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  1. #1
    Join Date
    Jul 2018
    Location
    france
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    49
    Posts
    65

    Dif rebuild questions

    Hi, hereafter a pic of my dif :
    Dif.jpg

    Can someone confirm that it's a XJ6 S1 60-63 dif ? (I have the stub axle big nut outside) : is-it a ball-bearing or a tapered bearing stub axle type ?
    I've done some searches but i can't find technical infos for this very earlier dif model. (I search for infos about preloads / shims / procedures / etc ...).

    Any help/advice will be really appreciated, thanks !

  2. #2
    Join Date
    Jul 2018
    Location
    france
    Age
    49
    Posts
    65
    Strange for me but after additionnal searches it seems to be a type E diff unit. I've found a thread (https://relicrecyclery.com/Jaguar/page30/63XKE_30.htm) and i think i have the same unit. If someone has a workshop manual section for rebuild a type E diff it will be very usefull.
    I've open the dif to see it's condition this afternoon :
    Dif_1.jpg
    Dif_2.jpg
    I have 2 questions :
    - the two output shafts are really "locked" together and i have not seen any damage so can the power lock plates be locked ? (assuming i have a power lock)
    - the dif cover was marked 3.31 but pinion vs gear test give me a 3.54 ratio (confirmed i think by the 46 13 marking as 46/13=3.54) : this ratio is too high for me, is it a good way to source a 3.07 pinion / gear ratio ? (and keep my power lock)

    Thanks to all.

  3. #3
    Join Date
    May 2004
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    Finchampstead, Berkshire, UK.
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    56
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    That big red thing is the lsd housing, which ratio is good depends on your gearbox ratio's

    Reds

    Jim

  4. #4
    Join Date
    Jan 2006
    Location
    Chelmsford Essex
    Posts
    1,725
    They should not be locked. The plates should slip after about 25 lbs I recall.
    If they do not that's like a locked diff or something has seriously gone wrong internally.
    Wards Engineering or Simply performance are your best places to call.
    You could check the crown to pinion bash lash and also blue the interference pattern of your gears . This will give you some indication of wear.
    If the ratio is wrong for your gearing I would just look for the correct ratio and have it rebuilt .
    Russel on the forum also does rebuilds.
    So lots of options.

  5. #5
    Join Date
    Aug 2004
    Location
    Christchurch, NZ
    Age
    60
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    2,518
    The diff may appear locked because of the preload; you'd need a decent size bar on it to get it to shift, particularly on the bench.

    You can get the diff re-ratioed to a higher ratio such as 3.07 even 2.8.
    Cheers

    Myles D-W

  6. #6
    Join Date
    Jul 2018
    Location
    france
    Age
    49
    Posts
    65
    No sign of wear of what i can see without dissassembly and oil was quite clean with no strange "things" in it.
    I will try with a bar to see if plates are really locked.
    I am searching infos of rebuild as i live in France and there is no real knowledge of these dif here. As for all my "full" restoration process i want to do myself when possible. I know that dif is a complex item but if someone can share all the delails that will help to rebuils it will be very helpful. (For tools and machining, not a problem all the staff at home and access to professionnal tools ).

  7. #7
    Join Date
    Jan 2006
    Location
    Chelmsford Essex
    Posts
    1,725
    The diffs are very similar in construction.
    The problem will be finding might be the bearings if you have a rare early diff but you will just need to find the markings on the bearings.
    A spreader plate helps to get the internals in and out as you set up the back lash correctly ,once you have replaced the bearings and seals.
    You say it's the wrong ratio so you would need to source a new crown gear and pinion drive which is a high cost of the whole diff.
    If it was the correct ratio then I would say refurbishment.
    The PL test is lock one side and the other side should turn with some force if the plates are not worn.
    With a lighter car like the cobra you need to reduce the amount of plates to reduce the clutch plated break away. This is known as de-rating. You can see this described in rebuild manuals showing now many plates need to be removed.

  8. #8
    Join Date
    Feb 2011
    Location
    Northampton
    Age
    43
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    4,925
    Quote Originally Posted by sunday View Post
    - the dif cover was marked 3.31 but pinion vs gear test give me a 3.54 ratio (confirmed i think by the 46 13 marking as 46/13=3.54) : this ratio is too high for me, is it a good way to source a 3.07 pinion / gear ratio ? (and keep my power lock)
    Definitely 3.54:1 - you're right about the 46 13 marking. I had a 3:54 (XJ40 XJ12) rebuilt to 2.88 which required some machining work, I believe, due to the different carrier thicknesses (to accommodate different size pinion wheels). Lore has it that everything 3.54:1 and (numerically) under has the same thickness carrier but that wasn't the case for me - that could have been because the 2.88 came from an earlier (Series XJ) diff, however.

    Can't help with the specifics unfortunately as I shipped it off to Russell - http://www.cobraclub.com/forum/member.php?u=14103 - given his work history (many years at Jaguar) it just made sense; but seeing as you are practically on another planet these days given travel restrictions and import/export fun Russ might be able to help you out with some details, though, if you reach out to him.
    My DeDion build diary..
    Hon Sec of the Digidash branch of the Unpopular Kit Car Design club

  9. #9
    Join Date
    Apr 2004
    Location
    East Leake, Nottinghamshire, England.
    Age
    57
    Posts
    9,651
    When I rebuilt my diff to break the lock originally locking the input shaft and one of the output shafts it took over 90 ft lbs after I had derated it, it took about 24 ft lbs and works fine.
    Martin

    351W 416.7 HP and 466.8 ft-lbs

    Running Mega Squirt and Edis 8


  10. #10
    Join Date
    Jul 2018
    Location
    france
    Age
    49
    Posts
    65
    Quote Originally Posted by TINKA View Post
    When I rebuilt my diff to break the lock originally locking the input shaft and one of the output shafts it took over 90 ft lbs after I had derated it, it took about 24 ft lbs and works fine.
    I am very interessed to know how derate the dif to lower friction, have you put new parts, suppress some plates or ???
    Also what range of derated locking torque will be fine on our light cars ?

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