wheel ratio

**thai_tiger** · 11th February 2020, 12:21 AM

Hi, after fitting MT 265/75/16 the auto change points and speedo are out. I understand that you can adjust wheel ratio in Nanacom which will correct road speed but will that in turn correct gear change positions, or do you still need to swap out ratio's in the TC.

**pojir** · 11th February 2020, 12:37 AM

The nanocom adjustment is for display purposes in nanocom itself only.

**thai_tiger** · 11th February 2020, 01:04 AM

Originally Posted by Fluids

To adjust the tyre co-efficient setting on the nanocom evo, page right all the way from the instrument mode screen ... It's found on the last page.

Sent from my iPad using Braille

I remember it being posted before but cant find the detailed instructions

when changing the values in Nanacon will that effect gear changes

**rick130** · 11th February 2020, 02:39 AM

You need a speedo corrector like the C6100 Hunterdi one, as said the Nanocom only changes the displayed speed in the Nanocom

**trout1105** · 11th February 2020, 10:08 AM

Find a nice quiet straight 10k stretch of road and sit on EXACTLY 100kph and Time how long it takes, This will give you a pretty accurate estimate of what your Actual speed is when the speedo is showing 100kph and drive accordingly

I run 245/70/16 tyres on my D2a and when new there is a 5% difference in the actual speed and that shown by the speedo, Your new 265/75/16's will be a higher percentage of maybe 8/10%.

**scarry** · 11th February 2020, 10:13 AM

Or just borrow a GPS such as a Garmin street finder,if you don't have one.

It will let you know what your actual speed is,and they are very accurate.

**PhilipA** · 11th February 2020, 10:37 AM

My speedo is out 5% with 255 70/16 BFGKOs. I just use the Garmin which also tells me if I am in a mobile camera zone and over with continuous dings.

I would think 245s would be more like 3%.

I don't seem to have any problem with change points, so I wonder if you have a dud MAF.

The biggest downside I have is when I want to lock up third in a 70 Km zone and have to do 74.

You need a box to change speedo, and from the several reports on here they can be troublesome.

Regards PhilipA

**gavinwibrow** · 11th February 2020, 10:41 AM

Originally Posted by rick130

You need a speedo corrector like the C6100 Hunterdi one, as said the Nanocom only changes the displayed speed in the Nanocom

Hunter corrector only affects speedo - doesn't affect revs for gear changes - ie the gear changes are rev/load based.

In my case 4th gear lockup changed from 80 to 89 kmph when I went to 265 75R 16, and all other gear changes likewise occurred at higher speeds after the tyre increase.

**rick130** · 11th February 2020, 10:48 AM

Originally Posted by gavinwibrow

Hunter corrector only affects speedo - doesn't affect revs for gear changes - ie the gear changes are rev/load based.

In my case 4th gear lockup changed from 80 to 89 kmph when I went to 265 75R 16, and all other gear changes likewise occurred at higher speeds after the tyre increase.

And speed it seems, too.

With 265/70's my 4th lockup is now 84-85 from 80 which tallies with your observation, but my 3rd lockup stayed the same at 70 and has now dropped to pretty much spot on 60 as the auto has 're-learnt' change points and driving patterns.
2nd lockup I'm not sure, never paid much attention to it.

Change up points under full load are obviously rev based.

**shack** · 11th February 2020, 11:27 AM

Originally Posted by rick130

And speed it seems, too.

With 265/70's my 4th lockup is now 84-85 from 80 which tallies with your observation, but my 3rd lockup stayed the same at 70 and has now dropped to pretty much spot on 60 as the auto has 're-learnt' change points and driving patterns.
2nd lockup I'm not sure, never paid much attention to it.

Change up points under full load are obviously rev based.

The shift points on all discovery 2 vehicles are decided by a number of factors-- only once the ecu estimates that the auto is up to operating temperature.

It relies on engine load, engine speed, throttle position, road speed and from memory a couple more things.

So putting bigger tyres on means that the real vehicle speed is now faster than before for the same engine revs, however this is often offset by the engine load being increased slightly due to the very same, so different outcomes will be had vs normal/original in different scenarios.

For instance driving up a slight incline will require less engine speed than before to maintain 85 kmh, but quite possibly more throttle% to maintain this, and then of course the vehicle may fail to lockup, or even come out of lockup where it didn't before.

As far as I'm aware the Bosch who didn't have the ability to really learn different shift points, but rather the potatoes required to complete the shift in a timely fashion without abuse to the box.

The later model ecu available seems to (from testing) have identical lockup patterns for 3 gear, including the point it unlocks at.

In fourth gear however the late model one provides a "better" driving experience.

Whilst the early ecu locks up 2 kmh earlier, the late one will maintain lockup in light/no throttle scenarios for 7 km below the initial lockup speed.

This is all td5 info.

The v8 uses a different ecu with vastly lower lockup points, and the American one has secondary mapping that can be selected if running the 4.6 vs 4

Cheers
James

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