I'm sure I saw a link on here last week to a company selling "bits", one of which was a spoiler to go above the rear window on the tailgate. As SWMABO is complaing about the "mess" all over the back I'm wondering whether one of these might stop some of the spray coming up into the low pressure area at the back. Certainly used to work on Estates in the past.

And yes, I have got rear mudflaps, but they don't help!

She says I do it on purpose.

I've been wondering about a different shaped tailgate, teardrop shape

I assume the problem is that air from underneath the car is being lifted up the rear end to deposit muck on the rear window before it mixes with the air flowing over the roof. So wouldn't a spoiler just discourage the air from the roof from flowing down to mix with the air from under the car? I would have thought this would make things worse??

Years ago, I had a Citroen Visa hatch which also suffered from a dirty rear screen, and I added some aerofoils which clipped on the sides of the hatch to encourage air from the sides of the car to flow round onto the rear screen. Don't think they helped much though in retrospect. But perhaps what is needed is not a top spoiler but a top aerofoil to encourage the air from the roof to flow down the rear screen and mix with the air from under the car at a lower level??

Chris

It certainly needs something . I've never known the rear screen on a car get dirty so quickly.:(

At present the air leaving the rear of the car appears to vortex behind the car, and causes a low pressure area immediately behind the car, around the window area. This "sucks" any spray up from the wheels.

By putting a "lip" on the top of the hatch this can affect the way the air leaves the roof and "spoils" the smoothness of the airflow, thus reducing the low pressure area, so reducing the "sucking" of the spray.

Supposedly!! :S

Graham,

I suspect it is a non-solution. You are talking about a wing at the top of the hatch, re-directing a stream of air down the rear window. It might work with a sedan type sloping shape, but the vertical Yeti rear is most likely too steep to be able to make something that makes the air flow adhere to the window far enough down to be effective.

My Octavia Combi had the same problem - but to a lesser degree - and it's slope was a lot less vertical. I still used more ww fluid on the rear than on the front on that too.

Its one of those things you learn to live with. A bucket of water and a sponge. And, with the summer fast approaching the problem will fade in the bright sunlight.

Another annoyance is the water that drips from a gutter along the top of the rear doors just after they are opened. The gutter forms part of the door seal but when the door os opened the water runs from it towards the hinge end and falls just inside the car by the footwell.

I'm sure I saw a link on here last week to a company selling "bits", one of which was a spoiler to go above the rear window on the tailgate. As SWMABO is complaing about the "mess" all over the back I'm wondering whether one of these might stop some of the spray coming up into the low pressure area at the back. Certainly used to work on Estates in the past.

And yes, I have got rear mudflaps, but they don't help!

She says I do it on purpose.

Would it be www.superskoda.com?

John

I suspect you will need to pop down to Mclaren HQ in Woking, shove the Yeti in their wind tunnel, hook up the computers and see how the air flows. They love sticking bits on cars to move air around how they want it to. V. complicated.

I tend to clean the back every so often when I get to work, my business so no one complains. I keep a bucket and some cloths by the back door and do it when I get to work. The back does get far dirtier than the front which seems odd to me when you would think the front hits all dirt first of all. I do understand the concepts being talked about here though. I would be reluctant to add bits to a car on the off chance it may work. Once added, difficult to remove cleanly.

Would it be www.superskoda.com?

John

Well done John! :thumbup:

http://www.superskoda.com/Skoda/Yeti/Skoda-Yeti-roof-spoiler-SPORTIVE-by-KI-R

Would it be www.superskoda.com?

John

Yes but they are selling roof spoilers. From what we know about mudflaps and the gunged up side panels, would it not be more likely that the crud is coming around the side from the wheels?

The "crud" certainly appears to be coming UP, as it is mostly dirty spray, and to be honest I don't notice that much being thrown sideways by the rear wheels.

On the Freelander the rear window/door on my old 3 door seemed to keep cleaner than the 5 door. The rear shape was exactly the same, but the 3 door had a roof bar over the rear window which I'm sure "spoiled" the air flow over the car.

If the air pressure behind the rear window can be increased then this stops some of the spray rising into that area, and by "spoiling" the air flow off the rear of the car then this could help.

Would it be www.superskoda.com?

