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Slow clutch pedal return

Discussion in 'Bay Tech Clinic' started by Stormin12345, Aug 13, 2021.

  1. Stormin12345

    Stormin12345 Member

    Messages:
    59
    Location:
    Sydney
    OK - I tried your test @rstucke - my measurement from the pressure plate being hand tightened to fully done up is 4.46mm...so it seems within your suggested range. I have attached some pics - the fingers seem ‘flat’ oncetight. @T1 Terry that link from samba is really interesting. It suggests a 215mm flywheel like mine should have a step of 22.73mm vs 24.66 for a 228 mm clutch as per @rstucke measurement above of 25mm and 21mm for a 200mm as per @Wayne murray ‘s numbers. So it looks like these specs might be right, and my step of 22.56mm is close to the 22.73mm recommended. So if we believe this my flywheel could be 0.15mm too short in the step (my measuring may not be that accurate I will go back for a second measure) is that enough to make a big difference in line with the problems I am experiencing?
    025F217F-B17E-48CD-A675-EEDF9A5ADA14.jpeg 14D4D85E-85FE-484A-93FC-BB58A92CF008.jpeg
     
  2. Stormin12345

    Stormin12345 Member

    Messages:
    59
    Location:
    Sydney
    I will go try this
     
  3. rstucke

    rstucke Well-Known Member

    Messages:
    1,808
    Location:
    Wamberal NSW AUS
    When you do the bolt height test you need to leave the spring washer off
     
  4. Stormin12345

    Stormin12345 Member

    Messages:
    59
    Location:
    Sydney
    I didn’t measure from the bolt height - I measured the outer edge of pressure plate eg beside the bolt to the flywheel rim before and after doing it up - would that not get same result?
     
  5. rstucke

    rstucke Well-Known Member

    Messages:
    1,808
    Location:
    Wamberal NSW AUS
    all good
    how did you go comparing old to new pressure plates?
     
  6. Stormin12345

    Stormin12345 Member

    Messages:
    59
    Location:
    Sydney
    Have just been out trying @T1 Terry S suggested method and I reckon using my vernier that the old pressure plate is about 0.2mm thinner than the new one. This doesn’t seem a lot given I am measuring through the bolt hole where the old one would have been clamped down before and compressed? I also remeasured the step and it’s more like 22.65 when I carefully make sure it’s all square. Is this enough of a delta to make a difference? Thanks all again.
     
  7. T1 Terry

    T1 Terry Well-Known Member

    Messages:
    1,704
    Location:
    Mannum South Australia
    It there any where near by that could measure the pressure plate load when the clutch assembly is mounted on the flywheel? Then you could do a comparison between the old pressure plate and the new pressure plate with the new clutch disc installed ....... and maybe even try with the old clutch plate installed to see if there is a marked difference. The pressure plate manufacturer will know what the release pressure should be, so making a judgement call should be much easier.

    T1 Terry
     
  8. Stormin12345

    Stormin12345 Member

    Messages:
    59
    Location:
    Sydney
    Hey T1 Terry I’m in Sydney so chances of going anywhere that may be able to help unfortunately are slim right now thanks to lockdown. I guess I can put the old pressure plate with the new clutch back in the bus and see what happens?
    I have also been thinking about how the clutch works, and given everything seems close to spec (is it close enough?…. I don’t know… would love people’s thoughts) my thoughts have been turning to the throw out bearing…given I need to wind the adjustment right on so the arm/bearing is not in its rest position rather under tension at rest, clearly the arm/bearing needs to travel further than it would normally to to push the pressure plate all the way in to disengage the clutch. Could this be an issue with the arm (it looks ok), or could it be that the flywheel has been potentially been machined so many times that the clutch and plate is sitting too far away. Either way doesn’t explain to me why it’s slipping. Perhaps I am grasping at straws now?!
     
  9. Wayne murray

    Wayne murray Well-Known Member

    Messages:
    4,525
    Location:
    Seven hills
    Seen on another website for a 215 mm flywheel machined at 22.5 mm which is with in a range of yours. Couldn't find the machine tolerance allowed for a 215mm flywheel, which is what I would like to know. So I don't thing it's the issue.
    If you got the old throw out bearing compare it to the new one.
     
  10. rstucke

    rstucke Well-Known Member

    Messages:
    1,808
    Location:
    Wamberal NSW AUS
    I've run out of ideas
    but if your fingers are dead flat this may still be your problem as the spring in that plane can't exert pressue and will over centre when you go to disengage, they should be just slightly out and flat to disengage.
    Your distances are pretty much on spec (depth etc)
    maybe a dodgy pressure plate.
    I'm done.
     
    David H likes this.
  11. David H

    David H Well-Known Member

    Messages:
    6,587
    Location:
    newcastle
    That's my bet as the bowden tube/adjustment is just cable length (and a wear problem as @rstucke says). Manual says 5/8ths inch free play at pedal. A position I liked & my mechanic didn't:rolleyes:. Each to their own;). My current cable has 5 thick washers (20mm total) on the Bowden tube to get adjustment within the threaded range which leads to wear on the bottom turn & KILLS cables every 20,/25,k.
    Found that out on this site:).
    Waiting for current cable to break so I can put in the right length cable from under the back seat & get rid of the cable killing Bowden tube excessive bend washers;).
    Mechanic just replaced the cable with the same length for 30 years. Just made the same mistake over many many times:(. T'was a great mechanic tho'. I wish he'd come out of retirement:).
    Cheers
     
