Should we even be downshifting at all? How much damage does it to our components?

How do you guys downshift if you do @ all?

I liked using the engine to slow down .. however .. now that I'm contemplating a flywheel ... with the lightened flywheel .. I don't think downshifting will be AS effective as it has been ...

Your thoughts?

 

Whats wrong with down shifting??? I do it all the time, everytime I turn a corner I down shift into second or third.

When down shifting just make sure you select the right gear for the speed you are going. Either modulate the clutch when down shifting into a turn or use the accelerator if down shifting for speed.

 

Usually the only times I downshift is if I need a sudden burst of speed on the highway or something otherwise if I wanna slow down I just use the breaks. I kind of look at it like Id rather pay $100 or whatever costs for new brakes every how many years then shell out $400 -$500 bucks for clutch and install. Even though the clutch should last a long long time there are many other things that can go wrong when you down shift like going into the wrong gear and the after effects of that can be such things as the tranny takes a toll!

My advice, only do it if you are totally comfortable with your car and the way it works. Otherwise get comfortable with it an know it inside and out then let the fun begin.

But man downshifting is fun!!

Just my $.02

 

Double-clutch your shifts on the 5-4, 5-3, and 4-3 shifts. You'll be amazed at how much easier the shifter goes into gear and how smooth the transition is. I still can't double-clutch into 2nd because the syncronizers are too beefy and stiff. It usually takes a little tug to go into the 2nd from 4th or 3rd.

The double-clutch:

Clutch in, move shifter into neutral, clutch out, clutch in, move shifter to lower gear, blip the throttle to match entering rpm, release the clutch fairly quickly. Done. If executed correctly you should barely feel the downshift. Double-clutching also helps out when trying to get into 1st from a slight roll.



Dave

 

i look at downshifting as one of the more "fun" aspects of driving a stick. i beleive that if done properly it will have no noticeable adverse affects on your engine/clutch.

to downshift properly, like someone mentioned, make sure you know which gear you want to go to. take a few minutes to go out on a highway and see where each gear winds out to (what speed) and try to remember this. it will help you know which gear you should be selecting. let's say you're on the parkway and want to go from 5th to 4th. push the clutch in and bring the shifter from 5th to 4th. while you're doing this with your right foot you want to "blip" the throttle... basically bringing your revs up. you'll get a feel for how much gas you have to give to get the revs to match the gear. a good starting point is if you are downshifting one gear (like 5th to 4th or 4th to 3rd) try to raise the revs about 1000 rpms. again, it takes practice and after you do it a few times you'll see exactly where the revs should be for a perfect downshift. after you blip the throttle let the clutch out and the engine speed should be properly matched... and off you go. notice that if you don't blip the throttle when you let the clutch out the engine has to speed up through the clutch and this i believe will definately put premature wear on your clutch so make sure you are raising those rpms.

for a good time hop on the parkway and shift from 5th to 3rd and then give it full gas.

 

Personally I think your all crazy!

Look at it this way, one of the hardest things you can do to a car is have the motor running with no load on it... Revving it with no load, ie the "blip" is even harder... You'll wear out you main bearings much faster. However, IT WILL TAKE YEARS and years, and years for this to make a difference... double clutching, downshifting, not downshifting, using the brakes hard, using the brakes light, trying not to turn the steering wheel as often to save your powersteering box (extreme example)... I mean when it all comes down to it the wear and tear is soooooooo minimal that its almost insignificant... If you were revving up to 5000rpm and dropping the clutch all the time, you'll wear it out faster yes, but cars these days take abuse very well... Moral here is that unless your doing something retarded ALL the time, just drive it and enjoy it... Don't worry about, oh, I have to make a mental note not to downshift to save my clucth.... Thats my rant, I'm all done now

Phoenix1911

 

press the clutch and switch to a lower gear...

 

but use common sense when doing it.

 

Rev-Match.

 

Can you explain why blipping the throttle with no engine load is worse than hitting the throttle with a load? I would think that with no load, the engine doesn't have to work as hard to get it to move faster, ie. less gas. Since it is using less gas, and air, the pressure building up in the cylinder after combustion is less and thus the forces acting on the cylinder walls by the piston are but a fraction of what they would be if you were to bring the engine up to the same speed with a load. I would also conjecture that bearing loads would be less simply due to less downward force on the piston. Given that the engin is working within its operating range, I don't see how blipping the engine could be noticably more damaging to it than idling. Or am I missing something here? The worst thing for the engine is just starting it up and unless you plan on not driving your car, this is a necessary evil. Someone please give me the technical low-down if I am mistaken.

