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Discussion Starter #1
Does anyone have any ideas or opinions as to the cause of the 1st-2nd gear 'bunny hopping' that some M5 owners have been reporting recently. I've had my M5 for four months now, and i've experienced this problem from the start. My dealership are implying that it could be related to the DSC system being activated, but i very much doubt from the symptoms that i have experienced, that this could be the case. It's also been put to me that this is a characteristic of the M5, so i'd be interested to know whether this is common to all M5's, or just occurring on a select few. Any feedback on this would be much appreciated...
 

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I have no such problem. My car is extremely smooth shifting easy or shifting hard.
 

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Mine is smooth also.

The only thing I notice is that the engine hesitates a little when it's cold. This goes away in about a minute though and is only after the car has sat overnight.

For what it's worth, I'm always in sport mode and usually have the AC on.

Rick
 

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While my E39 M5 was in for service today, the dealer loaned me a 323 convertible with a 5 spped manual transmission. Now, I'm no expert (the M5 is only my second manual car and the first was a Toyota Celica I had about 20 years ago) but I did notice that the 323 did not seem to lose RPM's during lift throttle shifts as fast as the M5 and the clutch engagement seemed somewhat less sensitive than the M5. I felt the 323 throttle position during shifts was less critical than the M5. This made for smoother shifting with less concentration on my part. Of course, the 323 couldn't touch the M5 from a performance standpoint but it was esier to drive smoothly. With the M5, the 1-2 shift is by far the worst. After that, it is fairly smooth.
 

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I have always had the "bunny hopping", but only when the engine is cold, in first or second gear, and low throttle positions (<40%). Once warm, no issue.

Andrew E
'99 E39 M5 (July 99)
30,000km and rocking!!
 

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As has been mentioned there is a slight hesitation in the 1st-2nd shift briefly when the engine is cold. This is typical of nearly all manual shift cars and especially so in big engine cars. When the engine oil warms the power is delivered more smoothly and so the shifts are smoother. Shifting into higher gears at a relatively low speed provides less torque which translates into a smoother shift. This lower power and torque is also what makes driving a lower powered car like the 323 easier.
I have had several high performance manual transmission cars over the past 30 plus years ranging from a mid 60's muscle car, to a 1986 porsche 928, and presently a 1995 Porsche 911 in addition to my new M5. The M5 is by far the smoothest shifting with the best clutch feel of them all.
 

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I forgot to mention the rapid loss of rpm's in throttle lift. I have noticed this as well and it must be related to the electronic as opposed to mechanical throttle linkage.
This rapid drop in rpm's makes doing a proper heel-toe downshift when entering a sharp curve difficult.
 

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Huh? I thought the entire purpose of heel-and-toe was to modulate the throttle with your foot while braking - so what difference does it make what the "natural" deceleration of the engine is?

Sorry - maybe that sounds snotty - but I am just not having any trouble shifting smoothly, cold or warm, natural or heel and toe.

I've yet to see any evidence here that there is anything "wrong" with the M5. I believe this is driver style only. More powerful cars ARE more difficult to shift smoothly, because the engine has such great ability to move the car. I had a '63 VW where you could floor it and drop the clutch say, from 2nd to 3rd, and it would still be smooth. The car's momentum just totally overwhelmed the engine's power, and set the speed of the engine accordingly - not the other way around.

With the M5, you MUST shift with TIMING. The engine speed and wheel speed have to match as you let the clutch out. If they don't, your foot/brain have to feel this and let the clutch slip until they do. The driver has to adjust to many factors - cold, hot, speed of shift, uphill or downhill - OK, I'm done. Flame suit on.

(I am willing to be convinced there is a real issue here when someone complaining of the problem has someone who isn't drive their car. Then we'll know once and for all whether its car or driver. )

Ooooh - I'm almost out of Jr. Member range

Originally posted by TWC:
I forgot to mention the rapid loss of rpm's in throttle lift. I have noticed this as well and it must be related to the electronic as opposed to mechanical throttle linkage.
This rapid drop in rpm's makes doing a proper heel-toe downshift when entering a sharp curve difficult.
 

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I have a different theory about the cause of the characteristics of the car when shifting from first to second that have been the subject of much discussion.

First, the characteristics of the car when it is cold are probably unrelated to anything else. Almost all cars, and high performance cars in particular, are never as efficient when the engine is cold. The clearances change as the individual components reach normal operating temperature (which they do at different rates). Plus, the smog controls operate differently on a cold engine. For example, my E34 M5 had an exhaust port air injection pump that only ran when the engine was very cold. Sitting overnight on a warm summer night wouldn't get it cold enough to engage in the morning. It only had two operating states: on or off. When it was on you could hear it running. When it shut off it felt like the car received a sudden jolt from 50 additional horsepower! I have concluded that my E39 cold run characteristics are the function of cold components and the smog controls because they disappear as soon as the car is up to temperature.

