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Re: Final drive play
Well, I don't claim to be an expert...
When I say 15mm, I mean at the perimeter of the rear drive flange, which is
about 15mm across, maybe a little less. I'd say it's 10-15 degrees of play.
Also, your diff is not limited slip. Honestly, I don't think open
differentials ever "wear out." or rather, I think it would take 1 million+
miles. The reason a torsen wears out is because friction is an integral part
of how it works. The whole concept behind a Torsen is that the gear faces
are angled so that they can slide, but if they slide "a lot" and the
friction adds up enough, then they turn too. This is why you can't tow a
quattro w/ a Torsen center diff on a front-wheel only lifting tow truck
(even in neutral). Your Torsen would burn up. Conversely, towing a 4kq w/
front wheels only lifted is no problem.
From: Huw Powell <firstname.lastname@example.org>
To: Avram G. Dorfman <email@example.com>
Cc: quattro list <firstname.lastname@example.org>
Date: Friday, August 13, 1999 10:05 PM
Subject: Re: Final drive play
>Avram G. Dorfman wrote:
>> When someone held the drive shaft & front axle flanges, we could turn the
>> rear drive flange by hand *easily* about 5mm, and if we really twisted
>> 15 mm.
>excuse me for being a nerd, but how many degrees is that?
>> When my brother accellerates after coasting, there is about 1/4 second of
>> free engine spin-up before the driveline "catches up" and then there's a
>> clunk, and the car starts to accelerate. This is just our analysis, but
>> believe the slack is in the differential. The trouble is, we don't really
>> know how much play there is supposed to be.
>yikes. See, I asked because I noticed my 2wd coupe has a few degrees of
>play between the fron (of course) shafts. Wondering how tight is new,
>what is "acceptable" if there is a spec, etc. I should take a look at
>the old tranny that *should* have been in my car anyway. I'm planning
>on changing to an 84 coupe unit anyway, but this would a nice "spec" to
>know, even if we make it up.
> of course a Q gives you a few more differentials in which this play can
>add up ferociously!
>82 Audi Coupe; 84 4kq; 85 Coupe GT