Politics, Economics and other Stuff

Car Repair

I brought my car into the shop today since it was making a scrapping/grinding noise when making a left turn, sounding a bit like an old van.  Turns out that the problem was that the left front rotor was hitting the backing plate (which seems to have the function to hold the parts, but not the caliper, of the disk brake in place, the rotor being the disk part of the disk brake -- ah, it may mostly be the hand-brake drum brake), so for $64.78 the backing plate was adjusted to no longer do this.  No sign of any damage to the rotor that I was told about, but we'll see.  The part of the backing plate that I think was scrapping against the rotor doesn't look substantial to me and it is unclear to me what its function is, besides being a sort of mud catcher for the rotor. 

I suspect the cause of this was the alignment I got when I bought new tires back in early June, something that shouldn't happen.  So count this against Town Fair Tire in Hamden. 

Here's a backing plate behind a rotor on a disk brake (in this case an E39 BMW, also see some nice photos of cutting back the baking plate so it won't scrape the larger rotor for this brake upgrade):

Update #1: having felt the backing plate with my hand, this piece of metal is so insubstantial that there is no way it is going to damage the rotor.  The puzzle now is how the backing plate keeps its shape as well as it does in order to not scrape the rotor and make noise all the time.  Not too many flying rocks under foot it seems. 

Car Size and Weight: 2004 4 cylinder Honda Accord vs. 2009 BMW M3

My car, the 2004 4 cylinder Honda Accord, is approximately (given or take a sun roof etc.):

Length: 189.5 in.    
Width: 71.5 in.
Height: 57.1 in.    
Wheel Base: 107.9 in.
Curb Weight: 3144 lbs.

Front Head Room: 38.3 in.    
Front Hip Room: 54.6 in.
Front Shoulder Room: 56.9 in.    
Rear Head Room: 36.8 in.
Rear Shoulder Room: 56.1 in.    
Rear Hip Room: 53.5 in.
Front Leg Room: 42.6 in.    
Rear Leg Room: 36.8 in.
Luggage Capacity: 14 cu. ft.    
Maximum Seating: 5

The 2009 BMW M3 is:

Length: 180.4 in.    
Width: 71.5 in.
Height: 57 in.    
Wheel Base: 108.7 in.
Curb Weight: 3726 lbs.    
Gross Weight: 4740 lbs.

Front Head Room: 38.5 in.    
Front Shoulder Room: 55.4 in.
Rear Head Room: 37.5 in.    
Rear Shoulder Room: 55.1 in.
Front Leg Room: 41.5 in.    
Rear Leg Room: 34.6 in.
Luggage Capacity: 12 cu. ft.    
Maximum Seating: 5

So what we have here is that the BMW is smaller than the Honda, nine inches shorter while just as high and wide, with almost 600 lbs more curb weight. Two offsetting effects here, I assume: the BMW is shorter and uses more expensive construction methods to obtain weight savings, while having a much larger motor (4 liters vs. 2.4 liters, 414 hp vs. 160 hp) and stronger and stiffer transmission, body, suspension and brakes.  It would be nice to know where the weight differences come from.  And yes, the BMW does have a longer wheel base, which ought to add weight. Finally, the standard complaint about the M3 is that it is too damn heavy for a sports car. 

The 15 inches shorter Porsche 911 weighs about what my car does, or 100 lbs. less for the less powerful versions.