Rear differential compatibility B3 - B4

[Radek]

1988 90Q, located in Ottawa, Canada.
The differential has been like this since we bought the car a couple of 
years ago, never have been able to trace it down.    Other issues (like 
leaking fuel lines and the like) took precedence.  The linkage seems to work 
properly, but internally, it never releases completely.  There is some 
interference with ABS too, the locking switch in centre console causes the 
ABS light to be on.  Pressing the ABS Off switch causes the light to go off 
.  ABS relay, ABS controller under rear seat and lock controller under the 
rear seat are ok (replaced with known good ones).  I suspect wiring problems 
on top of internal diff issues.
BTW, could a faulty speed sensor have anything to do with this?  The system 
is supposed to unlock the diff at higher speed, but what if there is no 
signal (speedo has been intermittent, but then, it could be just the 
instrument cluster)?

Radek.

----- Original Message ----- 
From: "Huw Powell" <audi at humanspeakers.com>
To: "Radek" <radek at uniserve.com>
Cc: <quattro at audifans.com>
Sent: Thursday, June 21, 2012 3:04 PM
Subject: Re: Rear differential compatibility B3 - B4


> What year is it and where are you located?
>
> And can you tell why the diff is permanently locked?
>
> On 6/21/2012 2:35 PM, Radek wrote:
>> Hi Guys;
>> My son's 90Q broke its rear differential support - an aluminum casting 
>> part no. 893-599-131.  All this due, I suppose, to the permanently locked 
>> rear differential that we neglected to fix.
>> Our options are:
>> 1. get new support, fix diff lock, reassemble;
>> 2. get new support, install new diff, reassemble;
>> 3. possibly:  get the diff from a B4 that's at the local yard - but will 
>> it fit?  FA says no, but I recall seeing somewhere that the whole rear 
>> assembly (rear subframe and diff) can be transplanted from B4 to B3.
>> Is this true?  Any other options?
>> TIA.
>>
>> Radek.
>> _______________________________________________
>> quattro mailing list
>> http://www.audifans.com/mailman/listinfo/quattro
>> http://www.audifans.com/kb/List_information
>>
>>
>> -----
>> No virus found in this message.
>> Checked by AVG - www.avg.com
>> Version: 2012.0.1913 / Virus Database: 2433/5083 - Release Date: 06/21/12
>>
>>
>
>