Used Cars: bought a high miles, used car lemon, negotiation power, torque converter

Question
I purchased an Audi A4 Quatro 3.0v6, 113,000 miles (AS IS)last week for $8000 in Minnesota. I negotiated the price down from $8900 because there was not service history and the timing belt is a $1300 repair.  Within 50 miles of driving, the check engine light came on.  I brought it to a reputable independent repair shop and found the torque converter needed replacement at a cost of $2500.  So I now have $3800 in repairs on a car I've driven 50 miles.  My question is: Do I have any negotiation power for some kind of refund from the dealer.  I know legally I do not. They are a very small independent operation with very high marks in customer satisfaction.  Would there be an effective way for me to get them to cover some of the repair cost?  Needless to say, I learned alot about how not to by a used car.

Answer
Well I would approach it this way, be respectful and kind, and see where it goes.  If they have a reputation for high marks in customer satisfaction, remind them of why you chose them.
Truth is both of these repairs would have been hard to catch in advance, You can do a lot of checking of a car, but you cant look internally and predict things, which is the case with both of these repairs, just no way to know.  As well the Audi's are pretty good vehicles, and with these repairs done, you should have a really good car from here out.  I dont think you necessarily bought a used car the wrong way, I think you might have could have found cheaper ways to do these repairs, around here I could have got that timing belt and water pump done for about $500.00, and not real sure on the torque converter, but I am sure it could have been done for less than half that as well.  Both of those repairs are not that complicated for those who truly know what they are doing.
So in summary, I would not hold this against this dealership, and if they are small, it may be hard for them to help a whole lot, but in the end, show them what you spent, and see how far kindness will take you with this.  I promise you this, small dealerships with good reputations would MUCH rather catch this stuff before they sell it.  It is tough to negotiate a car deal, keep your profits fair, and then participate in almost $4000 in repairs.  We would much rather fix it in advance, work our profits from there, and know the car is good to go, then have a unhappy customer spouting off to everyone he knows.  One unhappy customer, can cost a dealership about 10 potential deals.