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  1. #1
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    Prop-to-diff flange bolts

    I've been searching, but most threads that I can find talk about the three-bolt flanges which take M12 metric bolts; I have the older style four-bolt flange that takes 3/8" bolts (the holes are ~0.377" which is just a hair larger than 0.375") - there's no rubber donut so I need short, high tensile, 3/8" bolts with about 15mm of plain shank (pardon my mixing my measures!)

    Any opinions on whether a grade 5 (roughly 8. bolt with 1/2" of plain shank (12.5mm) is suitable, or should I keep searching for something more esoteric?
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  2. #2
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    8.8 is not strong enough

    You need some 12.9’s
    Classic Replica Viper currently in build

  3. #3
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    I haven't managed to find any 12.9 grade (would be "grade 8" since they're imperial) bolts that small yet.. must be available somewhere, though. Actually, that's a lie - I can find 3/8 Cap Head bolts in 12.9, but only fully threaded, not part threaded with a plain shank..
    My DeDion build diary..
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  4. #4
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    Classic Replica Viper currently in build

  5. #5
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    Maybe .. impossible to say without ordering them (And they don't accept questions via eBay ) - I suspect the 3/8 is the fully threaded small one in the picture Finding fully threaded is easy, but it means the shear loading is on the threaded part of the bolt less resistant to fretting, rather than plain shank.. perhaps I'm over-thinking it, but I know the three-bolt flanges are designed to have plain shank bolts for that reason.
    My DeDion build diary..
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  6. #6
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  7. #7
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    Aaron, if you look on wards or one of the other jag suppliers you'll find the correct bolts which have the correct non threaded section for the diff, they are specials and only used on jags I believe.

  8. #8
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    I'd only been able to find the part number for the later (3-bolt) flanges searching earlier, but thanks - prompted by you, I did more digging and it looks like part number C19827 might do it.

    Actually.. having found the part number (here: https://parts.jaguarlandroverclassic...e=910442685024) I was able to find the thread I knew I'd read here which .. has the part number in it This one: http://www.cobraclub.com/forum/showthread.php?t=61676

    Of course.. having had another go I realise I don't need bolts yet because, drumroll.

    I can't get the prop shaft in without taking the engine and gearbox out.

    It's the right length, but about a half inch too long to be wiggled in between gearbox and chassis due to the limited articulation in the joints FFS.

    [edit] Actually can probably get it in without taking the engine & gearbox completely out if I:
    1) Undo the engine mount-to-chassis nuts
    2) Undo the gearbox mount
    3) Jack the gearbox up as high as it will go
    4) Remove the gearbox mount
    5) Drop the gearbox back down as low as it will go
    6) Put the prop in and hold it roughly in place
    7) Jack the gearbox back up as high as it will go
    Put the gearbox mount back on
    9) Drop it back down onto the mount.. etc
    Last edited by aaronjb; 25-01-20 at 01:44 PM.
    My DeDion build diary..
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  9. #9
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    STOKE ON TRENT, U.K.
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    Call Ben at Simply Performance Jaguar Spares.
    Hell have your diff bolts.
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  10. #10
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    If the bolts you are referring to are what I think they are then punch in this number on eBay. 253740861648.
    I bought two sets of these and many more sets are available.

    Prop shaft bolts are not necessarily high shear items, more high tensile strength as the security relies in the friction between the two mating flanges brought about by the correct torque loading of the hardware. Much like the road wheel on the car.
    I'm just completing a gearbox swap from a 4 speed to a 5 and found that my bolts were well undertorqued hence why I binned the bolts immediately and fitted new ones.

    David.
    Life is driving the Cobra. The rest of the time is just waiting.

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