Cvx or active drive8

powerontheland

Member
Arable Farmer
Location
Hockley Essex
If your doing any amount of roadwork with trailers then Active8 I have a Blue one and no whine from my transmission. I believe if you have GSM unlocked she will behave like an auto command within a certain range.
 

Fragonard

Member
If your doing any amount of roadwork with trailers then Active8 I have a Blue one and no whine from my transmission. I believe if you have GSM unlocked she will behave like an auto command within a certain range.
"Behave like an autocommand"
Is that good or bad, in your opinion..
 

Frankzy

Member
Location
Jamtland, Sweden
Once you've gone CVX you'll never want to go back so that should tell you all you need to know..

It’s just practically impossible for a dual clutch transmission to be 100% reliable and last a long time. Look at cars such as the VW DSG or Stronic in Audi guise. When you think that the synchroniser has to do nearly double the work a normal synchro box does and under mechanical shifting they just can’t possibly last to silly hours.
I'm certainly no proponent for DCT's but what do you mean by the synchros having to work twice as much?
 

Mur Huwcun

Member
Livestock Farmer
Location
North West Wales
Once you've gone CVX you'll never want to go back so that should tell you all you need to know..


I'm certainly no proponent for DCT's but what do you mean by the synchros having to work twice as much?

When you consider the basic principle of how they operate with two clutches so for example if tractor is in first gear or range clutch 1 will hold onto 1st while clutch two has already selected 2nd so the change is nearly seemless. Once it’s changed up clutch 1 will now drop 1st and select 3 in anticipation to shift up but sometimes the job or hill etc will require a downshift to first so then clutch 1 will gave to quickly and mechanically disengage 3rd and very quickly re select first and transmit the drive. The synchros therefore in principle can be subjected to engage and disange a lot more than a normal operator controlled box.

Every one in the car trade now tells you to change the so called auto boxes oils at low milages such as 40-50k although manufacturers try to sell them as sealed for life. I think you woukd struggle to buy a family car size with a proper torque converter auto box now, they’re all pretty much dual clutched manual boxes although 90%+ of the general public have no idea that their auto cars are a computer changed manual box.
 

Frankzy

Member
Location
Jamtland, Sweden
When you consider the basic principle of how they operate with two clutches so for example if tractor is in first gear or range clutch 1 will hold onto 1st while clutch two has already selected 2nd so the change is nearly seemless. Once it’s changed up clutch 1 will now drop 1st and select 3 in anticipation to shift up but sometimes the job or hill etc will require a downshift to first so then clutch 1 will gave to quickly and mechanically disengage 3rd and very quickly re select first and transmit the drive. The synchros therefore in principle can be subjected to engage and disange a lot more than a normal operator controlled box.

I always figured that the clutch currently not engaged would wait in neutral until the controller feels confident that an up or downshift was imminent, and only then would it tell the other shaft to engage a gear..
Would I be right in saying high performance racing cars have been using this for years?..
Yes, the first real use was by Porsche racing team in the 80s. The car won a bunch of championships IIRC.
 

ColinV6

Member
When you consider the basic principle of how they operate with two clutches so for example if tractor is in first gear or range clutch 1 will hold onto 1st while clutch two has already selected 2nd so the change is nearly seemless. Once it’s changed up clutch 1 will now drop 1st and select 3 in anticipation to shift up but sometimes the job or hill etc will require a downshift to first so then clutch 1 will gave to quickly and mechanically disengage 3rd and very quickly re select first and transmit the drive. The synchros therefore in principle can be subjected to engage and disange a lot more than a normal operator controlled box.

Every one in the car trade now tells you to change the so called auto boxes oils at low milages such as 40-50k although manufacturers try to sell them as sealed for life. I think you woukd struggle to buy a family car size with a proper torque converter auto box now, they’re all pretty much dual clutched manual boxes although 90%+ of the general public have no idea that their auto cars are a computer changed manual box.

There’s a hell of a lot of cars that use the ZF 8 speed torque converter.
 

ColinV6

Member
I’m struggling to find a nice estate one to tow caravan etc from a German manufacturer. What’s in a 520? Audi A4 and A6 style have all gone DSG.Don’t need a Q7 or X5 type although would be nice……

BMW autos are all ZF nowadays. Even the M cars sadly. In which they are arguably too smooth and undramatic for their own good.
 

