changing from 3rd to 2nd at 60mph

[3.0 Si Anderson]

Just been out for a spirited drive and noticed that when I change down from 3rd to 2nd at 60mph I get can feel a vibration. Its like when you go over tramlines on the motorway. I dont think I have ever gone from 3rd to 2nd at that speed before and realise it may not be the best thing to do as that 60 mph is almost at the limiter in 2nd.

Chill with you and that exhaust debacle and now trying to blow up your gearbox and transmission I really do worry about you......

However, I have to say I am looking forward to the next installment of guess what i am going to do next

 

[ChillZ4]

Just been out for a spirited drive and noticed that when I change down from 3rd to 2nd at 60mph I get can feel a vibration. Its like when you go over tramlines on the motorway. I dont think I have ever gone from 3rd to 2nd at that speed before and realise it may not be the best thing to do as that 60 mph is almost at the limiter in 2nd.

Chill with you and that exhaust debacle and now trying to blow up your gearbox and transmission I really do worry about you......

However, I have to say I am looking forward to the next installment of guess what i am going to do next

:lol:

cheers

 

[ChillZ4]

UPDATE - it does the same at 50mph and you can feel it slightly at 40. Those speeds in 2nd are not that high up the rev range. This cant be right sureley. Having a bad few weeks and all self inflicted

 

[Smokin]

Why are you trying to downshift to 2nd at those speeds? Really, 4th is fine. !st and 2nd are to get the car going not to slow it down for a turn you should have anticipated.


Peak horsepower and torque are NOT at redline--engine and transmission woes are.

 

[Wondermike]

UPDATE - it does the same at 50mph and you can feel it slightly at 40. Those speeds in 2nd are not that high up the rev range. This cant be right sureley. Having a bad few weeks and all self inflicted

40 is pushing it I suppose, but I can't see where you would need to drop down to 2nd at 50 though :scratchhead:

Note to self - never buy a car from ChillZ4

 

[ChillZ4]

Can someone please try it on a smooth road, not 60 but at 50.

 

[ksher]

Can someone please try it on a smooth road, not 60 but at 50.

Not me. How do you explain it when you try to claim a new gearbox under warranty? :lol:

 

[Smokin]

Can someone please try it on a smooth road, not 60 but at 50.

You've got to be kidding.....

 

[BigChewy71]

Can someone please try it on a smooth road, not 60 but at 50.

Dream on!!!!!! :lol:

 

[ovrkll]

The BMW mechanics have a term for this type of behavior,,,,"The Money Shift"

 

[ovrkll]

Yep, about a $15k shift

 

[Mr Whippy]

2nd gear with no rev match/throttle on, and clutch up, quickly, would likely have activated the DSC to prevent a spin out of the back end, I would have thought.

Just do it again at 50mph... I've gone down to 2nd at about 45mph before without noises but I always rev match at least half way, if not fully, before I do. Not rev matching is just a bad idea for stability first and foremost... I'd not worry too much about engine/gearbox, what they see is not much different to lifting off the throttle fully at 60mph in 2nd in the first place.

Dave

 

[Caddyshk]

2nd gear with no rev match/throttle on, and clutch up, quickly, would likely have activated the DSC to prevent a spin out of the back end, I would have thought.

Just do it again at 50mph... I've gone down to 2nd at about 45mph before without noises but I always rev match at least half way, if not fully, before I do. Not rev matching is just a bad idea for stability first and foremost... I'd not worry too much about engine/gearbox, what they see is not much different to lifting off the throttle fully at 60mph in 2nd in the first place.

Dave

It's a mechanical over rev, DSC won't do anything to prevent a lockup of the rear wheels.

 

[TO//M]

Thank God the clutch slipped and/or the rear tires locked up. Everything from the flywheel back could have been toast. Suffice to say that you have scratched off at least some of the drive trains cat's nine lives. Any idea what the tach read at your moment of maximum brain fade?

 

[Aebous]

I think it's just a lack of revmatching on your part with the tires/trans breaking traction as others have said. On the track I'll downshift for one turn and rev-match heel-toe (not perfectly) from a high speed and when I'm ready to enter into the turn I'm in 2nd gear usually (unless I missed a shift or took too long or just lazy). I've never noticed any vibes when downshifting using heel/toe rev-matching

 

[thestig]

Why are you trying to downshift to 2nd at those speeds? Really, 4th is fine. !st and 2nd are to get the car going not to slow it down for a turn you should have anticipated.


Peak horsepower and torque are NOT at redline--engine and transmission woes are.

Theyre not far off you know!
(Credit to Mr Whippy for the Graph not me!)

 

[Mr Whippy]

2nd gear with no rev match/throttle on, and clutch up, quickly, would likely have activated the DSC to prevent a spin out of the back end, I would have thought.

Just do it again at 50mph... I've gone down to 2nd at about 45mph before without noises but I always rev match at least half way, if not fully, before I do. Not rev matching is just a bad idea for stability first and foremost... I'd not worry too much about engine/gearbox, what they see is not much different to lifting off the throttle fully at 60mph in 2nd in the first place.

Dave

It's a mechanical over rev, DSC won't do anything to prevent a lockup of the rear wheels.

Good point, DSC can only apply brakes, or cut power, but when the power is applied through the speed and gearing, and the engine is already braking anyway

Either way, the simple lesson is, don't do what the OP did without at least rev-matching

 

[Rick Hunter]

Threadfail.

 

[Aebous]

Not completely, some good info in here.

 

[Aebous]

Down there