Help,shifting gear noise. It is not grinding ,not clunk sounds. It is slippery sound

[cobinwei]

Hi, guys, can anyone tell what is wrong with my car, when shifting gear from 1 to 2 and 2to 3' there is slippery noise occasionally, especially, when shifting quickly and high rev. Is this because clutch need replacement? But the noise only appear when shifting gear, it does not appear when I release the clutch pedal

Anyone can help appreciate!

[RedDjinn]

??? try a new engine mount ( cpe/sure/trz etc..

[rogwick]

How many kms have you done? Stock clutch I presume?

[Doug_MPS6]

A "slippery noise"??
What make and model of car?
Does it do it when not at high loadings?
How many kms on the car?

Reading between your vague lines:

If it does it when shifting and not when the clutch is released (I assume, as you have some text missing), then it sounds like you are overtaxing the synchro by shifting too fast. That will give you a noise that sounds like a "slippery noise" which is friction between the synchro driving and driven rings.

Try shifting slower and let the synchro do its job properly.

[cobinwei]

??? try a new engine mount ( cpe/sure/trz etc..

thanks for help, engine mounts will arrive shortly, hope those mounts solve this problem

---------- Post added at 11:40 AM ---------- Previous post was at 11:39 AM ----------

How many kms have you done? Stock clutch I presume?

it is just about 60000' and yes it is stock clutch, any suggestions appreciate

---------- Post added at 11:53 AM ---------- Previous post was at 11:40 AM ----------

A "slippery noise"??
What make and model of car?
Does it do it when not at high loadings?
How many kms on the car?

Reading between your vague lines:

If it does it when shifting and not when the clutch is released (I assume, as you have some text missing), then it sounds like you are overtaxing the synchro by shifting too fast. That will give you a noise that sounds like a "slippery noise" which is friction between the synchro driving and driven rings.

Try shifting slower and let the synchro do its job properly.

my car is 2007 ms3' has been done about 60000km. And it is not only happen on high rev, sometimes it happens when i shifting quickly while the car is stay still.

[Doug_MPS6]

Synchro rings are like little clutches. They act via a frictional relationship to match the speeds between gears or gear shafts (hence "synchro"). You can hear them being pushed if you try to shift faster than they are capable of synchronizing, for there is a finite minimum amount of time required for the shafts to synchronize speeds. It is possible to "beat" the synchro in any gearbox, at any speed.

As I noted before, shift slower and give these little guys time to do their job. The MPS3 is so fast that any slight delay in progress is unlikely to be significant in the great scheme of things. I don't launch hard and take my time shifting 1st and 2nd and let 3rd gear reel in any opposition. Shoving all 200+Kw and 400nm torque through these transmissions is asking a lot - be kind to it and it will last longer.

Note also that 1st and 2nd gears in the MPS carry double synchro rings which slows them down a bit but is intended to deal with people who want to shift too fast by offering some protection to the box. The alternative is noisily crunched gears, which occurs when you "beat" the synchro.

Too much hard shifting will eventually wear out these rings and your gears will crunch ALL the time, unless you are skilled at matching engine, gear-shaft and road speeds, which most people can't do any more.

[Caffeine Fiend]

Great info Doug

Helps me understand it better too

Question though, I thought these boxes had triple synchro in the lower gears? Did I misread somewhere?


Sent from my iPhone using TapaTalk

[cobinwei]

Synchro rings are like little clutches. They act via a frictional relationship to match the speeds between gears or gear shafts (hence "synchro"). You can hear them being pushed if you try to shift faster than they are capable of synchronizing, for there is a finite minimum amount of time required for the shafts to synchronize speeds. It is possible to "beat" the synchro in any gearbox, at any speed.

As I noted before, shift slower and give these little guys time to do their job. The MPS3 is so fast that any slight delay in progress is unlikely to be significant in the great scheme of things. I don't launch hard and take my time shifting 1st and 2nd and let 3rd gear reel in any opposition. Shoving all 200+Kw and 400nm torque through these transmissions is asking a lot - be kind to it and it will last longer.

Note also that 1st and 2nd gears in the MPS carry double synchro rings which slows them down a bit but is intended to deal with people who want to shift too fast by offering some protection to the box. The alternative is noisily crunched gears, which occurs when you "beat" the synchro.

Too much hard shifting will eventually wear out these rings and your gears will crunch ALL the time, unless you are skilled at matching engine, gear-shaft and road speeds, which most people can't do any more.

appreciate for your help, I will change the way I drive, shifting slower, do not want the gear box wear out that quickly.and I just found out when I release the clutch pedal quickly, it also appears slippery noise, does that mean the clutch wear out and need replacement? By the way, what is the best rev or speed to shift from gear 1 to 2 and 2 to 3? Thanks for ur time

[Doug_MPS6]

If you have the brochure you will see the peak of the bhp and torque curves. The MPS is really gutsy, very under-stressed and has a very flat torque curve. High rpm are an engine killer, not only via the almost certain approach to potentially destructive imbalance (in unbalanced engines) but mainly through the simple effect of high piston speed = high wear. There's not much point in revving the guts out of the engine as the torque peak is at relatively quite low rpm. Just take it to peak power (peak torque and peak power are closely coincident, though I don't have figures in front of me), so your revs come back enough for you to be back on song again on the next gear. I'm not a slow driver but almost never see 5000rpm on mine, maybe 4500 is max for me, even in high speed passing manoeuvres. If you search my posts you will see a .pdf of gear speeds that I posted a while back - it might prove useful.

BTW in 60,000km you might have killed your clutch if you have been driving (and especially if launching) hard but soften your driving and see how it all works out before getting too worried about the clutch.

I can't recall if it is double or triple syncho on 1st and 2nd but it is beefed up. There is some discussion on it, including by KMH001 who laments it somewhat.

[cobinwei]

If you have the brochure you will see the peak of the bhp and torque curves. The MPS is really gutsy, very under-stressed and has a very flat torque curve. High rpm are an engine killer, not only via the almost certain approach to potentially destructive imbalance (in unbalanced engines) but mainly through the simple effect of high piston speed = high wear. There's not much point in revving the guts out of the engine as the torque peak is at relatively quite low rpm. Just take it to peak power (peak torque and peak power are closely coincident, though I don't have figures in front of me), so your revs come back enough for you to be back on song again on the next gear. I'm not a slow driver but almost never see 5000rpm on mine, maybe 4500 is max for me, even in high speed passing manoeuvres. If you search my posts you will see a .pdf of gear speeds that I posted a while back - it might prove useful.

BTW in 60,000km you might have killed your clutch if you have been driving (and especially if launching) hard but soften your driving and see how it all works out before getting too worried about the clutch.

I can't recall if it is double or triple syncho on 1st and 2nd but it is beefed up. There is some discussion on it, including by KMH001 who laments it somewhat.

thanks mate, great points. The gearbox or clutch so annoying, slippery noise and clunky sounds and rough feeling of shifting from 1 to 2. I am planning to go to Mazda dealer do a diagnosis. See what they will say about it.