MANual talk: Engine braking

[rowd22]

staying in gear will make sure your wheels don't lock up

Although it does reduce the chances of your wheels locking up, it will not stop them doing so, especially in wet/oily conditions.

 

[narf]

ABS makes sure the wheels don't lock up?




Oh, and if Zesty's car is too light... shouldn't the effect of engine braking be even greater?

 

[rowd22]

I agree with narf, lighter cars are more sensitive to engine braking

 

[equiraptor]

ABS makes sure the wheels don't lock up?

Right, ABS is what stops wheels from locking up under braking. Engine braking can actually cause the wheels to lose traction, depending on the conditions and how it's done.

I agree with narf, lighter cars are more sensitive to engine braking

"Engine braking" is also called "compression braking". Cars with greater compression are more sensitive to more engine braking - a lighter car with low compression will likely exhibit less engine braking than a heavier car with high compression.

If your vehicle isn't engine braking well at high RPM, it may either not have high compression (in its design) or it may have lost some compression over the years. Lost compression is likely a result of the piston seals wearing (or not being set properly) and will result in a loss of power, as well as compression braking.

 

[narf]

Engine braking can actually cause the wheels to lose traction, depending on the conditions and how it's done.

Bad downshifts can make the wheels spin slower than the car speed would suggest, indeed - that's what the MSR is for in my Octavia :lol: I wouldn't call that locking up though.
Enginge braking while in gear should not, unless on polished ice.

 

[equiraptor]

I did say "lose traction," not "lock up." The drive tires actually won't lock up if the transmission, etc. is properly engaged and the engine is running - turning engine requires turning tires or slip somewhere in the system. Polished ice isn't needed for engine braking to cause the tires to lose traction. Generally it's a sideways slide (from the rear tires in RWD) rather than a lock up, but it's still a loss of traction.

 

[Night_Hawk]

I usually do the coasting with the regular brakes, maybe a couple rev matched downshifts here or there if I'm bored. I think I have a pretty good idea of what the clutch goes through in different situations.

The way I look at it, The brakes are supposed to stop the car so that's how I use them. As someone mentioned before if engine braking was the "right" way of doing things wouldn't automatic cars have extra tough brake systems?

I don't really have any racing experience but I'll just guess both techniques are used at the same time to get the most braking force possible in that situation.

 

[Twerp128]

Depends, but typically it's good form to let the brakes do the work on the track.

 

[narf]

get the most braking force possible in that situation.

Braking performance is limited by tyres, not the brakes. Adding the engine doesn't make you stop faster, your pads/discs can generate massively more friction on their own.

 

[equiraptor]

Braking performance is limited by tyres, not the brakes. Adding the engine doesn't make you stop faster, your pads/discs can generate massively more friction on their own.

*nod* This. When I use "compression braking" on the track, I'm not using it in the place of the brakes or to assist the brakes. I'm using it to cause weight transfer to the front so that the rear will slide. The goal isn't to slow the car efficiently, but rather to cause slip. The compression braking results in some slowing, which causes the weight transfer, which causes the slip I need. I'm actually using compression braking instead of the actual brake system because the compression braking is so weak compared to the brakes - I want just a slight slow as weight transfer is caused, not actual braking.

 

[GRtak]

If you talk about your heel and toe technique, some peeps are going to have a crisis!

 

[Zesty]

ABS makes sure the wheels don't lock up? Oh, and if Zesty's car is too light... shouldn't the effect of engine braking be even greater?

Bah, I worded my post completely wrong. I meant that the lightness means my brakes have an easier job of slowing my car down without needing to engine brake, but I tend to brake and downshift simultaneously because that's the way I was taught and habits are hard to break! I think having ABS does reduce the chance of the wheels locking up, which my car does have. I have tried rev-matching on downshifts for fun before, but TBH I'm not very good at it, and there's really no need for it under normal driving conditions. I'm sure if I use engine breaking more, my car would be slowed down just as quickly, but I'd prefer to be replacing brake pads rather than a clutch.

EDIT: I could just be that I trust my brakes to stop my car when they need to, after I've been sitting in my mother's heavier automatic Peugeot with no ABS and shitty worn brakes that are well overdue for an overhaul. Seriously, that thing scares me....

 

[Polygon]

For normal driving ABS is great in an emergency situation, as long as it works. If you know how to drive it's merely a annoyance.

 

[Zesty]

I never thought much about the effectiveness of ABS brakes until they saved me from sliding underneath the back tray of a small truck when it pulled out right in front of me on a slick, oily, freshly rained on road while I was doing 70 km/h, not long after I bought my car just over two years ago. I always look back at that thinking, 'Now if I'd been in my mum's car....'

At least that wasn't my fault, one moment I'm cruising along, the next this truck came out of a concealed driveway without even looking (the ass was on his phone, in fact, and I couldn't see that there was anything about to come out onto the road). I missed rear-ending him by centimeters, and all I got out of the retard when he realised he'd just 'appeared' in front of me was a 'sorry' sort of shrug.

 

[brydie76]

I brake and downshift at the same time, just because often you will start braking only to have to set off again immediately. Also that being how I was taught.

I also never put my car in neutral at stop lights- push the clutch in and leave it in 1st (same with my parents) and I will feather the clutch occasionally (less than 10 seconds at a time I would hope, and not very often!!!!) if I know I am setting off quickly again (eg stop on a hill and the lights ahead have just gone green- doing a hill start properly would slow up traffic behind me). And doing all of that stuff for 16 years and 176 000 kms between me and my parents, we still have the original clutch on my Suzuki. Touch wood!

 

[TC]

I'm curious about something. My Honda is the first high revving manual car I've owned and it's taken me quite a long time to get use to it. All my other manual cars made most of their power lower in the rev range, so getting off the line is easy enough. But with the SI I have to give it some revs when taking off from a stop.

Anyway, my question is do high revving motors go through clutches faster than cars that make their power at low revs?

 

[rowd22]

I dont have the answer, but my Alfa is also very high revving (Boxer engine) - all the torque is above 3000rpm

It could be related, but every wrecked 'Sud ive dismantled has had worn out clutch fingers. Must be an Alfa foible :lol:

 

[rustyknife]

I'm curious about something. My Honda is the first high revving manual car I've owned and it's taken me quite a long time to get use to it. All my other manual cars made most of their power lower in the rev range, so getting off the line is easy enough. But with the SI I have to give it some revs when taking off from a stop.

Anyway, my question is do high revving motors go through clutches faster than cars that make their power at low revs?

I'm guessing that because the engines are less torquey they can install a clutch made of a material that generates less friction. This way the clutch will last longer? Could be completely wrong.

 

[Polygon]

Anyway, my question is do high revving motors go through clutches faster than cars that make their power at low revs?

The simple answer is no.

 

[argatoga]

When I first got my MG I stalled it for awhile. The thing needs to be rev'ed quite high. For those of you not in the know, it doesn't have the stock engine in it.


//To be honest right now it has no engine in it.