The_Doc Posted January 24, 2018 Report Share Posted January 24, 2018 Hi All I was wondering what people thoughts were on lightening the flywheel of my 4A. Currently the flywheel, including ring gear, is approx. 23 lbs. I'm not looking to go down the competition route so don't need to get it down to a couple of lbs. However, it would be nice to try and increase the responsivness of the car, but not sacrafice the tick over at idle. Is there an ideal amount to shave off or is it better to leave it stock? Any thoughts or suggestions would be welcome. Thanks Adam Quote Link to post Share on other sites
iain Posted January 24, 2018 Report Share Posted January 24, 2018 I think you are about at the limit of weight reduction for a road car. 22-23lbs is about right. Iain Quote Link to post Share on other sites
john.r.davies Posted January 24, 2018 Report Share Posted January 24, 2018 Adam, You would need to reduice it a LOT to feel any added 'responsiveness'. Revington offer an alloy one at 14.5lbs. The T six cylinder engines varied from a whopping 24lb one on the 2.5 saloon to 'only' on a GT6. I've got mine down to 7kgs (15.4lbs) but I honestly can't tell the difference. JOhn Quote Link to post Share on other sites
Chris59 Posted January 24, 2018 Report Share Posted January 24, 2018 Balancing the whole thing (flywheel, clutch, crankshaft, conrods, pistons..) would be more sensible, imho. Quote Link to post Share on other sites
iain Posted January 24, 2018 Report Share Posted January 24, 2018 +1 Quote Link to post Share on other sites
ChrisR-4A Posted January 24, 2018 Report Share Posted January 24, 2018 My flywheel is 20lbs and it's fine. Most difference in new engine was a result of balancing everything and not having a fan extension on front, they very rarely run true and fitting narrow belt with damped pulley. Done nearly 20,000 miles since rebuild and am pleased with everything as is. Engine built by Carlow Engineering of Benfleet, Essex. PS. When balancing everything, don't forget the prop shaft. Chris Quote Link to post Share on other sites
Malbaby Posted January 24, 2018 Report Share Posted January 24, 2018 Adam, mine is similar to Chris...20lbs...narrow belt conversion with harmonic balancer and fully balanced engine and clutch components. Quote Link to post Share on other sites
Drewmotty Posted January 24, 2018 Report Share Posted January 24, 2018 The early flywheels weigh little more than 20lb as standard. Quote Link to post Share on other sites
iain Posted January 25, 2018 Report Share Posted January 25, 2018 From recollection, that could be wrong, there where two fly wheels. One at 21 lb (early) and another at 31 lb. (Stock TR4). Iain Quote Link to post Share on other sites
TR 2100 Posted January 25, 2018 Report Share Posted January 25, 2018 Adam, Unless you went for an ultra-light flywheel, I think you would be hard pushed to notice any difference. As Chris says, balancing is far more important and, unless you have been exceptionally lucky with the factory balancing, you will notice a much smoother engine, at speed and at tickover. AlanR Quote Link to post Share on other sites
BlueTR3A-5EKT Posted January 25, 2018 Report Share Posted January 25, 2018 (edited) Go the whole hog... A Fidanza aluminium one which is supposed to weigh 10- 12 lb ish..... http://www.ebay.co.uk/itm/Fidanza-172441-Aluminum-Flywheel-fit-Triumph-TR4-54-65-All-24-HOUR-SALE/380490598853?epid=195055798&hash=item589701c9c5:g:FmYAAOSw9YNZuHHX You will probably still have a tick-over as the standard clutch is a lump in itself. Other peoples comments and experience http://www.britishcarforum.com/bcf/showthread.php?94078-Lightening-a-stock-TR3A-flywheel Peter W Edited January 25, 2018 by BlueTR3A-5EKT Quote Link to post Share on other sites
john.r.davies Posted January 25, 2018 Report Share Posted January 25, 2018 (edited) That Fidanza is cheap, but yu'll still have to pay VAT on it. If you must then machining you own might be cheaper. Remove from the rim as far as posible, the hub contributes little to inertia and needs to be strong. But not as much as this Spitfire 'wheel. This is my Vitesse flywheel: John Edited January 25, 2018 by john.r.davies Quote Link to post Share on other sites
ianc Posted January 26, 2018 Report Share Posted January 26, 2018 David Vizard's "Tuning Standard Triumphs over 1300cc" has a section on lightening components, and "How to improve Triumph TR2-4A" by Roger Williams also covers clutches & flywheels. Ian Cornish Quote Link to post Share on other sites
Chris59 Posted January 26, 2018 Report Share Posted January 26, 2018 (edited) That Fidanza is cheap, but yu'll still have to pay VAT on it. If you must then machining you own might be cheaper. Remove from the rim as far as posible, the hub contributes little to inertia and needs to be strong. But not as much as this Spitfire 'wheel. VERY lightened flywheeel.jpg This is my Vitesse flywheel: reduced wt flywheel (1).JPG John John, what kind of flywheel bolts do you use ? They seems to be hi tensile bolts from ARP, if I'm not wrong ? Edited January 26, 2018 by Chris59 Quote Link to post Share on other sites
john.r.davies Posted January 26, 2018 Report Share Posted January 26, 2018 Chris. That is NOT my Spitfire flywheel! I value my ankles too much, and think that one is lightened to the point of being a high explosive! And I am not enamoured of ARP bolts. Had one give way on a big end last year. John Quote Link to post Share on other sites
Chris59 Posted January 26, 2018 Report Share Posted January 26, 2018 I value my ankles too much, and think that one is lightened to the point of being a high explosive! Well, it's a FLYwheel after all Quote Link to post Share on other sites
Motorsport Mickey Posted January 26, 2018 Report Share Posted January 26, 2018 Unbrako good thick washers close fit, torqued up as per workshop manual with a dab of blue loctite. Fit and forget. Mick Richards Quote Link to post Share on other sites
