Manual transmission questions - '88 TQ

[Eyvind Spangen]

I have a problem with the transmission in my '88 100TQ. With 240k
miles, the 2nd gear synchro is gone. I just bought the car and got it
cheap because of this. It will work relatively good when the
transmission is cold, but once it warms up, it grinds every time I try
to change into it. I tried changing the oil - the level was waaaay
low, it got much smoother, but the synchro was still bad.

I understand that replacing this is not a DIY job, even for an
experienced home-mechanic, so I'm seeking alternate solutions.

The transmission in the car is code AAJ and has got a very "long" 5th
gear, about 2050 rpm in 60 mph. I have another transmission here from
a 100q non-turbo with the same final drive ratio, but it has got about
2800 rpm in 60 mph. I know I could swap in that transmission, but will
it hurt the mileage a lot? I seldom drive more than 75 mph for
extended periods, but I think that regular highway use (50-60 mph)
will consume quite a lot more gas than with the AAJ transmission..

Any tips? Of course I can find a used AAJ-transmission (please, no
offers, I live in nothern Europe!), but if I could use the
transmission I already have, it'd be great..

--
E. Spangen
'86 Audi 100 2.2 CS quattro - 358000 km!