AO

Jeff-

Here are some pics to show you what to look for. In this first image, this is the section that comes out of the firewall (I've got it backwards - the left section is what sticks out).



Here's a better pic showing what to pull forward. My finger is pointing to where my cable was frayed.


Not much else to show. Good luck.

928SS

nice story and post. gotta print it out for when I get caught speeding and go to court, lol

can you even tell if the throttle is stuck open on a toyota?

AO

Dunno, but I could on my SC'd GT! Things get close in a real hurry!

ew928

On the GT, the brake has to fail. The clutch hydraulics has to fail. The gear shift to transmission mechanical link has to fail. I think that's about it before you're in real trouble.

pcar928fan

I have heard the number 1400... that is how many HP the S4 brakes are worth...roughly. The point being for an engine to overcome the brakes that engine would need 1400 HP! I don't know of any 928's even close to that and few with even half that! In fact maybe NONE have even half that at the wheels...

I need to check those things on my '94 GTS... I had a strange throttle sticking a few weeks ago. The cable has now become disconnected from the back of the pedal even...arrrgh!

928SS

I'd guess a lot less than that.

My stroker will break the rear loose at will, even w/the parking brake pulled up tight and brakes engaged. and if the brakes get hot, like on a track and you have fairly sticky rubber - forget about it. you can easily overpower your stock S3 brakes in a few laps.

thats why I upgraded to 993 stuff in the front, and S4/GTS for the rear. helps a lot, but I can still overpower the rear brakes at will.

maybe inspecting and lubing the cable from time to time would be cool? I'd guess you might find it's stretching before it finally frays and jams.

U might even find some lost power if you find it did stretch, cause you won't be hitting the stops on the TB or the WOT switch

pcar928fan

Rob, I disagree with you in part. The "rating" is NOT for already heated up brakes and YES JUST ABOUT ANY rear wheel drive car can do a break stand. From a stop try and get the car to roll the front tires with the break applied... not gonna happen! You might get the TIRES to slide if the rears are very sticky and the fronts are very slick, but I doubt you would even be able to do that.

928SS

true, the fronts will hold when powerbraking.

never tried full brake and throttle at speed w/my new setup. could be U tube material - and require a trip to the mechanic, tire shop, etc, lol...

but IIRC, the police officer that got killed when his pedal stuck, fried his brakes with just a toyota.

problem is, at speed they are fairly warm already. so unless you can manage to lock them up fast, they'l just super heat and fade in a flash, so to speak... and with ABS, I suspect locking them enough to not super heat may not even be possible.

pcar928fan

Clearly we are not talking about the same thing... the power of the brakes vs. if they overheat are two different problems... Once they are overheated you are out of luck. If you are also not smart enough to bump the car that is running away in to "N" then you probably should not be driving...

928SS

not sure what U ment by 1400 hp holding power then. if it is in a lab under ideal conditions, it's kinda useless from a practical standpoint, no?

some new cars have trans lockouts that prevent shifting at speed. combine that w/a push button that needs to be held for what probably seems like an eternity under out of control WOT, and I think it's easy to see how something bad could happen, even with an above average driver.

at least our retro 928's don't have those issues

jcorenman

James, I think it is more complicated than that. The wreck in San Diego (Mark Saylor and family) was a loaner Lexus ES-350 with floormats from a different model. Toyota's accelerator pedals are top-hinged, and can jam on even a relatively small obstruction on the floor (the bottom of the pedal was found fused to the mat). That car also had a push-button start, no key-- and required a full 3-second push to kill the engine when driving (Saylor's own Lexus had a conventional key).

And I believe that Lexus also has a sequential-shift mode for the gearshift, with a separate fore/aft gate for upshift/downshift. Once you move the lever sideways into that gate, you cannot simply bump it forward into neutral-- it needs to go sideways first, then forward. It won't even downshift if that would put the rev's too high for the lower gear.

The ES-350 is close to 300hp, but I am sure that it had the usual cheesy brakes. Remember that brake-assist runs on vacuum which goes away pretty quick at WOT, a couple of pumps is all you get. Braking and WOT don't work well together-- which is why a lot of cars with electronic throttles have an interlock in the ECU to kill the throttle when the brakes are applied.

As for the driver, he was a 20-year-veteran CHP state-patrol officer, I've got to believe that he was well-trained and pretty savvy with respect to cars. It was a tragedy that didn't need to happen.

The problem, in my mind, is the lack of standardization in how basic things work-- like starting and stopping the engine, shifting gears, etc. Keys, or something similar, which turn-to-start and un-turn-to-stop seem really important. Steering wheels should not lock until the key is physically removed from the lock (as you've noticed on the 928). Accelerators should be bottom-hinged, or have gobs of clearance- sticking an aftermarket floor mat under/over/around an accelerator should not jam it.

And if the driver puts on the brakes while the ECU is getting a WOT signal from the accelerator then override the accelerator-- if for no other reason than to get some engine vacuum to run the brakes. And of course brakes ought to be the limiting factor for HP.

We are truly blessed to be able to own and drive these cars. They were engineered to a level of detail that seems hard to find these days.

[/RANT]

pcar928fan

Totally agree it was a tragedy that should not have happened... I think you give to much credit to law enforcement as car guys. Maybe he was, maybe he was not. You would also probably think that most law enforcement types are gun guys... I can probably out shoot most of them though! Many don't know anything about guns other than the basics and a bit more about their own carry weapon. So just be careful when you generalize...does not always apply.

My point didn't really have anything to do w/ the accident...only that brakes are more powerful than engines. Even crappy brakes. As you noted at full throttle the vacuum assist will go away quickly and leave you dead in the water that may well be what happened to this car. I don't think I have ever been in a car where the brakes could not (under normal conditions) stall the car. Of course performance cars have brakes that are tested and tested some more to minimize fade and maximize stopping power...probably not so much in a Toyota/Lexus.

ew928

How often had you had a car go WOT at 70-80mph out of the blue and try to stop the car with the brakes? And how long does it take the brain to realize that the car is going to WOT and not coming back down before one jams on the brakes with fading vacuum boost.

I hope I don't have to try that. Ever.
I've tried the 928 with no vacuum brake boost. Wasn't fun.

dprantl

The vacuum in the booster will not fade unless you actually press the brakes. The check valve is there just for situations like that. Damn, I want to try this but really don't want to subject my car to that kind of abuse.

Dan
'91 928GT S/C 475hp/460lb.ft

jeff spahn

How about that guy that jumps the 928's down south somewhere. Let him beat the **** out of a 928 this way and see what happens.