Wading depth bad day in Glasgow

Wading depth bad day in Glasgow

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Discussion

ashenfie

Original Poster:

714 posts

47 months

Saturday 8th October 2022
quotequote all
Air suspension now that something I have neaver had or considered. So I can adjust the suspension harder and higher too then?

Edited by ashenfie on Saturday 8th October 12:14

OutInTheShed

7,676 posts

27 months

Saturday 8th October 2022
quotequote all
If a car is wading 600mm, either it's got a whole lot of ground clearance or it's letting a lot of water in, or it's in danger of floating away.
If you take the enclosed area as about 3m x 2m, that only needs to be immersed to 0.33m to provide 2 tonnes of buoyancy.
The risk is that a small cross current will take you off the road.
If you've got enough buoyancy to take a significant fraction of the weight, you lose that fraction of traction, steering, braking.


You really don't want a car that's done excessive wading.
Even if it's only trivial stuff that goes wrong it can be a world of pain.

IC, EV, even a pushbike can run up a fair old bill a few months later.

Pica-Pica

13,833 posts

85 months

Saturday 8th October 2022
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My F30 says 250 mm wading depth. That assumes calm water, which is never a given. If you try wading through flood water, there are so many unseens; rocks, lifted inspection-covers. Finally with under-shields there is the risk of the whole vehicle floating away.

TheDeuce

21,737 posts

67 months

Saturday 8th October 2022
quotequote all
ashenfie said:
Air suspension now that something I have neaver had or considered. So I can adjust the suspension harder and higher too then?

Edited by ashenfie on Saturday 8th October 12:14
Yea, the coilovers/struts are replaced with cylinders of air, along with a compressor, and by altering the air pressure in the cylinders the car can be raised/lowered.

As another benefit, on most cars with air suspension on all four corners, if you load the car unevenly the air pressure is altered to level the car and return it to the ideal rolling height.

Yet another benefit is that at higher speeds the car can squat down to create more controlled airflow between the floor of the car and the road surface which reduces aero drag = increases range.

This stuff used to be the preserve of heavier luxury SUV's, Range Rovers have used air suspension for donkeys years. But most EV's are pretty heavy lumps.. In EV world, at least the more premium end, it's commonplace - sometimes as an option but often included by default.

Back in the day air suspension was seen as 'something to go wrong' which was fair enough, but it's been around for decades now and is extremely reliable. Obviously it's more likely to eventually go wrong than traditional suspension.. but traditional suspension starts to compress and soften as it ages and whilst not 'broken' should probably be replaced on older cars anyway to return the ride and handling to design spec. Air suspension by contrast will never 'age' it'll perform the same as new until the day it eventually gives up.

JLR were one of my clients and I've spent many hours in bars chatting to their engineers about the merits and complexities of air suspension smile


TheDeuce

21,737 posts

67 months

Saturday 8th October 2022
quotequote all
OutInTheShed said:
If a car is wading 600mm, either it's got a whole lot of ground clearance or it's letting a lot of water in, or it's in danger of floating away.
If you take the enclosed area as about 3m x 2m, that only needs to be immersed to 0.33m to provide 2 tonnes of buoyancy.
The risk is that a small cross current will take you off the road.
If you've got enough buoyancy to take a significant fraction of the weight, you lose that fraction of traction, steering, braking.


You really don't want a car that's done excessive wading.
Even if it's only trivial stuff that goes wrong it can be a world of pain.

IC, EV, even a pushbike can run up a fair old bill a few months later.
A typical SUV EV is about 2.2-2.8 tonnes and if it were in 600mm water only about 400mm would be beneath the water. The door seals would be about 300mm beneath the water, so under very low hydrostatic force, they won't form perfect seals but under such low pressure any water that does get in would be minimal.

Just don't hang around in the water all afternoon as you'll eventually get soggy feet.

OutInTheShed

7,676 posts

27 months

Saturday 8th October 2022
quotequote all
To be fair, even conventional suspension will extend some when you take half the weight off due to buoyancy.

But really, you don't want to be wading in a car. Just so many things to go wrong, either instantly or later.

I used to drive down a road with some dips which now and then flooded to a max of a foot or so.
My favoured method was to follow the lorries which would race through emptying the dip, giving me just enough time to nip through before the water flowed back.