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Old 07-19-2011, 02:29 PM   #79
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Join Date: Jul 2009

Originally Posted by 745 TurboGreasel View Post

I've been considering putting one in the front axle, but the Dana44 Ujoints aren't that great, and I'm not sure how bad the grab on the steering wheel would be when it locked.
Ah,.... that one failed in the rear axle of a big 4X4 at low speed/ from rest. With big, large-diameter knobbly tyres there's probably even more of a shock load there when it engages than with slicks that are already rolling at speed but due to slippage have the necessary speed difference across the axle.

I wonder if it is the same kind of loading that could be distorting the friction disc ears during the short period where the are coming into play, just before the ramps have fully engaged? Has this ever been known to happen in tarmac use?

I don't quite understand the conditions where there might not be enough grip for the G80 to lock up..... unless grip levels were so low that both rear wheels were to spin, but with less than a 100rpm speed difference between them, frying the clutch packs??

Diff oil grade and type could also have an effect on the clutch packs if they are slipping excessively, in the same way as it would on bike wet multi-plate type clutches.

Even with part worn friction plates, the ramps should just ride up each other a little more for the same transmitted torque, so plate pressure should be unchanged. Any 'burning' friction plates might be the result of oil type or something else rather than overloading during lock-up?

At low speed, as long as the speed of one wheel exceeded that of the other by the required amount surely it would lock?

I'm really a bit surprised that these units are giving trouble in 4X4s though, I thought that was largely the market they were aimed at. This video makes much play on the use of the G80 in large 4X4s....

Maybe very big knobblies and enthusiastic throttle use are just too much for it? They seem to be more of a useful 'get you out of trouble' diff than a true 4X4 (or 4X2 even) performance one.

For road/ tarmac use, even with slicks and/or engagement speed mods, I'd like to think they might stay in one piece a little better?

Last edited by Turbeam; 07-19-2011 at 02:32 PM.. Reason: clarity
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