nakagusukumike Posted October 24, 2007 Share Posted October 24, 2007 Is there a technical term for this...? best thing I can think of is "clutch braking". Not engine braking. Say your decelerating from a high speed (and of course in a RWD or 4WD car). shift into 2nd gear and suddenly partially engage the clutch to use the engine (not reved up) resistance to slow the rear wheels down (without locking them obviously). Does anyone know what I'm talking about? It's obviously not good to do to your clutch at all. But it REALLY helps for quick deceleration and panic stops in a RWD car with a big engine and 2/3 plate clutch. What is the correct term for this? Disclaimer if you ruin your clutch or lock your wheels and crash Quote Link to comment Share on other sites More sharing options...
naviathan Posted October 24, 2007 Share Posted October 24, 2007 It's still engine braking as you're using the engine to slow down whether it's revving up or not. Quote Link to comment Share on other sites More sharing options...
nakagusukumike Posted October 24, 2007 Author Share Posted October 24, 2007 is it? I thought engine braking was the resistance of the engine rotating when you are off the gas and the engine revs down. This is using the pucking action of the clutch to act as a literall brake for the rear wheels. Quote Link to comment Share on other sites More sharing options...
naviathan Posted October 24, 2007 Share Posted October 24, 2007 Engine braking is using the slower rotating force of the engine to slow the vehicle. Using the clutch in that manner is still engine braking you're just not giving the engine time to rev up from the momentum of the drive train. It's a bad idea anyhow as you run a risk of over revving should your foot slip on the clutch or you release too far. Quote Link to comment Share on other sites More sharing options...
nakagusukumike Posted October 24, 2007 Author Share Posted October 24, 2007 Engine braking is using the slower rotating force of the engine to slow the vehicle. Using the clutch in that manner is still engine braking you're just not giving the engine time to rev up from the momentum of the drive train. It's a bad idea anyhow as you run a risk of over revving should your foot slip on the clutch or you release too far. it's a bad idea if you mess it up, yes. but correctly applied it gives more braking power than you might think if you haven't ever tried it. It's a bad idea driving a manual transmission if you mess it up. In practice I've seen this done on many skylines and Zs over here and the engine never gets about 2500 when doing so. From the wiki on engine braking, this is not engine braking. Quote Link to comment Share on other sites More sharing options...
nakagusukumike Posted October 24, 2007 Author Share Posted October 24, 2007 engine braking it is then. Wiki FTL! Quote Link to comment Share on other sites More sharing options...
JMortensen Posted October 24, 2007 Share Posted October 24, 2007 I would call it "ruining your clutch". That's a REALLY poor way to use the clutch. Put it in gear, let the clutch all the way out and let the engine decelerate the car. Preferably doing a heel/toe shift so that you don't use up any more clutch than you have to. What you're talking about is the slowing down version of holding yourself on a hill with the clutch halfway out. Very bad form. Not trying to insult you, but that's the truth. Quote Link to comment Share on other sites More sharing options...
BobbyZ Posted October 24, 2007 Share Posted October 24, 2007 How is this different from applying the emergency brake while you are driving? You are using the engine to slow down only the rear wheels of the car. Wouldn't it be better to just change the braking bias if you think the rear tires can handle more braking without breaking loose? Quote Link to comment Share on other sites More sharing options...
nakagusukumike Posted October 24, 2007 Author Share Posted October 24, 2007 I would call it "ruining your clutch". That's a REALLY poor way to use the clutch. Put it in gear, let the clutch all the way out and let the engine decelerate the car. Preferably doing a heel/toe shift so that you don't use up any more clutch than you have to. What you're talking about is the slowing down version of holding yourself on a hill with the clutch halfway out. Very bad form. Not trying to insult you, but that's the truth. believe me you're not insulting me. Obviously it's really bad for your clutch as I first stated. The people that I've seen doing this mostly run triple plate clutches to begin with. Changing the braking Bias is not a bad idea but doing it with the clutch lets you instantly control the ratio of front to rear brakes. If you get a feel for it and learn how to do it and aren't worried about your clutchs it works VERY well. If it didn't work as well as it does they wouldn't be doing it. Mechanically it seems like it would be the same thing as using the ebrake but in practice it's not. Think of the difference between using a coaster brake (pedal brake) on an old kids bike versus using a cantilever or V brake or disk brake. same thing is happening but one has a much higher level of control. Putting the car in gear and letting the clutch all the way out and letting the engine decelerate the car is not what the topic was. Didn't mean to open a can of worms and get into a debate on what's good or bad for your car or ask for a lesson on engine braking. If I was reading this and had never experience it I would post and say how bad it is and express concern as well. I'm with you guys, really. But it works VERY well and has actually saved me from an accident before. Don't knock it till you tried it (after having it properly demonstrated first). Quote Link to comment Share on other sites More sharing options...
