Toyotec's how to refit a 16v EA827 crankshaft drive gear and bolt after removal.

Discussion in '16-valve' started by Toyotec, Jul 12, 2013.

  1. Toyotec

    Toyotec CGTI Committee - Happy helper at large Admin

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    Background

    It was not so long ago, that vw_singh, experienced a wobbly crankshaft pulley on his way to a Curby sprint day.
    This concern turned out to be a slack crankshaft cog, that was 'missed' when the base engine was retrofitted with dresskit from another, before fitting to the vehicle.
    The circumstances and experiences regarding this component were well chronicled and can be viewed in this link post 865.
    There were some misunderstandings that seemed to spiral out of that thread, which caused me to put on my OEM research hat to find out what triggered the concern and what could be done as a permanent fix.

    Info about bolt N 90367001

    [​IMG]

    The 12 point damper bolt, with the part number N 90367001, was used on serpentine belt driven engines and superseded the 6 point bolt and washer as found on early KR/PL engines N 10089001 M14x1.5x46x25 with a 20mm washer 068105193A.

    [​IMG]

    The crankshaft cog 027105263B, is fastened to the engine crankshaft by the clamping and frictional forces of the bolt. In many OE cases, a key or locator is placed or molded into the cog to make refitting and the amount of man hours easy for a service technician.

    [​IMG]

    This very system was utilized on the VW Group A Golf 3 16v w/220ps. A similar system without key or locators is used on Ford powertrains to this day.
    The oscillation and second order forces from the cylinders firing, can cause micro slip between the faces of the bolt and crankshaft nose, if this bolt is not torqued properly. This in turn reduces the clamping force between the bolt and the crank cog. The cog is made of a sintered material and it is for this reason, adding a dowel on the crank nose and in the cog, is not recommended to reduce micro slip.

    Bolt Clamping force

    The theory of behind the clamping force or bolt preload is based on the formula below:

    P= T/KxD.

    T Target tighten torque N/m
    K (nut factor), based on mu (friction) of thread vs force of bolt face
    *K for oiled steel bolts to steel is ~ 0.14 and for non oil ~0.2 for 8.8 steel grade bolts

    D is the bolts nominal diameter in mm
    P is the bolt's desired tensile load in Newtons (generally 75% of yield strength)

    Aim for project

    As there was a request to have increased insurance from micro slip, my interest was to increase bolt preload by reducing K for the same final torque of 90Nm + 1/4 or ~ 180Nm on the car with an assistant holding the brake and in 5th gear. This should not be a nesscesity if the OEM procedure is followed.

    Method

    Using the formula above, for stock components, the clamping force, where the OEM procedure for tightening was followed, would be around 91.84kN. Just simply tightening to 90Nm results in a clamp force of 45.9kN or half of what it should be. On a bolt that is just 'nipped' at say 60Nm (typical power bar and a strike with a hammer) clamping force = 30.61kN. If the clamping forces associated with 60Nm and 90Nm tightening torque are between 30.61kN and 45.9kN, the damper can start to oscillate due to harmonics, start fretting the mating surfaces, damage the crank nose and start to wobble. This is the reason to always ensure the bolt is in good condition and it is at least torqued to factory recommendations.

    Consultation with work colleagues, to add abit of insurance, resulted in a solution which was to lap coarse valve compound on the face of the bolt washer and damper seating faces to provide a similar effect as a diamond washer or disc locking washer.

    [​IMG]

    [​IMG]

    This would reduce K to ~0.12 and increase the clamping force of the of the M14x1.5X39 bolt to beyond that of standard specs to 107.14kN.

    Conclusion

    On ABF and other 16v engines with this bolt, always torque the bolt N 90367001 to 90Nm + 1/4, with the bolt oiled to increase clamping force.
    To reduce micro slip and increase clampng force, attempt to lap valve grinding paste to damper face, crank nose and bolt face
    This is what was done in addition to dressing up the damaged crankshaft nose on Gurdip's engine.
    .
    Other factors to consider

    Total Bolt length (mm)
    New -52.58
    Old -52.74 (still usable IMO)

    Cog face diameter and locating keyway (mm)

    [​IMG]

    Cog face diameter
    New -31
    Old (beaten unit) -32 oval -scrap

    Keyway width
    New - 8
    Old (may give slight cam to crank offset) - 7.6mm from ben's old cog offset cam timing by almost Adv 2.5 degs.
    Old cog from 9A - 8

    Crank nose diameter (mm)
    New -31
    Old -31

    And undamaged cranknose is inspected for fretting, caused by micro slip.

    [​IMG]

    Once faces where prepared, the cog was reassembled

    [​IMG]

    Bolt lubricated

    [​IMG]

    The torqued to spec with an additional 90 deg turn

    [​IMG]


    Many thanks to Gurds and Ben for the components Old and new used for measurements :thumbup:
     
    Last edited: Jul 13, 2013
    Nige, Trev16v and EZ_Pete like this.
  2. GVK

    GVK Forum Addict

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    pics not working Eddie?
     
  3. Jon Olds Forum Junkie

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    Just replaced the belt on the F2Stu engine. Its keyed with a rollpin. Looks ok to me. Always worried me on every vw 4 pot engine I have built. Anyway, its just done half a rally at full throttle and near max revs. Typically, gearbox failed. Bit of anecdotal info..
    Regards
    Jon
     
  4. Toyotec

    Toyotec CGTI Committee - Happy helper at large Admin

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    Can see then from my end. Can rectify tomorrow if you still cannot see them.
     
