CVT Transmissions

Y Fan Wen

Member
Location
N W Snowdonia
A manual might fail at 100,000 miles as well. I remember a time, not so long ago, when gearboxes generally needed an overhaul at 50,000 and cars were very unlikely to travel 100,000 before being scrapped. I also know a driver that is so rough with his gearbox that almost every car he drives has the gear-lever break off in his hand at some point and he can't understand why car manufacturers have not sorted gear lever and gearboxes out in this day and age. :eek:
There was one farmer, deceased now, who was notorious for his use of the clutch. He always bought his cars at the local garage, who, when he changed vehicle, would order a new clutch the day he took delivery and then another every time they replaced it. It was the complete clutch they used to replace, not just the clutch plate, 'cos other elements of the clutch mechanism would have been cooked as well.
 

Cowabunga

Member
Location
Ceredigion,Wales
Do CVTs have engine braking?
How do automatics of all sorts manage downhill as surely as speed rises they would sense a upshift would be wanted when you actually may want to downshift?
They have inclination sensors and use the ECU like you would a brain. All good automatics nowadays downshift for engine braking. Some more than others, depending on their programming.
I had the same engine and gearbox combination in a BMW X5 and Range Rover, nearly twenty years ago. The BMW down-changed rather too enthusiastically at times and frightened the peasants walking on the pavement as it changed down two gears with the engine rising to 3000rpm. Yet the same BMW engine and General Motors five speed auto in the Range Rover was programmed more sensible and only ever down changed appropriately. The Audi and Volvo with different models of Aisin transmissions also changed down just nicely but my Ford Ranger doesn't really downshift enough at all. My latest car with eight speed DCT falls somewhere between the BMW and Range Rover and sometimes chooses one ratio too low for my liking, but only on quite steep roads and not as extremely as did the BMW.
 

Cowabunga

Member
Location
Ceredigion,Wales
Magically! Simpler ones have just an inclinometer sensor so it knows if the car is pointing up or down hill (might also be combined with a G sensor)

More serious autos using ZF's 8 or 10HP use input from the Sat Nav and GPS sensors to know the topography of the area - they will often change down a cog at the base of an incline or just as you begin to descend a hill, in anticipation, rather reaction.

Plus alot more computing power - if for instance you're pressing on and throwing the car about alittle more (from the G sensor) and there is a series of bends but on level road, they will often hold a lower gear because they know the road. Do the same more calmly and it will stay in a higher gear.

They also monitor throttle angle, rate of attack on the pedal, brake pedal, steering angle and rate of attack on the steering - but the G & GPS sensors are responsible for most of the decisions. BMW & LR switch to different mapping when they sense a plug in the trailer socket.
Have ZF got a ten speed? They have a nine speed for transverse engines but most are eight speed. Not heard of a ten speed ZF yet. The only ten speed transmissions I know of are the Ford/GM and Honda's new one.

I have a nine speed ZF but it doesn't do what you say in my car. In fact I've only heard of the very very latest models of cars with adaptive cruise control changing their speed for bends according to sat-nav but not actually changing gears. They will downshift for engine braking when cruise control, active or not, is engaged, as well as brake down hills as appropriate. Adaptive cruise control and pilot assist type auto-steering are great on dual carriageways and motorways with the adaptive cruise being particularly useful even in a queue on A roads, but it does use the brakes more than I normally would. The automatic functions generally react rather than anticipate, although there are some exceptions where systems do anticipate, such as DCT's pre-selecting the next ratio that it thinks will be appropriate from a choice of an up or down change.
 

Cowabunga

Member
Location
Ceredigion,Wales
There was one farmer, deceased now, who was notorious for his use of the clutch. He always bought his cars at the local garage, who, when he changed vehicle, would order a new clutch the day he took delivery and then another every time they replaced it. It was the complete clutch they used to replace, not just the clutch plate, 'cos other elements of the clutch mechanism would have been cooked as well.
There are 'animals' out there. Which is why I prefer to buy new or an idiot-proof used automatic. Nothing is completely foolproof though, so I seldom buy used.
 

essexpete

Member
Location
Essex
Son had an old Audi A4 estate with a form of CVT. Not everyone's choice, even when new, but it was seemless. Always reving at the point that was needed. If you cruised away it shifted quickly to high ratio. If you booted it it would rev and not move the ratio so quickly. The car had 155k on the clock when he bought and he sold it to a friend at 225k and still going strong another 2 years on. It need a transmission oil change every 40k but less of a problem than a worn out duel mass fly wheel set up.
 

Timbo

Member
Location
Gods County
Son had an old Audi A4 estate with a form of CVT. Not everyone's choice, even when new, but it was seemless. Always reving at the point that was needed. If you cruised away it shifted quickly to high ratio. If you booted it it would rev and not move the ratio so quickly. The car had 155k on the clock when he bought and he sold it to a friend at 225k and still going strong another 2 years on. It need a transmission oil change every 40k but less of a problem than a worn out duel mass fly wheel set up.
Bloody hell he did well with that - the Multitronic was renown for strange behaviour and not long lasting as a rule !
 

Chips

Member
Location
Shropshire
I had an A5 with multitronic , nicest gearbox I've used in a car and far nicer and reliable than the dual clutch q5 we had later on , nicer than the zf 8speed I've got now just
 

Mur Huwcun

Member
Livestock Farmer
Location
North West Wales
You can pick up cars with the Multitronic box seriously cheaper than the manual or excuse of an auto DSG box. Both according to the VW and Audi forums are only ok if you buy new, drive them correctly and change the oil every about 40k miles. No good for me unfortunately as I buy them after they pass 100k so had to go for another manual!!!
 

Get ready for pest monitoring, advises PGRO

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Written by Charlotte Cunningham

The Processors and Growers Research Organisation (PGRO) has issued new advice to help growers understand the importance of measuring pest populations before any decisions are made on insecticides. Charlotte Cunningham reports. Ahead of the trapping season, the PGRO has produced a new masterclass video to help growers understand how to trap and assess pest populations. The key advice is that using a range of preventative tools will be crucial for farmers looking to reduce cases of pea and bean weevil, pea moth, and silver Y moth this spring, while finding more sustainable ways of farming in line with new agricultural policy, according to the PGRO’s research and...
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