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Post by astro49 on Aug 3, 2006 23:59:09 GMT 11
Hi all! Have a '93 MU and just installed a surplus pullout LSD that supposedly came off from a JDM MU. Its also 41/9. Loaded it with 2 liters of Castrol LSX90, which says its also suitable for LSD diffs.
After the install, roadtested it and fortunately it was silent and no whines or anything.
I now did a test by jacking up one rear tire then shifted the MU to drive to see if it would fall off the jack and move forward. I'm assuming with the LSD diff, the other tire would rotate and move the MU.
What happened was the lifted tire just spun but the MU wont budge or move. And I could also hear whining or slight grinding sound on the unlifted side tire, more than likely coming inside the diff.
My question is.. IS THIS NORMAL??
Do I have to at least let the lifted tire touch the ground a bit so the other tire would bite and spin?
Would a 90/140 gear oil improve the bite of LSD clutch?
Or hopefully not, the LSD is defective?
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Post by James W on Aug 4, 2006 7:44:00 GMT 11
With a slippy diff and both wheels jacked up they should rotate in the same direction. With an open diff opposite direction. With one wheel on the ground and slippy diff you should feel resistance to turn the liffted wheel. The more resistance the tighter the diff and closer to a locker you are. Oil plays a big part and you can add slippy diff aditives for more bite. If it's dirty or contaminated an oil change helps. However it is possbile it is worn.
Your one wheel lifted and in drive test may be normal. They are only a limited slip diff. That is limited tourque, only SOME tourque would have been applied to the wheel on the ground. Limited by how much bite there is in your LSD. Touch the brakes and more tourque has to be applied to the wheel off the gound, and thus more to the one on the ground... an old trick :-)
Some noise is normal, for example a quick u-turn under power will typically produce suddering that you can feel and hear.
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Post by mudgrip4 on Aug 4, 2006 15:40:06 GMT 11
I think try James idea and jack both rear wheels off ground and spin one. Generally if lsd the other wheel will spin in same direction. If it doesn't could just be a matter of getting another oil more specifically for lsds. Wouldn't bother putting in just a heavier grade 90/140 oil. Best I know is Redline Heavy Duty Shockproof Gear oil, available from car performance shops and used in race cars - dear but makes lsd bite like hell.
If your lsd still not operating properly after using a top lsd oil, then its either defective, or needs to be tightened up some by a diff specialist.
Mike
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Post by mudgrip4 on Aug 4, 2006 15:43:20 GMT 11
I think try James idea and jack both rear wheels off ground and spin one. Generally if lsd the other wheel will spin in same direction. If it doesn't could just be a matter of getting another oil more specifically for lsds. Wouldn't bother putting in just a heavier grade 90/140 oil. Best I know is Redline Heavy Duty Shockproof Gear oil, available from car performance shops and used in race cars - dear but makes lsd bite like hell.
If your lsd still not operating properly after using a top lsd oil, then its either defective, or needs to be tightened up some by a diff specialist.
Mike
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Post by astro49 on Aug 5, 2006 4:02:38 GMT 11
James and Mike, thanks a lot for your inputs! Btw am sure as day I got LSD since there's a clutch housing inside unlike an open type diff, you could see the exposed spider gears. And ofcourse, it passed the rotational test same direction wheel spin.
This afternoon we drained the Castrol LSX90 diff oil (caught it ofcourse then drained the front diff and reloaded this there) and refilled it with a US made brand 85/140 weight (though forgot the brand, not Redline). Will try again tomorrow the lift one rear tire and put on Drive test and see if the MU would move forward and fall of the jack.
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Post by astro49 on Aug 11, 2006 19:13:57 GMT 11
Havent done that lift a wheel-fall of the jack test yet but just been back from the mountains these past days. Definitely an improvement while navigating an uphill S-curve road with loose gravel. Before my rear tires would chop while making a U-turn on that steep climb and S-curve (on 2wd). Virtually no chopping now (still on 2wd)! On a mud trail, I noticed a slight spin of one of the rear tires but since its just LSD, its to be expected. A diff locker be best for those conditions.
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