Fitting dynamo G80S

Information relating to the Matchless G80 or AJS Model 18 500cc Heavyweight.
markwhitelock
Posts: 208
Joined: Sat Sep 07, 2019 5:51 pm
Location: Hampshire UK

Fitting dynamo G80S

Post by markwhitelock »

Gents, I need some advice regarding fitting my dynamo please!

I just rebuilt the damaged dynamo that came with my G80S and am now trying to fit it. The dynamo engine sprocket was already in place when I bought the bike and I assumed all was well with it.

When trying to install the magneto chain, it is fouling on the bolts holding the chain case in place. First question is do these bolts look correct..? Second question, which way round should the dynamo sprocket be orientated? It seems to have a wider shoulder away from the engine (or it's a spacer). There appears to be damage to the casing, the armature was also bent, I'm thinking something snapped and wrecked havoc inside.

Image
Image
image hoster
User avatar
spookefoote1956
Member
Posts: 1836
Joined: Mon May 01, 2017 7:32 pm
Location: Wales Innit

Re: Fitting dynamo G80S

Post by spookefoote1956 »

I think mine have a domed or pan slotted head.
Hail Joe Lucas ............ Prince of Darkness!
All my bikes are original........ to me!
"Creativity is your intelligence having fun" Albert Einstein
User avatar
clive
Member
Posts: 5657
Joined: Mon Jan 01, 1990 12:00 am
Location: LONDON UK

Re: Fitting dynamo G80S

Post by clive »

Looks to me as though the spacer netween the engine sprocket and the main bearing is missing. This would give you more clearance from the chaincase bolts which look ok to me.the quiz picture last week was of such a spacer. As for the dynamo sprocket it should only be able to fit one way round as it fits on a tapered shaft. Do you have the right sprocket? The timing sprockets have the same taper and will fit but not giving you any clearance. The dynamo sprocket has x slots into which the tabs on the special lock washer fit. You also need a special nut and retaining circlip.

On reflection perhaps you meant the sprocket in your picture. This is the engine sprocket and the primary sprocket and dynamo sprocket are all one part. The comment about the spacer behind it still holds.
clive
if it ain't broke don't fix
G15 Roy
Member
Posts: 3546
Joined: Sun Jan 01, 1995 12:00 am
Location: ESSEX UK

Re: Fitting dynamo G80S

Post by G15 Roy »

The bolts seem to be wrong and no lock tabs.
Roy
User avatar
clive
Member
Posts: 5657
Joined: Mon Jan 01, 1990 12:00 am
Location: LONDON UK

Re: Fitting dynamo G80S

Post by clive »

Do you still use locktabs Roy. Abandoned them some years ago in favour of locktight. Looks to me as though these may be oversize bolts owing to the original rather small threads giving up. Provided the heads are inboard of the casting the dynamo chain ought to miss them. Sometimes being a master bodger gives you extra knowledge!
clive
if it ain't broke don't fix
markwhitelock
Posts: 208
Joined: Sat Sep 07, 2019 5:51 pm
Location: Hampshire UK

Re: Fitting dynamo G80S

Post by markwhitelock »

I haven't ever had this bit apart, I stupidly assumed it looked ok!

I'm having trouble getting the fixing bolt off to remove the gears, tried in gear and brake on but the cush drive bit keeps moving and overcomes my strength! Hahaha. Need to borrow the neighbours wizzy gun.

Once I get it off I will see what's there!
markwhitelock
Posts: 208
Joined: Sat Sep 07, 2019 5:51 pm
Location: Hampshire UK

Re: Fitting dynamo G80S

Post by markwhitelock »

clive wrote:Do you still use locktabs Roy. Abandoned them some years ago in favour of locktight. Looks to me as though these may be oversize bolts owing to the original rather small threads giving up. Provided the heads are inboard of the casting the dynamo chain ought to miss them. Sometimes being a master bodger gives you extra knowledge!
This bike seems to be one bodge after another! :headbang:

Does anyone have a photo of what the bolts should look like? I would rather not have to live without a dynamo, especially after rebuilding it with new armature etc!!!
G15 Roy
Member
Posts: 3546
Joined: Sun Jan 01, 1995 12:00 am
Location: ESSEX UK

Re: Fitting dynamo G80S

Post by G15 Roy »

Bodge ;) ;)
Roy
56G80S
Member
Posts: 3354
Joined: Wed Oct 12, 2005 10:45 pm
Location: N YORKS UK

Re: Fitting dynamo G80S

Post by 56G80S »

Bolts don't look right to me. I'm sure the head in the pics is deeper than on mine. My recollection is that they right bolts are also smaller across the flats than they appear in your pic. There also seems to be a lock washer and a plain washer under the head unless my eyesight is wrong.

I'm with Roy, I still use the tab washers but add loctite! The tab washers are thinner gauge than the arrangement in the pic and that would give you some leeway.

Ironically, on the advice of Tony Cooper, I stopped using the dynamo sprocket arrangement of the long nut with groove, special "washer" and circlip. He advocated thorough cleaning and use of loctite. This has worked well for me but I also added a spring washer.

Johnny B
markwhitelock
Posts: 208
Joined: Sat Sep 07, 2019 5:51 pm
Location: Hampshire UK

Re: Fitting dynamo G80S

Post by markwhitelock »

I think my original post was somewhat confusing...

The dynamo sprocket is fine, I have all the correct parts to fit the sprocket to the dynamo - locking washer, special nut, circlip etc. My concern is to do with the sprocket on the engine. I have subsequently seen that what I thought were two different sprockets (primary chain and dynamo chain) are in fact joined together! :lol: so there is no way that is on the wrong way round!!

So that leaves me scratching my head about the bolts used to hold the chain case on and whether there is a spacer....
Locked