This may be a silly question, but I was wondering what determines the deceleration rate of a car? We've all had cars that "feel" differently with your foot off the gas at velocity and I am not sure if it has to do with the gears or something else and wanted to get educated if possible.

My 442 and Jeep Wrangler for example, decelerate much quicker than some previous Cutlasses and modern cars I've owned. Just wasn't sure if it is specific to each vehicle, or if manufactures can dictate this and dial them in accordingly?

Thanks!

 

gear ratio is a big factor. a 411 gear will decelrate faster than a 2.56 due to the engine brake effect. Much like a manual trans an engine will decelrate faster in 1st gear than say 3rd gear.

 

Mainly gearing, like said above. Tire size, smaller would be slowing down faster, and displacement of the engine, bigger will slow you down more. Clutch or lockup TC vs non locking TC. Drag of the vehicle. How wide the tires are.

 

On a side note i was told not to decelerate to quickly with a gear of 456 /488 as can do damage!True i don't know just what i heard from a fellow racer. I have never used those gears.

 

Three factors:
• Displacement
• Compression ratio
• Gearing

Displacement and CR determine the resistance of the engine to turning with a closed throttle, and gear ratio determines the amount of that resistance applied to the rear wheels over a given interval.

Obviously, how tightly connected the wheels are to the engine will matter as well, so a fluid-coupled transmission will pass less force through than a friction clutch.

- Eric

 

And for the 76 and later cars... a headwind. Oh wait that affected acceleration...

 

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Tailwind and steepness of the road grade

 

I forgot about CR. Good point.

 

Great info guys, thanks!

 

You're welcome! As they say, we're full of it.

- Eric