Mountains, gliding and wearing out brake rotors and drums - Fuel Economy, Hypermiling, EcoModding News and Forum

blueflame · 05-30-2009, 07:28 PM

Had 2 new front tyres fitted which increased FE and comfort. Damn those old tyres!

However, the tyre guy showed me considerable wear which has occured on the front disks since I have been EOC down a mountain range almost every day for the last 6 months.

Now I'm gonna be engine braking a lot more when it comes to large downhills....

Incorrect hypermiling just cost me a lot of time and money!

The front disk rotors may need replacing soon.

Grrrr

Bicycle Bob · 05-30-2009, 07:31 PM

I used to always use engine braking, until someone mentioned the relative ease of doing brakes vs clutch work.

Frank Lee · 05-30-2009, 07:45 PM

Engine braking doesn't wear the clutch.

Bicycle Bob · 05-30-2009, 07:53 PM

it isn't the braking per se, it is shifting into those lower gears, especially with a conservative blip on the gas.

Junimrox · 05-31-2009, 06:25 PM

you may reduce clutch wear by revving up the engine while releasing the clutch. Since there is no load and its used only to match rpms the fuel comsumption is minimal and probably will cost you less than clutch wear and much less than brake wear... Also if your car cuts fuel when you are geared but not accelerating, its now wise to EOC and use brakes.

NeilBlanchard · 05-31-2009, 09:31 PM

Hi,

If you can downshift and use the engine to brake, then you use the same amount of fuel as EOC'ing and you get to not use the brakes. Best of both...

dcb · 05-31-2009, 09:46 PM

If blessed with mountains, I would turn off my injectors and engine brake (hold in the kill switch).

For reference, I did the rotors today, they were $18 apiece, but would still rather use the engine to control my decent and save the brakes for an emergency.

blueflame · 06-02-2009, 06:31 PM

Citroen AX rotors are much harder to find, 3 were crushed and melted recently and I should have grabbed a pair as there are none around here at the moment. Except for my complete and running other 2 AX's, maybe I should wreck/break/part one of them, probably worth more that way anyway, AND I have my rotors right here

Being carburetted I use gas when engine braking, ignition on or off.

Over the last 6 months hardly more than a couple of dollars gas MAXIMUM would have been used, during needed engine braking.

Better than worn rotors. I was penny pinching and look what happened.

bgd73 · 06-05-2009, 09:32 PM

Quote:

Originally Posted by blueflame

Citroen AX rotors are much harder to find, 3 were crushed and melted recently and I should have grabbed a pair as there are none around here at the moment. Except for my complete and running other 2 AX's, maybe I should wreck/break/part one of them, probably worth more that way anyway, AND I have my rotors right here

Being carburetted I use gas when engine braking, ignition on or off.

Over the last 6 months hardly more than a couple of dollars gas MAXIMUM would have been used, during needed engine braking.

Better than worn rotors. I was penny pinching and look what happened.

I am carbed, but do not notice gas, it would rather the pcv and suck on the engine base in a round about feed. In a way this is good, but the reason for good is too rare to keep it that way. Fuel injection has a thing called "air bypass" when engine braking, it is supposed to just let air in and not the fuel. I was just pondering using the uselss egr valve filtered to open air and let the high vacuum of letting off throttle open it..work like a charm and get it past the carbs venturi, carb would think it was idling

As myfuel is already in the hyper realm, this bypass would make it for anyone to keep acheiving. I know what engine brakes do to natural venturi, alot don't. the king of fuel air and its simple problems...

ShadeTreeMech · 06-07-2009, 10:15 AM

I would suspect that with the carb, having the throttle closed would reduce the amount of air coming in quite a bit, and so you wouldn't be using the same amount of fuel per rpm as you would if you were powering it to that rpm. The throttle plate is after the venturi, right?

Also, I wonder if you have an electric fuel pump, or the more likely manual fuel pump. If you were lucky enough to have the electric fuel pump, a on off switch for the pump would be nice; you'd only lose the gas in the carb's bowl, and refilling it wouldn't take but a second. But I suspect you'd have a manual fuel pump, which makes it a bit trickier...