Thread: 18" Compomotive Wheels

Originally Posted by Graeme

The tyre size is equivalent to only an extra 5% load so minimal impact and accommodated by the gearbox hanging onto lower gears for a fraction longer.

Hmm ... that is the 285/60 compared to the 255/60.

I trailered up to Alice Springs on the bitumen, and watched the instant fuel economy gauge (for something to do ... I was alone going up to Alice).

Towing maybe 2.3 tonne with the GOE wheels on the 255/60 Grabbers. An interesting thing was that there was a big difference in economy, running in 8th gear, rather than 7th, when on a slite incline (going up), at about 90-95 KMH (real speed). Between 3 and 2.5 litre/100 KMH. So - I changed into 8th several times, to keep the fuel consumption low.

But I also noticed when I did this, that eventually, the gear selector (the rotating nob where the gear shift lever should be) became warm. Yep ...

So ... I don't know how the car knows the gearing, or when to change the gears. But ... since the gearbox hangs onto gears more when the trailer light is activated, I presume it changes gears on some formula of variables, and I don't know if gearbox temperature is a variable.

It does concern me a bit if the motor sits in a higher gear, and stress the gearbox more. Its not an issue if one does not tow. Maybe its not an issue anyway ... I am not sure. I'd like to see the gearbox oil temperatures though while I drive. I do not know how strong the 8th gear is ... there's lot of gearboxes with overdrive top gears, that are a lot weaker than they should be.

With a Toyota, you add another transmission cooler. Those that do, see major lower temperatures in their gearboxes ... and high temperatures in Toyota gearboxes mean the gear boxes may not last. Evidently no one adds a trannie cooler to a D4???

I am happy to save fuel though ...

I too like to not unnecessarily use fuel. I often up-shifted my 3.0's 6-speed and now do so with the RRVs 8-speed, but don't let revs get too low for the work being done by the engine. The RRV's TDV8 is happy to run down to 1000 rpm in 8th uphill although I like to see 1200 rpm as a minimum in this situation, mostly because the engine is not very responsive below 1200 rpm especially with the 1T its had in tow a few times recently. The RRV is more highly geared than the D4 and moreso with its oversized tyres, so low revs are the norm.

Apparently MR auto in brissie do an extra tranny cooler for the d4, they've mentioned it a couple of times to me

Originally Posted by Melbourne Park

Hmm ... that is the 285/60 compared to the 255/60.

I trailered up to Alice Springs on the bitumen, and watched the instant fuel economy gauge (for something to do ... I was alone going up to Alice).

Towing maybe 2.3 tonne with the GOE wheels on the 255/60 Grabbers. An interesting thing was that there was a big difference in economy, running in 8th gear, rather than 7th, when on a slite incline (going up), at about 90-95 KMH (real speed). Between 3 and 2.5 litre/100 KMH. So - I changed into 8th several times, to keep the fuel consumption low.

But I also noticed when I did this, that eventually, the gear selector (the rotating nob where the gear shift lever should be) became warm. Yep ...

So ... I don't know how the car knows the gearing, or when to change the gears. But ... since the gearbox hangs onto gears more when the trailer light is activated, I presume it changes gears on some formula of variables, and I don't know if gearbox temperature is a variable.

It does concern me a bit if the motor sits in a higher gear, and stress the gearbox more. Its not an issue if one does not tow. Maybe its not an issue anyway ... I am not sure. I'd like to see the gearbox oil temperatures though while I drive. I do not know how strong the 8th gear is ... there's lot of gearboxes with overdrive top gears, that are a lot weaker than they should be.

With a Toyota, you add another transmission cooler. Those that do, see major lower temperatures in their gearboxes ... and some temperatures in Toyota gearboxes mean the gear boxes don't last. Evidentally no one adds a trannie cooler to a D4???

I am happy to save fuel though ...

Originally Posted by sctsprin

Apparently MR auto in brissie do an extra tranny cooler for the d4, they've mentioned it a couple of times to me

I am in Melbourne ... is there an auto trannie place in Melbourne expert in the ZF gearbox and Land Rovers?

It's not rocket science though ... if I could see the live temperature of the gearbox, then I'd know what was necessary ... either use 8th more, or use 7th if the temperature rises. I do not know if the gearbox temperature increases if you force the gearbox to stay in 8th? I do think it increases stress on 8th though.

I also don't know about whether the ZF 8 speed gearbox LR uses has a strong 8th gear ... one sees Toyota 76s, people are told not to use 5th when towing, as the gear is purely an overdrive. There's lots of rebuilds for those gearboxes where they put in a stronger 5th gear...

