What side should dynamo tension adjuster go on dynamo?

[minstix]

Hi,

Having finally worked out the correct fan belt length as per a couple of topic posts ago with help from you guys, I'm now in some confusion as to which side of the lower dynamo tension adjuster mount the adjuster bracket should go. This is on a standard Mini Cooper S MK2. Does anyone know whether the adjuster goes on the left or the right of the dynamo threaded hole?

Mine was originally a bit of a botch and used two brackets on top of each other. I'd like to fit it the way it should have been. I've got a new bracket, straight and straight sided (not banana shape) as per the original. See the attached pictures with it temporarily fitted with both options.

If on the right side, which is where I've seen it mounted in the past on standard minis, the slightly fan clashes with it but that could easily be sorted out.

Thanks as always for your help.

Steve

Right.jpeg

Left.jpeg

[Peter Laidler]

I would say that the tension adjuster strap should go in the position that it lines up EXACTLY at both ends. Unless I am missing something. That said, it is important that the fan belt is also accurately aligned across the three pulleys

Do you have a parts list and a workshop manual Ministiks? It is sometimes easier to refer to a picture or wording

[GraemeC]

How are you spacing it off the engine frontplate? There is a proper post for this, which will dictate where it goes:
https://www.minispares.com/product/Clas ... o%20search

I would say the first picture is correct and you may find you need a spacer between the cooling fan and the water pump pulley:
https://www.minispares.com/product/Clas ... o%20search

[minstix]

Hi,

I bought one of those official spacing posts (12G289) and the spacing works out inconclusive because whichever way I try it, it doesn't line up at all, leaving a big gap to fill with washers or a suitably made spacer. Neather position gives any clue if the 12G289 post is used. I don't remember seeing one of these on my car, I think it was just a long set screw and nuts and washers. However, I don't think it was as it should have been. I should have taken more pictures when I took the car apart.

(I definitely had one of those spacing posts on my old 1965 Wolsely Hornet I remember though but thsat was a very different car).

The dynamo is the original, as fitted from the factory I'm pretty sure, because the date stamped into the body of it totally ties up with when the car was made.

My dynamo has quite a thick area where the screw goes through. I've seen pictures of other, maybe earlier mini dynamos, that are much thinner there. So in other words there's more tread on mine. If it were a thinner version then the brackert wouldn't fowl on the fan but because it's thicker, it does.
I can't move the pulley or fan because at the moment the pulley alignment is absolutely bang on lining up with the water pump pulley and crank pulley.

Interseting conundrum.

Steve

[minstix]

I should have said that if the bracket is as in the second picture, on the left side, then you couldn't use that special post at all. It's thicker than the gap then. Is that a clue? Maybe but were these posts used at all on these later cars with dynamos with thick threaded holes?

I've seen a few drawings but are general for all past dynamo cars and are a bit misleading.

Steve

[Polarsilver]

I fit as your photo no 1 .. if things do not align ..shim the sliding tension adjuster strip at the timing cover end to get the alignment .

[minstix]

I think you’re right Polarsilver. I’m modifying the bracket so it clears the fan.

Steve

[TECH396]

As far as I know the mk2 S did use two adjustment brackets and certain it fit to the inside of the generator. The reason for two brackets was to reduce vibration at high rpm.

[floormanager]

I had a similar issue with the straight bracket hitting the dynamo fan. I gave up and used a banana bracket. Good luck!
Paul

[minstix]

The two brackets on the inside of the generator is, I think, how it was on my car when I got it. Having looked at fuzzy pictures I've now found that I took when I dismantled the car. I thought the two brackets and just a simple screw, nuts and washer was a bodge that someone had done in the past. No specially made post.

I think it may have been on the inside, ie further from the radiator side. Is it just Cooper S that was this way perhaps? Maybe it wasn't a bodge?

The threaded mounting hole in the dynamo aluminium seems thicker than other perhaps earlier mini C40 dynamos I've seen. Maybe the treads were ripping out? See the picture. The bit between the two arrows is what seems to be the extra thickness. The fan blades have a little curved cutout on their ends which I imagine was to clear the bracket on dynamos without the extra thick mounting threaded piece. Not enough clearence on mine though. The fan blades hit the bracket.

I fitted the special post and the bracket on the radiator side, as in the picture. The 'would be needed' extra spacer thickness ties up with that distance between the two arrows. I think I'll order another straight bracket and fit it behind instead and not use the special post. i must admit I do keep swithering from one option to the other.