The shift "problem" is different and unrelated, once the engine is warm. My theory is that it is the electronics and vanos at work. In a previous post, about my experience with the car on a race track, I described how the suspension design caused the car to change its handling characteristic in turns depending on throttle attitude and other driver inputs. I believe we have the same happening with changes in driver inputs to the engine and these manifest themselves in ways described by many. (By the way, moderate to hard acceleration away from a stop will invoke the traction control if the DSC isn't disengaged. I'm not talking about this situation.)

What I believe is happening is the engine management control computer, working in concert with the constant/variable changing of the cams by the vanos system, makes every shift potentially different. And that is at any specific engine speed. To illustrate, the valve timing will be different, even though the engine speed is the same, depending upon the accelerator position. For example, the valve timing/overlap/advance, etc. will be different for an engine running at 4000 rpm depending whether the throttle was just slightly open or was half way down. Things like accelerating versus coasting versus decelerating will result in the vanos having the cams in different profiles. The net result for us drivers is it is very difficult to know what the throttle position should be and at what engine speed we should be at when the clutch comes out.

I for one am having difficulty getting my shifts perfect every time. This wasn't a problem for me with my last M5, which I owned for 9 years. In that car when I accelerated and shifted my foot never came completely off the gas and I knew instinctively how much gas to keep on so when the clutch came out the tach didn't move. The engine speed was already matched to the wheel speed for the next gear. Downshifts were the same. EVERY downshift I do is a double-clutched heel and toe shift (a habit I started when I bought a 911 in 1970). Downshifts were the same, when the clutch came out the tack didn't move -- the engine speed and wheel speed were already matched. A side benefit, in addition to the fun I have, is that I've never worn out a clutch.

In my new M5, which I've had since mid-December, I still can't consistently get the engine and wheel speeds perfectly matched. I believe this is because no two conditions are perfectly the same even though I know the wheel speed (MPH) and what gear I want. I attribute this to the constant "tuning" the engine management computer and the stepless (e. g. constantly changing)dual vanos are doing to the engine while we are shifting.

Driving easy, which I find hard in this car, doesn't exhibit the same problem. My guess is that all the moving components and computer directed changes have time to take place. When we're doing things fast (as in accelerating, shifting, etc.) I think what we're describing as the shifting problem is all the little changes taking place in the engine at the same time making it difficult for us to "get our timing down."

Just my theory -- which may have no basis in fact.
 

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The problem with the heel-toe downshift which I mentioned previously is related to the way in which I was taught at the Bondurant high performance racing school. A proper heel-toe downshift, as I was taught, is to hit the accelerator with the heel while braking with the toe to match the rpm with wheel speed and before the rpm drops, downshift. With the rapid loss of rpm upon lift-off from the accelerator in the M5, the only way to match rpm with wheel speed is to brake and hold some pressure on the accelerator simultaneously which I find difficult to do smoothly.
 

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I've recently experienced the "bunny hopping" effect. My E39 M5 has a little more than 4400 miles on it and for the first time, since taking delivery, the "hopping" happened right after switching into second gear. Now in my episode, the hopping happened immediately after making a turn at an intersection. I suspect the sensitive nature of the DSC, coupled with my shifting (into second) while finishing the curve/turn, and pressing on the throttle induced the effect. It almost seemed as if the car couldn't make up it's "mind" as to engage the DSC or not. I would be curious to know what specific situations other owners have experienced the "bunny hop."

ALX
 

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Discussion Starter #12
As i originally kicked this topic off, here's a bit more info on what i have personally experienced in relation to this characteristic/problem/fault or whatever. My M5 has been doing this in first and second gear during the acceleration phase, immediately after a gear change has been made, with the juddering sensation normally going away once the engine has warmed up. Recently however, i have been experiencing intermittent minor juddering mainly in second gear, even after the car has been driven for a while. For me at least, a quick journey with the DSC system switched off, made no difference whatsoever, with this 'bunny hopping' being easily recreatable. This leads me to conclude that it can't in any way be related to the DSC system. I have also noticed over a period of time, the severity of the 'bunny hopping', is normally greater in relation to a decrease in outside temperature, ie the colder it gets (0-3c), the worse i experience it, as opposed to say 7-10c, where generally the effect is more moderate. This is not helped by the fact, that over here in the UK, outside temperatures vary greatly from one day to the next.
 

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Does the "bunny hopping"(cute but not terribly descriptive) seem to come from the engine or the drive wheels or the driveshaft, the transmission or what?
 

