Lowering a P38

[mbm]

Is it possible to fool the electonics to lower an 99 RR 2.5 DSE it by 1 ½ inch?

In my country cars are taxed in motorways according to the height over the fist axle: under or equal to 1.10 m or over; the difference in is roughly 100%.

Using stock tyres RR measures 1.12 m, lowering tyre pressure from 34 to 25 psi measures 1.07 m.

You can ask motorway administration for a new measurement of your car, but you must go in and out "using" the measured height, so the easier way to go shall be another setup in electronics.

As well I dont think that in motorways an 1 ½ inch less makes any difference.

Thanks,

Mário

[David Sparkes]

Try using this circuit, but connect the 1.5 volt battery the otherway round, so that instaed of "subtracting a constant voltage"', you add voltage.

http://tinyurl.com/axkck

I have not tried the circuit in either configuration.

You say "you must go in and out "using" the measured height," presumably this is in and out of the measurement centre on a special visit, not in and out of a toll booth on your normal journeys.

I assume you are already holding the motorway height when you go for measurement?

Let it drop down normally, as it does over 50 / 55 mph, then press the inhibit button.

This Motorway height will be maintained at all times, even when restarting after switching the engine off.

Assuming that doesn't give you the required height,

If you can move slowly over the required distance, have you tried the 'Manual Access' mode?

With the engine running, select the Access height. When that is reached, press the Inhibit button. The Control Centre should beep and display Manual. If you keep your speed to below 5mph the suspension should stay in Manual mode. Note that if you switch the engine off, you have to reset the Manual mode, release the Inhibit button, select Access height, then press the Inhibit button again.

This may be too risky for your measurement check, but it will at least show you if 'tricking' the suspension to Access height gives you the required reduction.

"I dont think that in motorways an 1 ½ inch less makes any difference."

Travelling at speed at the access height is dangerous. The car is on the bump stops, and hitting any sort of bump or pothole, or even doing an avoidance swerve, could esaily result in loss of control as the suspension becomes fully compressed, ie solid.

HTH.

[FridgeFreezer]

Surely rather than using a battery (which IMHO is a nasty electrical hack any day of the week) you could use diodes (which normally drop 0.6v across them) to the same effect?

You can either put more diodes in series to get .6v steps, or be sexercisey and buy a Zener of the right rating.

I drawed a piccyture:

And realised that whioever designed the battery-based circuit could've just shoved a diode/diodes into the + side of the sensor feeds rather than that lash-up of a circuit. I bet he uses Bodgelok connectors

[David Sparkes]

If you have a query with the circuit you can easily contact the originator.

His name is John Brabyn, he owns and runs www.Rangerovers.net

You will find he is always open to suggestions, be they either alternatives, or improvements.

HTH

[mbm]

Tanks to all, even for understanding my poor English.

A friend of mine is skilled in electronics, so we will try your sugestions.

Mário

[SteveG]

Mario

You have two choices.You can adjust the height at either your local LR dealer or at an indepedent that has access to diagnostic equipment.You could also do this yourself using Rovacom Lite and a laptop.

Or you can just simply put at resistance pot in the common neg circuit on pin 24.This adds an additional resistance to each height sensor effectively reducing the height all round. It's that simple and you can adjust the height to whatever level you need.

Cheers

Steve

[FridgeFreezer]

Why not have a pot for each wheel - hours of fun!

[SteveG]

yeah, was going to do a pot for each side so that you can tilt it on side slopes or to sneak under a tree on a lane, but never got round to it.

Steve

[FridgeFreezer]

Oooo you know you want to:

[geoffbeaumont]

yeah, was going to do a pot for each side so that you can tilt it on side slopes or to sneak under a tree on a lane, but never got round to it.

Steve

Now that's a good idea...I was toying with the idea of something like this, but I was thinking of replacing the control module with something possibly based on Megasquirt hardware*. That'd let you do a few other things, and (where the thinking started from) get round the problem of reseting the wretched thing after a fault, but you could do a lot with just a few potentiometers...

* - shouldn't be too tricky on a Classic like mine. I suspect it would be much harder on later land rovers as I think the EAS controller is linked to the rest of the electronics.

[FridgeFreezer]

Hang the joystick upside-down with a weight on the handle and it'll keep the vehicle level at all times! OK it's of limited use, but would be interesting...