JJC Posted February 29, 2008 Report Share Posted February 29, 2008 I've just fitted the pulley conversion kit and found that the fan belt supplied by our ever popular parts firm is too long. At least I think it is because the dynamo is leaning on the inner wing and the belt is still loose. The supplier checked in their parts bin and all the belts with their kits are the same as the one I have. Ever helpful they will send me a shorter one, I could guess at the correct length but would much rather know the correct Quinton Hazell (or whoever) reference number. Does anyone know? Would some kind soul with the lightweight narrow belt conversion running on their car go and read the QH number off the belt for me? Many thanks Quote Link to post Share on other sites
stuart Posted March 1, 2008 Report Share Posted March 1, 2008 I've just fitted the pulley conversion kit and found that the fan belt supplied by our ever popular parts firm is too long. At least I think it is because the dynamo is leaning on the inner wing and the belt is still loose. The supplier checked in their parts bin and all the belts with their kits are the same as the one I have. Ever helpful they will send me a shorter one, I could guess at the correct length but would much rather know the correct Quinton Hazell (or whoever) reference number. Does anyone know? Would some kind soul with the lightweight narrow belt conversion running on their car go and read the QH number off the belt for me? Many thanks Try QBA 963 thats the one TR Shop supplied me for the last one I fitted. Stuart. Quote Link to post Share on other sites
mog620 Posted March 1, 2008 Report Share Posted March 1, 2008 I too, have recently changed to the narrow belt conversion. The number on the belt I got with the "kit" was QBA975........Frank Quote Link to post Share on other sites
JJC Posted March 2, 2008 Author Report Share Posted March 2, 2008 I too, have recently changed to the narrow belt conversion. The number on the belt I got with the "kit" was QBA975........Frank Frank - thanks, did the belt fit? The ref number on the belt that came with my kit is also QBA 975 but is too long for my car. Perhaps I'd better go and have another look if yours fitted! John Quote Link to post Share on other sites
JJC Posted March 2, 2008 Author Report Share Posted March 2, 2008 I too, have recently changed to the narrow belt conversion. The number on the belt I got with the "kit" was QBA975........Frank Frank - I've been and had another look and the belt is definitely too long. So if yours fits, why? The only things I can see that can vary are the fan belt length and the dynamo pulley diameter. The dyno pulley in the kit I got is smaller diameter than the original. Why is that? And is that the reason for the belt appearing to be too long? I'll try and get the answer from Moss when they're open. Yes, I did ask specifically for a kit to retain the dynamo and not convert to alternator. Quote Link to post Share on other sites
mog620 Posted March 2, 2008 Report Share Posted March 2, 2008 Frank - I've been and had another look and the belt is definitely too long. So if yours fits, why? The only things I can see that can vary are the fan belt length and the dynamo pulley diameter. The dyno pulley in the kit I got is smaller diameter than the original. Why is that? And is that the reason for the belt appearing to be too long? I'll try and get the answer from Moss when they're open. Yes, I did ask specifically for a kit to retain the dynamo and not convert to alternator. Â Â JJC - I have a 1968 Morgan Plus 4 (TR eng) and I have changed to a ALTERNATOR as well. It's possible that my "adjustment arm" is longer now. More room to the inner fender(wing) than a TR? Â I also can use a AC Delco belt: 15380 88934310 12/32" x 36-5/8" OC Â But I really think you should take the belt to a factor and tell him your belt is too long. They should have a measuring device that will tell them what belt would work Cheers Frank (In deepest, darkest Texas) Quote Link to post Share on other sites
JJC Posted March 3, 2008 Author Report Share Posted March 3, 2008 Why are things always complicated? When I ordered the lightweight pulley kit I asked for a pulley that would allow me to retain the dynamo. Whilst talking to Moss this morning I was reading their catalogue and it clearly says that their kit contains an alternator pulley. I hadn't spotted that and to be fair (to me!) the catalogue doesn't really say up front that if you convert to narrow belt, lightweight pulley and electric fan then they expect you to convert to an alternator as well. So, my take on this at the moment, and this is just my non-engineer's guess, is that the kit supplies a pulley suitable for an alternator which will rotate the alternator at a lower speed than the original dynamo. Hence the pulley is smaller diameter than original hence the belt appears too long in my case retaining the dynamo. Mind you this theory does depend on the alternator being smaller than the dynamo (and I didn't think they were) so it can get closer to the inner wing. What I don't understand is why we haven't heard from lots of people saying they didn't have any difficulty. Has everyone else converted to an alternator? Quote Link to post Share on other sites
