I have a 1mm and a 2mm, with gaskets the 1mm should be ok but I'm in the process of getting a PK XL2 thrust plate as I only have a standard prim one to try at the moment but there does seem to be enough room
mmm.. ok.... cheers ian. Not sure I want to go that route. Just had a look on sip. Nice bit of kit but no woodruff key slot?? Or is that just the pic? also.. how heavy is it ian not including the supplied primary basket??
Yes you are correct mate, no woody slot in the spider, Jonny said he just uses a bit of loctite and with the DRT runner I have it comes supplied with a thick wavey washer, Jonny said he has no problems with it, cant wait till its built and trying it. Weight of clutch unknown but it feels light in my hand if thats any use, I shall of course weigh it when I restrip ok, just the inner part with plates?
Cheers mate... just the weight of the clutch itself. I want to compare to falc for weight. I am not sure the lack of key way is a good idea when you get to high powered race motors. I have had issues with a perfectly lapped in cnc falc spider and one off Falc gearbox using hi strength loctite designed for the job. Lauro also suffered in the same way. The little taper couldnt hang on to it even with the drt 'parastrappi' uprated cush system. Let me know how you get on.
OK mate, there is some score lines inside the spider where theres been obvious movement so fingers crossed, at a last resort I should think it would be possible to have a cutout put in if needed? I'll get back to you re this post when I have weighed it
Post by jonnysnatchsniffer on Feb 12, 2013 20:22:59 GMT
no need to offset the wheel, tho i forgot to say ive used studs and half nuts with some locktite, tho will change to tonys nut of choice the K nut ive used the short arm cover and a vma1/2 backplate so no need to fuck around with backplates as such, i also relieved the clutch cover a little on the inside where the top plate screws foul, i just cover everything in nail varnish and see where or if it fouls, the only reason i used a gasket on both sides was to get the clutch arm in the correct, so for me it was the 1mm spacer + 0.5mm gasket paper each side of the spacer, i got my clutch a couple of years ago so maybe now they come with decent screws, i wouldnt take the chance, as for a couple of quid my local place for such stuff is a no brainer, wish id known it would have saved me £60
eaan im really wanting to know if you are building a streamliner to go 1/4 mile sprinting or maybe fit an 11" rear wheel and gear up for a for flying jobby that might even break tonys record this is from a few years ago, i know its lammys but hey ho, interesting all the same, 90mph ts1 200s, in yer fucking dreams
I think leaving the key out is a very good idea. And leaving the slot out an even better one. This gives you more contact surface, and even if you resort to the old trick of cutting your own woodruf key out of a thick circlip (which makes it more ductile), or, god beware, use something even more brittle like a bearing needle (which was quite popular in the 80ies in Italy) the load still is transmitted via the taper, not the key. Some of the guys over here are now pushing 50BHP with 60mm stroke Quattrini casings and snowmobile or ultralight airplane barrels, and they are using just this setup. Using a christmass tree with iner pitch thread like the DRT certainly is a good idea though.
The Hartz IV (with 4 plates) does not require a spacer, the Hartz V does.
cool... so the 4 is ok then... on the subject of the taper my motor will and can break it... i have had charley lap this in precisely and it can still let go. I tried no key but that didnt work and still made a mess of things resulting in a new falc spider. My motor makes 30-32hp. No issues with a harder key though. It holds fast.
Lauro is using the hard key system btw. Martin has two factory falc motors here which I have rebuilt..(one is miki's 2010 race motor the other is a one off 'works' balls out sprinter with 56 stroke). The hard keys are present in both.
is it possible the hartz spider is made from a harder material enabling a higher torque to be used?
Post by jonnysnatchsniffer on Feb 12, 2013 22:00:57 GMT
no the hartz 4 that i have with 4 friction plates and a short arm cover (vma1 primmy) needed the 1mm spacer so it didnt rub on the cover, the extra gasket each side of the 1mm spacer was needed to allow for the use of an xl2 thrust bearing and to get the clutch arm in a decent position it maybe different with pk cases or even a pk cover or an xl2 cover ??