TriumphV8 Posted January 26, 2018 Report Share Posted January 26, 2018 A cast flywheel might break if too much shaved off before any bad influence is noticed. TR4 with its heavy crank is such an example. Like TR6 there are so many heavy components that the rotating mass is still on the safe side, whatever you do. Feel free to take material wherever you want but not weakening it too much. Besides the whole weight it is more important where to remove material. The more it is on the outside, the better it is. I prefer setting some holes at the ouside diametre additionally where the clutch cover is bolted. Also the back where the starter ring is settled might be removed. That is fully unnecessary for stability and the ring can be fixed with a little weld spot. The proper material is Nickel otherwise weld seam gets hard. Rebalancing is a must BASTUCK offers light steel flywheels at good prices. Steel wheels and ARP bolts is a good and cheap way to go. I have an ultralight Fidanza in the TR6 and also the crank lighter and light rods. The engine seems to have 50 BHP more than it has. I have to sacrifice that pulling under full load from idle is worse. Before I could do that from 800 rpm if you have no feeling for the engine that suffers badly from that. Now you notice a humming, suggests not to do that below 1400rpm. It is no problem to let the engine go down to 1000 rpm and accelerate with part throttle but full throttle seems to be not recommended. The smoothness is gone but do we need that? From 2000rpm on only benefits are noticed. Idle is no problem at all. I have a 290 degree cam and normal idle. Quote Link to post Share on other sites
Bfg Posted November 27, 2019 Report Share Posted November 27, 2019 . Good evening all, I was reading this post and referring to David Vizard's book p.93 it says "The four cylinder engines also have a heavy flywheel. For these engines, you can have one of two different flywheels depending on the type of clutch fitted, the one being heavier by far than the other." As I'm wishing to have a lighter flywheel, this would imply using one off the TR4. However, it was suggested in conversation today that the 4A flywheel has four mounting bolts whereas the TR4 ones have six bolts. Is this correct ? Might I also ask if the 4A clutch is better ? Thanks, Pete. Quote Link to post Share on other sites
Hamish Posted November 27, 2019 Report Share Posted November 27, 2019 Pete not sure it’s of any use to you. But this is my 3a lightened flywheel and the conversion to a diaphragm clutch. This needed the flywheel drilling and tapping to take the different clutch. Quote Link to post Share on other sites
Bfg Posted November 27, 2019 Report Share Posted November 27, 2019 (edited) Thanks Hamish, that is useful. I'm guessing the 3A and 4 flywheels were the same lighter ones - so the fact that it can be adapted (seemingly quite easily) is good to know. I presume you've not encountered subsequent issues with this conversion ? From my days with a Norton Commando I do like a diaphragm clutch, so I would consider that a worthwhile machine-shop expense (I would doubt if I might drill it accurately myself). I'm told that an engine rebuilder would first balance the crank, then the crank and flywheel together, and then the crank, flywheel and clutch all together, and then these plus whatever pulley / pulley + fan on the front end of the crankshaft. So these decisions are best made in advance of actually rebuilding the engine. Cheers, Pete. Edited November 27, 2019 by Bfg Quote Link to post Share on other sites
BlueTR3A-5EKT Posted November 27, 2019 Report Share Posted November 27, 2019 Remember that if you change flywheels you must get the correct starter to match the ring gear on that flywheel. fact. The TR 2/3/3A early flywheel (shrink on ring gear) as standard weighs about 22 lbs. the standard late 3A/4/4A (bolt on ring gear) is 30 lbs ish. Peter W ps. The combination I use is early flywheel from Sidescreen TR with 8.5” diaphragm clutch from TR 4A/5/6. Using suitable geared starter for shrink on ring gear. Quote Link to post Share on other sites
Hamish Posted November 27, 2019 Report Share Posted November 27, 2019 48 minutes ago, Bfg said: Thanks Hamish, that is useful. I'm guessing the 3A and 4 flywheels were the same lighter ones - so the fact that it can be adapted (seemingly quite easily) is good to know. I presume you've not encountered subsequent issues with this conversion ? Cheers, Pete. Hi i did have concerns about balancing as the old set up was so good. I was having the gearbox/od fixed and for a £30 extra the flywheel was drilled and tapped for the updated clutch. As I do sprints and hill climbs it does get abused so the later clutch copes with tr6 power ...... i weighed my flywheel at 8.5kg it was machine lightened in the ‘70’s and put it back in the same place. Thus it’s only the new clutch that is not balanced in the overall scheme. Ran all season without problems with the occasional over rev Quote Link to post Share on other sites
john.r.davies Posted November 27, 2019 Report Share Posted November 27, 2019 (edited) This is going into my next iteration. Tilton clutch, the plate is sintered bronze, and the steel 'wheel weighs FIVE KILOGRAMS! Used, the plate should be replaced, but else all in good nick. John Edited November 27, 2019 by john.r.davies Quote Link to post Share on other sites
Hamish Posted November 27, 2019 Report Share Posted November 27, 2019 What does that automotive eye candy do to the Tickover John ? i considered the tr enterprise light flywheel but didn’t jump that way. https://www.ebay.co.uk/itm/Triumph-TR4A-Lightweight-Steel-Flywheel-Assembly-can-also-be-used-on-TR2-3-A-4/184011808608?hash=item2ad7f55f60:g:IRYAAOSwEHhcE9q5 Quote Link to post Share on other sites
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