Larger/Heavier steel wheel & Stock braking/Clutch Questi

[Petervw]

if the van has stock brakes with even the organic front pads..how much of a change (if there is a change ??) will be experienced in added brakeing "distance" if one moves away from useing the 14" steel wheel which weights in at 15lbs. and then installs some 16" steelies weighting 26lbs....also.. then of course comes the larger tire with more added extra weight ...depending on the set-up, there could 15-17lbs. of extra weight per Axle...would the extra weight cause the clutch disc to "wear" out sooner

[Randy in Maine]

35 pounds is not much additional weight when talking about a 4000 pound vanagon.

Like 4 gallons of gas.

[ChesterKV]

[Christopher Schimke]

1lb added to a wheel (rotational mass) is the same as adding roughly 1.75lbs to mass of the body.

So adding 15lbs per wheel (60lbs total) would be roughly equivelant to adding 102lbs of payload (15x4=60x.75=42+60=102). Not that much really.

A more noticable factor in adding unsprung weight (weight not supported by the springs) is the loss of ride quality. By adding unsprung weight (whether through heavier tires, wheels, brakes, etc.), more of a jolt will be felt in the body of the vehicle due to the increased mass being thrown up toward the body when it hits a bump.

Imagine this: Toss a baseball into the air and catch it. Note how much energy it takes you to stop the ball from falling any further as it hits your hand. Now imagine doing the same excersise with a bowling ball. Even though you probably couldn't toss the bowling ball nearly as high into the air as the baseball, the energy that it takes to prevent the bowling ball from falling any further is many times greater than it was for the baseball resulting a much greater jolt to your body. In this excersise, the balls represent the unsprung weight in your suspension and your hand, arm and muscles represent your spring/ shock combination.

This is the same principal as adding or subtracting unsprung weight to your vehicle. It's easy to see how adding unsprung weight can have a profound affect on the ride quality.

Another example would be a loaded versus unloaded pickup truck. Take a unloaded pickup truck over a washboard road and note it's ride quality. Pretty bad, right? Now load that same truck up with payload in the bed a repeat the drive on the same road. The ride is much improved. This is because the increase in body weight makes the ratio of unsprung weight to sprung weight much less. The same affect could be had by reducing the unsprung weight on the truck.

This is why a fully loaded Westy will have a better ride than a base model 2wd given the same spring/shock and wheel/tire combination. The base 2wd would actually need higher rate spring and shocks with more control over the unsprung weight. However, this would come at the price of a rougher ride. There really is no good way to overcome high unsprung weight whether the FRACTION of unsprung weight comes from the heavy weight of the unsprung components themselves or by lack of weight in the sprung mass to compensate for the heavy unsprung mass.

Big expensive cars like Mercedes, Bentley, Rolls Royce, etc. acheive a smooth ride by having a large fraction of the weight sprung meaning that the body and chassis are very heavy in comparison to the unsprung weight of the wheels, tires, brakes, etc. The same affect can be achieved on a lighter vehicle by making the unsprung weight lighter. Simple as that.
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[Petervw]

[tencentlife]

An excellent and informative response by loogy. Nice job!

The "flipside" of unsprung weight: lighter reciprocating components (wheels, tires, brakes, control arms, etc.) have less inertia and so are able to change their direction more quickly. That is important for keeping the tires in contact with the road. A heavy unsprung combination, when deflected upward by a bump, has a greater tendency to continue traveling upward until spring counterforce returns it to the road; that's "wheel hop". Lighter unsprung combos with a well-matched spring rate dramatically improve handling and braking because they're better able to track the road in spite of surface irregularities.