    Last edited: Sep 15, 2021
  12. oldman

    oldman Super Moderator Staff Member

    Messages:
    10,482
    Location:
    Avalon Beach NSW
    Hey David……why wait for the cable to break before you replace it ….?
    You could be in the middle of an intersection, or similar……o_O
    With C19 travel restrictions in place, now would be the ideal time to get on your back and get your hands dirty ! :D
    Clutch cable replacement is not a hard thing to do and in my experience, best done without time pressures…..
    Not having a shot, I just remember what a pita it has been when my c cable has failed away from home. It’s a bit scary under a bus, roadside with traffic wizzing by at close proximity……:eek:
    Cheers,
    Mark
     
    Wayne murray and Wiz like this.
  13. oldman

    oldman Super Moderator Staff Member

    Messages:
    10,482
    Location:
    Avalon Beach NSW
    I’m no mech. but can’t help thinking that there’s something else going on here……o_O
    If all that’s happened is engine out , clutch replaced with like, then refitted, there really shouldn’t be any difference to the original pedal return…..( I know, I know…..stating the obvious….:rolleyes: )
    If the pressure plate fingers are exerting the correct compression under load, surely the issue/s must be forward of the clutch assembly ?
    Your early pics show the wing nut wound right down and little to no bend in the Bowden tube…
    I still can’t help but think that you should try and get the correct deflection in the bowden, which would , in effect, make the effective length of the cable longer, allowing more compression to be placed on the pressure plate fingers, sooner.......and more available adjustment.
    (If that makes sense…..?)
    You also mentioned that when you test drove it, the clutch felt like it was slipping……this is also normally a symptom that correct cable adjustment can rectify…….
    You really have nothing to lose by trying this….and everything to gain if it works….;)
    If everything was working before, it can be made to work again but it all has to be with the correct parts, installed per spec. and adjusted properly.
    Cheers,
    Mark
     
  14. grumble

    grumble Well-Known Member

    Messages:
    1,343
    Location:
    Taree
    Mark I am thinking along the same lines as you, the bowden cable bend needs to be adjusted with a few washers to give it a nice curve, the cable looks to be over adjusted. I would also suggest fitting a new one whilst the engine is out.- Was the cable adjusted after the new clutch was fitted? Did it have the 3mm free play at the lever? The flywheel looks like the friction surface and recess has been machined which should eliminate the lack of clamping tension on the clutch plate.
     
    oldman likes this.
  15. Wiz

    Wiz Well-Known Member

    Messages:
    392
    Location:
    Near Ballarat
    Adding to the above comments...
    How does the new wingnut adjustment compare with the old adjustment?
    PR
     
  16. Kai

    Kai Well-Known Member

    Messages:
    4,788
    Location:
    Sydney, NSW
    Little trick for everyone. If you are finding you have no cable adjustment left and the bowden tube bend is correct, you can fit a 68-71LHD cable. It is approx 15-20mm shorter and in my experience puts the adjustment closer to the middle. This is what I am using now.
     
    David H, cbus, Wayne murray and 3 others like this.
  17. David H

    David H Well-Known Member

    Messages:
    6,587
    Location:
    newcastle
    Just getting my moneys worth out of the cable Mark;).
    Can do a replacement in less than 15 mins!
    Want to try the Padstow to Newcastle 'no clutch cable' travel that I did in 79:p.
    They are so easy to drive without a clutch that I've taught both daughters to be able to drive without a clutch. Both now in modern Jap vehicles & can do same:).
    Proud dad moment:cool: given to us by Kombi knowledge:D.
    Cheers
     
  18. T1 Terry

    T1 Terry Well-Known Member

    Messages:
    1,704
    Location:
    Mannum South Australia
    Had many events driving without a clutch in many different vehicles, the kombi has to be the easiest .... although reverse is a tad tricky .... take off on the starter motor requires a bit of planning when attempting it in reverse :lol:

    As far as the pressure plate testing, find a wooden block that fits on the area where the clutch thrust bearing sits. Balance a set of bathroom scales on the wooden block and add weight until you see the fingers of the pressure plate start to compress .... you will see the point has been reached when more weight does not register on the bathroom scales until the wooden block has dropped under the rim of the pressure plate. A simple comparison between the new pressure plate and the old pressure plate and even the new clutch plate and the old clutch plate to see if that is affecting the pressure plate release weight.

    T1 Terry
     
  19. Stormin12345

    Stormin12345 Member

    Messages:
    59
    Location:
    Sydney
    I never ceased to be amazed by this forum, incredible people always wanted to continue to try and help - thank you - I was reaching a point there where I was wondering what on earth I was going to do next. @T1 Terry I will try the pressure plate test you suggest with old and new (best use for bathroom scales right now, don’t want to weigh myself after nearly 3 months of lockdown!). I also agree we need to eliminate everything in the front of the clutch if the plate proves to be OK - I will get the Bowden tube right and put in a new cable whilst the engine is out - at least that is then eliminated. I have no idea what the old adjustment was as I took the gearbox out as well when I was rebuilding the engine to allow me to replace the bushes in the shift linkage and didn’t pay any attention to what was there before - I am pretty certain however that it was not at full adjustment as it is now or I would have noticed.
    I don’t know how to drive without the clutch however hopefully that does not make me a lesser person ;-) something to learn when I get the thing on the road!
    Thanks all
     
  20. Wiz

    Wiz Well-Known Member

    Messages:
    392
    Location:
    Near Ballarat
    Ask any good truckie!
    upload_2021-9-17_18-4-45.png
    PR
     

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