Tire wear problems are a part of owning a front-wheel-drive Ford product and there's little you can do about that, but on the Aspire they finally went to a strut design that everyone else uses. On Chryslers and Toyotas one of the main alignment adjustments is built into the lower mount of the struts. On other brands that mount can be modified quite easily to make it adjustable. Most of the time there are things that can be done to correct the design problems on the rear of Fords. Those fixes were never used by Ford dealers, and since Ford won't admit there was a problem, and it was due to saving money, those fixes won't be found at their dealerships. Alignment specialty shops have all kinds of remedies for various design problems on a lot of different vehicles.
First you have to determine the type of tire wear. If you can still find a Tempo or a Ford-built Escort from the '80s around, you'll see the two front tires are tipped WAY out on top and the rear ones are tipped way in. That made them ride very smoothly on test drives over rough roads. Ride quality was better than that of their competitors, so they sold a pile of cars. The problem was by running on the outer edges of the tires, they scrubbed off by 15,000 miles and had to be replaced. The salesmen never mentioned the tire wear problem, just the nice ride.
The second problem was steering and suspension parts that break and separate leading to loss of control and crashes. Ford has more trouble with that than all other manufacturers combined. There are a lot of really high-quality aftermarket replacement parts that address these design problems, but they get installed too often after someone was in a crash.
The next thing to consider is switching transmissions. That is an awfully lot of work and expense to go through on this car. A much better alternative is to buy what you want. Automatic transmissions weigh a lot more than manual transmissions, and that relates to ride height. Included with an automatic transmission from the factory is a whole pile of different parts including stronger front springs. Even when you are able to set all the alignment angles to specs for best tire wear, those numbers on the alignment computer only apply to a vehicle that is at the correct ride height and will stay there on bumpy roads. The geometry of the suspension system is designed to keep the tires flat on the road surface, and to reduce how much they slide left and right as the car goes up and down. When the car sits lower on front, on this and most car models the "camber" can be readjusted so the wheel is perfectly straight up and down, but that only applies to when the car is standing still on the alignment rack. As it's bouncing up and down on the road, the wheel will be tipping in and out on top an exaggerated amount causing excessive wear on the inner and outer edges of the tires. No amount of alignments and no alignment adjustments will solve that until the ride height is restored and the replacement springs are stiffer to support the weight of the transmission. This is so important that the springs for a car model will be different between one with air conditioning and one without. All the air conditioning components, with the larger radiator, weigh a lot less than the difference between an automatic and a manual transmission.
All tire and alignment shops have small books that show every car model, where to take ride height measurements, and what they should be. If the front is low, new springs for a car with an automatic transmission will fix that.
A less-known issue with making the transmission change is how it adversely affected braking, handling, control, and steering response. The transmission is just one of a whole package of parts. All brake systems use a proportioning valve to limit rear brake pressure under hard braking to reduce rear-wheel lockup. With more weight on the front, there's less weight on the rear, and those tires will skid easier. A skidding tire has no traction and will try to pass up the front of the car. Lawyers and insurance investigators know all about brake balance, and especially all the things that are compromised when someone lowers their car or raises their truck. They will use that against you when the other person ran the red light and caused a crash. They will convince a jury that you were partly at fault because you were less able to avoid it, and they will be right. Between altering ride height on purpose, and having incorrect ride height as an unintended result of some other modification, it's the legal ramifications we worry about first, and the alignment problems next.
The first thing you need to do is describe exactly what kind of tire wear patterns you see on each tire and on each edge. The next thing is to have the ride height measured and compared to specs. If it's low or the springs can't hold up the weight on bumpy roads, the springs will need to be replaced, then the car will need to be realigned. I'm a suspension and alignment, and a brake system specialist, but even with my vast knowledge and experience, I can't say what the effect will be related to the brake proportioning valve. It could be no worse than adding one passenger to the back seat so you may not notice anything. At a minimum, you are aware now that there is such a valve, and its purpose, so you can make an informed decision if issues are noticed with braking balance.
You also need to include a lot more detail about the shaking. Does that occur when standing still with the engine running? Does the car have to moving, and if so, how fast? Where is it felt, in the steering wheel, brake pedal, seat? Did the shaking just start after a previous service?
Tuesday, October 21st, 2014 AT 11:00 PM