T140 Clutch Centre Puzzle

Discussion in 'Vintage Classics' started by Iron, Aug 26, 2022.

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  1. Iron

    Iron Elite Member

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    #1 Iron, Aug 26, 2022
    Last edited: Aug 26, 2022
    Diving into a T140 engine to check the recent claimed rebuild. :rolleyes:
    It had obviously had work done but push rod tube leaks meant at least the cylinder head back off to sort. Rockers off showed worn tappets. Head off revealed head bolts all in upside down. So a deeper dive to the sludge trap would ease the mind.
    Clutch all seemed fine until I freed the centre...

    1.jpg

    For some strange reason the bolt heads have been ground down. On closer inspection the inner plate bearing surface and whole clutch centre had all been ground down...
    The clutch basket and roller bearings look ok. The thrust washer is worn (the rebuilder didn't bother with a new one)

    2.jpg

    4.jpg

    3.jpg

    So, took the centre apart to have a gander

    5.jpg

    It's been apart recently as there's new rubbers.
     
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  2. Iron

    Iron Elite Member

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    #2 Iron, Aug 26, 2022
    Last edited: Aug 26, 2022
    Looking closer, removing the bolts, they're not correct and odd

    7.jpg

    The plate threads have been helixed to allow the bolts to fit

    6.jpg

    The whole assembly has taken a bit of a hammering (which I sort of expect if the repairs are by a lad in the late 70s or 80s armed only with a hammer and a pair of pliers) but everything - bolts, centre and hub have recently been ground down. By a gorilla with a hammer, a file and a grinder.

    8.jpg

    I'm obviously going to replace everything that needs it. But why carry out the grinding? I can understand the replacement bolts having heads too thick but the hub and centre? Any ideas?
     
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  3. speedrattle

    speedrattle Senior Member

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    i think the big bolt heads were ground to keep from rubbing on th ebasket. but im clueless about the center

    where exactly has the hub and center been ground? ive experimented with different bolts to hold the springs before but ive never had a reason to change anything else
     
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  4. Iron

    Iron Elite Member

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    The whole back side of the centre has been ground down. The inner plate roller bearing surface (including the marks left by someone digging into it - the red arrows show just a few), the bolt heads, the clutch centre has been ground all the way round - they've even filed a new chamfer around the outer edge and the spider has been ground down to match. The whole assembly is wanked.
    I thought for a while that they'd not been able to compress the rubbers enough or that they'd used a mismatched clutch basket but all look ok.
    I'll replace it all as the parts are easily available and relatively cheap. Why the dealer didn't do this is a bit worrying but I'll see when I get to the rebuilding stage I suppose.

    1.jpg
     
  5. sprintdave

    sprintdave Nurse,he's out of bed again

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    Cowboy dealer. Good job you know what you're doing.
     
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  6. Iron

    Iron Elite Member

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    #6 Iron, Aug 28, 2022
    Last edited: Aug 28, 2022
    I'm afraid it's been trial and error on my journey of limited knowledge on these machines. I sort of think I know what I'm doing, some of the time.....:confused:

    I bloody knew I had another one in the stash. Took a while to find it but here's one that I just separated from the basket. See how there's a chamfer on the inside edge. Compare to the next picture. Looks like a skim has been taken across the whole assembly with a file/grinder/cheese grater/chainsaw.

    2.jpg

    1.jpg

    Why would they need to do this? Lots of work with a file for what? Strange, but I expect I'll find out.....
     
  7. speedrattle

    speedrattle Senior Member

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    all i can think of is that he was trying to correct a misalignment of the basket with the front sprocket by moving the basket farther to the right by the amount he ground away on the thrust bearing surface. i have to dig out a hub here to compare with your pictures. the radial gouges concievably were an attempt to firect oil into the thrust bearing area.

    i would check very carefully for alignnent before i would use that clutch assembly.

    DPO for sure
     
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  8. Iron

    Iron Elite Member

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    I agree, a few measurements required to understand what's been going on. The clutch was a bit stiff but ran very well. I noticed the clutch adjustment access plug had been worn on the inside when it was removed but nothing else seemed out of place.
     
  9. Iron

    Iron Elite Member

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    #9 Iron, Aug 29, 2022
    Last edited: Aug 29, 2022
    So, this morning I did some comparison measurements between this one and one awaiting rebuild....ground down one on the left, to be rebuilt one on the right

    1.jpg

    The ground down clutch centre varies in width, across the flats, 1.47-1.48 inches (approx 37.5 mm) while the untouched centre measures 1.5 inches (38.1 mm).
    The baskets are different widths (depth of basket) across the flats

    2.jpg

    But why would someone take depth off of the centre if the baskets were the issue? It must only be the centre protuding too far so I checked the depths to the bearing race

    3.jpg

    The depths were the same on each. I checked the thrust washer thicknesses - they were the same - and the roller bearing lengths - they were the same.
    Then it came to me that perhaps the hub wasn't sitting right on the mainshaft. So I compared the tapered hole in the hubs. The measurements were very close - it's really difficult to measure a taper.
    But the gearbox was out so I removed top gear and offered up the hub. The red arrow shows where the hub used to press up to.

