A127MT alternator hex key

[baffle]

I have recently got hold of an A127MT 80amp alternator (Lucas copy made in Turkey I think). I want to change the pulley, but the hex key keyway in the end of the shaft is something like 8.25mm and an 8mm key is sloppy. I have found this Prestoite drawing for the same alternator and it specifies 8.19-8.04 for the Hex recess, so is this the design clearance for 8mm? If yes, then I suppose my one is a bit over machined. Any ideas (apart from get filing down a 3/8 etc, or trying an 8mm and rounding it out ....).

thanks

[onionbargee]

if you try to force a too small Allen key then you might knacker the hex for good, then you will be up s##t creek. Better to get a soft cheapo Poundland key and file it down.

 

You can cut a short section off the Allen key and fit it into a suitable socket to get more leverage.

[Boat&Bikes]

Bit late and had a beer but is that not about 21/64 in old money?

 

Ian

 

Sure your 8mm is not worn?

Edited October 6, 2013 by ianali

[onionbargee]

21/64 is 8.3 mm

[Ex- Member]

On my 90 amp I simply couldn't get it undone, nothing to do with the 8mm key, just bloody tight. I popped along to the local garage and there's a special tool for doing this, the chap in the garage did it in less than a minuet no charge. I'm assuming if there's a specific tool for doing the job them 8mm Hex is probably an industry standard size.

[Captain Fizz]

The drawing shows it as AF which means it is an imperial size key.

[Boat&Bikes]

The drawing shows it as AF which means it is an imperial size key.

Nah.

[RLWP]

Hmmm, I don't think I've ever tried to take a pulley off that way. I've always gripped the pulley and undone the nut

 

Richard

[Captain Fizz]

Nah.

5/16 AF

[Boat&Bikes]

5/16 AF

8mm AF

 

Not the same size i know but AF equals across flats metric or imperial.

Edited October 6, 2013 by ianali

[baffle]

Hmmm, I don't think I've ever tried to take a pulley off that way. I've always gripped the pulley and undone the nut

 

Richard

Ah now that makes much more sense. I shall give it a go with a filter wrench or something similar. Thanks for all replies.

[RLWP]

Sometimes you can get away with using a fan belt to hold it

 

Richard

[Timleech]

Impact wrench is the easiest way.

 

Tim

[bizzard]

If you squeeze the pulley in a vice your liable to damage it. I place the alternator on the ground and hold it down under my boot. If your right handed stick your left boot on it. Grasp and hold the pulley still firmly with your left hand, if left handed with hold the pulley with your right hand and use your right boot, if you happen to be ambidextrous it shouldn't matter. If you have delicate hands stick an industrial glove on the hand you grasp the pulley with. Place a stout shallow cranked ring spanner upright on the nut and clout it sharply in the undo direction. If this doesn't do it place an Alan key in the pulley shaft end, add a length of tube to the handle end of the key and swing it over in an anti-clock direction so it rests on the ground and carry out the spanner clouting again. I've never failed to shift these nuts using these methods.

[Sir Nibble]

Pneumatic impact wrench every time. There is no woodruff key on these things and trying to hold it with an allen key is likely to be futile.

[baffle]

Ok while you've all been helpfully adding various thoughts I've been failing to get it undone. I carefully tried winding the pulley up in a big wood vice, but the pulley is just spinning. Ditto with alloy liners on a metal vice, but I am being a bit coy with the pressure. On an associated note, I have got myself the biggest pulley that can go on my AS2s crank (217mm) with a taper lock centre. The key way in the taperlock is maybe 1/2" while key way in crank is something nearer 3/8s. Do I overcome this by filing up a stepped brass key ? Thanks

[Timleech]

Properly assembled, taperlocks don't really need a key but if you feel happier with one, by all means make up a stepped key. It doesn't need to be brass, though, steel is fine.

 

Tim

[baffle]

Thanks. I'll see that I assemble it properly then! Is there any rot for how much torque to give the grub screws, or does alignment of centre and pulley faces (so long as shaft and centre are correct diameters) indicate correct assembly?

[David Schweizer]

I have a spare A127 alternator in the workshop at the moment. I have just measured it with a vernier caliper and it is definitely 0.312.5 " ie: 5/16" AF.

 

For what it is worth I have always been able to remove the pulley by using an allen key and ring spanner, but maybe that is because I have always put the pulley on myself and not over tightened it with a Pneumatic spanner!!

[baffle]

Have been away for a few days but got back to alternator this morning.Couldn't shift nut by holding and whacking so wimped out and went to find local alternator man who removed nut with an impact driver. I picked up an old 3" SPA ( I think) pulley for alternator, which I then bored out to 17mm, and got on with bracket making. Tightened on new pulley with 5/16 allen key and tightened with ring spanner - allen key did twist and jam slightly as I think shaft is over machined as I posted originally (and had measured with digital caliper). Think pulleys are in same plane, but will have to wait til next weekend for picking up a belt. And then to add some wiring.

Here are some grainy piccies. My welds are functional, but not pretty.

[RLWP]

That's looking good. I love working with those Taperlock pulleys

 

A tip - I always resize my photos to 640x480 (or thereabouts) before bunging them onto the image host. It makes it easier to put together my text and words

 

Richard

[baffle]

Thanks - I need to resize using my smart phone, or as this is probably a bit fiddly take shots at a smaller size in the first instance before uploading from the phone. The direct uploading from the phone to in this instance a public dropbox folder is wonderfully easy.

[RLWP]

Sometimes image hosting sites offer simple editing, like rotating and resizing. I don't know about Dropbox

 

Richard

[baffle]

I can't see a resize in the mobile dropbox version. Am using dropbox cos it has a good and small size interface that works with an android phone, and my phone has very limited memory .....a bit like me!