  5. Toyotec

    Toyotec CGTI Committee - Happy helper at large Admin

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    Not a problem on a 300bhp + NASP Duratec though.
    If your bolt's clamping force is reduced due to lack of tightening etc to cause microslip, the pin will act as a ram for the cog to beat the drilled hole into an oval and sinter in the process.
     
  6. Toyotec

    Toyotec CGTI Committee - Happy helper at large Admin

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    Hope you can see the pictures now Gary.
     
  7. Jon Olds Forum Junkie

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    One thing I will say, if was effin tight to get off. My impact gun wouldn't touch it. Had to take the starter motor out and use the old screwdriver in the ring gear trick..
     
  8. Toyotec

    Toyotec CGTI Committee - Happy helper at large Admin

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    Sounds to me previous builder followed to procedure for tighting very well !
     
  9. RobT

    RobT Forum Junkie

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    Thats the way to tighten this bolt properly, i made a tool specifically to lock the flywheel ring gear, then the correct vag tightening procedure can be done. Only proper way imo. 5th gear/brakes there is still give in the drivetrain.
     
  10. Toyotec

    Toyotec CGTI Committee - Happy helper at large Admin

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    Rob obviously you took this seriously. Many garages unfortunately do not and with most of these engines changing the cambelt at least once in a lifetime, you can see how error and failure can creep in regarding bolt clamping and increased friction on the thread. Failure rate is increased when one of us enthusiasts take the stock engine and subjects it in an application where it will live at 4-7k rpm!
     
    Last edited: Jul 13, 2013
  11. RobT

    RobT Forum Junkie

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    There is a window in the top of the bell housing that exposes the ring gear. I am suprised some bright spark hasnt made a plug tool to go in there and engage/lock the flywheel for this and other service reasons.
     
  12. Admin Guest

    Rob, the tool for this job is called a screw driver! I did it mine a couple of weeks back and doweled it at the same time.
     
  13. Toyotec

    Toyotec CGTI Committee - Happy helper at large Admin

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    On the 02A/J yes there is partial access to the ring gear. However with two people one on tools and the other on the brake with the vehicle in top gear, once you take up the 'give' I found you can achieve the 1/4 turn after tightening to 90Nm. The 'give' makes it a bit more awkward to achieve the 90 deg turn and any way that robustly locks the engine would be more favourable.
     
  14. Toyotec

    Toyotec CGTI Committee - Happy helper at large Admin

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    You still need to ensure the assembly is torqued correctly for the reasons I described to Jon earlier. The clamping force is always critical
     
  15. Admin Guest

    Thanks Eddie, I do know how to tighten a bolt and strangely I have a pretty good understanding of clamping forces ;)
     
  16. RobT

    RobT Forum Junkie

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    agree - this is why I made a tool rather than used the screwdriver method.

    I have heard that Ford dont use woodruffs in their cam sprockets and rely totally on frictional clamping. BUT.....I am also told that the end of the camshaft is not machined square and has a slight taper to it. Such that when the cam sprocket is bolted on, the tapers give more of a frictional load than you would expect from a parallel sided joint. Wonder if this is the same with Ford crank gears....
     
  17. Admin Guest

    I do not believe the bolt tightening procedure from VW is good enough to ensure the bolt stays tight after track work etc. there have been many failures reported on here through out the years. I would also imagine that the bolt has never been taken off by a garage, it's not required to remove it for the cam-belt etc... So over time the bolt loosens off and results in problems as the clamping force reduces.

    Knowing the bolt is not torqued up enough by the VW procedure. You conclude that you should follow the clamping procedure of VW but in addition add valve grinding compound to the washer.




    Did you consider torquing the bolt further than VW recommend? What are the Ford bolts torqued too?


    Did you consider using a thread locker on the bolt?


    What is in the valve grinding paste? What is the material the bits are made from? Are these harder than steel and do they dig into the washer and mating surface on the pulley?
     
  18. Admin Guest

    Like wheel bolts...?
     
  19. Toyotec

    Toyotec CGTI Committee - Happy helper at large Admin

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    They do not use timing locators on the cams which can also house the VVT helix. I am familiar with the later 1.6 ECOboost/Sigma motors which have special tools for cam and crank to set up the cam to crank timing. On the ECOboost the damper is not keyed and carries the hall sensor for engine speed. If the damper were to move from a slack bolt your ignition timing will be offset.
    For the crankshaft bolt on one of these your final torque on the damper including extra turn is over 160lbft!

    This exercise was completed and written months ago and has rectified a concern on an engine that we thought would have been scrap. It also shows there is an alternative to drilling a sintered material and placing dowels in a mild steel crank nose (as also seen on the TDI forums), when you can simply increase the friction on the clamping surfaces using materials widely available. You can do the same for the PTO end of the crankshaft where the flywheel mounts as extra insurance.
    This method has been tested on racing engines up to 600bhp.
    I agree with Rob using a right tools to securely lock the engine for tightening, to achieve the required clamping force is also very important.

    Thanks for the discussion guys :thumbup:
     
  20. sambo Paid Member Paid Member

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    Any of you lads had a pleasure of using uprated ARP crank bolt which needs to be done even tighter then standard

    Install and tightening is not that much of a problem but trying to take one out is anothem matter!

    I had a leaky crank seal in my 1.8t after just 1500 miles which was new, grrrrr and obviously had to remove the crank pulley

    OMG, no matter how i tried to remove it, it just would not undo!

    In the end i had to use a spare crank damper pulley and make a locking jig from bits of steel tube welded to it and bolted to back of the block as well as welded length of tube wedging it self under the subframe

    Only then it shifted:o

    My crank cambelt pulley is also pegged by two pins and bolt is pain marked so i can keep an eye on it
     

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