Tr4aJim Posted August 16, 2018 Report Share Posted August 16, 2018 Folks, looking for opinions here. My winter project this year will be to install a narrow belt pulley conversion kit to my TR4a. Im doing this to have the convenience the narrow belt provides. My plan was to keep the stock fan extension and use a kit with an undamped crank pulley. My car currently has an 8 blade plastic fan installed by the PO, as well as the stock radiator, and I have not had any overheating issues. However, Ive been having second thoughts and dont want to regret later not getting rid of that heavy fan extension, and getting the required electric fan (and damped crank pulley). I have looked at the various parts suppliers and they all appear to offer either a damped or undamped kit, but dont appear to offer a separate damped crank pulley. So if I do decide in the future to dump the extension and go with an electric fan, I would have to then buy the full damped kit. So what do you folks think? Is going the electric fan route overkill for a car with no cooling issues? Or is getting rid of the fan extension worth the extra expense of the electric fan? Thanks! Jim Quote Link to post Share on other sites
BlueTR3A-5EKT Posted August 17, 2018 Report Share Posted August 17, 2018 My TR runs a crank extension with the mechanical fan removed and an electric fitted. That way I retain the starting handle. There is a shed load of room on the TR4A to fit the fan in front of the radiator, and if the electric fan fails you could fit the spare plastic mechanical one you stored in the boot..... The damped pulley comes from an MGB. Your challenge is getting/making the sleeve spacer to go over the MGB pulley seal area so you can run the standard front crank oil seal with the pulley in the right place to line up the drive belt. That is why the kit comes as a kit. Many owners run the non damped pulley arrangement and no extension. I thought the non damped pulley was created as a convenience for cars with starting handles that went across to the narrow belt set up. Electric fans eat electricity - be sure you have a charging system that will cope. That is why we talk about fitting alternators. Cheers Peter W Quote Link to post Share on other sites
Drewmotty Posted August 17, 2018 Report Share Posted August 17, 2018 I recommend going the whole hog. Fit the narrow belt, electric fan and an alternator. I have a damped pulley on my TR3 but after a lot of research went for an undamped pulley on the TR4. Quote Link to post Share on other sites
Tr4aJim Posted August 17, 2018 Author Report Share Posted August 17, 2018 (edited) Thanks! I should have mentioned that the car already has an alternator. Regarding damped vs undamped pulleys; Ive read on other forums that if the fan extension is removed, a damped crank pulley is required or you run the risk of crank damage, as the extension acts like a damper. However the Revington site says damped pulleys are not needed if the extension is removed. Jim Edited August 17, 2018 by Tr4aJim Quote Link to post Share on other sites
Malbaby Posted August 17, 2018 Report Share Posted August 17, 2018 I did a custom made conversion to narrow belt, alternator, thermo fan and harmonic balancer [damper]. Quote Link to post Share on other sites
RogerH Posted August 18, 2018 Report Share Posted August 18, 2018 Hi Jim, I am in the non-damped camp. Ask yourself two questions - 1 - how can a 3" diameter lump of steel damp anything. It just doesn't have the capacity to store energy. 2 - if you need a damped pulley why isn;t there a dedicated one for the TR 4 pots with associated math's. How can the pulley from an MGB with totally different characteristics benefit our engines. Cranks can break even with the extension and fan. Roger Quote Link to post Share on other sites
Andy Moltu Posted August 18, 2018 Report Share Posted August 18, 2018 Do they need a damper? The four pots have a reputation for breaking cranks. Whether that is a design fault exposed by use in a higher revving engine than the original use is a moot point. Half a ton of flywheel hanging off the rear end doesn’t help. Do the dampers work? They fitted them as standard on the 6 cylinder TRs so presumably they do. Probably don’t need to absorb a lot of energy to alter the resonant frequency of the crank. Quote Link to post Share on other sites
RogerH Posted August 18, 2018 Report Share Posted August 18, 2018 Do they need a damper? The four pots have a reputation for breaking cranks. Whether that is a design fault exposed by use in a higher revving engine than the original use is a moot point. Half a ton of flywheel hanging off the rear end doesn’t help. Do the dampers work? They fitted them as standard on the 6 cylinder TRs so presumably they do. Probably don’t need to absorb a lot of energy to alter the resonant frequency of the crank. Hi Andy, good points. The flywheel, when rotating, acts as a very stiff base for the crank to flex about. At the front end there is nothing to stop the crank flexing - the flex is shared either side of the main bearing. At the back end ALL the flex is on one side of the flywheel so is (sort of) twice as much. The 6 cylinder engine has a damper designed/installed by TRiumph for the purpose. And the 6 pot is a very well balanced engine The 4 pot never had such a thing. Fitting an MGB damper has no scientific reasoning. However if one does fit it then at least they are happy while driving. Roger Quote Link to post Share on other sites
monty Posted August 18, 2018 Report Share Posted August 18, 2018 As usual I would check out what the race & rally boys used to do or now do. Also the guys who work on these cars every day (the likes of Revington or TR Enterprises). If using a damper for racing or rallying then it may be good to have for everyday use. Overkill will not do any harm. What did the VC cars do? That wide belt system is so antiquated & difficult for maintenance so narrow belt with electric fan is the only way to go in my view. Cheers. Quote Link to post Share on other sites
