Auto or Manual?

[roachy]

I vote Simex!

??????? care to enlighten us??? or is it just a very random comment, lol

[FridgeFreezer]

Torotrak

Ooooo this, my dad's last car had CVT and it was bluddy brilliant.

[Cat_J]

They have sold the right to tata to build the boxes recently so we maybe seeing them in LRs in the coming years.

[Exmoor Beast]

I hate auto gearboxes with a passion.

The only good thing is they make eating a pasty easier when in traffic.

Will

[pat_pending]

I went from 26-28mpg down to around 20mpg, although I'm hoping to chase some of that back with the VGT and a higher ratio t-box. It sounds low but it's a V8 box and torque converter behind a 300Tdi and I really can't face pulling it all apart again to start experimenting with it...

I'm using a V8 zf auto behind a 200tdi in a 110 csw and i get 27/30 mpg. That's worked out on a brimmed to brimmed tank, not estimated. The box was modded to suit the tdi though.

20mpg sounds bad, what T/box ratio and tyre size are you running ?

I love my auto, on and off road, but TBH i think it comes down to personal preferences. It wont matter which transmission is "better" in any given situation you'll always feel happier with the transmission type you prefer.

An auto conversion is a lot of work to find out you don't like it.

An auto certainly takes the edge off a tdi at low road speed, although you can tweak the pump/boost to improve matters.

Off road, it works perfectly.

[extreme spain]

Auto is defo the way to go, for serious off road and desert use, I converted my V8 90 from manual to auto and runs so much better on sand, also on very steep sticky hills, missing a gear can be disaterous.

[Turbocharger]

I'm on a 1.4 t-box and 285/75 tyres. The box is an unknown quantity but it certainly kicks down like a V8 should (ie up to 4000rpm, which is "exciting" with a Tdi on the front). The odometer under-reads slightly but by a third! I'm hoping the VGT + 1.2 t-box will get me some mpg back.

[Pete Attryde]

I'm on a 1.4 t-box and 285/75 tyres. The box is an unknown quantity but it certainly kicks down like a V8 should (ie up to 4000rpm, which is "exciting" with a Tdi on the front). The odometer under-reads slightly but by a third! I'm hoping the VGT + 1.2 t-box will get me some mpg back.

mine is TDI auto (not V8 box attached to a TDI) and I am running smaller tyres (31x10.5x15 muds) but I get mid 30's MPG on a 1.4:1 t-box (with tweaked pump and boost). I was getting high 20's when I had the 1.2:1 T-box on it. I suspect this is due to the torque converter locking up at around 40 rather than 50 which better suits the roads I normally drive. Although a motorway run (70mph) also seems to return around the mid 30's . This is all in a Discovery by the way. I am about to change the tyres to 33" muds so I will see if there is a big impact on the MPG.

Hth

Pete.

[Turbocharger]

Hmm. My figures are brim to brim over the last 15,000 miles. It's not leaking fuel, the handbrake's not sticking and the wheel alignment is there or thereabouts. It dropped when the box went in and has been consistent, 2 or 3mpg either side depending on what I'm doing with the truck. Have I missed something like bleeding out the torque converter or setting the gearbox oil level to within a whisker of where it should be?

[pat_pending]

I run 235/85s and a 1.4 T/box. I know v8 spec boxes aren't ideally suited to a tdi, but as the internal gearing is the same it shouldn't make that much difference, it's all in the shift points. You could try fitting a tdi spec governor.

T/box will have to come off to do it, but the main box can stay in.

[MJIbex]

Ooooo this, my dad's last car had CVT and it was bluddy brilliant.

What was it then? I've never driven a CVT that I liked!

[T1G UP]

Navara auto's are CVT! shocking!! if it wasn't for the cooling fan roaring all the time you'd think the engine was on the limiter.To much slip.

DSG's the future.Best of both worlds.

[FridgeFreezer]

What was it then? I've never driven a CVT that I liked!

Nissan Primera, it was shocking just how quickly you got to be going very fast - the gearbox talks to the engine so when you hoof it the RPM needle hits the centre of the power band and then just stays there solid while the gearbox ramps up the gearing to match it. You don't get any sensation of speed because there are no shifts, then you glance at the speedo

[T1G UP]

Nissan Primera, ***** ****** ******* ***** very fast - **** ****** ****** ****** power band ***** ***** ***** ramps up the gearing to match it. You don't get any sensation of speed ****** there are no shifts, then you glance at the speedo

Having picked myself off the office floor my comment would be that you've been driving round in a series for tooo long, you know there are some cars available now that can break the national speed limit

[Dave W]

I'm on a 1.4 t-box and 285/75 tyres. The box is an unknown quantity but it certainly kicks down like a V8 should (ie up to 4000rpm, which is "exciting" with a Tdi on the front). The odometer under-reads slightly but by a third! I'm hoping the VGT + 1.2 t-box will get me some mpg back.

You need to be careful changing transfer ratios with a ZF auto. The torque converter isn't particularly efficient in an auto and to improve on this the ZF 4 speed "locks" the torque converter up at certain speeds/pressures/throttle positions. This greatly improves the MPG. If your gearing is preventing the torque converter locking up then you'll increase your fuel consumption. Sometimes, especially with large tyres, going for a lower ration transfer box can actually improve MPG because the TC stays locked up for longer periods, particularly when cruising at a constant speed.