I intend just trying it as is, Paddy(who I bought from) said he used it with shims under the tree and an XL2 cover, I have not got this so using a standard cover and will check more thoroughly when I come to fit the cover like you did Jonny with varnish or something, with the standard push bearing there seems to be enough room butwith xl2 push plate it will be raised for the inserted bearing all good stuff and reading different ideas here Jonny Im doing it purely for the sprinting mate, whats the bit about an 11inch wheel and Lammys I dont understand sorry
The design of the clutch center (not the material) ensures that the metal doesn't float to the outside when it's forced onto the shaft. So even if weight on a scale is not superlow it's material in places where it's needed. And weight is not really the dominating factor with inertia of a rotating mass anyway, it's where the weight is which is much more important.
I know that Falc does it that way. He's a supersmart guy with supercool stuff, but that idea is shit. Unfortunately English doesn't have words for "Reibschluss" and for "Formschluss". These are the concepts used to tranfer loads from one mechanical part to another. A typical "Formschluss" would be a wrench on a bolt whereas a "Reibschluss" is what you have with the flywheel and the crankshaft, and also between the layshaft and the clutch. The load a "Reibschluss" can deal with is defined by the friction coefficient of the parts involved, and by the force with which the two are pressed together. The load a "Formschluss" can transmit is defined by the strength of the parts involved (wrench and nut again as an example. When you round the nut or split the spanner you've exceeded the limit). Within the given space there is no material in the world strong enough to make a woodruff key to transfer the loads of a powerfull engine. But with the DRT fine pitch trees and the Hartz clutch (with which you can use standard height nuts and torque them down with 120 Nm) the force of the fit is plenty strong for whatever torque it has to deal with. And there is no floating of the material around the negative cone in the clutch inner. Which makes for an absolutely bulletproof connection. Falc's idea to use use a stronger woodruff key ("Formschluss") which is still not strong enough to transfer the torque, hence still having to rely on the "Reibschluss" for the transmission of the load doesn't look like a solution to me. It's not going to work unless the two parts are pressed against each other with enough force, and if it goes wrong you've beefed up the cheapest part in the whole chain enough to destroy the two much more expensive parts. And you've reduced the surface area while still relying on it to do the main part of the job.
Another example for a "Reibschluss" would be the clutch. I mean who'd shoot bolts through it to stop it from slipping? And even without that it's quite capable of dealing with the exactly the same loads (if designed properly) as the connection between clutch and shaft.
That "Reibschluss" concept is used in car gearboxes, btw.. Once you are capable of manufacturing to tight enough tolerances it's cheaper to make than splines, and it still does it's job, even in superhigh-torque turbodiesel engines. I'm sorry about the clumsy explanation. The first time I had a Hartz clutch in my hands I was with a mate who does R+D in the automotive industry, and we both looked at the design and pretty much simultaneously said "what a clever cunt".
If you want to go for "Formschluss" the polygonal solution by one of the other Italian blokes is one possible way to go.
Long story short: I'd give it a chance before "improving". It's a great design albeit not in keeping with traditional wisdom, but it's proven to work really well just as it is.
I'll look into it Mathias. I need to get a good look at the hartz center. My gear box was made for me some 4 years ago now by Lauro. I first ran it in 2009 at the ring and it does have the fine pitch thread that drt uses now so all good there. 120nm is massive and tbh I do not tighten up the Falc that high but if the hartz can take it then great and at that torque it should hold. I need to test!
A brilliant explanation in terms for the common man Mathias, me in particular, on how it works without a woodruff key thanks, interesting reading, 120nm! wow scarey to think of me with the torque wrench getting.it to there without snapping something lol
Eean it's obvious how it works. It's a taper fit but it's a taper fit that was originally designed for a lot less power. The key was not designed to act as a drive lug at all , that too is obvious. I can tell you on my engine at 50lbs torque on that clutch nut I have spun it several times. Would the extra surface area prevent this spinning? Maybe. But I would want to test. As you said your one shows signs of spinning so make sure to check the surfaces for a good mating joint.
Eeeean Mine of course has slightly less power than the Racers BUT ive still used the woodruff key and used locktite on the taper and thread and since it was First built abused ,blown, stripped built blown need i say more hasnt shown any signs of the key giving up AT ALL.....i cant remember what torque its set at but its tight.... Good luck mate