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  1. #11
    Join Date
    Jan 2006
    Location
    Chelmsford Essex
    Posts
    1,739
    Tinkas figures sound right . I tested mine at 25lbs .
    You remove the amount of clutch plates from 5 to 3. If you do not derate the rear will only under high loads transfer and not progressive at a lower load so it will almost feel like a locked diff.

  2. #12
    Join Date
    Jul 2018
    Location
    france
    Age
    49
    Posts
    68
    Quote Originally Posted by jon1d View Post
    Tinkas figures sound right . I tested mine at 25lbs .
    You remove the amount of clutch plates from 5 to 3. If you do not derate the rear will only under high loads transfer and not progressive at a lower load so it will almost feel like a locked diff.
    Thanks for this info. I've tested with dynamometer and mine is locked at least until 100lbs so for sure not derated (this can explain "strange" behaviour on corners at low speed of the car before i dismantled it).

  3. #13
    Join Date
    May 2004
    Location
    Finchampstead, Berkshire, UK.
    Age
    56
    Posts
    3,855
    Don’t remove the plates, just re-order them to have less friction to drive plates. For example plate A is friction, plate B is drive, currently you will have ABABA, ABABA which gives you a total of 8 friction to drive faces, if you re-order to AAABB, AAABB then you only have 2 friction to drive faces and therefore you reduce the torque required to break the lock (ie, de-rate).
    You will need to experiment for the right number of faces to achieve the 25-35lb ft though.

    Regards

    Jim
    GD Mk3 Jag based
    Supercharged LS1
    GD J1M

  4. #14
    Join Date
    Apr 2004
    Location
    East Leake, Nottinghamshire, England.
    Age
    57
    Posts
    9,653
    I did exactly as Jim says, just put the plates in a different order exactly as he lists all the friction plates together and all the drive plates together. Worked a treat for me.

  5. #15
    Join Date
    Jan 2006
    Location
    Chelmsford Essex
    Posts
    1,739
    I think it does depend on your diff and the LSD clutch plates and friction surfaces. The build manual I had changed the quality but you should obtain a manual. I had one for the Dana 44 Spicer diff . The Salisbury diff manuals are more difficult to find. The is a very good youtube video on a diff overhaul. I will post the link.

  6. #16
    Join Date
    Nov 2007
    Location
    Shipston on Stour, Warwickshire
    Posts
    105
    Try the attached link.

    https://manualzz.com/doc/6355718/mas...service-manual

    Its a good place to start and covers aspects of the 4HA / 4HU diff. Gives backlash and preload setting and torque settings plus indication of gear pattern.

    I've got a 4HU service doc that I got when I used to work for Jag many years ago. I think its also available on the internet somewhere but I'll see if I can find it.

    Its similar to Dana 44 but not entirely so some build advice is the same and some, but not by any means all parts can be interchanged, mostly in the powerloc carrier. If you strip it down you can find matching bearings by the part numbers or by taking accurate measurements of bore and outer race size.

    As others have said, the friction discs can be reordered to reduce the "loc" plus there are some other discs you can get new which have less friction to them. I'll try and find the part number.


    This guy is good and worth watching.....https://www.youtube.com/watch?v=OurJHaiy6kI

  7. #17
    Join Date
    Dec 2009
    Location
    Barton Mills,Bury st Edmunds,Suffolk
    Age
    51
    Posts
    351
    Which DAX are you building what gearbox and engine do you have?
    mark chambers
    Dax de Dion 350 Chevy

  8. #18
    Join Date
    Jul 2018
    Location
    france
    Age
    49
    Posts
    68
    I've done some "homework" and plan to rebuild dif this winter to 3.07 ratio and with derating of clutch plates.
    I've ordered a Motive gear dana44 3.07 ratio crown+pinion which need some adjustements to be put in a salisbury (bolts/pinion bearings).
    If some of you are familliar with dana parts, i've a question : usually pinion has a marking which indicates either offset of pinion position vs therorical position (+2 for example indicates 2"625+2=2"627), either an absolute pinion depth. In my case pinion is marked with 23 (see picture attached).
    I assume it means a 2"623 absolute pos : in theory, according to motive documentation, motive gear are marked with a complete absolute pos ... so don't known if my assumption is correct ?
    DanaPinion.jpg

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