Quote:
Originally Posted by J P Stein
You've got everything on that car of yours so I'll assume you have an adjustable proportional valve for the rear brakes.
|
Yes, dual master cylinders and adjustable prop valve.
Quote:
Originally Posted by J P Stein
Keep backing off the rear pressure till the rear brakes work in concert with the engine braking, mark the spot, then return it to the normal position when the AX is over.
|
The issue is I don't think it's possible to adjust the brakes to fully work in concert.
I think about it this way- the first 10%, say, of braking comes only from the engine, and thus is only on the rear wheels. So if you're maxed out in a corner and then lift the rears will be braking, the fronts won't, so the rears are overloaded and the car will try to spin. As braking Gs build when you actually use the brakes you can eventually adjust the bias to work with the motor, but at low braking Gs the motor is always going to be braking the rear wheels with a much higher % than the fronts.
As you suggest some of this is a good thing- the 911 generally doesn't want to tuck the nose, and this helps. But lower the gear and the more compression braking the motor has the more "tucking the nose" becomes "totally sideways" when you lift. I suspect my car with the GT3 motor has twice the compression braking of most 911s, and geared to 66 in 2nd it's running a short gear.
Effectively I think I need to cut engine braking in half to have it behave like a normal 911 on lift-throttle. Not sure that's practical, but I suspect it would be helpful...
Edit: I see F1 cars used to have a knob on the wheel to control engine braking (before it was banned). And some motorcycle ECUs make a big deal out of adjustable engine braking. Perhaps it's a bigger issue at higher power to weight ratios...