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Purely mechanical does not mean failure free. I've had the throttle linkage stick such that the spring was insufficient to drive the throttle back when I remov

by gvb 13y ago

Purely mechanical does not mean failure free. I've had the throttle linkage stick such that the spring was insufficient to drive the throttle back when I removed my foot from the gas. Fortunately, the ignition key truly disabled the ignition (hard-wired). The thing you had to be REALLY careful of was to not twist the key back so far as to engage the anti-theft steering lock mechanism ('70s and newer?).

WalterBright 13y ago
I've had mechanical throttles get stuck, too. But it wasn't an issue as I would hook my foot under the pedal and pull it up, or just turn the key off. Or push in the clutch. Or shift to neutral. Or step hard on the brake (the brake is stronger than the engine). My car also has a separate switch for the fuel pump, which can be turned off. The point is there being multiple independent ways to stop the car. Running everything through the same central computer makes for a completely unsafe system.
drbawb 13y ago
I've had a similar "total clutch failure" before. 1993 Mustang's have a plastic ratcheting mechanism that picks up slack on their [very heavy] clutch cables. The teeth on the plastic ratchets eventually wear out (duh....) If you're FORD, you design it so that this piece fails catastrophically, releasing all tension on the clutch cable. (Instead of, say, hitting a bump-stop that keeps some minimum amount of tension on the clutch cable.) No tension on the clutch cable = no clutch. No clutch on the OEM T5 w/ a stock-spec clutch = good luck with the next downshift. (For anyone interested: firewall adjuster + aluminum clutch quadrant = sweet deal.) --- However I'd still argue the purely mechanical systems are _objectively better_ in that they lend themselves to preventative maintenance. Had I thought to look: I would've seen the _very_ worn teeth on my clutch quadrant. I knew the clutch cable was old, rusty, and starting to bind in the sleeve, which probably led to the wear of my clutch quadrant. As for a throttle cable: not only can I feel it binding in the pedal, but it's fairly easy to visually inspect a throttle cable or spring for faults, rust, etc. In addition mechanical fixes are all radically simpler. If my throttle is sticking, I lubricate the cable and replace the return spring. If your computer controlled throttle is sticking: you hope it's (A) an actual bug and not intended behavior, (B) a bug that the mfr. is aware about, (C) a bug that a patch is available for, (D) that the ECU flash can be applied free or inexpensively. Say you're an enterprising embedded electronics engineer and you wanted to fix it yourself? If you try to modify an automotive computer: you've just tampered with an emissions control device. Your car is no longer street legal in the United States. Purely mechanical systems by their very nature are perfectly transparent. Proprietary computer software is almost always a "black box." -- Due to federal regulations though: you have absolutely no legal way to repair or replace it on a street-driven vehicle. You are stuck with software you cannot see, understand, or control.
Spooky23 13y ago
I didn't mean to imply that. I've driven the same drive by wire car for several years, and I'm still around to tell the tale :) But consider that a good mechanic could figure out the failure in the analog world, and this Toyota issue has required deaths and 9-figure lawsuits to get close to an answer.

by gvb 13y ago

WalterBright 13y ago

I've had mechanical throttles get stuck, too. But it wasn't an issue as I would hook my foot under the pedal and pull it up, or just turn the key off. Or push in the clutch. Or shift to neutral. Or step hard on the brake (the brake is stronger than the engine). My car also has a separate switch for the fuel pump, which can be turned off. The point is there being multiple independent ways to stop the car. Running everything through the same central computer makes for a completely unsafe system.

drbawb 13y ago

I've had a similar "total clutch failure" before. 1993 Mustang's have a plastic ratcheting mechanism that picks up slack on their [very heavy] clutch cables. The teeth on the plastic ratchets eventually wear out (duh....) If you're FORD, you design it so that this piece fails catastrophically, releasing all tension on the clutch cable. (Instead of, say, hitting a bump-stop that keeps some minimum amount of tension on the clutch cable.) No tension on the clutch cable = no clutch. No clutch on the OEM T5 w/ a stock-spec clutch = good luck with the next downshift. (For anyone interested: firewall adjuster + aluminum clutch quadrant = sweet deal.) --- However I'd still argue the purely mechanical systems are _objectively better_ in that they lend themselves to preventative maintenance. Had I thought to look: I would've seen the _very_ worn teeth on my clutch quadrant. I knew the clutch cable was old, rusty, and starting to bind in the sleeve, which probably led to the wear of my clutch quadrant. As for a throttle cable: not only can I feel it binding in the pedal, but it's fairly easy to visually inspect a throttle cable or spring for faults, rust, etc. In addition mechanical fixes are all radically simpler. If my throttle is sticking, I lubricate the cable and replace the return spring. If your computer controlled throttle is sticking: you hope it's (A) an actual bug and not intended behavior, (B) a bug that the mfr. is aware about, (C) a bug that a patch is available for, (D) that the ECU flash can be applied free or inexpensively. Say you're an enterprising embedded electronics engineer and you wanted to fix it yourself? If you try to modify an automotive computer: you've just tampered with an emissions control device. Your car is no longer street legal in the United States. Purely mechanical systems by their very nature are perfectly transparent. Proprietary computer software is almost always a "black box." -- Due to federal regulations though: you have absolutely no legal way to repair or replace it on a street-driven vehicle. You are stuck with software you cannot see, understand, or control.

Spooky23 13y ago

I didn't mean to imply that. I've driven the same drive by wire car for several years, and I'm still around to tell the tale :) But consider that a good mechanic could figure out the failure in the analog world, and this Toyota issue has required deaths and 9-figure lawsuits to get close to an answer.