Tr4aJim Posted August 18, 2018 Author Report Share Posted August 18, 2018 Thanks for the feedback. It sounds like the consensus is the damped crank pulley is not needed if the fan extension is removed. But let me ask a slightly different question. Are there benefits specific to getting rid of the fan extension, (given the addition expense of the electric fan), if additional cooling is not required? Jim Quote Link to post Share on other sites
Tonyloz Posted August 18, 2018 Report Share Posted August 18, 2018 I was dead against changing over to narrow belt but wasn't happy with the old dynamo system I wanted to keep the starting handle for originality but in the end went for the narrow belt/alternator/no hole in rad and electric fan with damped pulley All works well with added cooling and enough electric power for all the upgrades Well worth it as the wide belt is just so rigid and i would hate to have to replace it at the road side! Quote Link to post Share on other sites
MRG1965 Posted August 18, 2018 Report Share Posted August 18, 2018 Hi Jim I fitted a narrow belt conversion and an electric fan a couple of years ago,well worth it. I also went for the thermo switch boss built in to the bottom hose steel section. Don't really know about the damped/undamped crank pully, mine came from the TR shop with a damped pully and it works. Mine had no overheating issues, just aware that sitting in traffic the temperature was only going to go one way. Mark Quote Link to post Share on other sites
MikeF Posted August 18, 2018 Report Share Posted August 18, 2018 I have the same setup as Mark. Benefits no power loss to mechanical fan which is on all the time.A little quieter possibly, faster warm up. Must be more economical but I never measured the before so can't compare. The electric one is rarely on. After some time in stop start traffic fan will come on especially if it is hot weather. I have an over-ride switch but never use it except to verify it works. I fitted all this myself and worried about crank extensions and dampers. I realised I didn't really understand the mechanics of rotating stuff, centrifugal forces and so on save that things that whirl round resist being turned and there's quite a lot of energy in whirly things. So in the end I decided it probably wouldn't do any harm and possibly some good so fitted one. Mike Quote Link to post Share on other sites
ianc Posted August 18, 2018 Report Share Posted August 18, 2018 When 4VC was re-built, it was without the front extension, with Kenlowe fan and alternator. That was 1993. Apart from a change to narrow belt after a water pump failed, that's how the car has been for 25 years. Neil doesn't fit vibration dampers to the engines of 4-pot TRs. Ian Cornish Quote Link to post Share on other sites
Andy Moltu Posted August 18, 2018 Report Share Posted August 18, 2018 Might be one for Stanpartman to answer he has built some of the most powerful high reving 4 pot race engines although these are probably on forged steel cranks. Quote Link to post Share on other sites
ChrisR-4A Posted August 18, 2018 Report Share Posted August 18, 2018 (edited) When 4VC was re-built, it was without the front extension, with Kenlowe fan and alternator. That was 1993. Apart from a change to narrow belt after a water pump failed, that's how the car has been for 25 years. Neil doesn't fit vibration dampers to the engines of 4-pot TRs. Ian Cornish Could that be because all Neils engines are fully ballanced?Not all engines may need a damped pulley, but can having one anyway do any harm? Edited August 18, 2018 by ChrisR-4A Quote Link to post Share on other sites
badhuis Posted August 19, 2018 Report Share Posted August 19, 2018 I have the same setup as Mark. Benefits no power loss to mechanical fan which is on all the time.A little quieter possibly, faster warm up. Must be more economical but I never measured the before so can't compare. The electric one is rarely on. After some time in stop start traffic fan will come on especially if it is hot weather. I have an over-ride switch but never use it except to verify it works. Exactly the same here. Very pleased with it. Never had the needle go high again. Quote Link to post Share on other sites
RogerH Posted August 19, 2018 Report Share Posted August 19, 2018 Could that be because all Neils engines are fully ballanced? Not all engines may need a damped pulley, but can having one anyway do any harm? Hi Chris, the damped pulley adds another level of complexity. There are a fair number of TR6 reports regarding the bonding giving way and the timing going out. As there is no purpose built damped pulley for the TR4 type engine why bother. What will it prove. Roger Quote Link to post Share on other sites
monty Posted August 19, 2018 Report Share Posted August 19, 2018 Could that be because all Neils engines are fully ballanced? Not all engines may need a damped pulley, but can having one anyway do any harm? I was told many years ago that most if not all engines benefit from balancing. Quote Link to post Share on other sites
Tr4aJim Posted August 20, 2018 Author Report Share Posted August 20, 2018 Thank you everyone for the input! I’ve decided to go with the damped kit and put in an electric fan. I was really on the fence with damped vs undamped. So I reread the info on the Revington site, and while Neil says a damped pulley isn’t needed, he doesn’t say not to use one. The difference in price between the kits is small, so I figured what the heck. Thanks again, Jim Quote Link to post Share on other sites
Fireman049 Posted August 20, 2018 Report Share Posted August 20, 2018 (edited) Hi Jim ~ My 3A came already fitted with a thin belt conversion and damper. No problems! I converted from dynamo to alternator and went for Negative earth conversion. The TR was already fitted with an electric cooling fan. Tom. Edited August 20, 2018 by Fireman049 Quote Link to post Share on other sites
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