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Diff Ratio variation

General Tech Talk

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Diff Ratio variation

Post by NJV6 »

Is a 4.90 ratio 'close enough' to a 4.875 to not be damaging a transfer case?

Most of my driving is on softer surfaces. The higher ratio (4.875) would be in the rear.
1994 NJ SWB, 3.5, 5 speed manual, 33's, XD9000, 4.9 diffs, Front & Rear ARB's, Safari Snorkel

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Post by -Scott- »

The difference between 4.875 and 4.90 is approximately half of one percent.

If you're running 33" tyres, that's equivalent to 4.3mm in overall diameter, or just over 2mm in radius.

What's your tread depth? 10mm? You'll get a bigger difference if you run new tyres on one axle, and 30% worn on the other.

Just do it.
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Post by Gwagensteve »

Should be fine.

Ford ran 4.10 in one end and 4.09 in the other in stuff for years and years from the factory.

You might not want to use 4WD high range on hard packed surfaces though (and why would you?) you might find a bit of bind that makes it hard to get out of 4WD.

Steve.
[quote="greg"] some say he is a man without happy dreams, or that he sees silver linings on clouds and wonders why they are not platinum... all we know, is he's called the stevie.[/quote]
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Post by NJV6 »

Thanks guys, when you put it into perspective like that its pretty darn close.

If it is onto harder surfaces the centre diff would absorb any differences anyway when in full time 4wd unlocked.

:armsup:
1994 NJ SWB, 3.5, 5 speed manual, 33's, XD9000, 4.9 diffs, Front & Rear ARB's, Safari Snorkel

2008-2009-2010-2011 Pavlova in the shed.
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Post by DamTriton »

Subarus ran 3.909 in the rear and 3.9 in the front....probably still do.
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