    4.jpg

    Here's the known good hub from the awaiting rebuild pressed on by hand, almost to the line

    5.jpg

    And here's the hub from the centre that's been ground down

    6.jpg

    I'm pretty sure this is the issue. The taper in the hub doesn't press on far enough.
    Still trying to figure out why the dealer/rebuilder noticed the centre was protuding too far. Maybe it interfered with the primary case. I'll have a look when I'm rebuilding to imagine what a milimetre lengthened centre would do.

    Well, I'm pretty sure I know what the problem was now. But I will be checking that the basket and the front sprocket gears line up and will shim the front accordingly.
    Always learning.......:neutral:
     
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  10. speedrattle

    speedrattle Senior Member

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    was the problem an out of spec clutch center or maybe an out of spec replacement main shaft?

    either way a misalignment could haveen corrected more easily by spacing the engine sprocket , i think
     
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  11. Iron

    Iron Elite Member

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    #11 Iron, Aug 30, 2022
    Last edited: Aug 30, 2022
    Agreed that the basket would have been thrown out of alignment due to the taper being incorrect. I didn't check the alignment during dismantle but there was an odd looking shim in there.

    1.jpg

    Shim is top right. Certainly nothing like any shims I've come across or used before and an odd thickness as well.

    2.jpg

    Shims I've used are either 10 or 30 thou. This one is 27.5 thou. Which is about 0.7mm. So that could be what they were aiming for.
    So why take that off of the clutch centre? It must've been interfering with something.....it's a mysteron. There's no marks on the primary casing from spinning clutch pressure plate or pressure nuts. Maybe the primary cover just wouldn't go on. Or maybe the clutch wouldn't operate with the cover on.
    Hopefully it all rebuilds ok with new parts.......
     
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  12. Iron

    Iron Elite Member

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    #12 Iron, Sep 4, 2022
    Last edited: Sep 4, 2022
    Came across another clutch hub today saved from a recent rebuild.

    1.jpg

    The 'orrible rusty one on the left and the centre one have come off of ex-running engines. The one on the right is the suspect.
    Both ex runners are 5 thou bigger diameter on the small end of the taper (the only end I can measure with any accuracy). The ex runners press onto the main shaft further than the suspect one so it's not the mainshaft.
    I'm a bit apprehensive but I can't think what else it may be. But I've got to order a new clutch centre (once I get round to it) so we'll see on the rebuild. :no_mouth:
     
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  13. Iron

    Iron Elite Member

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    #13 Iron, Sep 28, 2022
    Last edited: Sep 28, 2022
    I think it's solved.
    Before ordering a pile of clutch parts I thought I'd use the clutch centre that I already have and dry build the clutch with the existing basket.....
    I torqued the centre nut up and the whole clutch was locked solid. The centre would not spin independently.
    I dismantled and rebuilt replacing the basket with an old one I have from another build waiting in the corner. It all worked ok.
    So, it's the basket. I measured the races in the baskets and all seems ok.
    However, when placed flat the race protudes further on one than the other. It's hard to see from the photos but the old race is noticable from the rust pits in it.

    1.jpg

    While the new one can be seen to be slightly up from the roller bearings...

    2.jpg

    So, I knocked the races out of the baskets and replaced the older with the newer. Rebuilt and all works as it should. The cast iron baskets are indeed different. When torqued up the centre was pressed against the basket and locked up.

    Having been right through this engine now the last builder didn't get into the gearbox or the sludge trap. The sealer used on the cases and innder gearbox cover was the threebond grey stuff while everything else was red wellseal.

    As the previous rebuilder didn't get into the gearbox he wouldn't have noticed that the clutch hub didn't get pushed onto the taper of the mainshaft enough and as the clutch assembly was a cheap new one didn't have another basket hanging around so chewed the shit out of the centre to make it work.

