Braking downshift and rear tires lockup

[MR2turbo4evr]

Holy cow!! If you keep driving like this you'll wear out your synchros, clutch, engine mounts, tires, and who knows what else. Stop that immediately! Read Porsche's post. Then read it again. Then try to apply it to your driving.

[mangostick]

If the transmission was designed to be the primary force in slowing the car it would be gigantic like ones found in big trucks. There's a reason your car has brakes man, use them.

Use the drivetrain togo, the BRAKES to slow.

Why coming into a 90* turn so hot anyway? You've got to almost stop to take the corner, use more brake coming off the highway to scrub speed off and downshift only when your speed matches the lower gear.

Everything Porsche said is dead on.. follow it and you'll have a much more pleasant experience as well as a car that lives to tell the tale.

[Vic_RSA]

Originally Posted by dorifuto

What you doing is a drift technique called shift lock. Try downshifting at a lower rpm.

Which is torture on your drivetrain. Mechanical sympathy is imperative to your car lasting to the end of its warranty period. This video taught me a lot:

[ame="http://www.youtube.com/watch?v=qbwu83MO3ts"]The Drift Bible by The Drift King - Best Motoring International Vol. 09 - YouTube[/ame]

[bestwheelbase]

Also worth noting -- you can do a rev-matched downshift without heel & toe action. More like just toe action. To gradually slow down you can do just the toe part. Simply blip the throttle, downshift one gear, and let engine braking slow the car. Once the revs falls and it's comfortable to downshift into the next gear, do it. Sometimes heel and toe driving is suited to more purposeful inputs rather than casual driving. But there's still a benefit to rev-matched downshifts because they are smoother, safer, keeping you better in control of the vehicle as a whole. Really they are the only way to downshift correctly, anywhere, ever.

Learning this stuff takes time. Be patient and reward yourself with ice cream often. (It'll give the clutch time to cool off, mr. clutchdraggerdownunder! )

[JDM-dono]

I should probably make myself clear before everyone says I'm destroying the car by shifting to 2nd at 80kmh or 50mph...or before I'm notorious as mr.clutchdraggerdownunder

What's happening is I'm travelling at50mph but as I'm going into the slip lane I am braking to the the appropriate speed of the turn about 30kmh or 18.6mph. Once I get to around 20mph I downshift to 2nd and that's when the chirp (lockup) occurs. I'm not shifting to 2nd at 50mph lol. I'm shifting to 2nd at 18mph just before the turn.

I should've been more clearer in my opening post.

[BoostinIX]

Then just rev match and let it out easier.

[Pete156]

JDM

Check the reflexes in your left foot, or have your doctor do it.

Something about your story/scenario is not making sense, unless you are jack-hammering your clutch pedal and not reading your gauges correctly. Downshifting to 2nd at ~ 18 mph will not lock or spin the rear wheels unless you are on ice.

[sierra]

Originally Posted by JDM-dono

I should probably make myself clear before everyone says I'm destroying the car by shifting to 2nd at 80kmh or 50mph...or before I'm notorious as mr.clutchdraggerdownunder

What's happening is I'm travelling at50mph but as I'm going into the slip lane I am braking to the the appropriate speed of the turn about 30kmh or 18.6mph. Once I get to around 20mph I downshift to 2nd and that's when the chirp (lockup) occurs. I'm not shifting to 2nd at 50mph lol. I'm shifting to 2nd at 18mph just before the turn.

I should've been more clearer in my opening post.

Unless you're into the turn at 30kph when you drop the clutch it makes no sense that it's chirping the tyres? I would select 3rd just before the turn which will be more 'serene' for normal driving, better on fuel and able to quickly get you back up to whatever the speed limit might be.

For what it's worth I don't find braking exciting unless i'm stepping on it a bit.
What I do enjoy, if no traffic is following and time doesn't matter, is trying to judge when to start slowing for an intersection or turn from 110kph without using the brakes. It makes a difference to fuel consumption to ease down to say 80kph then back right off down to 60kph, into 4th and then 2nd just before you get there ready to use that saved up fuel for a good quick squirt through the gears back up to cruising speed.

[Jaylyons1]

You really shouldn't be locking up the rear tires even if you thew it in gear and didn't even touch the gas to match the revs. Sounds odd. I'd recommend learning to match revs though as it can make certain components last longer.

[mangostick]

If you can, get some vid of the scenario when you have a chance so we can see and hear what's going on. I think there's quite a bit lost in text here that we need to know to help you better.

[Markone]

How about you have your car in sports mode then break hard for the corner and then down shift the car will rev match automatically and you can then power out of the corner. All you need is a auto transmission on your BRZ!


Sent from Mark's iPad using Tapatalk HD

[LeeMaster]

You wanna learn how to heel toe shift without damaging your car? Go buy a G27 wheel and go buy a PS3 and GT5. Bingo! Thats how I learned it, now I can easily rev match without using my real car as the learning tool.

[JDM-dono]

Had a mate sit in the car to give me pointers. Turns out that I was releasing the clutch too quickly. When I was shifting from 3->2 there was a mismatch of engine speeds between the transmission and engine. When the clutch is suddenly engaged, one of these components (engine or transmission) has to play catch up so the rear tyres lock up or more accurately drag along the road.

[Porsche]

Originally Posted by JDM-dono

Had a mate sit in the car to give me pointers. Turns out that I was releasing the clutch too quickly.

See? What did I tell you?

When I was shifting from 3->2 there was a mismatch of engine speeds between the transmission and engine.

Yes.

When the clutch is suddenly engaged, one of these components (engine or transmission) has to play catch up…

Engine.

When you de-clutch, the revs drop towards idle speed of course. When you engage a gear, the rear wheels are now “driving” the input shaft and, thus, the clutch disk at the rpm determined by the road speed and gear ratio.

The clutch disk is spinning much faster than the flywheel which is connected to the engine. Abruptly clamping them together creates a shock and the slower one is suddenly dragged up to the same speed of the faster one.

so the rear tyres lock up or more accurately drag along the road.

Yes. Since the engine, via the flywheel, cannot speed up instantaneously to match the rear wheels, the drive wheels, rear tires here, are slowed dramatically and are literally dragged down the road, protesting loudly. The rear wheels are not actually locked up, they are skidding though, but it’s just easier to describe it that way since the dynamic effect is largely the same.

You’re very unlikely to crash doing this at 18 mph. Your tail end might twitch a bit, but if the car did start to go sideways on you, it would scrub off speed so fast that you’d be unlikely to loop it or hit anything.

ANY TIME you chirp the rear wheels under deceleration, you’ve done it wrong, mate.

At low speeds, this is just poor driving, "sloppy," you know, and hard on the machinery. At high speeds it can be dangerous and can even prove to be fatal in the ensuing crash.

It is difficult to cover all the details while writing a description, and I’m too lazy to do a thorough job of it. I can do better talking to you in person. I'm lazy, I tell you!

Are you getting a handle on this business, now?

And you youngsters out there who are reading and trying to learn on this forum… is this making sense to you, too?

Any questions?