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Alternative alternator arrangement

15 May 2011, 8:57pm
With the alternator on the M50 engine in its standard position it extends about 3" beyond the engine compartment side panels on the RHS (viewed from the front)

I've made up a new bracket and now fitted it on the LHS where there's loads of room (although its a bit close to the exhaust manifold and will probably need some shielding)

Before...............


Alternator conumdrum by MarlinBuild, on Flickr

After..................


Alternator conumdrum by MarlinBuild, on Flickr

Now it leaves me with a couple of concerns. The first is that the original drive belt is too long so I'll need a shorter one. Perhaps there's an OEM one that will fit but does anyone know where I can get custom made belts from if I need one.

And the second is the reduced purchase on all the pulleys with the new routing of the drive belt and the potential for slippage. I won't know if that's a problem until much later but I may need to find a way to fit additional guide wheels to improve the purchase.

We shall see...........................
15 May 2011, 10:18pm
NigelB wrote:

I've made up a new bracket and now fitted it on the LHS where there's loads of room (although its a bit close to the exhaust manifold and will probably need some shielding)


Alternator conumdrum by MarlinBuild, on Flickr

Now it leaves me with a couple of concerns. The first is that the original drive belt is too long so I'll need a shorter one. Perhaps there's an OEM one that will fit but does anyone know where I can get custom made belts from if I need one.

And the second is the reduced purchase on all the pulleys with the new routing of the drive belt and the potential for slippage. I won't know if that's a problem until much later but I may need to find a way to fit additional guide wheels to improve the purchase.

We shall see...........................


Nigel

If you lower the position of your concentric pulley by mounting it from the lower alternator bolt you can route your belt from the crank over the idler and get very good wrap on all the pulleys.
http://www.flickr.com/photos/mikes_bmw_marlin_cabrio/3562227521/in/set-72157618689127549 (Why does this appear as a url and not as the photo?)

I measured my belt length and sourced it easily from a local motor factor.
Mike
16 May 2011, 12:19pm
Mike wrote:
Nigel

If you lower the position of your concentric pulley by mounting it from the lower alternator bolt you can route your belt from the crank over the idler and get very good wrap on all the pulleys.


Thanks Peter and Mike.

I need to have the concentric pulley mounted on the top mounting bolt to ensure the drive belt doesn't foul the crankshaft position sensor in its run from the water pump pulley to the alternator. But there's no reason why I shouldn't fit a second one on the lower bolt and I like the idea that I can then use that as the belt tensioner.

Thanks for the ideas

Nigel
16 May 2011, 4:43pm
Hi Nigel
I used a similar solution and had no problem with the tension in the belt. The only thing I did find was that routing and connecting the bottom radiator hose was rather fiddly, especially as you have to avoid the steering column as well.
Tim
19 May 2011, 10:05am


Nigel
I guess your bracket for the alternator is different to mine - I did not have a problem with the belt going direct from the alternator to the pump and fouling on the crankshaft sensor.
Have you sourced a belt yet?
Mike
20 May 2011, 10:23pm
Mike,

I had to make up my own bracket. There was nothing supplied by Marlin so that probably accounts for the difference.


Alternator conumdrum by MarlinBuild, on Flickr

I could probably have made it so that the alternator was a little higher and the belt would avoid the sensor but I was worried about the proximity of, and the heat from the exhaust manifold. So I decided to let the concetric pulley provide the clearance from the sensor. It was only once it was all in place and I could see the layout of the belt that I became worried about the belt's purchase on the pulleys. But I think an extra pulley in the same place as yours and the consequent ability to remove the tensioner should do the job.

I haven't sources a belt yet. That's a job for another day.

Nigel