Downshifting?

[ivo316]

ok, sorry, I'm just old, carbs did have the bypass, I am a pre-fuel injection guy :(

[nando]

OK, but when you downshift you have better control of the car, the best way to prevent your rear end from going "loose" is downshifting, but youw don't HAVE to do it all the time, but if you are driving fast or close to the limit it's mandatory, your drivetrain is a lot cheaper than loosing it on a curve. The point of downshifting is to have the engine on the correct RPM range to have the right amount of power to get you safely through a curve ;)

About the fuel issue, remember carbs and fuel injection systems have a bypass that will still let fuel go into your chambers when you are downshifting, even if the throttle valve is closed, I'm not that familiar with motronic, I can't believe that any system cuts off the fuel completely, and if it does, it shouldn't.

there can't be any fuel going to the bypass if the injectors are shut off. and that's exactly what motronic does when you close the throttle... we've been over this a hundred times now.

[ivo316]

OK, but when you downshift you have better control of the car, the best way to prevent your rear end from going "loose" is downshifting, but youw don't HAVE to do it all the time, but if you are driving fast or close to the limit it's mandatory, your drivetrain is a lot cheaper than loosing it on a curve. The point of downshifting is to have the engine on the correct RPM range to have the right amount of power to get you safely through a curve ;)

About the fuel issue, remember carbs and fuel injection systems have a bypass that will still let fuel go into your chambers when you are downshifting, even if the throttle valve is closed, I'm not that familiar with motronic, I can't believe that any system cuts off the fuel completely, and if it does, it shouldn't.

[markseven]

The motronic system cuts fuel off if you have the throttle closed no matter what RPM you are at over 1000. So coasting at 3000rpm down to 1500, then popping in into another gear lower and watching the tach climb back up to 2500 will not use more gas.



No kidding, do we just have a bunch of retard drivers or something? I missed a shift ONE time in my e28, ever, and it was because as I was shifting from 2nd to 3rd, my shifter boot decided to come out of the hole and I mis-timed my shift because I looked down and thought "WTF?"

I was thinking about this thread a week ago...

Agreed that fuel is cut off when the throttle is closed (I assume the ECU cuts spark as well). Why is there still an audible exhaust note, a burble that sounds as though combustion is still occurring? Cylinder compression alone can't account for the exhaust note, can it?

[Mr.SWISS]

Sometimes, sometimes r3vmatch, it's just a damn eta. The i is a slushy :curse:

[euroshark]

The motronic system cuts fuel off if you have the throttle closed no matter what RPM you are at over 1000. So coasting at 3000rpm down to 1500, then popping in into another gear lower and watching the tach climb back up to 2500 will not use more gas.

How often do you guys miss shifts? I do it maybe once every 6months to a year, and thats if I'm distracted and its just kind of a "Doh!" moment.

No kidding, do we just have a bunch of retard drivers or something? I missed a shift ONE time in my e28, ever, and it was because as I was shifting from 2nd to 3rd, my shifter boot decided to come out of the hole and I mis-timed my shift because I looked down and thought "WTF?"

[backtrail69]

I do whatever I feel like... :P I can rev match, heel-toe, double clutch, clutchless shift etc etc.. :D

[MikeE30325i]

well after driving the car regularly for awhile i now downshift regularly and pretty well. i can stil get better, but i am not doing it so bad that i will break something.

[Gleb]

When BMW or any company makes a car with a manual tranny, they take into account 90% of people out there that don't know how to drive, so longer clutch pedal travel is needed. For everyone else clutch stop is a very good idea (I got mine from UUC, but yes, you can make one for just a few bucks).

Rev matching and heel and toeing while downshifting is 100% better and safer than not.

When driving around town I rarely use 4th gear, If you keep your eyes up, you will anticipate stops, lights, traffic etc... If I think that I have to slow down/stop for any of the above reasons, this is what I do:

If just slowing down, I always downshift with a rev match to be in proper gear if I suddenly need to accelerate.

If coming to a full stop, I heel and toe downshift through every gear down to 2nd, when I am slow enough in 2nd gear while braking, I will guide the shifter toward 1st without engaging, once your car slows down to almost walking pace, the shifter will pop into 1st almost by itself. Unless it's a vvveeerrryyy long stop, I will keep my foot in, yes it will cause some very minor wear on the throw out bearing, but I am always in control.
I have an excellent video on the subject, but have no idea how to post it, if someone wants to PM me with their email, I will be happy to share, maybe one of you guys can post it here.

[Propwash]

uh, no, everything on my car is new, and if it went bad I'd replace it, I wouldn't screw around trying to pump the pedal. and even IF I was forced to do so, I could unscrew the clutch stop in about 5 seconds!

Wow, EVERYTHING is new....props, but for everying else living in the real world that have failures and mechanical break downs because they hav'nt got around to replacing EVERYTHING on their cars, some day you will lose a slave cylinder suddenly, and at that point you will need to pump the clutch to get some pressure.
I'm just asking, why bother when you can regulate the pedal with your foot?

[luvin my 325es]

any idea what size nuts and washers and bolts u need to make these clutch stops??

I unscrewed the old one and used it to match up the new bolt.
I think it was 3/8 x 2in. long carriage bolt, 17mm nut and lock washer to fit.
I put a pad made for the feet of furniture on the head of the carriage
bolt to eliminate the metal to metal clicking sound. Very cheap and easy.

I feel like rev-match down shifting in the long run will cause more problems than it will prevent. flexing the guibo and other rubber parts in the opposite direction they are used to flexing will wear them out quicker.
Think about it: If you are trying to tear any type of material it is much easier if you loosen it up by bending it back and forth in opposite directions, not by continually putting preesure on it in one direction.
But just IMO and I am no mechanic.

[nando]

Have you ever had a slave cylinder go or anything like that? Where you have to pump for all your worth and smash the pedal to the floor to get into gear?

uh, no, everything on my car is new, and if it went bad I'd replace it, I wouldn't screw around trying to pump the pedal. and even IF I was forced to do so, I could unscrew the clutch stop in about 5 seconds!

[Propwash]

Have you ever had a slave cylinder go or anything like that? Where you have to pump for all your worth and smash the pedal to the floor to get into gear?

[nando]

Clutch stops are a waste of time. What happens when you NEED to push the clutch in all the way? And why cant you just modulate the throw with your FOOT! Do you really need to stop the pedal? I think they're a waste of time to install on anything other that a full out race car with a hydro clutch that will be damaged or prematurly (sp?) worn if the clutch is disengauged all the way.

huh? why would I ever need to press the clutch all the way to the floor? that's like 2" of travel that's completely uneccesary. and it's not like I spent a lot of money on it (under $5).

[Propwash]

Clutch stops are a waste of time. What happens when you NEED to push the clutch in all the way? And why cant you just modulate the throw with your FOOT! Do you really need to stop the pedal? I think they're a waste of time to install on anything other that a full out race car with a hydro clutch that will be damaged or prematurly (sp?) worn if the clutch is disengauged all the way.