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Thread: Fault with Mk1 Mexico Diff LSD /CWP

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    Fault with Mk1 Mexico Diff LSD /CWP

    Anyone knowledgeable diagnosing diff faults please?
    I recently put a second hand mexico diff with LSD into my Mk1 to trial, I have no idea what setup it was, but when I drove it, I was getting slight rubbing noise approx once every revolution of wheel.
    This rubbing noise was heard on acceleration & deceleration and seem to get worse/louder at higher speeds.

    I took diff back out and and on the bench I can turn the pinion flange freely by hand for approx 3 turns then it becomes tight & difficult to overcome resistance for approx half a turn of pinion flange then continues to turn freely again.

    Its a 3.77 so im thinking the crown wheel may be the issue because of the resistance only happens at same point on every 1 x revolution of crown.

    Any ideas what it might be before i send to specialist?

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    Bodger

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    Fault with Mk1 Mexico Diff LSD /CWP

    I've no idea but Andy from Arrow Auto would have. He's on here from time to time.....

    Sent from my SM-G900F using Tapatalk

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    Re: Fault with Mk1 Mexico Diff LSD /CWP

    loose crown wheel bolts, iffy, crown wheel, dirt between crown wheel and lsd, or damaged mating surface

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    Re: Fault with Mk1 Mexico Diff LSD /CWP

    Sounds like the crownwheel isn't running true which is causing a tight spot once every revolution of the crownwheel.
    This can be a mixture of the diff unit (ie with the planet and sun gears) or LSD unit not having run-out within run-out tolerances. This can be exacerbated by a worn gear set giving more and less backlash depending on which teeth are meshing with other teeth. The crownwheel may not be sitting flat if it has something under it. Otherwise the mounting face(s) are not running true.
    For starters it sounds like the diff doesn't have any backlash - I would be checking what the maximum backlash currently is and then adjusting the diff until it has no tight spots and see what the minimum and maximum backlash is - this will tell how bad things are. Next step is then to find out if the crownwheel mounting (on the LSD, not the CWP) face is running true. Shouldn't be more than 0.001" - genuine ford standard open diff units are usually 0.0002" or less. Some new LSD's are not so good though.
    After adjusting, the mesh pattern needs to be checked as it will have changed.
    Doesn't sound like the diff is going to be in a good state if it's been running with tight spots - while also being out of mesh - as this will stress and wear the teeth.
    Last edited by HonkyWhiteTrash; 09-01-2019 at 12:34.

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    Re: Fault with Mk1 Mexico Diff LSD /CWP

    Many Thanks for replies!

    Plenty to check out..

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    Re: Fault with Mk1 Mexico Diff LSD /CWP

    Update, almost embarrassing
    3 x consecutive crown bolts were only finger tight!
    Heads catching the casing. Torque & loctite I think.. hopefully diff ok

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