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post #1 of 4 (permalink) Old 03-26-03, 05:26 AM Thread Starter
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Question Diffs??....

hey guys...my diff is on its way out in my EA... ive got rough ideas on wats wat but just wondering if any one can help me out.... i want to ditch the single spinner and im after a higher ratio diff...say 3.45 or being a manual ive heard doesnt hurt to go 3.9's??.... can any one explain the differences?? or advantages of LSD compared to spooling diffs or locking them.... any input appreciated thanks
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post #2 of 4 (permalink) Old 03-26-03, 03:00 PM
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EA will have 25 spline axles. I recommend you go 28 spline axles and four pin hemisphere. With good suspension most cars will go alright with open diff on good road surfaces. Beyond that, go to LSD. Spools are illegal and dangerous. A properly built LSD will do the job. I wouldn't go lower diff than 3.27 with an EA five speed without serious engine mods, due to the 3.5 first gear. An XR manual (3.28 first) will be fine with 3.45 diff.

If you're not driving a manual you're really just steering.
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post #3 of 4 (permalink) Old 03-26-03, 03:59 PM
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You are after a lower ratio (higher number) diff, not a higher ratio diff as you have put it. Yes, I know that's confusing.

I agree with WBT56, 3.9's are too low for street use, leave them from dragstrip specials.

The differences;

Single spinner or open diffs will transmit equal torque to both axles, so if one side losses traction it will not be able to resist the torque and spin until traction is regained.

LSD diffs work the same until one axle tries to rotate noticably faster than the other. This differential in rotational speed is limited by clutch packs or viscous fluid ensuring that some rotational forces are sent to both axles at all times.

Spools are permanently locked diffs. That is there is no differential action and both wheels are forced to rotate at the same speed all the time. No good if you need to turn corners and you respect your tyres, axles, diffs etc. Not for street use.

Locking diffs (Detroit locker etc). Will allow differential action for turning by disengaging the outside wheel and allowing it to turn faster (meaning all the torque then goes through the inside wheel). Under power the slower turning wheel will be receiving all the torque or the diff will lock turning both wheels at the same speed. Can cause trouble on high powered road cars with engaging/disengaging of rear drive wheels - spooky on fast sweepers at full throttle. I wouldn't recommend this for a powerful street car either, fine for four wheel drives that require the locking action off-road at slow speeds and that acknowledge the limitation on road.

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post #4 of 4 (permalink) Old 03-28-03, 12:53 AM
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i have had a lock-rite center installed on my ea with 3.7 gears and 28 spline axels and 4 pin hemi.

the dif can now handle 900hp but it all cost about 1300 bucks to do.

in my opinion if ur wanting just pure street driving then a 3.23 is good as it will help ur economy
but if you intend on giving it a sqirt some times on the street a 3.45 is better
but for a manual a 3.7 is good for street/strip duty's and 3.89 for auto.

lsd would prob be best bet for steet applications up to 400-450 hp max after that a locker (not welded is best)
but keep well away from spooled or welded diffs unless u are only gonna be gong in a straight line.


live in S.E. queensland? bit of a revhead? click here!!--> speedphreaks

1000hp is underway. rods,pistons here!! t88 on its way!!
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