Nick Jones Posted February 1, 2018 Share Posted February 1, 2018 Ah ha, you're speaking of JC & Guy with the 1500 estate. We followed them for quite a bit of the last part of the last 10CR. It goes very well....... I've broken a 1300 small crank crank. Between #1 BE and the front main. That used to get revved to Smiths - it just never gave up, until it did, 20k hard miles after it was built. No other damage though. This one I didn't break but discovered in an engine I bought. broke from a badly machined fillet radius by the looks of it was an "ES" stamped factory replacement engine with crank ground -0.010 Actually it came free with another 2.5 I bought, described as unknown. The other one was meant to be "good". To be fair it did run and even gave good oil pressure when cold (I ran it on the garage floor, there is a vid somewhere) but having gone to the trouble of fitting it to the car it had very low oil pressure once hot and made rather scary noises. Turned out to have non-matching main bearing caps and shims made from a coke can to make them "work". Not my best shopping day that. The block was good on this one though. Nick Link to comment Share on other sites More sharing options...
JohnD Posted February 1, 2018 Author Share Posted February 1, 2018 (edited) Peter, Those TR4 fan bolt holes are in line with the fanblades, so only two positions it will fit on the hub, and they all look the same, so no less. How does the firing order affect any damping the fan might provide? The drag from all four blades is constant, whatever the angle at whihc an firing impulse arrives. And interesting stories from roulli and Nock - I'm taking notes, I promise. John Edited February 1, 2018 by JohnD Link to comment Share on other sites More sharing options...
PeterC Posted February 2, 2018 Share Posted February 2, 2018 John, I was thinking that the blades offer an elastic element to the crank nose, the crank torsional vibrations being 'buffered' by the drag. Transiently the drag wont be constant. A bit like the fluid filled torsional vibration dampers. But I take your point, the angles should not matter. Peter Link to comment Share on other sites More sharing options...
SDerbyshire Posted February 6, 2018 Share Posted February 6, 2018 This arrived in the post today, hot from ‘a friend in america’ a new, balanced and timing-marked Crank Damper ! once its fitted i’ll donate my old ‘slipped a bit’ damper to the ‘John’s Experimental Labs’...... steve Link to comment Share on other sites More sharing options...
JohnD Posted February 6, 2018 Author Share Posted February 6, 2018 God Bless You, Sir! You have a lucky face! When you can, Steve, when you can. John Link to comment Share on other sites More sharing options...
Nick Jones Posted February 6, 2018 Share Posted February 6, 2018 That pic reminds me...... While the 2.5 damper design means that the damping material also has to transmit torque from the crank to the pulley (and thus on to water pump, alternator PAS pump etc), on the 2L ones the pulley is part of the centre and the outer ring is just a dumb weight. Suspect the 2L ones last better...... Nick Link to comment Share on other sites More sharing options...
SDerbyshire Posted February 6, 2018 Share Posted February 6, 2018 37 minutes ago, Nick Jones said: That pic reminds me...... While the 2.5 damper design means that the damping material also has to transmit torque from the crank to the pulley (and thus on to water pump, alternator PAS pump etc), on the 2L ones the pulley is part of the centre and the outer ring is just a dumb weight. Suspect the 2L ones last better...... Nick I suspect the 2.5 arrangement is using the load from the alternator/water pump as damping? my old pulley looks quite ‘tired’ but then it is 44 years old :-) Link to comment Share on other sites More sharing options...
oldtuckunder Posted February 6, 2018 Share Posted February 6, 2018 49 minutes ago, Nick Jones said: That pic reminds me...... While the 2.5 damper design means that the damping material also has to transmit torque from the crank to the pulley (and thus on to water pump, alternator PAS pump etc), on the 2L ones the pulley is part of the centre and the outer ring is just a dumb weight. Suspect the 2L ones last better...... Nick Yes looking at that you realise that there is a lot more weight outside of the rubber on the 2.5 pulley than there is on the 2ltr, so even without the load of the water pump and alternator (and alternators can exert quite a lot of load with a low battery) there is a lot more torque being applied to the 2.5 rubber ring. Makes one wonder when/if they discovered that the 2.5 needed a different weight on the damper, given that the 2L came first. Also wonder if some people may have put a 2.5 crank in and kept the 2L damper without realising the possible consequences. The rubber in my now 50 year old 2L pulley looks surprisingly good. Alan Link to comment Share on other sites More sharing options...
JohnD Posted February 7, 2018 Author Share Posted February 7, 2018 15 hours ago, Nick Jones said: That pic reminds me...... While the 2.5 damper design means that the damping material also has to transmit torque from the crank to the pulley (and thus on to water pump, alternator PAS pump etc), on the 2L ones the pulley is part of the centre and the outer ring is just a dumb weight. Suspect the 2L ones last better...... Nick I've learnt from elsewhere, thanks to this project, that people who have run a supercharger off the pulley have had to go with solid pulleys, they say without ill-effect. The drag (?torque) of the 'charger' rips the damper apart. A 'charger' won't affect the vibrations, or only by putting more impulses through the journals, but maybe a supercharged T6 doesn't need to go up the dangerous revs? One for Peter C, of https://supertrarged.wordpress.com/ fame. John Link to comment Share on other sites More sharing options...
