Heights confusion.

Ok so following on from sill and chassis welding I have these possible? Issues. I had to patch behind the left hand height sensor and fabricate and fit a new bracket for the sensor.
So the issues were an uneven height at rear due to sensor readings changing. I set nanocom up and recalibrate them and l seemed ok. Then a couple of days later when the door was opened and ignition turned on the rear dropped to the ground. Closed door and started engine and it rose back to ride height. Car ran to mot test and no issues but it failed on springs and hoses. All new hoses and front springs fitted etc so tonight it was reset suspension on flat surface of garage floor.
I made up 61mm spacers from wood and using nanocom set the drivers side and pass side heights. Loaded these settings to ecu and again all seemed good. A spirit level on roof rails showed all to be level so I was happy with that and the wheel centre to arch was 473mm as many posts state.
However the sun visor says roof rail to floor height should be 1980mm but it's only 1925mm. So this has confused me.
Anyone care to discuss why at 61mm bump to axle clearance and 473mm centre of wheel to arch then why is it 55mm short on height?
Thanks in advance
Gary

The height is declared for vehicle unladen weight as it came out from factory, is your's free of any additional load and front springs and shocks as new? all these elements would lower the body, also the std height is measured to 61.5mm from the tip of a NEW bump stop, an old one gets compressed in time with some mms as well

No additional load. Just under 1/2 tank fuel. Dog guard. Boot empty.
I'm more worried about it dropping at rear and not rising up again. But restart it and it rises to its height. It never did this before. Also i would have thought on airbags the weight was relatively irrelevant as it would self level.
Strange.

You said 61mm spacers but the std height is 61.5 measured from the tip of the bump stop to axle, did you fit the spacers as to have 61mm from the tip of the bump stop? If the target heights are below a limit the SLS will play up like your's

Also i would have thought on airbags the weight was relatively irrelevant as it would self level.
Strange.

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it would self level to the target heights which are dependant by the front's height

One bump stop is missing. So I set other st 61mm as it was as close as I could get. Then levelled other side with spirit level on roof rails at rear as I have full length roof rails
I would have thought that I was near enough at 61mm but maybe not.

You might want to replace the missing bump stop in case the bag goes pop.

They wouldn't be the original bump stops anyway. Is it as crucial as that.

Shimsteriom said:

You might want to replace the missing bump stop in case the bag goes pop.

Click to expand...

Yes good shout

sierrafery said:

You said 61mm spacers but the std height is 61.5 measured from the tip of the bump stop to axle, did you fit the spacers as to have 61mm from the tip of the bump stop? If the target heights are below a limit the SLS will play up like your's
it would self level to the target heights which are dependant by the front's height

Click to expand...

Well I have just fitted 2 new front springs as well. But they're heights are fixed and non adjustable.

What i was trying to say was that the rear will self level according to the front height too... measure the rear height then ask a heavy guy to stay on the front bumper, let the vehicle self level and measure rear height again... you'll be surpised to see that it will be different

sierrafery said:

What i was trying to say was that the rear will self level according to the front height too... measure the rear height then ask a heavy guy to stay on the front bumper, let the vehicle self level and measure rear height again... you'll be surpised to see that it will be different

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So to clarify. Fit 2 new bump stops. Then space axle at 61.5mm both sides by removing air from bags and supporting body with 2 jacks one at each side. Then "get current readings" then "get current heights and save heights. And that's all.

That's for hawkeye but if you have nanocom you dont need any blocks nor jacks, it's much simpler especially if you have assistant, measure front heights from middle of wheel to arch, go with nanocom to calibration menu and raise or lower each side in the menu(it will move about 5mm at each command) untill both rear measurements are equal with the fronts then prompt on "store heights;" ..job done, ...even if after that the readings are different while the physical measurements are equal dont bother with that, it's irrelevant cos there could be objective reasons, long story

sierrafery said:

That's for hawkeye but if you have nanocom you dont need any blocks nor jacks, it's much simpler especially if you have assistant, measure front heights from middle of wheel to arch, go with nanocom to calibration menu and raise or lower each side in the menu(it will move about 5mm at each command) untill both rear measurements are equal with the fronts then prompt on "store heights;" ..job done, ...even if after that the readings are different while the physical measurements are equal dont bother with that, it's irrelevant cos there could be objective reasons, long story

Click to expand...

+1
Yes, this is how I have also done on mine and it works and really easy.

My TD5 is bog standard on springs. But I had need to measure the height in order to determine if I could drive it into a mates garage in an emergency. It measured quite a bit lower than it should according to the thing on the sun visor. Maybe they put that measurement there for twits who put the rear springs right up then try to drive into a car park!
Any one else bored enough to measure the height of their Disco?!

after modifying mine back to normal height (removed 2" lift) I have measured mine and it almost met with the specified. Even my front a bit higher (due to new springs and Bilstein shocks) the rear is on standard height so the roof is around the specified height as well.

Thanks for all the replies folks. I'll get on it at the weekend.