User Tag List

+ Reply to Thread
Results 1 to 20 of 20

Thread: Flywheel Runout

  1. #1
    Pit Crew Decade Plus User MK1_Oz's Avatar

    Join Date
    Nov 2008
    Location
    Adelaide, Australia
    Posts
    1,331
    Thanks
    96
    Thanked 42 Times in 40 Posts

    Flywheel Runout

    When I bought the new clutch, they pointed out to me that there was an apparent alignment issue with my old broken clutch. I therefore decided to measure everything and check it all out.

    I am not sure if this is an issue as I cannot locate a spec for it. I measured the runout on the friction surface of the newly machined flywheel - mounted the magnetic base on the end of the head and touched the tip of the dial indicator onto the flywheel face at around the halfway point of where the clutch friction material runs. I found that I have 0.19mm of runout which I feel is quite large.

    As a check I pulled teh flywheel back off and measured the runout of the crank face. This was 0.05mm.

    Doing some triganometry then double checking using AutoCAD it appears that pretty much all of the 0.19mm flywheel runout is generated from the crank face runout (runout gets amplified the further out from the point of rotation).

    Once clamped this runout will not cause the clutch any grief but it may upset the friction plate to input shaft splines. More triganometry and it appears that a 0.19mm deflection to the friction plate at 215mm from the centre will cause each end of the friction plate splines to move 0.76mm. I would have thought this would cause substantial wear and may be the cause of the wear to the splines in the old friction plate.

    Question: As I said I cannot find a spec and have never bothered to measure this before so should I be looking to true this up or is it nothing to give another thought to? I cannot pull the crank out so the only option would be to shim between the flywheel and crank with a 0.05mm shim???


    PS - I realise I am sounding like an old hypochondriac lately but I really am thinking about the detail of this new build-up - 1 chance to get things 100%
    Last edited by MK1_Oz; 14-09-2017 at 14:04.
    1970 Mk1 Escort Tarmac Rally Car

  2. #2
    World Champion Decade Plus User alladdin's Avatar

    My 1st Project
    My 2nd Project
    Join Date
    May 2005
    Location
    s.wales
    Age
    60
    Posts
    9,200
    Thanks
    167
    Thanked 446 Times in 432 Posts

    Flywheel Runout

    I would say your barking up wrong tree. I say this as friction plates are generally Spring mounted to Ctr splines and I wouldn't think it would cause spline wear ?
    Just an opinion 👍


    Sent from my iPhone using Tapatalk

  3. #3
    Pit Crew Decade Plus User MK1_Oz's Avatar

    Join Date
    Nov 2008
    Location
    Adelaide, Australia
    Posts
    1,331
    Thanks
    96
    Thanked 42 Times in 40 Posts

    Re: Flywheel Runout

    This most wonderful drawing shows how the splines may wear in my mind. If the flywheel is all cock-eyed then the friction plate will be clamped to its flat surface but will then itself start to run cock-eyed. The input shaft does not move but the friction plate will 'rock' on the shaft.

    1970 Mk1 Escort Tarmac Rally Car

  4. #4
    Pit Crew

    Join Date
    May 2010
    Location
    london
    Age
    60
    Posts
    1,139
    Thanks
    48
    Thanked 110 Times in 99 Posts

    Re: Flywheel Runout

    I dont think it would matter for the spline alignment...i would think you have more movement on the spline and shaft( ive never measured ) but from memory there is side movement... but i would want the flywheel to run parrallel (i would image at 7000 rpm the vibration would be quite large) but again its something ive always taken as good(never measured)...have you checked the nose on the crank has not got some damage from something getting inbetween the flwheel and causing some form of deformation...cheers mark

  5. #5
    Racer Decade Plus User

    Join Date
    May 2012
    Location
    Camberley, Surrey
    Posts
    3,237
    Thanks
    5
    Thanked 353 Times in 339 Posts

    Re: Flywheel Runout

    If you do have run out and it is from the crank face, then shim the flywheel to run true - probably only take a couple of bacofoil shims!

  6. #6
    Racer Decade Plus User Forest_rallying's Avatar

    Join Date
    Feb 2013
    Location
    Derbyshire
    Posts
    2,438
    Thanks
    92
    Thanked 393 Times in 348 Posts

    Re: Flywheel Runout

    I would n't want to be shimming anything between crank and flywheel as you'll never manage to keep the bolts tight.