Mur Huwcun

Member
Livestock Farmer
Location
North West Wales
BMW autos are all ZF nowadays. Even the M cars sadly. In which they are arguably too smooth and undramatic for their own good.

But the 7 speed is dual clutch? 8 speed with a torque converter? Had a look into it last night. Most of these Dual clutch or manual cars now have a first gear too high to comfortably handle their towing capacity
 

oil barron

Member
Location
Aberdeenshire
I always figured that the clutch currently not engaged would wait in neutral until the controller feels confident that an up or downshift was imminent, and only then would it tell the other shaft to engage a gear..

Yes, the first real use was by Porsche racing team in the 80s. The car won a bunch of championships IIRC.
There isn’t really a neutral as such on the gear shafts. The synchros are always engaged in a gear. The break in drive is purely from the odd and even powershift clutches. As has been said if you are in 3rd, and varying your driving style then 2nd and 4th synchro could have been engaged 10 times before you actually go into a gear.
 

ColinV6

Member
But the 7 speed is dual clutch? 8 speed with a torque converter? Had a look into it last night. Most of these Dual clutch or manual cars now have a first gear too high to comfortably handle their towing capacity

Which age of 520d would you be looking at? My knowledge is mainly on the full M cars which have 7 speed M-DCT gearboxes but older generations of normal models may also feature a DCT but I’m sure they are mainly all torque converter. BMW have used the ZF box in most things since approx 2012.
 

Frankzy

Member
Location
Jamtland, Sweden
There isn’t really a neutral as such on the gear shafts. The synchros are always engaged in a gear. The break in drive is purely from the odd and even powershift clutches. As has been said if you are in 3rd, and varying your driving style then 2nd and 4th synchro could have been engaged 10 times before you actually go into a gear.

Think you've misunderstood what I was getting at, while the first shaft is engaged and transmitting power I've always assumed that the gear selectors on the second shaft are all in neutral until the controller thinks a gearshift is close. So rather than constantly moving between say 4th and 6th gear the forks would mostly stay in between gears.
 

oil barron

Member
Location
Aberdeenshire
Think you've misunderstood what I was getting at, while the first shaft is engaged and transmitting power I've always assumed that the gear selectors on the second shaft are all in neutral until the controller thinks a gearshift is close. So rather than constantly moving between say 4th and 6th gear the forks would mostly stay in between gears.
No, I understand what your saying. The forks go straight from 2nd to 4th if you change to 3rd and the odd powershift clutch engages drive. If there was a control logic glitch and both the odd and even powershift clutches engaged the tractor would be in two gears and destroy the box.
 

Mur Huwcun

Member
Livestock Farmer
Location
North West Wales
Which age of 520d would you be looking at? My knowledge is mainly on the full M cars which have 7 speed M-DCT gearboxes but older generations of normal models may also feature a DCT but I’m sure they are mainly all torque converter. BMW have used the ZF box in most things since approx 2012.

I’d be swapping a 15 plate A4 so would have to be 16 onwards. Audi don’t fit the tiptronic box in cars anymore unfortunately
 

lux99slovenia

Member
Livestock Farmer
Tnx for all the answers. So a cvx would be my safest bet. Whats the cvx life span in comparison to fendt vario or JD autopower. Is it more about the driver or workload or brand??
 

Finn farmer

Member
Tnx for all the answers. So a cvx would be my safest bet. Whats the cvx life span in comparison to fendt vario or JD autopower. Is it more about the driver or workload or brand??
More about driver. Been told by a mechanic that the Cvx box costs around 7k€ to fully rebuild if it sh!ts itself. Not cheap, but way cheaper than many others.
 

Frankzy

Member
Location
Jamtland, Sweden
No, I understand what your saying. The forks go straight from 2nd to 4th if you change to 3rd and the odd powershift clutch engages drive. If there was a control logic glitch and both the odd and even powershift clutches engaged the tractor would be in two gears and destroy the box.
Doesn't seem like it...
Actually the video does show that they work like I assumed except rather than shifting the unused shaft into neutral it remains in the gear it was last in right up until the moment you change to a different gear.
IE when shifting to 3rd gear the other shaft keeps 2nd engaged all the way until you actually tell it to shift into 4th and only then does the fork move.

So no, the synchros don't have to work any more in this type of DCT...
 
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