Rev matching downshift in autobox (tip)

[I-S]

Am I the only one? I demonstrated the technique to kieran a couple of weeks ago but surely other people are doing the same?

[Physician]

Yes .......... :happy:

[Wodjno]

Maybe/Hmmm

Maybe Not:thinking:

Depends :vulcan:



SPEAK ENGLISH MAN /pan

[Physician]

Maybe/Hmmm

Maybe Not:thinking:

Depends :vulcan:



SPEAK ENGLISH MAN

That's a 'no' from Glen then Isaac :evilgrin:

[The Vee]

hmmm go on..............I hope this doesn't involve the use of neutral in some sort of bastardised double de clutch for autos/help

[I-S]

Good man physician.

No, it's only as boring and as simple as giving the engine enough throttle as you change down so that while the clutch is disengaged, the engine gets closer to the output speed and you get a smoother shift.

I have come across many people who think that because a car is an auto that means they don't have to think about gears or shifts at all. Since I've not seen it discussed here I thought I'd open the discussion.

[Wodjno]

Good man physician.

No, it's only as boring and as simple as giving the engine enough throttle as you change down so that while the clutch is disengaged, the engine gets closer to the output speed and you get a smoother shift.

I have come across many people who think that because a car is an auto that means they don't have to think about gears or shifts at all. Since I've not seen it discussed here I thought I'd open the discussion.

Ahhhhhhh ! :scholar:


Yes i do this under heavy braking, like from 100+ and dropping down a couple of cogs at a time(4th to 2nd) But normal driving no i don't. Theres no point in IMHO :happy:

[zentac]

first can you explain why you would want to?

[I-S]

Smoothness - it's much gentler on the gearbox.

An example is my drive home, there's a tightish left-hander up a hill. Approach in 3rd about 50mph, let the car slow to 40, take 2nd, down to about 35, around the corner and accelerate out. If you don't give the engine some throttle when downshifting into 2nd then the shift goes "thump" and the car stands on its nose momentarily, and drops to 30mph or so. With throttle the shift is smooth.

[bradc]

Isaac, I never change down into too high a gear like that in the VR-4. I remember in my GDI I always did that due to a lack of power to start off with, but also due to the gearbox having 4 widely spaced ratios. In the VR-4's I've had, I very rarely downshift at high rpm at all. 90% of the time when I downshift I am doing it at less than 3000rpm, and the car is nice and smooth anyway.

What rpm's does your car jump up to when you take 2nd gear into that corner?

[I-S]

It isn't "too high a gear". It goes to about 3500rpm at the downshift which isn't unreasonable.

[zentac]

The INVECSII should never "thump" so that suggests you have a problem slowly manifesting its self with your box.

PS, In january were going to be looking at the INVECSIII (6 speed Tip) boxes to see if they will fit an FTO, if they do Im sure the 4WD version will fit the VR4 and that uses Mitsubishis Continuously Variable Transmission which sounds quite interesting.

[bradc]

ok you're right, 3500rpm isn't too high, I was thinking it would be something like 4500rpm or similar.

I've changed down from 5th into 3rd multiple times in my cars at 100kmh to really accelerate hard and to piss someone off, It changes from about 2200rpm to 3100rpm to 4300rpm and is nice and smooth the whole time. If I don't have any pressure on the throttle then you can feel it change gear and start to engine brake quite quickly. If I have the throttle just open enough to maintain speed then it doesn't thump or anything on the change from 5th to 4th or from 4th to 3rd.

That is the normal way I downshift by the way, just keep the throttle at the same position the whole way through the downchange. I find that while it is possible to blip the engine sometimes, lots of the time the gearbox gets confused and changes gear quite aggressively and the change isn't smooth at all.

Richard - I'm scared of CVT transmissions after the rubber band model in my cousins Primera blew up, so forgive me for not knowing anything about the invecs III, but does it use a similar rubber band concept, or is it a chain drive? Would it really stand up to 300 or more horsepower?

[zentac]

they are used in the V6 shoguns which have torque by the bucket load, so should be ok