could someone define?

[jonchai]

I was reading a magazine and one of the topics was learning how to heel-toe and the benefits of getting it right!
One of the benefits was preventing a HYDRAULIC LOCK-UP. What is this and why does it happen?
i was doing this while on the track and it certainly helped but could someone explain what a hydraulic lock-up is?

[oldcorollas]

what they mean is,

when you change down and let off the clutch, the engine has to revved up by the drivetrain. and this imparts a braking force to the rear wheels (since the engine doesn't want to speed up with no throttle), and if you let off clutch too quickly, it causes the wheels to slow down to less than the speed of the car. the wheels don't stop, they will only go to the speed determined by the engine, but they may lose traction.

in trucks, because they have no throttle, they have "compression braking" but that is different.

sounds like they just used whatever terms took their fancy at the time?

[Draven]

as stu said. This is particularly a problem when you're in a car with the brake bias set up well (not like factory cars, where there is a BIG front bias - safe, but not optimal). When you're braking and at the threshhold of locking up (as you should be when approaching a corner on a track), if you drop it down a gear without a heel-toe that braking force to the rear wheels will be enough to lose traction in the arse, which is a really bad thing when your car is already on the limit, and possibly turning

[jonchai]

Oh ok....i thought this was something to do with the engine. i was doing the heel-toe with my Celica (fwd) and it really helped with both entering a corner in the right gear, but also, was much easier to slip into gear.
but i still wonder why they call it a 'hydraulic lock-up' and not just....preventing a lock-up! which would really simplify the thing.

[Draven]

it's much easier to slip into gear because your engine is already going at the right speed for the tailshaft (or drive shafts in fwd). The principle of my description is the same for a FWD, but instead of rear lock-up and your arse wiggling, you'll get front lock-up, and happily understeer off the track

[oldcorollas]

it is to do with the engine...

"Engine braking lockup"

bumping up revs will SAVE your synchros.

i think they were just trying to be fancy and give it a technical name instead of engine braking lockup, or whatever

[jonchai]

i think they were just trying to be fancy and give it a technical name instead of engine braking lockup, or whatever

Agreed...bloody High Performance Imports

Draven: I only ran off the track twice and yes...one was fwd related..the other was distraction

[kingmick]

prob a case of another jorno that knows nothing about what he is writing!

compression lockup is simple the engine compression being stronger that the grip of the tires, happens more on RWD as they unload the rear{wait transfers to front} tires under hard braking. you blip the throttle to mate engine speed to tire speed to reduce the chance of compress lockup!

HYDRAULICED is when water gets into the piston chamber and as water isnt very compressable it punches a hole threw the piston!
lmao HYDRAULIC lock up would be locking up the brakes idiot jorno! or when it locks up because of water in the chamber right before it bends a rod and punches a hole in the piston.but dont worry this will only happen once, while your doing laps. thn you get towed back to the pits!lol

can you tell i hold automotive jorno's in high regard! if they actually new what they where talking about it would make there job easyer and the information they give first hand!

[kingmick]

practicing pedal dancing in traffic isnt recommended!lol

[love ke70]

lol, like kingmick said (god bless him ) dont try it in traffic, coz its real embarassing when your still doing the blip and you lift the clutch i got very good at not doing that after a little while.
http://bbs.scoobynet.co.uk/archive/i...t484903p1.html
have a read of this, very interesting with a couple of vids towards the end and gives you some detailed descriptions of it

[AE86slut]

Probably just typed "hydraulic" instead of 'compression' I dare say. Automotive journalists are human after all!

[crowncustom]

It used to be called a compression lock up.Caused by dropping the clutch while downshifting usually at high revs.
Cheers Brett.

[kingmick]

It used to be called a compression lock up.Caused by dropping the clutch while downshifting usually at high revs.
Cheers Brett.

so they call it HYDRAULIC LOCK-UP now? is that what you mean?

dosnt make sense? its not a hydraulic action?
i have never heard it called that, you learn something new everyday

[crowncustom]

You sure do and I've been in the car game for 20+yrs and never ever heard it called "Hydraulic Lockup".Oh well shit happens
Cheers Brett.

[jonchai]

"Traction Loss" is still preferable but a lock-up would be good for initiating a drift though yeah?