Stiff sleeving

[Phil C]

Morning all. Interesting little thing I came across (well, everything's relative  )  (that was meant to be a smiley emoji): the three wires coming from the alternator, through the grommet and away to the outside top of the casing, on my bike (1965 B40F), are held together in a shiny black hard plastic sleeve, about 5mm dia. I noticed it was extremely stiff, hard to bend. A bit like trying to bend a metal rod of that diameter.  That would make it very difficult or impossible to pull the wires through the grommets towards the stator. I don't need to do that but thought I might anyway in order to renew the grommet while I'm in the primary chaincase. I played a heat gun on it and it softened, but then stiffened again when it cooled. I was just wondering: do you think the material has age-hardened in some way, or would it have always been like that until warmed? Maybe it's meant to be like that in order to prevent it snagging in the chain? Just asking out of interest.  Phil

[DAVE BRADY]

Hi Phil,

Age hardened and you may find that the coloured coating on the wires is also quite hard and brittle.  What I have just done on my alternator is pull the wires out from the grommet completely, remove the old sleeving and inspect the coloured wires.  Mine did have a few cracks but the wire itself was fine so I threaded some heat shrink sleeving on each wire to re-establish the insulation and then put new piece of outer sleeving on sealed with Araldite to the stator to prevent ingress of oil.  I am fitting a new grommet where the wires leave the the case as that has also gone quite brittle.  This should mean that the alternator will go for many years to come.

Dave.

[Phil C]

Interesting, thanks Dave. I was hoping that if it was age-hardening then heating it up might make it soft for a good period of time, like with metals, but no, it went hard again when it cooled.

Mine goes through two grommets, one of which is  awkwardly placed on the outside of the top of the casings, which I guess makes threading the wires through a bit tricky. Did you use wire/, string to pull it through?  Phil

[DAVE BRADY]

Hi,

It is easier if there are no connectors on the end.  I get a piece of string and tape it to the wires so that there is nice taper.  That way it is easier to pull though. Use a bit of WD40 or vaseline to help it slide through.

Dave.

[A10 JWO]

Would a nice new piece of heat shrink replace it. The engine can warm it up for shrinking a bit.

[DAVE BRADY]

Hi,

I thought about heat shrink instead of the usual sleeving but I am not sure the heat shrink is oil proof.  I suppose both could be used but a bit of flexibility for threading through grommets could be lost.

Dave.

[Pete A10]

Trouble with heat shrink is that it goes quite hard and rigid when it has been heated and shrunk. Just replace with auto cable sleeve. If you get the right size it will form a good seal in the grommet. Plenty of washing up liquid to lubricate the grommets both when fitting and threading the cables.

[Phil C]

Or maybe the stiffness is an advantage in that it holds its position and so doesn't in the chain?  Phil

[Phil C]

In my previous post I meant to say doesn't snag in the chain ( missed out the word snag.)

[Phil C]

Just looking through the Vehicle Wiring Products catalogue for suitable sleeving. The old, stiff, hard, sleeving that's on the bike at present is about 5mm o/d and has three wires, each about 2mm o/d fitting inside quite snugly. The choice in the VWP catalogue is: pvc sleeving, 6mm the nearest size (for 4x 1sq mm wires),resistant to oil, temp rating up to 70 deg C,   OR: heat resistant sleeving, made of fibreglass with acrylic coating, protects cables against heat up to 155 Deg C, unaffected by oil, again 6mm.   What kind of temperature will it have to endure in the primary chaincase and sitting on top of the casings? Also, what is a suitable way to seal the end of the sleeving where the wires protrude at the alternator?   Thanks for any thoughts.  Phil

[Phil C]

Any thoughts on those two types of sleeving please anyone?  Phil

[Bess]

Hi,
    Generally as Dave described on his first post, I don't use Araldite, I use heat shrink without issue by stress relieving it using a few overlapping sections forming a taper.

The cable from the alternator to the exit grommet should be secured inside the primary drive to the casing with a cable tie to stop the cable moving, there should be a small hole to do this.

Best wishes...

[Phil C]

Thanks Bess, but I don't really get this. I don't understand the stress relief bit, and it looks on your diagram (thanks very much for taking the trouble to do that) as though you have a cable tie going up through the grommet? By the way, your photo looks nothing like mine.
The main thing I'm trying to decide is which of the two types of sleeving I described, if either, is suitable. Maybe you're saying you don't use any sleeving, just heat shrink?
Sorry to be so slow on the uptake!
Phil

[Bess]

Hi,
    The casing I have shown is a example of the cable support hole. If the inside of you casing has a support hole; the cable tie wraps around the cable and passes through the hole to secure the cable to prolong the life of the cable. You may not have this on your bike, worth checking or consider making one.

Do the drawings help now?

The heat shrink used for stress relief will prolong the life of your cable in the casing and stop the cable overly flexing at the exit area around the casing. Try and get the OD diameter of the heat shrink where it passes through the grommet  slightly larger to seal it to the grommet. Use a new grommet.

Its your decision on the type of sleeve around the cable coming from the back of the casing to your loom. You can match the sleeving your loom has or go for any of the suggestions. I have used them all in the past but now use heat shrink as I find it neat and unobtrusive.

Best wishes...

[Phil C]

Thanks again Bess, much appreciated. My main concern about the type of sleeving out of the two options I mentioned from the VWP catalogue was heat resistance, given that some of it is within the primary chaincase. I noticed the pvc had a lower rating than the other and wondered if it would be okay. Phil