Graham Baggaley Posted June 23, 2022 Report Share Posted June 23, 2022 Has anyone else suffered the indignity of not being able to get their (thick original) fan belt on? I have admittedly got an alternator on the set up using the original pulley from the dynamo; but try as I may the bloomin’ belt is not going on. Any tips of the trade anyone fancies sharing with me? thanks all. Graham Quote Link to post Share on other sites
RobH Posted June 23, 2022 Report Share Posted June 23, 2022 Do you mean you can't get it through the gap past the steering rod and onto the crank pulley Graham, or that it just seems too short ? Quote Link to post Share on other sites
Graham Baggaley Posted June 23, 2022 Author Report Share Posted June 23, 2022 I have it over the steering rod/arm, on the bottom pulley, on the water pump pulley but I can’t get it over the alternator pulley. Yes it feels like it’s too short…which is clearly nonsense I’m sure so I was wondering if it was the location of the alternator pulley relative to the dynamo pulley that would have been there that is the issue? Quote Link to post Share on other sites
RobH Posted June 23, 2022 Report Share Posted June 23, 2022 The alternators are a wee bit fatter than a dynamo I think, so might not swivel as close to the block when the linkage is loose. I take it there is no more movement possible ? Quote Link to post Share on other sites
Graham Baggaley Posted June 23, 2022 Author Report Share Posted June 23, 2022 The alternator is loose and I can press it against the block. Do more movement. Very frustrating. I think a cup of tea and a think about it is needed. Quote Link to post Share on other sites
RobH Posted June 23, 2022 Report Share Posted June 23, 2022 (edited) In that case I suspect you may need to take off the pulley, fit the belt to it and then replace with it fitted. The alternative is to junk the original style fat belt and use a modern 17mm wide BX cogged belt like this, of the appropriate length: https://www.bearingshopuk.co.uk/bx33-5-cogged-v-belt/ They sit deeper in the pulleys so you would need to measure the length you need for your particular set-up. (I have used a 17 x 965 belt for about 10 years now, but that length is for a small diameter home-made alternator pulley.) Edited June 23, 2022 by RobH Quote Link to post Share on other sites
rcreweread Posted June 23, 2022 Report Share Posted June 23, 2022 Graham - if you are sure it's not too tight. put the belt on the alternator and water pump pulley first and start it off on the crankshaft pulley on the correct side so that when you turn the engine over on the starter. it pulls it on . It will be a bugger to get off! Cheers Rich Quote Link to post Share on other sites
Graham Baggaley Posted June 24, 2022 Author Report Share Posted June 24, 2022 Great stuff. Thanks Richard Quote Link to post Share on other sites
Ralph Whitaker Posted June 24, 2022 Report Share Posted June 24, 2022 10 hours ago, Graham Baggaley said: Has anyone else suffered the indignity of not being able to get their (thick original) fan belt on? I have admittedly got an alternator on the set up using the original pulley from the dynamo; but try as I may the bloomin’ belt is not going on. Any tips of the trade anyone fancies sharing with me? thanks all. Graham Take the belt to a bearing shop and you will be able to buy another slightly longer which will prevent damage to the belt while trying to force it on the pulleys. In fact get a spare at the same time. B section belts are still used in industry so are readily available in different sizes. Ralph Quote Link to post Share on other sites
Graham Baggaley Posted June 24, 2022 Author Report Share Posted June 24, 2022 Thanks Ralph. Great suggestion. Quote Link to post Share on other sites
Ian Vincent Posted June 25, 2022 Report Share Posted June 25, 2022 By using the original dynamo belt on an alternator, surely you are losing one of the advantages of an alternator? Namely its ability to run at higher RPM than a dynamo and thus charge better when the engine is idling. Rgds Ian Quote Link to post Share on other sites
RobH Posted June 25, 2022 Report Share Posted June 25, 2022 Yes you are right Ian but it is better than nothing if you don't want the hassle of doing a narrow belt conversion. I doubt whether there are any wide-belt alternator pulleys generally available - I can't recall seeing one. Having a lathe I was able to make my own suitable pulley but few people have that facility. I guess a local machine shop might oblige at a price. Quote Link to post Share on other sites
BlueTR3A-5EKT Posted June 25, 2022 Report Share Posted June 25, 2022 (edited) 49 minutes ago, RobH said: Yes you are right Ian but it is better than nothing if you don't want the hassle of doing a narrow belt conversion. I doubt whether there are any wide-belt alternator pulleys generally available - I can't recall seeing one. Having a lathe I was able to make my own suitable pulley but few people have that facility. I guess a local machine shop might oblige at a price. If it is a Lucas alternator the wife belt dynamo pulley is a direct fit. If Nippon Denso alternator the pulley recess where the nut goes needs enlarging/adjusting on a lathe to give sufficient clearance for nut that holds the pulley to the alternator shaft. ND units do not have a woodruff key shaft. I have had no issues with this using old wide belt dynamo pulleys. Edited June 25, 2022 by BlueTR3A-5EKT Quote Link to post Share on other sites
RobH Posted June 25, 2022 Report Share Posted June 25, 2022 Yes they fit OK but the issue is the diameter. For the alternator to work optimally - i.e. to produce a better charge at low revs - the pulley diameter needs to be rather smaller than the old dynamo pulley, as Ian pointed out. Quote Link to post Share on other sites