    Hopefully, it's all been sorted now but we'll see once I get it all back together. Laters ya'll......:), over
     
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  14. Sandi T

    Sandi T It's ride o'clock somewhere!
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    Holy moly, @Iron! Your depth and breath of knowledge and your mechanical skills continue to astound me. Lots of times I don't know the half of what you're working on or writing about but I find myself really enjoying reading your threads and seeing the photos you post. And I do think I learn from you along the way so thanks for sharing your projects with us! :):kissing_heart:
     
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  15. Iron

    Iron Elite Member

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    #15 Iron, Sep 30, 2022
    Last edited: Oct 1, 2022
    Thanks @Sandi T , muddling on I think is the term. :) I probably will just go buy new clutch parts but thought I'd have a go at playing with the rusty bits I already have as 300 squids is 300 squids and a bit of filing may well work.
    Here's the clutch centre from a 1980 T140E that's been sitting around in boxes. A bit crusty. You can see where the clutch plates have worn into the centre where they bang into the slots. Sitting in the weather since 1985 doesn't help either

    1.jpg

    It's certainly not as badly worn as I've seen them but the rust on the top I haven't seen eaten into it. Anyway, using a file, started to take the bad bits down to good.

    2.jpg

    Took the flats down until the slotting was gone. You can see where the plates have worn into the slots.

    3.jpg

    A right arse getting a file into the slots to get rid of the grooves. The plates really need to slide along this groove or the clutch gets grabby. i.e. the bike moves forward even with the clutch pulled right in.

    4.jpg

    Once the sides are filed flat then the bottom of the slot is filed.....phew, takes bloody ages....

    5.jpg

    The rubber bushes were ok, which is surprising as they've been sitting around for nearly 35 years. A bit of cleaning up and finishing off

    6.jpg

    And the clutch centre can be bolted back together

    7.jpg

    Obviously the slots are quite a bit wider and deeper than they were so we'll see what effect that has once it's running. Maybe it'll cause a lot of clunking into gear or when the clutch is used but there's not that much more movement when a clutch plate is put in there. We'll see....
    Now I have to move onto the basket as it's in a similar state...

    8.jpg

    Obviously cast in January 1979 but the part number is odd (well, it's actually even) 4642, the parts catalogue shows 4640 up to 77 but later models have no parts number for the basket in the catalogues. I'm sure I could investigate further but hey ho, let's crack on.....

    9.jpg

    Again, after cleaning and installing the retrieved race that I've replaced in the centre there's a lot of filing to do, ho bloody hum, elbows require more grease.
     
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  16. Iron

    Iron Elite Member

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    #16 Iron, Sep 30, 2022
    Last edited: Sep 30, 2022
    Carried on filing the rust and slots away from the basket until all looked ok

    1.jpg

    Then to the build up ready to install. Here's the hub (it's taper gets pressed onto the gearbox main shaft when the whole thing is bolted up) and the roller bearings and the thrust washer

    2.jpg

    Whack a finger full of grease onto the race of the hub and stick the 20 roller bearings on. Count them once they are all on just to make sure. Make sure they are pressed onto the centre as the basket has to fit over them and it's a tight fit.

    3.jpg

    Plonk on the thrust washer. It's plain metal on the other side so put it this way up as the basket runs against it.

    4.jpg

    Place the basket over the rollers. This can be an arse to get on sometimes and other times the same one will just slip straight on no bother

    5.jpg

    Then, not forgetting the clutch spring bolts (those need to be held while the centre is going on - it's a bit fiddly) push the centre onto the hub without displacing anything. This can be a tight fit so have a practice while it's all apart and mark the correct tooth for fitment if it's tight.

    6.jpg

    Push everything together and while it's being held the basket should spin freely independent of the centre. And this one does......hoobloodyray :cool:
    Here's the whole clutch assembly ready to be installed

    7.jpg

    This is a Hyde 7 plate clutch and an alloy pressure plate.
     
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  17. Adie P

    Adie P Crème de la Crème

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    I'm reminded, somehow, of a line from a modern movie classic ....

    "A man can be an artist - in anything, food ...... whatever ........ it depends on how good he is at it."

    You and darkman just keep delivering masterpieces.
     
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  18. darkman

    darkman Crème de la Crème

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    Great work on recovering the clutch parts and 7 plate is a great upgrade.
     
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  19. Sandi T

    Sandi T It's ride o'clock somewhere!
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    What an amazing transformation using that "elbow grease", @Iron! It's something to watch those parts get shinier and cleaner...while your hands do quite the opposite. :eek: I'm enjoying this this "puzzle"! :grinning:
     
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  20. speedrattle

    speedrattle Senior Member

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    #20 speedrattle, Oct 1, 2022
    Last edited: Oct 2, 2022
    ive never had to file the bottom of the slots. just cleaning up the sides has always worked well enough for me.

    i think removing the hammered-flat tabs of the plates made the most diffe re nce, as the mushrooming can be substantial.
     
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