Graeme, the SD6 3 litre diesel motor - as you well know - also has quite a defined bottom end on torque ... which I presume happens higher than the V8's. I am not sure when it runs out ... Land Rover claim that 85% of its 600Nm is available almost instantly, so that's at least 510 Nm ... hmm.

In the Range Rover sport now, they have dropped the twin turbos in the TD V6 but retained performance and improved fuel economy and emissions. IMO the V8 (now 4.4 litres and made in Mexico) may have a restricted life ... evidently Ford have not been able to sell it into their petrol F250 350 markets ... its not a cheap motor to make it seems, even in Mexico. Also IMO, with LandRover having a new diesel engine operation in the Midlands, perhaps the V6 is the last of the Land Rovers using a motor built by Ford at their joint venture (with Peugeot) operation? Got to love the idea of the V8, and also, I particularly like the chain timing gear rather than need to replace belts.

In the SD version of the 3 litre V6 in the Range Rover Sport now, they have kept the twin turbos, but claim by calibration changes and an injector change, they now have 700Nm available at 1450 RPM, and better fuel economy. Those revisions sounds good for towing. A chap I know has had his SDV6 Disco ECU flashed and reckons there's a lot more go and better fuel economy too ... but for me, I suspect upping the torque will just add stress to the driveline.

At an indicated 100 KMH, which is about 96 KMH actually - my engine speed is I think about 1430 RPM. Interestingly if I control the gearbox with the steering wheel flap switches ie manually - the gearbox will not automatically change up when the motor falls of its healthy torque behaviour (unlike in a Toyota when the gearbox will take over and change gears despite being in a manual mode). There does seems heaps of torque though at a real 96 KMH or 1430 RPM. But at 90 its feels as if its fallen off its strong torque IMO, so I guess below at 1330 RPM the torque curve isn't healthy like the V8's is.

A review I recall in Australia said that the 2013 TDV6 had 520Nm (its maximum) available at 1500 RPM, and that is what LR specify the TDV6 as having ie 520 NM from 1500 to 2500 RPM; yet they say the SD has 600NM @2000. But they do not provide data that I have seen, saying what the torque is at 1500 RPM. On my tests, the SD felt quite a bit quicker than the TD, but I did not do tow and have a lugging comparison during a suburban test drive.

As far as lugging the diesel engine, I doubt that it hurts it at all ... but that is not the case with the gearbox IMO ... but I do not know much about the 8 speed. Perhaps a gearbox that can handle a top level 7 series BMW on the autobahn might have a strong 8th gear ... but I have no idea whether that is the case. Not sure if the 8 speed gearboxes have been revised for the latest power and torque increases for the diesel motors in the UK either ... from the test reports, the 4.4 litre V8 isn't performing as well as the revised V6s.

Regards

Doug

The biggest generator of heat in auto boxes is torque converter slip. Keeping a look-out for TC slip and up-shifting or down-shifting as appropriate will reduce heat. The 8-speed in mine likes to slip whilst in 2nd when slowing for street corners then doesn't lock until speed and revs are considerably higher. Dropping to 1st or up-shifting to 3rd will result in a locked TC.

LR announced at its release that the 4.4 TDV8 was deliberately detuned (lower specific output) for improved longevity compared with the 3.6 TDV8 and the 3.0 TDV6/SDV6. However its no longer favoured by LR due to it being heavier than the V6 - at least that's what LR is saying publicaly.

Way off topic but how can you tell the slip is happening in second gear?

Scott

Let me bring it back on track.

Rims and tyres, done and dusted with OEM TPMS. 6 x D697, 265/60R18 balanced and fitted $2K.

Wow, how quite. First thought rear bearing. GG AT 255/55R19 after 55,000km get pretty hard, noisy and side wall cuts with several trips to the cape and back and the high country.

Great product Gordon, combined with the GEO rods, protection plates. Very pleased with the outcome, ready for the trip north again with the X20 in tow.

Will weigh the spare in the morning..

Thanks to all those providing constructive feedback on selection.



Regards

Gerald

Originally Posted by VK3GJM

Let me bring it back on track.

Rims and tyres, done and dusted with OEM TPMS. 6 x D697, 265/60R18 balanced and fitted $2K.

Wow, how quite. First thought rear bearing. GG AT 255/55R19 after 55,000km get pretty hard, noisy and side wall cuts with several trips to the cape and back and the high country.

Great product Gordon, combined with the GEO rods, protection plates. Very pleased with the outcome, ready for the trip north again with the X20 in tow.

Will weigh the spare in the morning..

Thanks to all those providing constructive feedback on selection.



Regards

Gerald

Bloody neat looking D4 there
Andrew