PeterC Posted February 7, 2018 Share Posted February 7, 2018 2 hours ago, JohnD said: I've learnt from elsewhere, thanks to this project, that people who have run a supercharger off the pulley have had to go with solid pulleys, they say without ill-effect. The drag (?torque) of the 'charger' rips the damper apart. A 'charger' won't affect the vibrations, or only by putting more impulses through the journals, but maybe a supercharged T6 doesn't need to go up the dangerous revs? One for Peter C, of https://supertrarged.wordpress.com/ fame. John John, Indeed I hardly ever go over 4000 rpm or so, drive the torque like a diesel. The blower has two three lobed solid ali rotors about 8 inches long, 3 diameter . So it will offer considerable resistance to the belt tension fluctations induced by the crank, more than water pump or alternator. So the belt's elastcity could perhaps act as tv crank damper . The boost will increase the torsional amplitude of the crank, but as I keep to low rpm the crtical frequencies exciting the crank should be avoided. And when the blower is delivering boost of say 9psi the resistsnce seen by the belt will be greater as the belt will be under greater tension. IIRC the mass of the flywheel/clutch affects the amplitude of the vibrations, or maybe the critical frequencies ? Does a lighter flywheel help to eliminate the vibrations ? or make them worse? Peter Link to comment Share on other sites More sharing options...
JohnD Posted February 7, 2018 Author Share Posted February 7, 2018 Well, as you know, the natural frequency of a spring and mass is Fn = (1/2Pi) x SQR(k/m) where k=spring stiffness and m=mass So the larger the mass the lower the frequency, and vice versa, but this is a very complex spring! With masses all over it! I've got some other work to do before I can get down to the crank calculations! JOhn Link to comment Share on other sites More sharing options...
The Space Binman Posted February 8, 2018 Share Posted February 8, 2018 On 25/01/2018 at 3:15 PM, PeterC said: John, You deserve a degree just for tacking the question......waterfall plots etc. Am looking forward to seeing the finished project on here! I think the first harmonic resonance on 6 pot cranks is at 5000rpm.....................well above my comfort zone. Peter And also the first harmonic is the biggest, all other things being equal... Link to comment Share on other sites More sharing options...
SDerbyshire Posted February 8, 2018 Share Posted February 8, 2018 Hmmm, my engine pulls really hard to 6000, and the 1980s rebuild notes say ‘safe to 6000’ ..... well i guess it’s lasted this long ! steve Link to comment Share on other sites More sharing options...
SDerbyshire Posted February 11, 2018 Share Posted February 11, 2018 Update from me, my TR6’s damper os off! ive posted more details in ‘another place’ but suffice to say an easy job this afternoon to remove the damper. the timing marks from my new damper courtesy of Tom do not lign up with the old ones, but i wont know for sure whether the old damper had slipped untill i install and do a tdc measurement. so, soon i’ll be able to donate a ‘well used’ damper for John to experiment on ! steve Link to comment Share on other sites More sharing options...
oldtuckunder Posted February 11, 2018 Share Posted February 11, 2018 1 hour ago, SDerbyshire said: so, soon i’ll be able to donate a ‘well used’ damper for John to experiment on ! way way better than a "well used" diaper Link to comment Share on other sites More sharing options...
SDerbyshire Posted February 12, 2018 Share Posted February 12, 2018 Sunny again today so took a few hours off to fit the new damper, no need for a diaper change as it all went smoothley ! the new damper fitted like a glove, i thought it might need tapping on but it slid on beautifully. back in with the steering rack, cross tube, radiator and the car fired up just as before, which of course it should as i hadnt changed anything! next i’ll check the new damper’s timing marks against true tdc, and set up the 123tune+ correctly. ’whilst down there’ i fitted new bushes, poly, to the arb...... which turns out to be 7/8” so back to Moss for the correct set.....nice run in the Alpina once all is settled i’m thinking a rolling road setup for the 123tune+ to get the best out of it, And get some numbers :-) steve Link to comment Share on other sites More sharing options...
roulli Posted February 13, 2018 Share Posted February 13, 2018 Steve, your new damper appears to be plain metal, I can't see any rubber. Who's actually manufactured the new damper? Patrick Link to comment Share on other sites More sharing options...
SDerbyshire Posted February 13, 2018 Share Posted February 13, 2018 There is a thin band of rubber Patrick. its a Moss damper , but balanced and maked in the US steve Link to comment Share on other sites More sharing options...
SDerbyshire Posted February 15, 2018 Share Posted February 15, 2018 Just spent 30 mins checking tdc, and the timing marks line up perfectly! car is now basically ready for a rolling road session and then perhaps a trackday or two :-) ive done trackdays on motorbikes, and with Prosche, but never in an old sports car Brands Hatch is nearish and i know the track well, so might look for something there in the spring steve Link to comment Share on other sites More sharing options...
Nick Jones Posted February 15, 2018 Share Posted February 15, 2018 Castle Coombe 4th April....... TRR organised. See you there? Nick Link to comment Share on other sites More sharing options...
oldtuckunder Posted February 26, 2018 Share Posted February 26, 2018 Here's one for you John What is reported as being a Triumph Spitfire pulley but from picture incorporates a harmonic rubber, and I though the 4 cylinders never used them? ebay item 222855898630 Alan Link to comment Share on other sites More sharing options...
JohnD Posted February 26, 2018 Author Share Posted February 26, 2018 I'll ask him if he's sure. The hub on that has a much smaller diameter in relation to the outer than 6-cyl ones. J Link to comment Share on other sites More sharing options...
Nick Jones Posted February 26, 2018 Share Posted February 26, 2018 Google Holset R19524B...... Says MGB. My first guess was A-series. Nick Link to comment Share on other sites More sharing options...
Recommended Posts
Create an account or sign in to comment
You need to be a member in order to leave a comment
Create an account
Sign up for a new account in our community. It's easy!
Register a new accountSign in
Already have an account? Sign in here.
Sign In Now