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    Can I key the crank myself?

    Good Day to all:

    First of all, when is necessary to key the crank? Is 8000rev limit with single crower racing springs using Cosworth 9.5mm lift int and exh cams in racing ?

    Is it possible to key the crank and chain sprocet, trigger wheel in the local machine shop? The reason I am asking this is I believe that chain sprocket is surface cemented. If I cut the grove in it this will not be hardened and will not be able to hold?
    Can I key the crank and still torque trigger wheel by the book and have as primary diamond washer friction and keyed as secondary retention?

    Thanks,
    Luka

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    Re: Can I key the crank myself?

    Hi bud the crank is hardened steel and the normal method of cutting the key way is the spark eroded method. If you have access to this then no problem. If you somehow manage to cut the cog then you won't need the diamond washers even if you cut through the case hardening.

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    Re: Can I key the crank myself?

    not so on the cutting of the key way, cranks are not that hard, you can drill into them with normal HSS drill bits. i believe most do it in a milling machine, but you could do it in a lathe if you chuck crank up and lock the chuck so it cant rotate and mount a cutting tool in the tool post on its side, working the apron up and down the bed to cut like a shaping machine does

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    Re: Can I key the crank myself?

    Thank you for your replys and your time.

    Do I need to key the crank if the limiter will be set to 8000rpm, using single racing valve springs and 9.5mm valve lift cams?

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    Re: Can I key the crank myself?

    use a new diamond washer and torque the bolt correctly and theres no need for a keyway

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    Re: Can I key the crank myself?

    Hi Graham,

    Do you have experience with reusing the pulley bolt?

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    Re: Can I key the crank myself?

    ive known them reused loads of times, but when i say than i am only referring to standard not modified engines,

    BUT its one of those things which doesnt suffer a lot more stress by modification, in any case keyways are only intended to locate pulleys, the are not supposed to take drive loads

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    Re: Can I key the crank myself?

    Note: you would require 2 diamond washes if you don't key crank. I've re-used bolt of 4 engines with no issue although only ran to 7500 rpm
    Last edited by Hornet600; 06-02-2017 at 08:41.

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    Re: Can I key the crank myself?

    Two diamond washers you said? Where the second washer goes Hornet?

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    Re: Can I key the crank myself?

    1 washer between crank and timing gear, 1 washer between timing gear and harmonic balancer.
    If you do keyway, EDM (spark erode) the harmonic balancer and the timing gear, crank machined at local shop.
    You also have to split the key because of the diamond washers which will still be used as the primary force of securing that assembly.

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    Re: Can I key the crank myself?

    Pardon the stupid question but why do you need to fit the washers if the components are keyed - they can't rotate which is the purpose of the washer/s isn't it?

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    Re: Can I key the crank myself?

    Katana keyways are for location only and should not be under load
    Keep her lit

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    Re: Can I key the crank myself?

    It's all about safety margins, of course you can run without diamond washers and just go with locktite and brute force and if it slips rely on the key saving your engine from damage. Personally after spending all that serious cash I would prefer washers and key if high rpm is your target.

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    Re: Can I key the crank myself?

    Quote Originally Posted by cosworth4door View Post
    Katana keyways are for location only and should not be under load
    That is a pretty thin explanation since keyways have been around in all types of engineering / mechanical devices since the year dot compared to diamond dust washers in the last 10-20 years? How many crankshaft / timing wheels have been locked together with woodruff keys over the last 100 years - are they wrong?

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    Re: Can I key the crank myself?

    Not for one minute did I say it was wrong but you will find it is the torque of the bolt and washer that has held the pulley in place for the last 100 years and not the keyway as the keyway should not be load bearing
    Keep her lit

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    Re: Can I key the crank myself?

    From my understanding the oem sprockets are hardened on the surface. If we talk the oem keyed cranks and sprockets are not those factory hardened including the key area.

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    Re: Can I key the crank myself?

    no they are not hard, they dont need to be

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    Re: Can I key the crank myself?

    Maybe I used wrong term "surface hardened". What I meant, from my understanding, once the element (sprocket) is completed, prior to use the sprocket surface need's to be hardened or tempered (a heat treatment) that gives a hard surface resistant to wear and inside the element retains elastic toughness.

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    Re: Can I key the crank myself?

    you dont need to harden the key way because it doesnt take any drive loads its for location only

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    Re: Can I key the crank myself?

    It's very common in supecharger circles to pin the crank...

    ie lots of modern stuff run no keyway too, and securing the pulley against rotation requires some form of pin or key.

    They basically offer you a small jig, and you drill axially into the crank between the crank and pulley, essentially making a round key you can then tap into place. This can all be done with the engine in-situ if needed. Size of hole is entirely up to you, but these kits generally offer around 6mm.
    On some steel cranks an HSS bit will barely mark it but a cobalt bit will go through it like butter.

    For the keyway/pin itself I've used the supplied pin with the kit, or had some made from stainless. I've even cut down a couple of drill bits and used them too.

    eg



    9.85 @ 145mph 202mph standing mile

    https://www.youtube.com/watch?v=Ss_c7fML3rw

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    Re: Can I key the crank myself?

    most old keywayed cranks are interference fit with harmonic balancer leaving the clamping force and keyway to bear the brunt of valve train load on the timing gear. Diamond washers and clamping force, suit modern automated assembly
    Geared industrial electric motors tend to rely heavily on the keyway so their is no real wrong or right here

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    Re: Can I key the crank myself?

