Alternator wires

[Phil C]

Some time ago on this forum we discussed replacing the grommet where the alternator wires go through the primary chaincase, in order to try to ensure oil-tightness. It is difficult to get at the inboard side of that hole, so sliding the new grommet down the wires from that end might not be feasible One way suggested was to split the new grommet lengthwise in order to get it over the wires inside the chaincase. And I might well do that, and give it a dob of silicone sealant for good measure. But I was just wondering whether, in order to avoid splitting the grommet, it might be possible, with a soldering iron, to disconnect the wires from the alternator in situ, slide the grommet on, and resolder the wires to the alternator. Any advice please?  Phil

[Pete A10]

There should be connectors on the wires from the alternator just inside the valance. you may need to take the battery out to get at them. Disconnect them here and the wires can then be pushed back through the grommet in the valance (assuming it hasn't disintegrated and disappeared in the mists of time) and then back through the grommet in the chaincase - do them one at a time with the bullets staggered. You may need to remove the sleeving from the three wires. You can then remove the old grommet from the chaincase (if it hasn't already disintegrated with all the pushing and pulling. With the ends of the wires now in the chaincase fit the new grommet over the wires, put the wires back through the chaincase hole and the new grommet is now on the inside of the chaincase. Fitting the new grommet back into the chaincase hole is an absolute pig and needs lots of lube (washing up liquid) and a couple of small screwdrivers and considerable patience to persuade the lips of the grommet over the thickness of the chaincase. Once fitted the wires can then be rethreaded into the valance and reconnected. Mark which wires are which before removing unless the colour coding is clear.
If getting the wires out is a problem I would go for desoldering the bullets on the wires then resolder them back on afterwards rather than disturbing the connections on the alternator.

[Phil C]

Please excuse my ignorance: what is the balance?

[Phil C]

Obviously I meant to say what is the valance? (Predictive text can be annoying!)

[Pete A10]

Sorry Phil, valance (probably not the correct use of the word) is what I call the thin sheet steel cover plate that sits between the oil tank and the tool box. Part No 40-7825 - the plate that holds the ignition switch and the air filter.

[Phil C]

Okay thanks Pete. I do have a hole in the bottom of that valance (no grommet - presumably long lost or disintegrated, as you suspected) but I have only one wire going through the hole - the wire to the contact points. My three alternator wires I've got entering the toolbox area a bit rearward of that hole. But thinking about it now I guess they should share the same hole as the points wire, so four wires should be going through a grommet in that valance hole? Is that right?

I don't have the chaincase cover off at the moment, but going from memory and from what I can see at the moment, my alternator wires go through a grommet as they leave the chaincase, then an inch or two later go through another grommet (see pic) and then head off towards the valance. I'm not sure of the reason for that second grommet - maybe it's to keep the wires well clear of the rear chain?

Any thoughts about any of this please anyone, ie  should four wires go through the valance hole, and why is there that second grommet hole?

Thanks as ever,  Phil.

[Pete A10]

I haven't got the B40 anymore so can't go out and look at it. However I've got some photos of when I was doing the rebuild. Within the chaincase/crankcase there are two grommets for the alternator wire. One in the side of the crankcase, accessible through the primary chaincase. This is meant to keep the oil in the chaincase and stop the wire chafing. The one on the top of the crankcase does not go into any oil filled compartment and is just through a plate cast with the crankcase. The grommet here is just to stop chafing.
On my B40 (it was a distributor model not integral points) there were two holes for wires though the valance. One on the left took the alternator wires whilst the on the right (D-shaped and open sided) took the distributor wire.
Hope the attached photos and sketch help.
I have also got some photos of the wiring when I got the bike before rebuilding it, but they would probably confuse the situation as they had clearly been altered. As always it takes a bit of detective work and lots of questions to work out what is correct on 50+ year old machinery.

[Phil C]

Thanks very much for this, Pete. My valance looks to be a bit different (see pic, sorry it's not a great photo.) It seems only to have one hole for wires which is where the points wire is (you can see the wire, it is red, whereas I think really it should be black and white.) So I'm not sure whether the points wire should budge up and make room for three more, or whether the three alternator wires should carry on as they are and go into the tool compartment a bit further back and underneath. So that's one thing I need to decide.

Regarding the grommet through the cast plate on top of the crankcase: what is the purpose of that plate, and why do the wires need to go through it after they've come out of the primary chaincase? Why don't they just head straight for the battery compartment/toolbox area?

Any thoughts/advice on any of this, Pete or anyone, would be much appreciated.   Phil

[berniej]

Phil,

Looking at your last pic, the bullet connectors for your alternator wires are outside of the tinware so I would have thought that you could disconnect there by pulling the wires out on the alternator side and then fitting your new grommet over those and sliding down to the crankcase.

Does that make sense or have I misinterpreted your pic?

Cheers,
Bernie

[Phil C]

I guess removing the bullets and pulling the wires through into the chaincase and then fitting the grommet is the way to do it, although Pete says the fitting of the grommet in the chaincase hole is a bit of a pig, and maybe the same applies to the one in the cast plate.  But then getting the wires back through the cast plate grommet from the chaincase side might be the hardest part of all, as both access and view in the area are extremely limited. I'm not even sure it's doable. What is the purpose of the cast plate?  Phil

[Pete A10]

The cast plate causes the wires to rise up out of the way of the final drive sprocket. If the wires don't takes that route they may get caught on the chain and sprocket.
The connectors on the wires should be inside the tinware. I would fit a grommet into the valance hole and take all the wires through there.
To fit new grommets I would pull all the wires back through the chain case, remove the old grommets, put the chaincase grommet over the sleeved wires, use a copper wire hook to pull the wires through both holes, fit the outer grommet over the wires and then manipulate the two grommets into place. Then reconnect the connectors inside the valance.
You need special grommets as the aluminium castings are quite thick - standard auto-shop grommets only work on 1 - 2 mm thick plate.
On your last point - it is doable but takes time and a lot of fiddling - make sure all the hammers are locked away as the urge to hit something when messing with the grommets will be immense!!!

[DAVE BRADY]

Hi,

If you are going to remove the bullets from the end of the wires get a piece of strong string and tape it and the wires together.  Pull the wires back in to the primary case with the end of the string.  Undo the tape and thread on the new grommet and fit it in the case - easy without the wires through it.  Tape the string back to the wires tightly so that you can now carefully pull the wires back through the grommets with a bit of lube.  Make the taped bit pointy so that it goes through easily.

Dave.

[Phil C]

Okay thanks, I hadn't thought of using a bit of string or wire. Pete and Dave suggest a bit of lube. What is a good lube, bearing in mind that I would be thinking of adding a blob if silicon sealant to the new grommet to help the seal - seems to me fairy liquid might repel the silicon?
Regarding my alternator wires connector tubes, I'm afraid mine aren't long enough to be inside the tinware. Why should they be? I guess either so that they look tidier or so that if a wire came loose it couldn't then fall into the rear chain? But  mine are safe enough, aren't they?
Any advice please on those two points: the lube, and the connector position?   Thanks again. If anybody ever asks me who maintains my bike, I'd have to be honest and say the BSAOC forum.    Phil

[Pete A10]

If done properly you won't need silicone so washing up liquid is fine.
The connectors are not waterproof so are better protected if inside the valance - and it looks a lot neater. I would extend the wires by soldering with some heat shrink over them and extend the black sleeving. You then get one neat sleeved wire from the crankcase to the valance.

[Phil C]

Yes I suppose that would be more waterproof and maybe neater, but I think I saw recently on this forum that soldering wires was not a good idea because you get brittleness? Phil