Menno van Rij Posted March 3, 2008 Report Share Posted March 3, 2008 Why are things always complicated? When I ordered the lightweight pulley kit I asked for a pulley that would allow me to retain the dynamo. Whilst talking to Moss this morning I was reading their catalogue and it clearly says that their kit contains an alternator pulley. I hadn't spotted that and to be fair (to me!) the catalogue doesn't really say up front that if you convert to narrow belt, lightweight pulley and electric fan then they expect you to convert to an alternator as well. So, my take on this at the moment, and this is just my non-engineer's guess, is that the kit supplies a pulley suitable for an alternator which will rotate the alternator at a lower speed than the original dynamo. Hence the pulley is smaller diameter than original hence the belt appears too long in my case retaining the dynamo. Mind you this theory does depend on the alternator being smaller than the dynamo (and I didn't think they were) so it can get closer to the inner wing. What I don't understand is why we haven't heard from lots of people saying they didn't have any difficulty. Has everyone else converted to an alternator? Â A smal pulley on the alterator will make the alternator spin more quickly that a dynamo with a large pulley. Say, the large pulley turns ones, a smaller pulley will turn twice during the rotation of the large pulley. So, when your engine is at idle speed, say 800 rpm, the alternator pulley will turn at 1600 rpm at the same time. Most alternators start charging around 1200 rpm (if I have this figure right). So, when the engine's idle speed is below 600 rpm, the charging light will start to glow. Â Therefore, I think your are right with your theory! A dynamo with a small pulley: a hibrid, I think. Having said that, did you consider the fact that a large belt should be attached very loosely to the pulley (see this in an other topic as well)? The belt will snap when tensioned too much. But... a small pulley has to be tensioned quite firmly to the pulleys. And I seem to remember a topic about the bearings: the dynamo bearings will not comply with the tension of the small belt. Therefore, I think it's wise to find this out before you put all things back together. Â Menno Quote Link to post Share on other sites
stuart Posted March 3, 2008 Report Share Posted March 3, 2008 The belt number I quoted originally ( QBA 963) was fitted to a dynamo setup on a TR2 with a crankshaft damper fitted and apart from having to mill off the rear of the dynamo pulley to bring the belts in line fitted perfectly, with the adjuster at about half reach. Supplied by TR Shop. Stuart. Quote Link to post Share on other sites
JJC Posted March 3, 2008 Author Report Share Posted March 3, 2008 Sigh..........Like I said, nothing's ever simple. It looks as though the alternator would mount with it's spindle further away than the original dynamo so it might be that the requires the longer belt rather than it really being down to the pulley. I've just looked at the pulley supplied with the kit and it's about 10% less circumference (at the belt) than my original. Moss have offerred a part said to be for use with the dynamo and a shorter belt. I reckon it needs a belt about 87cm long. Not only that, when I've fixed this I've then got to get the gearbox out to find out why that's making unpleasant noises. Sigh........ Thanks for the tip about belt tension and bearings. Quote Link to post Share on other sites
unclepete Posted March 4, 2008 Report Share Posted March 4, 2008 (edited) JJ It is not too complicated. Wrap a piece of string round the pulleys you have and measure in mm - that is the length of the belt you need. The profile of the belt is SPA - 'A' being the wedge belt depth, pitch and width. Look on the Web and find your nearset 'Wyko' outlet for industrial bearings and belts, quote the length you need and 'spa' as the profile and they will let you have the nearest size. I normally set the adjustments mid way before measuring the length of belt you would need. Order a couple (1 for spare) they will usually take a card order over the phone and the belts are relatively cheap £3 or £4 each. Good luck Unc Edited March 4, 2008 by unclepete Quote Link to post Share on other sites
JJC Posted March 4, 2008 Author Report Share Posted March 4, 2008 Thanks for the gen on where to get belts. I did measure with a bit of string and made it about 87cm. When I've got it all back together I'll let you know how I get on. Quote Link to post Share on other sites
unclepete Posted March 4, 2008 Report Share Posted March 4, 2008 JJ I must admit that 870mm does seem small - the string may be a bit thin and be dropping too far into the pulleys? The thin belt conversions are usually around 955 - 975mm. Unc Quote Link to post Share on other sites
JJC Posted March 8, 2008 Author Report Share Posted March 8, 2008 Even deeper sigh......................... The fan belt arrived from Moss really quickly. So I fitted the correct pulley on the dynamo (also rapidly supplied by Moss), and the belt (which fits fine), radiator back, quick test, and it all fell apart from there. The dynamo seems to be overcharging (nothing to do with the pulley, most likely control box again), the radiator leaks at the end of the filler neck, and the new Kenlowe didn't switch on. Oh yes, and the fan belt was made in Germany (see the other thread on fan belts)! So one way and another not a good day. It's not even my car, it's my daughter's. But she did say I could do Prescott in it if I get it fixed (at least that's my story). It's days like this I regret selling my wife's MG. Quote Link to post Share on other sites
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