Steve

Dynamo extra thick mounting point.jpg

[TECH396]

The best thing to do is make sure the generator and water pump pulleys are inline with the damper pulley. Here is a poor picture of the lower bolt attached to the timing plate. From L-R
Nut, lock washer, plate, large hex, double adjustment plates, flat washer, nylocknut.

[minstix]

So you’re saying that the ‘bolt’ that attaches the adjustment brackets to the plate is a special two ended bolt with a hex in the middle of it, part of it? Or is it just a length of 5/16 threaded rod with a nut halfway along it? Or something like that?

Steve

[TECH396]

So you’re saying that the ‘bolt’ that attaches the adjustment brackets to the plate is a special two ended bolt with a hex in the middle of it, part of it? Or is it just a length of 5/16 threaded rod with a nut halfway along it? Or something like that?

Steve

Yes, it's a special double ended bolt and is 3/8" not 5/16"

[minstix]

Thanks Paul,

You’re a star. That has completely solved the mystery.

I’ve been looking high and low for the original brackets and fixing to attach to the engine plate. Gave up in the end. But yesterday I found a few pictures of when I took the engine out two or three years ago. Zooming in on the plate part, it’s all pretty low res by then, I now realise my mistake.

The engine went off to the engine rebuilders. It was gone for over a year. It went with the special double ended bolt and two brackets still attached to it and of course they never came back. Would have been rusty but would have then been obvious how it is supposed to go together. I don’t think the engine builder will have any memory of them now.

Anyway, you solved the problem Paul, thanks. I hope you didn’t take it all apart just to answer my question. If so, extra thanks.

All I need to do now is to try and track down one of those special double end bolts. Maybe some 3/8 UNF thread and a nut the right depth would do.

Thanks,

Steve

[TECH396]

You're most welcome. I would advise against using a long bolt and spacer because there is a higher risk of it loosening off, as opposed to the proper one piece one. If you need more info, just ask.

[GraemeC]

If Paul is willing to get the dimensions, then I'm sure some kind soul could make you one from hex bar.
You'd need to know:
- A/F size of the hex (spanner size) - I'd guess at 3/4"
- Thickness of hex portion
- Length of 3/8 UNF thread to each side

You'd might get away with a length of 3/8"UNF thread and a custom-made nut threaded and loctited (bearing fit strength) onto it, which would be a lot less machining.

I'd have a go myself but I think the largest hex bar I have is 9/16". Easy enough to get a short length of something off ebay - depends how quickly you need something.

[TECH396]

There were three different part numbers for these. Here they are from my AKD book.

2A128 PILLAR, adjusting, 850cc and 1000cc to 1969; Cooper 1961-63.
12G289 PILLAR, adjusting, Cooper Models, 1963-69; all models except Cooper S, 1969 on.
AEG182 PILLAR, adjusting, Cooper S models.

https://www.somerfordmini.co.uk/dynamo- ... -mountings

The other thing worth mentioning is if you look these up on Somerfords website (link provided) , it leads you to a superseded part that I believe to be wrong.
If you want more specs. Let me know. PS. they're 3/8NF

[Peter Laidler]

Don't bother making one, I've got one in an old box of bits. PM me your address and I'll send it on. No charge except a 4 pack of Fosters from Tescos.....

Sorry to raise your hopes. Just found the bit but the centre hex part is .75 AF and .5" wide. My car is a cop car with an alternator so this must have been taken off when I replaced the old crap 11AC alternator. And has new nylocks and washers fitted

Free for the cost of postage and a couple of Fosters if you want to machine it to suit. Say, a crisp fiver in the post

[minstix]

Hi chaps,

Thanks for all this info. It’s very helpful. Especially the part dimensions and it even comes with a selection of dogs.

I’d be very grateful to get your spare spacer Peter if you’re happy with that. Are you saying that the hex bit in the middle is 0.2” thicker than the standard part was? I’m sure I can get it modified to be the same as the standard part would have been at my local friendly engineering workshop. Sounds like it just needs turning down a bit. Are the other dimensions the same and 3/8 UNF threads?

I’ll let you have my home address and if you do the same I’ll send something to add to your beer account, cheers Steve

[Peter Laidler]

On its way first thing Monday morning. A fiver by return will pay for postage, jiffy bag and a couple of tinnies! Cheaper than making one too!