    I have been advised by raceline that keying the crank is not required for up to what I will be revving to which is 8500, none of the caterhams do

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    Re: Can I key the crank myself?

    Good info! Thank you all.

    I've just dissasembeled my duratec from a rally car (fiesta st). It's my own first duratec dissassembly. I wonder where is this diamond washer? There is trigger wheel, cover with seal and timing chain. Am I blind?

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    Re: Can I key the crank myself?

    exactly which engine is fitted? ford called a lot of things a duratec, it could be whatever engine you have isnt one we all know as a duratec

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    Re: Can I key the crank myself?

    The diamond washes sit either side of the crankshaft gear that slides over the nose of the crankshaft behind the big pulley

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    Re: Can I key the crank myself?

    So this is the timing sprocket. But I can't see any friction or diamond or any washer?!...


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    Re: Can I key the crank myself?

    [QUOTE=Sivi Ptich;3082995]So this is the timing sprocket. But I can't see any friction or diamond or any washer?!...

    Block code: N4JB

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    Re: Can I key the crank myself?

    Yep should have one there and one behind it mine did same block number I think I will check tomorrow

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    Re: Can I key the crank myself?

    Keying the crank. I've decided to key the crank only the sprocket. Crank was easy cut for 3mm key but sprocket is hardened, cemented it was impossible to cut it...I knew it that it would be cemented....brutal hard. So we had to cut it using 0.4mm diamond wire with electro...+/- using special liquid...(I don't understand this process completely since it was explained to me over the phone.)

    For all you just to know... maybe is easier to purchase one of fabricated sprocket with key.

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    Re: Can I key the crank myself?

    Quote Originally Posted by Sivi Ptich View Post
    Keying the crank. I've decided to key the crank only the sprocket. Crank was easy cut for 3mm key but sprocket is hardened, cemented it was impossible to cut it...I knew it that it would be cemented....brutal hard. So we had to cut it using 0.4mm diamond wire with electro...+/- using special liquid...(I don't understand this process completely since it was explained to me over the phone.)

    For all you just to know... maybe is easier to purchase one of fabricated sprocket with key.
    This proces is called Spark erosion

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    Re: Can I key the crank myself?

    Quote Originally Posted by cosworth4door View Post
    Not for one minute did I say it was wrong but you will find it is the torque of the bolt and washer that has held the pulley in place for the last 100 years and not the keyway as the keyway should not be load bearing
    the woodruf key is there to stop the parts turning and undoing the bolt that can happen in high speed /changes in rotational speeds i.e turbo coming on boost or banging through the box

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    Re: Can I key the crank myself?

    Quote Originally Posted by Geordie View Post
    the woodruf key is there to stop the parts turning and undoing the bolt that can happen in high speed /changes in rotational speeds i.e turbo coming on boost or banging through the box
    key is for location only, there are millions of engines out there running without keys, they are not all undoing the bolts every time someone accelerates, if manufactures were worried about bolts undoing they would be using left hand threads

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    Re: Can I key the crank myself?

    Is the reason for keying the crank more for piece of mind, it's like wearing a belt and braces.

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    Re: Can I key the crank myself?

    with an engine builders head on if nothing else a keyed crank makes cam timing easier/more reliable

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    Re: Can I key the crank myself?

    Quote Originally Posted by Graham View Post
    key is for location only, there are millions of engines out there running without keys, they are not all undoing the bolts every time someone accelerates, if manufactures were worried about bolts undoing they would be using left hand threads
    to a certain extent i agree i work mostly on renaults and the majority of crank sprockets are non keyed but the later sport and turbo petrols are keyed as the inertia on rapid acceleration can undo the pulley as the inertia is started from the actual crank going in a clockwise direction the bolt head is pressing on the pulley if the pulley is not keyed the inertia can and does undo the bolt thus all comming loose and failing

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    Re: Can I key the crank myself?

    Quote Originally Posted by Geordie View Post
    to a certain extent i agree i work mostly on renaults and the majority of crank sprockets are non keyed but the later sport and turbo petrols are keyed as the inertia on rapid acceleration can undo the pulley as the inertia is started from the actual crank going in a clockwise direction the bolt head is pressing on the pulley if the pulley is not keyed the inertia can and does undo the bolt thus all coming loose and failing
    If thats happening your bolts tension load is way too low, or you got thread lube on the clamping faces of the assembly. The Duratec/MZR seem so picky about oil/lube on the clamping faces in a high performance application that its recommended to completely cleanse all the clamping faces of all the parts (sprocket, diamond washers, pulley, bolt face, crank snout), and even wear rubber gloves to prevent your skin oils from getting on the mating surfaces. Possibly overkill. I agree with everyone else that keying isnt necessary and should not be locating the assembly once the bolt is torqued. I'm not sure if you've ever seen an engine with a keyed crank where the crank bolt was insufficiently torqued, the keyway and key will both be destroyed in short order. Mechanics under torquing the crank bolt and the keyway getting destroyed was a common problem on the early miata engines.

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    Re: Can I key the crank myself?

    https://www.google.co.uk/search?q=re...JypN2dlj7GQfM: this is the one used on the turbo and later rs200 clio

    https://www.google.co.uk/search?q=re...oL_JE9GDaJmQM: this is the normal one

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