Pop N Wood Posted October 27, 2007 Share Posted October 27, 2007 I have always heard it called compression braking. Leaving it in gear and using the engine to slow a vehicle is really not that uncommon. Truck drivers do it all the time. A number of engines are even fitted with compression releases to allow the engine to coast with the motor still in gear. I once had a dirt bike with a compression release. And the gravel trucks driving behind my house definitely use compression braking when rolling up to the traffic light. Flipping loud Quote Link to comment Share on other sites More sharing options...
savageskaterkid Posted October 27, 2007 Share Posted October 27, 2007 Jake-Brake? Quote Link to comment Share on other sites More sharing options...
G.I.jonas Posted October 27, 2007 Share Posted October 27, 2007 Jmortensen is right,you are basically doing a clutch slip in reverse,and regardless of what kind of clutch you use this is a bad thing,good clutches just hold power better it doesnt mean that they like being slipped better as well...cuz no clutch(or flywheel)likes that. Quote Link to comment Share on other sites More sharing options...
280zwitha383 Posted October 28, 2007 Share Posted October 28, 2007 I've been told it's hard on rod bolts, the sudden reverse torque thing... I've had to do it before in my auto. I figured if I killed the tranny or F'ed a rod bolt it would be better than totaling the whole car. (I was going WAY too fast and didn't notice everyone else was stopping when they should have been going at least 60). I kicked it down into 2nd and the back end locked up, I did a little skid thing and I'm sure the people in front of me had to go to the bathroom and clean their car seats but at least I didn't hit them... Quote Link to comment Share on other sites More sharing options...
m4xwellmurd3r Posted October 28, 2007 Share Posted October 28, 2007 ah, you shifted too low and the wheels locked up since the engine speed couldn't keep up with the tranny speed. Kinda like if you're in first gear, and you drive it all the way up to like 5k, then just let off suddenly. it'll chirp. I can't help but engine brake/heel toe a bit. it lets me use the brakes less, and if i REALLY need to stop faster, i've got all that extra brake left to use since the engine's doing most of the work. Quote Link to comment Share on other sites More sharing options...
JMortensen Posted October 28, 2007 Share Posted October 28, 2007 I don't think you guys are reading what Mike's friends are doing. They are engine braking, but instead of letting the clutch all the way out they only let it halfway, and in doing so let the clutch slip the whole time. This is a really bad idea, and using really good equipment (triple plate clutch) to do it doesn't make it a good idea. Mike says it's a great way to slow down fast. BS. There is NO way to slow down faster than using the BRAKES on the car. Half assed "clutch braking" with only the rear wheels does not work better than braking with both the front and the rear. Try coming to a stop with your ebrake from 60 mph a couple times and you'll see what I mean. The front brakes do MOST of the braking, and choosing to burn your expensive triple plate clutch in order to get some braking force on only the rear wheels is NEVER a good way to slow your car down. Quote Link to comment Share on other sites More sharing options...
Mr.INSANE Posted October 28, 2007 Share Posted October 28, 2007 I can lock up my rear wheels by braking. I don't need to slow down more than that Quote Link to comment Share on other sites More sharing options...
nakagusukumike Posted October 28, 2007 Author Share Posted October 28, 2007 I don't think you guys are reading what Mike's friends are doing. They are engine braking, but instead of letting the clutch all the way out they only let it halfway, and in doing so let the clutch slip the whole time. This is a really bad idea, and using really good equipment (triple plate clutch) to do it doesn't make it a good idea. Mike says it's a great way to slow down fast. BS. There is NO way to slow down faster than using the BRAKES on the car. Half assed "clutch braking" with only the rear wheels does not work better than braking with both the front and the rear. Try coming to a stop with your ebrake from 60 mph a couple times and you'll see what I mean. The front brakes do MOST of the braking, and choosing to burn your expensive triple plate clutch in order to get some braking force on only the rear wheels is NEVER a good way to slow your car down. it's not BS. they are not doing this as opposed to using the brakes. it's in addition to using the brakes. It's basically temporarily changing the bias. that's all. keep in mind the engine never gets above 2K or so. Yes it's bad. it's bad it's bad. it's bad it's bad it's bad. just wanted to know what it was called Quote Link to comment Share on other sites More sharing options...
JMortensen Posted October 29, 2007 Share Posted October 29, 2007 I'm going to try one more time, then I'm going to leave your friends to burn their clutches in stupidity and perpetuity. A properly balanced braking system will be set to lock the fronts just before the rears at max effort. That means the rears might be at 95% when the fronts are at 99%, and to then try to add more rear braking via the clutch at that point is a very bad idea. I would venture a guess to say that actually improving braking distances by doing this would be damn near impossible, while making them longer would be very easy. I can only think of two reasons to engine brake (the correct way, not the way your friends are doing it). The first is to be in the correct gear when you exit the corner. The second is to try to save the brakes. That's it. I think Danny Sullivan actually has a bit in the book Going Faster about not engine braking and how it improved his lap times. What your friends are doing is useless in improving braking. Challenge them to a test of braking with the car in neutral vs doing the clutch burn and measure it out and see for yourself. Quote Link to comment Share on other sites More sharing options...
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