  7. #7
    TURBOSPORT SPONSOR Turbosport Subscriber
    Turbosport Moderator
    Turbosport Administrator
    Graham's Avatar
    My Race Car
    My 1st Project
    Join Date
    Feb 2006
    Location
    Ely, Cambs
    Age
    56
    Posts
    25,110
    Thanks
    310
    Thanked 2,476 Times in 2,250 Posts

    Re: Flywheel Runout

    Quote Originally Posted by Forest_rallying View Post
    I would n't want to be shimming anything between crank and flywheel as you'll never manage to keep the bolts tight.
    agreed, especially on a pinto, they like eating flywheel bolts at the best of times, and thats caused by the flywheel moving in relation to the crank

  8. #8
    Pit Crew Decade Plus User MK1_Oz's Avatar

    Join Date
    Nov 2008
    Location
    Adelaide, Australia
    Posts
    1,331
    Thanks
    96
    Thanked 42 Times in 40 Posts

    Re: Flywheel Runout

    I would have thought that once the shim is in place and the bolts tightened there would be no increased chance of those bolts coming loose? We are only talking about 2 thicknesses of aluminium foil! Does sound like a fudge though.

    I suspect nobody on here has ever actually measured this face runout so maybe most engines end up with something similar?

    Will talk to the builder again.
    1970 Mk1 Escort Tarmac Rally Car

  9. #9
    Pit Crew Decade Plus User MK1_Oz's Avatar

    Join Date
    Nov 2008
    Location
    Adelaide, Australia
    Posts
    1,331
    Thanks
    96
    Thanked 42 Times in 40 Posts

    Re: Flywheel Runout

    I would have thought that once the shim is in place and the bolts tightened there would be no increased chance of those bolts coming loose? We are only talking about 2 thicknesses of aluminium foil! Does sound like a fudge though.

    I suspect nobody on here has ever actually measured this face runout so maybe most engines end up with something similar?

    Will talk to the builder again.
    1970 Mk1 Escort Tarmac Rally Car

  10. #10
    TURBOSPORT SPONSOR Turbosport Subscriber
    Turbosport Moderator
    Turbosport Administrator
    Graham's Avatar
    My Race Car
    My 1st Project
    Join Date
    Feb 2006
    Location
    Ely, Cambs
    Age
    56
    Posts
    25,110
    Thanks
    310
    Thanked 2,476 Times in 2,250 Posts

    Re: Flywheel Runout

    the thing is pinto flywheel bolts do shear its caused by the flywheel moving in relation to the crank, putting anything between the crank and flywheel must make that more likely

  11. #11
    Pit Crew Decade Plus User MK1_Oz's Avatar

    Join Date
    Nov 2008
    Location
    Adelaide, Australia
    Posts
    1,331
    Thanks
    96
    Thanked 42 Times in 40 Posts

    Re: Flywheel Runout

    Mine is doweled but hear what your saying.

    I measured the bellhousing alignment today. I need some 22 thou offset dowels. Problem is there are none in Australia that i can find and the usa ones are 2-4 weeks away and i need them now. Might just leave it - the front bearing design allows some input shaft play which should account for the misslignment. Might have to be s job for next time. .....
    1970 Mk1 Escort Tarmac Rally Car

  12. #12
    Racer Decade Plus User

    Join Date
    May 2012
    Location
    Camberley, Surrey
    Posts
    3,237
    Thanks
    5
    Thanked 353 Times in 339 Posts

    Re: Flywheel Runout

    I think you should put your measuring tools back in the drawer - and just build it without overthinking everything. Not being critical but who really has measured crank / fly nose for run-out...... except you? Surely a good dynamic balance job on all the rotating components would be more critical in the grand scheme?
    Re : the shimming situation - no, its not ideal but neither is removing the crank to grind the nose true. Shim it and add some sheer pins / dowels - should keep everyone happy?