[Pete Attryde]

You need to be careful changing transfer ratios with a ZF auto. The torque converter isn't particularly efficient in an auto and to improve on this the ZF 4 speed "locks" the torque converter up at certain speeds/pressures/throttle positions. This greatly improves the MPG. If your gearing is preventing the torque converter locking up then you'll increase your fuel consumption. Sometimes, especially with large tyres, going for a lower ration transfer box can actually improve MPG because the TC stays locked up for longer periods, particularly when cruising at a constant speed.

Thanks for that Dave, that ties up with my experience so far. Having changed from the 1.2:1 to the 1.4:1 box but the same size tyres i found I was using 15litres less fuel a week for the same amount traveled.

Pete.

[FridgeFreezer]

Having picked myself off the office floor my comment would be that you've been driving round in a series for tooo long, you know there are some cars available now that can break the national speed limit

I never said it was a Ferrari for what it was, it got up to speed very quickly and quietly compared to other 2.0 Hatchbacks including the two previous 2.0 Primeras with manual boxes that my dad owned. Happy?

[ibexman]

So what are we saying here auto works better with defender 14 transfer box or 12 disco box , ithought the discovery box would give you more mpg as you can hold gears for longer i suppose thats where compushift would come into the picture cheers chris

[T1G UP]

I never said it was a Ferrari for what it was, it got up to speed very quickly and quietly compared to other 2.0 Hatchbacks including the two previous 2.0 Primeras with manual boxes that my dad owned. Happy?

[Pete Attryde]

So what are we saying here auto works better with defender 14 transfer box or 12 disco box , ithought the discovery box would give you more mpg as you can hold gears for longer i suppose thats where compushift would come into the picture cheers chris

I think it depends on the type of journey the vehicle regularly does. Mine mostly does a 25 mile journey on narrow B roads and rarely exceeds 50mph due to the type of road. Because with the 1.4 transfer box I get torque converter lock up at about 40mph rather than the 50ish mph it was with the 1.2 transfer box i get better fuel economy, where as if I was doing lots of motorway driving the 1.2 box would give better economy as the engine would be at lower rpm for a given speed.

Hope that makes sense,

Pete.

[T1G UP]

So tyre size, when the gearbox locks and driving conditions all play a part.

This is where the compu shift would do it's bit i suppose.

[Dave W]

So tyre size, when the gearbox locks and driving conditions all play a part.

This is where the compu shift would do it's bit i suppose.

It's all about keeping the box in the best gear for the conditions so the overall gearing can have unexpected effects. An adjustable shift pattern like the compushift offers can help mask the effects a bit but you still need the right balance of final ratios, torque convertor etc...

Most RV8s, as an example struggle much below 2000 RPM so even when cruising on a motorway, if 70MPH drops you below 2000 RPM then the slightest incline or headwind will require you to kick down to keep a constant speed. As well as being tiring this will kill your fuel consumption. Whilst cruising at 70 with the auto box locked up you may feel that you'd get better fuel consumption at 2000 RPM but you'll actually get better overall consumption at around 2500-3000 RPM.

If you have enough torque to pull 70 up a moderate incline without much increase in throttle then you're in about the right place, gearing wise IMV. Having played around with lots of combinations of transfer box, gearbox, engines, wheel sizes I always seem to end up altering the transfer box to that point. I'm currently running a 1.2 transfer box with 35 inch simex but that's only because I have the torque in the engine to hold it.

[T1G UP]

It's all about keeping the box in the best gear for the conditions so the overall gearing can have unexpected effects. An adjustable shift pattern like the compushift offers can help mask the effects a bit but you still need the right balance of final ratios, torque convertor etc...

Most RV8s, as an example struggle much below 2000 RPM so even when cruising on a motorway, if 70MPH drops you below 2000 RPM then the slightest incline or headwind will require you to kick down to keep a constant speed. As well as being tiring this will kill your fuel consumption. Whilst cruising at 70 with the auto box locked up you may feel that you'd get better fuel consumption at 2000 RPM but you'll actually get better overall consumption at around 2500-3000 RPM.

If you have enough torque to pull 70 up a moderate incline without much increase in throttle then you're in about the right place, gearing wise IMV. Having played around with lots of combinations of transfer box, gearbox, engines, wheel sizes I always seem to end up altering the transfer box to that point. I'm currently running a 1.2 transfer box with 35 inch simex but that's only because I have the torque in the engine to hold it.

I see.

Torque is a given, so are the dia of wheels really. TB is easy to change.

[Bill Shurvinton]

Interestingly I had a long chat with a transmission engineer a while back who said he had never seen any evidence that a lock up gains you anything in real use. You need power to keep the TCC applied which in many cases is greater than any saving you have over leaving the TC unlocked.

[T1G UP]

Interestingly I had a long chat with a transmission engineer a while back who said he had never seen any evidence that a lock up gains you anything in real use. You need power to keep the TCC applied which in many cases is greater than any saving you have over leaving the TC unlocked.

As i understand it the lock up is an electronic thing with the compu shift. this would allow it to act more like a manual box, less slip and wasted energy when in the gloop. better control when on the road.