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Thread: McNamara Diff

  1. #1
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    McNamara Diff

    I have a McNamara rear diff and would like to fit 4.11 ratios so I can run my 33'' tyres, will standard replacement ratio crown wheel and pinion (Ashcroft) fit or do I need a McNamara crown wheel and pinion.

    Is there one brand better than another (Ashcroft) ?

    Thanks all help will be appreciated

  2. #2
    Katie Guest
    When I spoke to McNamara he said he only made centres and used a standard crown wheel and pinion, so you would be able to use any crown wheel that would normally fit in the diff.
    Katie

  3. #3
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    Do you have a rover McNamara, a Hypoid McNamara, or a salisbury McNamara???

    Rover type - any rover gears will fit
    Hypoid type - this is actually a converted toyota 8" so you will need low pinion toyota 8" gears.
    Sals type - you of course need sals gears.


    Quote Originally Posted by Katie View Post
    When I spoke to McNamara he said he only made centres and used a standard crown wheel and pinion, so you would be able to use any crown wheel that would normally fit in the diff.
    Katie
    For the hypoid type he uses custom made 3.54:1 and 4.7:1 toyota CW&P (he doesn't make them though).

  4. #4
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    Quote Originally Posted by isuzurover View Post
    Do you have a rover McNamara, a Hypoid McNamara, or a salisbury McNamara???

    Rover type - any rover gears will fit
    Hypoid type - this is actually a converted toyota 8" so you will need low pinion toyota 8" gears.
    Sals type - you of course need sals gears.



    For the hypoid type he uses custom made 3.54:1 and 4.7:1 toyota CW&P (he doesn't make them though).
    ^^^^^x2^^^^^^

  5. #5
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    All 3 diff types are easy to identify visually.

    I have only just put the Ashcroft 4.11 ratios in my diffs (Rover type).
    Setting them up is a real bastard. Rick spent a considerable amount of time on mine. Was tricky to get the drive side pattern, overun fell in.

  6. #6
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    Quote Originally Posted by buzz66 View Post
    All 3 diff types are easy to identify visually
    How do I identify what type I have?

  7. #7
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    Take a photo and post it here and we will tell you.
    I tried to find pics of the 3 types but had trouble with the Hypoid type.

    This is s pic of a standard rover diff.



    This is a typical salibury diff as viewed from the rear.
    Note the Diff Centre is much larger





    This is a typical Toyota Hypoid design. Note the offset of the pinion (IE Lower than the centre line of the diff)





    Best bet is to post a pic of your diff. Will take some guess work out.

  8. #8
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    McNamara make a new housing for the hypoid centre.

    The pinion is still below centre like shown in the last pic, but the shape of the casting is different so that there is enough clearance for the tie rod when it is used in the front. The diff is fitted to the stock rover axle casing.

  9. #9
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    I think I have the standard rover diff?
    Thanks for all your help.
    Attached Images Attached Images

  10. #10
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    Yep Standard Rover Center.
    Wow you still have the Boge installed.
    Most nearly all have been removed by now.
    You can see my in my pic of the rear Diff I have ground off the bottom ball joint to allow easier removal of the Diff Center.

    If you get any clunks in the rear the first port of call will be the Boge followed closely by the A Frame Ball Joint.

    From what I can gather the setting up of the aftermarket Crown & Pins varies between manufacturers. Make sure you get the Diff set up by someone with Rover Diff experience. The Basin Rover C & P are easier to set the Drive pattern where the Ashcroft have the overun just fall in.

    Just because they are Differential Experts doesn't always mean they know what they are doing.

    I asked a Differential Expert company what the numbers on the end of the Pinion Gear was all about and they couldn't give me a definitive answer.
    Needless to say they didn't get a look in.

    Any aftermarket C & P set are stronger then the standard setup.
    Just be careful of the 4.10 set as compared to the 4.11.
    The ratio is almost identical but the pinion is smaller again compared to the 4.11 set.
    Also having a C & P set with reverse cut gears for the front is worth considering. From what I'm told the strength is not so important as the drive from the front diff with a reverse cut set of gears will load the larger rear facing pinion bearing instead the normal cut tends to drive the pinion in towards the smaller froward pinion bearing. Splitting hairs now unless you are running larger than 35 inch tyres or a comp truck.

    Apparently 4.14 gear set gets the green light also.

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