  13. #13
    Pit Crew Decade Plus User MK1_Oz's Avatar

    Join Date
    Nov 2008
    Location
    Adelaide, Australia
    Posts
    1,331
    Thanks
    96
    Thanked 42 Times in 40 Posts

    Re: Flywheel Runout

    I do over think alot but then i don't have the experience to know what is important and what isn't hence my questions. ....
    1970 Mk1 Escort Tarmac Rally Car

  14. #14
    Pit Crew Decade Plus User MK1_Oz's Avatar

    Join Date
    Nov 2008
    Location
    Adelaide, Australia
    Posts
    1,331
    Thanks
    96
    Thanked 42 Times in 40 Posts

    Re: Flywheel Runout

    I very much suspect that high performing race teams do skit of measuring.
    1970 Mk1 Escort Tarmac Rally Car

  15. #15
    Racer Decade Plus User Forest_rallying's Avatar

    Join Date
    Feb 2013
    Location
    Derbyshire
    Posts
    2,438
    Thanks
    92
    Thanked 393 Times in 348 Posts

    Re: Flywheel Runout

    If you think by putting silver paper or a very thin shim between the crank and flywheel then you are asking for BIG trouble. For one thing you are never going to get a true flat surface for the flywheel to bed to. The chance of your flywheel coming loose and shearing even with dowels are almost certain. They are n't a pretty sight when they come adrift.

    Are you sure your DTI gauge's accurate? If it's manufactured in China then that could be part of your problem, they have led me a dance in the past.

    If I were you I would either leave well alone or remove the crank and get it accurately machine by a competent engineering company.

  16. #16
    Racer Decade Plus User rallyrob's Avatar

    Join Date
    Apr 2010
    Location
    Middlesex
    Age
    55
    Posts
    2,656
    Thanks
    267
    Thanked 221 Times in 208 Posts

    Re: Flywheel Runout

    If it was all balanced properly together in the 1st place it shouldn't matter...

    Crank, flywheel and clutch cover.
    That's how mine was balanced years ago, the whole lot together.

    I know it doesn't help if you have to put a new clutch in it but it should be right to start with at least.

    Or let them true the rear face of the crank and the flywheel up for minimum runout.
    Last edited by rallyrob; 15-09-2017 at 17:17.

  17. #17
    Racer Decade Plus User

    Join Date
    May 2012
    Location
    Camberley, Surrey
    Posts
    3,237
    Thanks
    5
    Thanked 353 Times in 339 Posts

    Re: Flywheel Runout

    Quote Originally Posted by Forest_rallying View Post
    Are you sure your DTI gauge's accurate? If it's manufactured in China then that could be part of your problem, they have led me a dance in the past.

    If I were you I would either leave well alone or remove the crank and get it accurately machine by a competent engineering company.
    Could be on to something! I'm struggling to think how this face has gone bad? Cranks are all generally turned on a single lathe / VMC for machining the base casting with bearing journals and faces all ground to size to be parallel / perpendicular to the rotating axis. Maybe its been dropped sometime or someone has clouted the flywheel and its bent?

  18. #18
    Pit Crew Decade Plus User MK1_Oz's Avatar

    Join Date
    Nov 2008
    Location
    Adelaide, Australia
    Posts
    1,331
    Thanks
    96
    Thanked 42 Times in 40 Posts

    Re: Flywheel Runout

    Could be the gauge. I have 2, 1 mechanical and 1 digital so will try with the other. I have decided to just leave it as it is.

    Btw this is not an issue of balance but one of alignment and wear.
    1970 Mk1 Escort Tarmac Rally Car

  19. #19
    TURBOSPORT SPONSOR Turbosport Subscriber
    Turbosport Moderator
    Turbosport Administrator
    Graham's Avatar
    My Race Car
    My 1st Project
    Join Date
    Feb 2006
    Location
    Ely, Cambs
    Age
    56
    Posts
    25,110
    Thanks
    310
    Thanked 2,476 Times in 2,250 Posts

    Re: Flywheel Runout

    tbh, i cannot see you having enough run out to wear the clutch, more likely an issue with the bellhousing not being true so theres a slight gearbox miss alignment

  20. #20
    Racer Decade Plus User rallyrob's Avatar

    Join Date
    Apr 2010
    Location
    Middlesex
    Age
    55
    Posts
    2,656
    Thanks
    267
    Thanked 221 Times in 208 Posts

    Re: Flywheel Runout

    Quote Originally Posted by MK1_Oz View Post
    Btw this is not an issue of balance but one of alignment and wear.
    Surely something out of alignment could put it out of balance? No?

+ Reply to Thread

Bookmarks

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts