Dealer vs. Local Mechanic in diagnosing problems

I own a 1999 Subaru Forester (stick shift) the engine, heads and timing chain were replaced 14 months ago by a Subaru dealer for $6,000.I now have transmission problems. When making a slow sharp turn the wheel area vibrates and makes a drum like noise (not the noise wheel bearings make)I had 4 new tires put on but tire shop could not get car to align,the car stays out of alignment because my driveway is so bad. The Subaru dealer wants to replace transmission for $4,000, A local mechanic (with a good reputation)says it only needs a rear transmission(?) something. He will fix it for about $700. The dealer put car on lift,hooked it to computer and spent 30 minutes diagnosing problem. The local mechanic drove car for 10 minutes heard a whining noise and jacked car up enough to slide under it. Obviously I would rather spend $700 than $4,000. Who is right? Is it common for"old fashion" mechanics to know better than the computer aided guy?

The human brain can beat a computer because the brain can reason and the computer can’t. A top notch mechanic that can drive the car, listen for the noise and then do a little exploring is great, no matter whether the mechanic works in an independent shop or works in a dealer’s service department. I knew one great mechanic that worked for a dealer. I would specify that this person was to do the job. I knew another fine mechanic that had his own shop. In your case, I think I would go with the local mechanic who has the good reputation.

For this type of a problem, and in fact for many problems, an “old fashioned guy” with years of knowledge and experience is a far better bet. The computer is a great first step, but hands-on diagnostics are then necessary. Besides, the computer doesn’t monitor the rolling stock, only the engine and tranny, and then only for emissions system stuff.

Now, why did the shop say they could not align your car? There’s a real good chance that the reason is related to your problem. Driveways do not count. They cannot affect the car’s alignment even if they need repaving.

I’d go with the local mechanic with a good reputation. And I’d ask him about the alignment too.

Does this car have an automatic transmission?
Did this problem surface after an oil change?

If the answers are yes then you should inspect the transmission gear oil level. This is NOT the ATF.
It is not unheard of for someone to mistakenly drain the hypoid oil from the transmission while changing the engine oil. Symptoms can vary, all depending, but low gear oil can cause these kind of problems and it can very well lead to an expensive transmission replacement.

As to who is best that also depends on the abilities of the person who has the car in hand.

As to the alignment issue, I find it hard to believe your driveway is that bad. The problem is more than likely related to worn and/or bent suspension components.
Tie rods, tie rod ends, and ball joints are the likely suspects in that pecking order.

The sharp turn issue is usually the $700 fix not the entire transmission. Specifically the back of the automatic has a clutch pack and your finally wore out or was pushed over the edge with mismatched tires.

Since the dealer already robbed you of $6,000, give the local mechanic a shot.