"Rolling" Speed

manga_blue · Postby **manga_blue** » Mon Oct 28, 2013 9:18 pm

AntHarmer wrote: The reason I mentioned the safety factor in the OP is because I wanted people to discuss the speed at which cars roll in neutral not whether it was safe to do so. Didn't work too well did it?

It's completely typical.
The golden rule of forums is that once you start a topic you no longer have any control over it.

Silvia · Postby **Silvia** » Mon Oct 28, 2013 10:34 pm

A couple of points....and I like to coast in neutral
It is possible for the engine to stall leaving you without power steering and braking
When you re-engage gear it is possible to engage the wrong one causing a dangerous overrevving, gear crunch or jump forward..
I really should stop doing this if it is true in the MX5 that you would use less fuel than idling....
I was getting pleasure from neutral long downhill rolls and red traffic light approaches in the belief I was saving fuel
(and my fuel economy is well above average....)

taminga16 · Postby **taminga16** » Tue Oct 29, 2013 2:27 am

There is a "game" that American motorcyclists play called 'Canyon racing', where they find really steep hills and race down them in neutral. Lots of competitors get killed!
Sorry to move off topic, has the OP check for brake drag yet?
Greg.

davekmoore · Postby **davekmoore** » Tue Oct 29, 2013 7:37 am

The body shell of the NA was all-steel with a light-weight aluminium hood. Without options, the NA weighed only 2,150 lb (980 kg). Drag coefficient was indicated as 0.38. Suspension was an independent double wishbone on all four wheels, with an anti-roll bar at the front and rear.

Maybe all MX5s should have a wing to get down to Magpie's to 0.29?

Blade_Hunter · Postby **Blade_Hunter** » Tue Oct 29, 2013 8:35 am

Silvia wrote:I was getting pleasure from neutral long downhill rolls and red traffic light approaches in the belief I was saving fuel (and my fuel economy is well above average....)

Just did some research, it appears it is true

http://www.mpgtips.co.uk/faq/if-i-freew ... save-fuel/

Magpie · Postby **Magpie** » Tue Oct 29, 2013 8:42 am

davekmoore wrote:Maybe all MX5s should have a wing to get down to Magpie's to 0.29?

It has had other aero mods, I will do some testing on a stock NA6 that I have at home to confirm the factory figures, however there are a lot of other factors like tyre pressures, road surface etc that will afect the rolling resistance. I'm not a fan of using values that have not been verified and wikipedia is not always reliable.

Now I have to repeat all the testing once I have the new engine in, that will be fun

AntHarmer · Postby **AntHarmer** » Tue Oct 29, 2013 11:11 am

taminga16 wrote:Sorry to move off topic, has the OP check for brake drag yet?
Greg.

I have had the car up on axle stands this morning. Spinning any wheel allows it to spin freely and there is no rubbing noise when doing so. It doesn't "appear" that there is any drag but I am sure there are more accurate ways to tell. Do you have any suggestions?