On both my sets of wheels and tyres, my original Turbo set and my alternative S2 set, I've had a lot of wheel balance problems which have only been resolved by, er, having the wheels balanced.
Properly.
The thing is, very few people seem willing and able to balance wheels with any finesse, and in my experience a 944 is very sensitive to wheel balance, possibly because the wheels are a lot lighter than you would find on your average BMW or Golf, and the tyres are therefore heavier in relation to the wheels than on most cars.
I've had quite poor wheel balancing done, or perhaps more accurately "attempted", by tyre places generally, and by one well known old Porsche specialist in the north of England (not Hartech!)
I've had very good wheel balancing done by Promax Motorsport in the past, though Andy has sold the good wheel balancer now as it wasn't getting enough volume of throughput to justify its keep. When I had a new set of tyres on the newly refurbed S2 wheels that are currently on the car, Promax hadn't got their balancer any more and no-one else could get it right. The car had perfect wheel bearings, all fully rebuilt suspension with every bush replaced, new factory dampers, and a full geometry set-up, so I knew that wasn't the problem It was driving me mad. I ended up taking the car to a place in Gateshead, Tam Tyres, where they have a Hunter GSP9700 road force balancer - that's one of these...
http://www.pro-align.co.uk/proalignproducts/roadforcebalancer/
It measures a lot more parameters than a standard wheel balancer, and with a good operator can work to much finer tolerances than most tyre places are prepared to work to. It was about an hour's work, involving demounting and rotating one of the tyres on its rim, and the end solutions they came up with involved the car having far fewer balance weights on it than either of the two previous attempts. It drives perfectly now from a standstill to autobahn speeds of over 130 mph. It was not expensive to do, I think they did it for the same price as a standard balance because I had already taken the wheels off the car and cleaned them up, so it took them less time.
Makes a huge difference to the car, getting it absolutely, spot-on right.