Drewmotty Posted June 25, 2022 Report Share Posted June 25, 2022 (edited) It’s prudent to do a few sums to ensure that the alternator doesn’t rev over its maximum at peak revs. It can be a good few times faster than crank speed. Edited June 25, 2022 by Drewmotty Quote Link to post Share on other sites
RobH Posted June 25, 2022 Report Share Posted June 25, 2022 Moss sell a 2.5 inch (narrow belt) pulley for road use with the 4-pot engine, so the calculation has already been done. A tuned engine revving a bit higher may need a slightly larger one. Quote Link to post Share on other sites
Drewmotty Posted June 25, 2022 Report Share Posted June 25, 2022 Max revs vary a lot between different brands and sizes of alternator. Quote Link to post Share on other sites
RobH Posted June 25, 2022 Report Share Posted June 25, 2022 Common Lucas types (ACR and LRA) typically 16000 rpm and Denso and WOSP 18000 rpm I believe, so not wildly different and both usually have similar-sized pulleys. The crank pulley is 5.4 inches dia so you aren't going to get anywhere near the limit with the 2.5inch alternator pulley on a 4-pot road car, even using up to the 5000rpm red line (= 10800 rpm alternator speed). Even an engine capable of sustained 6000rpm will only give 12900 alternator rpm which is a fair safety margin. Obviously if you have a trick engine that pulls mega-revs you need an alternator set-up made for that use. Quote Link to post Share on other sites
Jean-Marie Raedts Posted September 12, 2022 Report Share Posted September 12, 2022 PulleyAlternatorWideBelt.pdfMy Powerlite alternator does not load sufficiently in idle mode of the engine in my TR4A. That's why I want to make a pulley with a smaller diameter for the alternator. I still have the wide belt. What is the angle for the V? I found 30°, but also 32°. Quote Link to post Share on other sites
RobH Posted September 12, 2022 Report Share Posted September 12, 2022 That is not an easy question to answer because the available literature doesn't seem to cover use with the small pulleys in cars. For a 'B' section belt British Standard BS3790 quotes 38 degrees for pulleys over 190mm diameter, and 34 degrees for pulleys of less than that down to a minimum of 160mm - so the very small diameter pulley in question could need to be even narrower angle and 32 degrees may be right. https://www.roymech.co.uk/Useful_Tables/Drive/Vee_belts.html If you have an old pulley which works why not just copy the angle on that ? When I made my own I copied the dynamo pulley angle ( but unfortunately I didn't record what it was ). Quote Link to post Share on other sites
BlueTR3A-5EKT Posted September 12, 2022 Report Share Posted September 12, 2022 1 hour ago, Jean-Marie Raedts said: PulleyAlternatorWideBelt.pdfMy Powerlite alternator does not load sufficiently in idle mode of the engine in my TR4A. That's why I want to make a pulley with a smaller diameter for the alternator. I still have the wide belt. What is the angle for the V? I found 30°, but also 32°. The problem you may find is that the wider belt may not be good on a smaller diameter pulley unless the belt you have is the type with internal ‘cogs’ or teeth. That allows the belt to pass around a smaller diameter pulley than the original plain belt. Quote Link to post Share on other sites
Jean-Marie Raedts Posted September 13, 2022 Report Share Posted September 13, 2022 Thanks for your inputs. I measured the angle on my original pulley (102266) which was mounted on my Lucas dynamo C40 and which has an outer diameter of 82.6 mm. The value is 30°. I plan to keep this value for the newly to made pulley with a diameter of 68 mm. I will also use a belt with internal cogs. Quote Link to post Share on other sites
Z320 Posted September 13, 2022 Report Share Posted September 13, 2022 On 9/12/2022 at 7:04 PM, BlueTR3A-5EKT said: The problem you may find is that the wider belt may not be good on a smaller diameter pulley unless the belt you have is the type with internal ‘cogs’ or teeth. That allows the belt to pass around a smaller diameter pulley than the original plain belt. The recommended pulley diameter for the classic typ 20 belt is about 160 mm!!! Why is the shortest typ 20 belt 900 mm long? This is the length you get the belt over 2 pulleys with 160 mm diameter + some mm to get it tight. 160 mm x 3.14 x 0.5 + 180 mm x 3,14 x 0.5 + 2 x 180 mm = 900 All 3 original TR pulleys are too small for a typ 20 belt and 900 mm has never been recommended for 3 pulleys. Anyway I use a coged Flennor 20X900 which came with the car 14 years ago, it was new on the cars rebuilt in 1992. Quote Link to post Share on other sites
BlueTR3A-5EKT Posted September 13, 2022 Report Share Posted September 13, 2022 15 minutes ago, Z320 said: The recommended pulley diameter for the classic typ 20 belt is about 160 mm!!! Why is the shortest typ 20 belt 900 mm long? This is the length you get the belt over 2 pulleys with 160 mm diameter + some mm to get it tight. 160 mm x 3.14 x 0.5 + 180 mm x 3,14 x 0.5 + 2 x 180 mm = 900 All 3 original TR pulleys are too small for a typ 20 belt and 900 mm has never been recommended for 3 pulleys. Anyway I use a coged Flennor 20X900 which came with the car 14 years ago, it was new on the cars rebuilt in 1992. Thank you for the forensic evidence. I rest my case m’lord. I too have been running the Fenner 20x900 clogged belt for some years on standard pulleys Quote Link to post Share on other sites
roy53 Posted September 13, 2022 Report Share Posted September 13, 2022 1 hour ago, BlueTR3A-5EKT said: Thank you for the forensic evidence. I rest my case m’lord. I too have been running the Fenner 20x900 clogged belt for some years on standard pulleys but where do you get them ?????? i have a friends TR2 here that has just had a new 20x900 belt fitted from Moss that is at it's max adjustment and still not tight. Roy Quote Link to post Share on other sites
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