John

Yes it is Superskoda:

http://www.superskoda.com/Skoda/Yeti/Skoda-Yeti-roof-spoiler-SPORTIVE-by-KI-R or

http://www.superskoda.com/Skoda/Yeti/Skoda-Yeti-roof-spoiler-SPORTIVE-by-KI-R-V2

You could also have a look here: http://milotec.de/index.php?language=en

Johann

Keep up at the back!!

See my post #10

And Milotec don't list one ........ yet.

Edited 23 March, 201115 yr by Llanigraham

Johann

Keep up at the back!!

See my post #10

And Milotec don't list one ........ yet.

Oops! I should have had something stronger over lunchtime then!

The "crud" certainly appears to be coming UP, as it is mostly dirty spray, and to be honest I don't notice that much being thrown sideways by the rear wheels.

On the Freelander the rear window/door on my old 3 door seemed to keep cleaner than the 5 door. The rear shape was exactly the same, but the 3 door had a roof bar over the rear window which I'm sure "spoiled" the air flow over the car.

If the air pressure behind the rear window can be increased then this stops some of the spray rising into that area, and by "spoiling" the air flow off the rear of the car then this could help.

If you do fit a spoiler please keep us informed of the effect. You might just cause a trend.

I'll just stick with the bucket and sponge for now.

Some cars ago I had a Honda Stream. Good in parts BUT when the boot lid was opened after it had rained all the water poured into the boot. It was like a waterfall.

It also had a bad habit of the drive wheels "tramping" when accelerating from standstill. Asked Honda - it was reported as a design fault and could not be cured. SOLD - one Honda Stream.

Some cars ago I had a Honda Stream. Good in parts BUT when the boot lid was opened after it had rained all the water poured into the boot. It was like a waterfall.

Terfyn you should visit the Octavia forum! Apparently they also have this exact same free waterfall feature when you open the boot.

It will be great if there is a simple solution to the problem - I agree the window gets very dirty very quickly on the road - and the whole back gets filthy off-road - especially the 'bumber' ledge below the back door, which is kind of hollow, and often holds enough dirt to grow tomatoes. I love the car but it definately has a problem keeping it's 'bottom' clean!

Same issue here. It gets really dirty.

Could mudflaps improve this?

I think most (if not all) muck comes from wheels or from under the car and get pulled up on a rear of a car.

When I drive through water I look in the rear mirror and see rear wheels throwing water 1 meter behind.

All cars that I owned that had back part straight like this had this issue. And if the paint is damaged at some place it would start to rust quickly. At least thats my experience here in Norway where besides snow in the winter we have to deal with fair amount of salt also.

This sounds to be a regular problem but what about caravan tuggers? Does the front of the caravan get shot blasted?

Fred

This sounds to be a regular problem but what about caravan tuggers? Does the front of the caravan get shot blasted?

Fred

No worse than normal. My biggest problem is normally flicking sheep poo at it!

TBH the muck on the back is only spray, not bits, but it covers everything, and Sheila doesn't like to get her hands dirty. At the moment it is covered in dust!

And for those that wondered, the rear mud flaps make no difference. I wonder if a set of "rally flaps" might be better?

Yes but they are selling roof spoilers. From what we know about mudflaps and the gunged up side panels, would it not be more likely that the crud is coming around the side from the wheels?

I could be tempted with the roof spoiler though.

John

Would be interesting to see the effects on the Greenline versions, its been lowered to reduce drag and increase fuel efficiency. Mine's still clean just now (from new) once I've been about a bit I'll see the results.

This sounds to be a regular problem but what about caravan tuggers? Does the front of the caravan get shot blasted?

Fred

Let's hope so!

No worse than normal. My biggest problem is normally flicking sheep poo at it!

TBH the muck on the back is only spray, not bits, but it covers everything, and Sheila doesn't like to get her hands dirty. At the moment it is covered in dust!

And for those that wondered, the rear mud flaps make no difference. I wonder if a set of "rally flaps" might be better?

I suspect that rear mudflaps make it worse. There was a big to do about those here many years ago, when the government wanted to make them mandatory. Testing with photos from above showed that mudflaps in the rear generated more division of the spray droplets, so more would be sucked up into the turbulence behind the vehicle.

To keep the rear clear, you need the air flow to adhere to the surface of the car in an almost laminar fashion. The Yeti shape at the rear makes this neigh impossible.