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Ed said:
As i originally kicked this topic off, here's a bit more info on what i have personally experienced in relation to this characteristic/problem/fault or whatever. My M5 has been doing this in first and second gear during the acceleration phase, immediately after a gear change has been made, with the juddering sensation normally going away once the engine has warmed up. Recently however, i have been experiencing intermittent minor juddering mainly in second gear, even after the car has been driven for a while. For me at least, a quick journey with the DSC system switched off, made no difference whatsoever, with this 'bunny hopping' being easily recreatable. This leads me to conclude that it can't in any way be related to the DSC system. I have also noticed over a period of time, the severity of the 'bunny hopping', is normally greater in relation to a decrease in outside temperature, ie the colder it gets (0-3c), the worse i experience it, as opposed to say 7-10c, where generally the effect is more moderate. This is not helped by the fact, that over here in the UK, outside temperatures vary greatly from one day to the next.
Took delivery of my SG 02 late Nov. Since then I've noticed several instances of the bunny hop. Ed seems to describe EXACTLY what I have experienced.

Only occurs from 1st to 2nd. Only occurs in the beginning of my trip - ie. when the engine is cold and moreso when it is the morning and colder outside. In addition, I notice VERY slight bunny hopping (probably only noticeable because I am the driver) when the engine is cold WITHIN the same gear (either 1st or 2nd) - as if its getting a slightly different amount of throttle as its accerlerating.

In any case, I've learned to take it easy when my engine is cold. Warming the car up a bit when I can. And shifting early with less throttle in 1st and 2nd. But only until the car is warmed up.

Bunny hopping obviously cant be too good for the M. But my question is - is there something inherently wrong with the car, and can I get this fixed?
 

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Wow - this was an old thread!

I notice the engine is sometimes a little less smooth when cold. I have simply learned to be a little more careful when shifting. Leave your clutch foot in the mid-position (enough to allow slip, enough to allow hook-up) a little longer, roll on the throttle after the shift more carefully.

It has nothing to do wth DSC for sure. However it could be with the relationship between how sensitive your throttle foot is and how the car reacts. For those of you who frequently experience this problem - if you normally drive with sport mode on, turn it off. If you drive with it off, turn it on. IF the problem corrects itself, great. If it gets worse, the problem is you haven't learned to modulate the throttle carefully enough during and immediately after a shift. Sport mode gives you more instant control over the throttle in slight-throttle situations - and if it helps, it just means you weren't reacting quite enough on the gas pedal. Non-sport mode adds a little damping and slows down the reaction a bit. If this helps, you were being a little too aggressive.
 

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I thought it was just me and my lousy clutch work when I was being lazy (too much gas or something)! Is this a problem or should I continue to think I suck at changing gears??? At least occasionally.

It definitly seems to happen after I had a couple of tall ones!!! And the car has been sitting in the pub's lot all night. (cool engine).

cherrsagai cherrsagai cherrsagai cherrsagai cherrsagai

j/k!!!



:happybirt :happybirt :happybirt :happybirt :happybirt
 

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I'm sure that some of this can be explained by Greg's insistance (small flame) that the driver is partially at fault, but I can attest that it sometimes happens after first is fully engaged and there is no action other than throttle. Always the engine has been cold and there is a moderate throttle being applied. The car will surge and jerk even if you apply more throttle, let off or stay the same. This is certainly temperature dependent, as it hasn't happened to me in many, many months but did the other night when it was around 40 ish. Occassionally, it will also happen after the 1-2 shift but I believe it is an engine situation since it is identical to what I experience in a cold-start first. This phenomenon was there from when I first got the car, 3/00, and seems a lot less frequent now. I'm sure operator input has something to do with it, but not all. JMO

Jim
 

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This "bunny-hop" phenomen did happen to me a couple times when I first got the car but has since then disappeared! At first I thought I was doing a bad job shifting but then it just suddenly stopped doing it one day. Go figure.

Jason
 

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Haha, welcome to my life story guys. My 540/6 bunny hops all the time thanks to its Clutch Delay Valve. 40% of the time I can get a smooth shift from first to second. The rest all jerk your head:( As for heel and toeing, I beleive that the heavier flywheel and engine components will lose their momentum fast as they are heavier then m3, or m coupe internals. I have this problem on my 540 also and I have to keep my heel on the gas a lot longer to keep the rpms up. But I have now been really deligent in practicing heel and toe all the time and I can now get away with jabbing the trottle and doing a quick gearchange. Just takes practice. By the way, does anyone else get yelled at by cops when you heel and toe? Seems to happen to me all the time:confused2 .
 

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What do you mean you get yelled at by cops? For doing what?What do they say to you?
 
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