03 M3 SMG clunk / bang from rear when changing gears

[RetroTed]

Hi All

M3 is new to me and when driving normally the gears are ok, bit lurchy changing up but livable. However when i'm driving in anger at high revs and using the paddles the gear change is horrible, it has what I would describe as a bang from the rear end

No visable issues, floors rock solid as are the bushes and shocks. Is this normal or something more serious

Box had £2k spent last year on a new pump and switch

Any ideas ?

[mark.c]

Without being in your car and experiencing it it would be hard to say wether it is normal or not.

What I can tell you is I have a CSL here and the gearchanges when pressing on with the gear change selected high can be best described as brutal. A definated thud as the next gear is selected.

So with that in mind I would say your car is spot on 😀

[RetroTed]

mark.c said:

Without being in your car and experiencing it it would be hard to say wether it is normal or not.

What I can tell you is I have a CSL here and the gearchanges when pressing on with the gear change selected high can be best described as brutal. A definated thud as the next gear is selected.

So with that in mind I would say your car is spot on ??

Great, sets my mind at ease

[essayer]

I had one from new and they were always brutal in S6

[gizlaroc]

You lift off the gas for a second when you change if you want it to be smoother.

[SS2.]

If it's new to you, have you tried resetting the SMG ?

[Pughmacher]

Hopefully not this but if the pinion and crown gears in the diff are worn you can get excess lash and that makes a racket on hard changes. Agree with the lift when changing gear. Makes it so much better. Also I found running the box in its sharpest setting was smoother.

[gizlaroc]

Yeah, s5 and lift off slightly when you change and it is pretty smooth.

[village24]

Totally normal and the best bit about the smg.

Especially in s5 and s6. Gives it that race car feel when your banging through the gears and not lifting.

Loved mine going through 2nd,3rd and 4th at 7k. Bear in mind at redline in 3rd you will be over 100.

As others have said, lift off like you would in a manual and it will smooth out the changes.

Also to reset smg I believe you need to be doing 40mph, knock the shifter into neutral and pull both paddles together for a few seconds and it will reset adaptations

[Tommie38]

I think that is normal.

Remember, SMG is really a manual gearbox with a mechanism changing gears for you. Obviously the mechanism can change gear faster than you can, but if you could change that fast in a manual car (you can’t) you would get the same effect.

You probably want to dial the shift speed down a bit, you don’t need to drive at the fastest shift speed.

For coming down the box, lifting off the throttle lightly will do wonders for smoothing the shift.

Think of SMG as an automated manual and that should help. Most people need to adapt to it in a way they don’t need to with dual clutch or torque converters.

Much easier to learn than a manual!

[gizlaroc]

The faster shifts, combined with lifting off, actually produce smoother shifts.

[MikeM6]

gizlaroc said:

Yeah, s5 and lift off slightly when you change and it is pretty smooth.

Shouldn't lift off with the SMG. Reset the adaptations (whilst over 20mph, pop it in neutral and pull both paddles back, then back into drive).

It might be different between the SMGII and SMGIII, but the system controls the clutch and throttle to smooth the changes. Lifting off confuses it.

If the brutal changes are too hard (which is part of the appeal to be honest) then turn down the shift settings.

[gizlaroc]

We shall agree to disagree.

7 years with SMG M3s taught me that S5, so nice quick shifts, was all that was ever really needed, keep your foot down for hard shifts and lift off for seemless shifts.

Turning the shift settings down just made it shift too slowly, with no benefit to shift 'smoothness'.

[MikeM6]

gizlaroc said:

We shall agree to disagree.

7 years with SMG M3s taught me that S5, so nice quick shifts, was all that was ever really needed, keep your foot down for hard shifts and lift off for seemless shifts.

Turning the shift settings down just made it shift too slowly, with no benefit to shift 'smoothness'.

Might be different for the SMGIII then.
https://youtu.be/olXT8l0RgfA

Decent explanation from this chap on why he recommends not to lift off between.

[Wills2]

Brutal shifts at WOT in S5 or 6 are normal for SMGII, lifting off smooth's them out, they engineered a bump into the MDCT box to ape them slightly and on the M ZF8 box as well although much less than the single clutch system in the SMG.