 

double clutching makes it a lot easier, smoother and less harmful.

 

Idleing is bad for a few reasons. The most obvious is that oil pressure is VERY low as well as coolant flow is minimized. Also your plugs will get fouled because of the richer air/fuel mix. Engines are happyiest on the highway lots of cooling and high oil pressure.

But with regards to load. The pistons, rods, crank and bearings are all designed to work best under load. its hard to explain. The best example I've got is this. Throwing a football, or punching someone.

Pistons in an engine always go up and down the same distance and the same speed depending on the rpm. Try throwing a football say 20 times. Now (if you can) go through the motions again trying to match the same speed and effort you put into throwing the ball without actually having a ball in your hand 20 times... Your shoulder will hurt. Same goes for punching someone REALLY hard and missing. The bearings are like your shoulder, coupled with the fact that there is little oil pressure right before you "blip" the throttle, it wears the bearings more on one side... The engine is designed to handle a load. taxis are VERY well maintained (which is why you get 400K on 'em) but notorious for wearing out the bearings before any other part due to frequent maintenace and most importantly oil changes at 5000km... The old engines are pretty much bullet proof, but they idle a lot at the stands and the bearings are always worn on one side... If you look at a daily driven car you'll find the rings go before the bearings, and wear on the bearings is fairly equal all around...

Phoenix1911

 

press the gas more

 

WRONG! OIl pressure at idle is almost at max. PLENTY of oil flow avail.



Wrong! Again, at idle, the water pump is flowing plenty.



Wrong! Welcome to the wonderful world of modern computor controlled electronics and sequential fuel injection!



Of course it's hard to explain, BECAUSE IT'S COMPLETE NON-SENSE!



Uh taxis are maintained like crap. And it's because they are idling and are running most of the time, they can run for 400k. Great! You just contradicted yourself.

Please stop now because you are hurting yourself in the head.

 

Interesting read, but most of us aren't driving taxis and most of our extended idling is simply something we can't avoid whether it be sitting at a stoplight or sitting in traffic. As for blipping the throttle on a double-clutch, I don't see how it's any worse than normal driving. You've got to rev-match (ie blip) to make a smooth shift. When I say blip the throttle, I mean just that. The throttle is only stabbed for a second. It's not extended.

As for the bearings, the VQ uses a very beefy 4-bolt main which is signicantly better at dispersing bearing loads than the simple 2-bolt main used in run-of-the-mill cars.


Dave

 

I think your argument is a little flawed here. The reason your shoulder may be sore is because you are over extending it. You are exerting a huge amount of force which isn't absorbed by anything until you get to the point where your arm can't extend any further. The shoulder, as you say, is then required to exert a force capable of stopping your arm in a very short amount of time (F=m*a where a will be high die to short time period), unless someone wants to argue that you're arm is going to separate and fly away. That is why your shoulder may be sore. The engine equivalent would be revving your engine and then dumping the clutch forcing it to slow down very quickly. In this case, many engine components have a rotational momentum that must be taken up, again in a very short amount of time. I would admit that doing this isn't so hot for your car though it happens. I know I sometimes bring the clutch up to quickly and can feel a slight jerk as everything synchronizes.

As for everything else, well Jeff did a good job explaining that away.

 

short,sweet, and to the point.

in between clutch and gear tap gas to "rev-match"

Usually if going to a lower gear..(one gear lower) you only need to rev the engine 500RPMS higher than what the RPMS are currently at.

 

But again it brings us back to the beginning of the thread... Unless your doing something dumb all the time, just drive how you want... Car manufacturers have refined the motor, and most other moving parts to the point where changing driving styles (street driving of course) will produce VERY minimal differences in wear. With regards to my previous post. My hobby is rebuilding BB & SB Chevy engines for hot rods and drag cars. Nothing to serious, just something streetable. I'm a virgin to the EFI & ECU world, I was using mechanically tuned engines as examples, which was obviously the wrong thing As for revving under load (not sitting idling) it does wear out bearings, ask any old school mechanic, because piston X with no/very little load (explosion in combustion chamber) pulls on the crank when cylinder X is at TDC harder than if there was a force acting on it..

Phoenix1911