Shifting Smoothly?

I've been a little frustrated lately as I've been driving stick for 4 months now and still sometimes have unsmooth shifts, particularly into 3rd and 4th. The transition isn't jerky or anything, but a lot of time there is a clunk from the rear upon releasing the clutch. Other times, it's perfectly smooth.

Now I'm pretty sure this has something to do with timing the clutch release - I think when I get the clunk it's because the revs are dropping too much. Some people just ride the clutch to smooth out the transition, but I don't think this is ideal. Really, you should be able to release the clutch quickly from any RPMs by making sure the revs match.

Here are a few observations:

-There is no drivetrain shock if I select neutral - and sort of "pre load" the next gear - a moment before depressing the clutch. However, this produces a sort of "crunchy" feeling through the shifter.

-Depressing the clutch halfway eliminates the drivetrain shock as well.

-Seems to be better when accelerating. There is more of a shock if I hold the RPMs.

-I can be perfectly smooth when just putting around the neighborhood, shifting at low RPMs. Only when the RPMs are high is there is a problem.

Car is a 1991 318is. Shifter throw is long (stock) and clutch engagement point is maybe 3/4 of the way off the floor. I feel like I'm always in a rush to shift and release the clutch, but I'm still too slow. I'm wondering if the long throw from 2nd to 3rd plus the high clutch makes it impossible to shift smoothly at high RPMs, since there will be such long time between when the clutch disengages and reengages, unless you shift to neutral first or don't use the full pedal stroke.

Any thoughts?

I have a few!

1. When street driving I always just slip a bit on all gear changes cuz im lazy that way. Unless I am practicing rev matching, then I shift sans clutch and use left foot brake or heel-toe.

2. If you are matching revs on upshifts, keep in mind that the gears get closer together (ratio wise) as you go up, so you need the RPM to go down LESS between 3 and 4 as you do from 2-3. This translates to "you need to shift FASTER between higher gears so the RPMs don't fall as much".

3. A lot of BMW "tuner" shops sell clutch pedal stops which are basically big bolts that bolt to the floor under your clutch pedal to reduce overall throw, and put the engagement point closer to the 'bottom' of clutch travel. Never really thought that they were necessary though.

The clunk is more likely to be play in the drive train that manifests itself when you shift a specific way rather than an issue with your shifting technique. The fact that there is no clunk when you keep the drive train preloaded (by not disengaging the clutch fully) would back that theory.

That said, I think you're unduly worried that you're not shifting fast enough. In almost any road car, trying to shift super fast actually works against you as the gearboxes aren't quite designed for forceful, fast shifts. I'd focus on being precise with the shift rather than being super fast.

Welcome to the world of driving a stick. With practice, it will all feel natural.

See if this article about driving smoothly helps, too.

Thanks for the replies. I'm mainly just looking for some perspective on what's normal as it's my first M/T car.

I've been driving stick for over 20 yrs. since before I got my license. I am usually nice and smooth. I still have bad days where I can't shift worth a E36 M3. Smoothness comes with time and practice. But do check for worn drivetrain bushings too.

That was my first thought - bad motor mounts, for example, make it really difficult to shift smoothly.

Good choice of car; I also have an E30 318is!

If your engine speed is slightly above your 'target' speed for the next gear when you let the clutch back out, it will be smoother than if you are slightly below your target speed, for whatever it's worth. It will also get rid of the clunk, which probably comes from the driveline going from neutral load, to motoring, to the engine applying power. That load reversal can be pretty severe.

My car also has a lighter flywheel, among other things. I've ended up in the habit of never fully releasing the throttle when I shift, since I don't like rushing the transmission on the street. Datalogs say I'm right around 5% open, just resting my foot on the throttle so it doesn't drop as fast. It's not really a conscious thing though, just a weird habit I developed in the 9 years I've had the car. On the track, I just shift smoothly and quickly and it seems to work itself out; I don't rest my foot on the accelerator if I'm really getting after it. It may just be a practice thing; it takes time.

clunking is probably caused by mounts. The E30 should have two under the engine that are easily replaced, one under the tail end of the tranny that is relatively easy and the ones on the diff that are more difficult. You could also be looking at a loose rear suspension or subframe. You might as well look at the flexible coupler of "Guibo" at the tail end of the transmission as well.

Clunking could also be lifting off the gas slightly before the clutch is disengaged, imagine a tiny front end dive.

Practice - Practice - Practice.

mad_machine wrote: clunking is probably caused by mounts. The E30 should have two under the engine that are easily replaced, one under the tail end of the tranny that is relatively easy and the ones on the diff that are more difficult. You could also be looking at a loose rear suspension or subframe. You might as well look at the flexible coupler of "Guibo" at the tail end of the transmission as well.

Was also thinking there's something loose in the drivetrain. This sounds worse than a technique problem.

The 318is uses hydraulic engine mounts, and they tend to tear in half when they fail. Also, E30 front subframes are somewhat known for damaging the holes that the mounts use, and eventually tearing through. Both good things to look at. OEM replacement mounts are definitely the way to go for that car if you need them, btw.

I blasted around a bit during lunch and found that there is really only a shock when I'm shifting in the normal lazy daily driving fashion but with the revs higher.

Makes sense since with the revs higher you have to shift faster. Anyone know why it seems like the revs don't drop as fast when accelerating, versus keeping the revs constant at say 4k, and then shifting?

c0rbin9 wrote: I blasted around a bit during lunch and found that there is really only a shock when I'm shifting in the normal lazy daily driving fashion but with the revs higher. Makes sense since with the revs higher you have to shift faster. Anyone know why it seems like the revs don't drop as fast when accelerating, versus keeping the revs constant at say 4k, and then shifting?

Probably as much to do with the syncros/transmission gears and how fast they rotate or slow than just the motor speed.

No matter what engine speed, the "slower" you shift, the more time the trans gears (and car) have to slow down. Syncros will let it go in to gear when you depress the clutch, but when you let the clutch out, those speeds need to match better than not or you get herky jerky.

the revs don't drop because of a heavy flywheel. Revs that drop quickly lead to both high emissions from deacceleration and worse shifting among the 90% of the people who actually shift for themselves.

I remember getting humbled in a friend's fiat spider years ago. I have driven a stick for the past 28 years, but going from my (then) Hyundai Tiburon with it's heavy two piece flywheel and forgiving clutch to a lightweight Fiat spider, I stalled it 5 times trying to get going.

Lots of good advice above. I'd check engine and tranny mounts.

If the E30 is similar to an E36, a poor mans clutch stop can be found at any Lowes store. Just buy an elevator bolt. I find it makes a lot of difference, but one of my winter projects is to learn to heal-toe properly.

http://forum.e46fanatics.com/showpost.php?p=2076472&postcount=1

I've driven stick since 1977. The other day I was shifting poorly and bouncing my wife's head off the headrest and her question back was - your next cars not going to be stick shift, is it?