Rear wiper query.

  • Thread starter Thread starter DQuaN
  • 26 comments
  • 1,006 views
DQuaN

DQuaN

Goat of the Year
Premium
Messages
12,299
United Kingdom
Ealing-London
This has been bugging me for a while and i was observing it on the way to work this morning.

Why do all hatchbacks have a rear wiper, and all salloons/sedans do not?

Why is it neccecary on one car but not the other?

At first i thought it might have somethigng to do with the gradient of the rear window and how water might run off. But as I was driving to work i saw many cars with varying gradients on their rear window, but it had no effect on whether they had a rear wiper or not. Only hatchbacks have them. Why?

Answers on a postcard please.
 
It is generally to do with gradient, and the fact that the more gradient you have - the bigger the window is and therefore potentially a bigger obstruction to rear sight. Personally i think its because its mostly women who own hatch backs and they need all the help they can get when it comes to reverse parking :sly:
 
What boggles me even more is that the Hatchback version of the Mazda 6 has a rear wiper, whereas the Saloon version doesn't. Both cars are very similar at the rear.
 
DQuaN
Why do all hatchbacks have a rear wiper, and all salloons/sedans do not?
Click to expand...

My car is a hatchback, and does NOT have a rear wiper. The rear window is huge, tinted, and generally impossible to see out of at night, or in the rain.
I'm sure it doesn't have a rear wiper due to the odd shape of it, and that it's massive.
 
I've just moved from a hatchback to saloon version of the same car and it anoys the hell out of me that i can't just use the (now non-existant) rear wiper to clear my rear screen. I suppose i should just clean my car more often instead of its usual bi-yearly wash.
 
haha, well ive never owned a car with a rear wiper, so im not used to the luxury of having one. but have never seen it as a necessity other than to give women more of a view when backing up or parallel parking :)

please hold all verbal bashings to PM's
 
My car is not a hatchback but does have a rear wiper.
 
I always thought the reason for hatches having a rear wiper is the steeper angle of the rear window and the fact that there's no boot preveting rain from being thrown onto the window by the back wheels. With a sedan, that won't happen, but with a hatch, it sure can.
I have a sedan as well, and I really like rear wipers. So here's what I did. I bought a bottle of this anti-rain stuff that makes your windows so smooth, the rain will just run off. Actually, this is meant to be put on the windscreen, but I only used it for the back window. It works very well, the airstream blows all the water away immediately.

Regards
the Interceptor
 
I think it's all supposed to be based on the way water is sucked from the rear of the car and onto the glass. In a station wagon (or an Estate) the glass is pretty much vertical - spray builds up very quickly.

In a sedan the boot section is there and prevents spray from landing on the glass.

At least this is what I understand as the theory.

Now, I just think it's a decision that is made by the factory/designer as to what looks good rather than having a functional reason to have one or not.

I've got a Mini with a near vertical rear window and that ain't go no rear wiper. My hatch does though...

If I can't see out the back I just use the side/wing mirrors anyway.
 
Don't know how true this is, but a friend of mine works at Toyota and told me it's a European law that all hatchbacks must have a rear wiper...

Moreover, iIf you look in GT4 (sheesh, what an example) many non-hatchbaks have a rear wiper, like some Imprezas and Skylines.

But I think the Intrerceptor and ferrari_chris are on the right track as to it being because the rear wheels build up much more water on the rear window tan on a saloon car.
 
ferrari_chris
I think it's all supposed to be based on the way water is sucked from the rear of the car and onto the glass. In a station wagon (or an Estate) the glass is pretty much vertical - spray builds up very quickly.

In a sedan the boot section is there and prevents spray from landing on the glass.

At least this is what I understand as the theory.

Now, I just think it's a decision that is made by the factory/designer as to what looks good rather than having a functional reason to have one or not.

I've got a Mini with a near vertical rear window and that ain't go no rear wiper. My hatch does though...

If I can't see out the back I just use the side/wing mirrors anyway.
Click to expand...


i agree with you completely. that makes perfect sense and it very true at the same time.
 
Diego440
Don't know how true this is, but a friend of mine works at Toyota and told me it's a European law that all hatchbacks must have a rear wiper...
Click to expand...

If its european law, then it must be a new one - i've had hatchbacks in the past with no rear wiper - looking out of my office window i can see a couple of hatchbacks, no older than 2-3 years old with no rear wiper.
 
TheCracker
If its european law, then it must be a new one - i've had hatchbacks in the past with no rear wiper - looking out of my office window i can see a couple of hatchbacks, no older than 2-3 years old with no rear wiper.
Click to expand...

yeah, but you're in the UK, and you guys always need to have it all your way... :lol:
 
Wow, DQuaN, you’ve read my mind! I was seriously going to post this exact same question this morning! :eek: I’ve been driving the Subie wagon for a long time, and it had a rear wiper, but today while driving my Mazda 3 I became really annoyed with it not having a rear wiper, because it was raining really bad and I couldn’t see anything behind me (ended up cutting off a few cars because of that). Then I also noticed that the Lancer Evo sedan has a rear wiper, but no other sedan seems to.

Anyway, everything said in this thread makes sense, but it still sucks ass in the rain. :grumpy:
 
My truck is a hatchback more or less and it doesn't have a rear wiper. It sucks to since my back window gets really nasty after it rains.
 
I've owned two Chryslers, a Plymouth Voyager Minivan and a Reliant-K Wagon. Both had a rear wiper, though the one on the Voyager, like most others of it's kind, didn't work.

I think it also has to do with areodynamics. my Nova sedan - I'm sorry, Saloon - doesn't have rain build-up on the rear window, because the slipsteam is all behind the trunk. The slipstream pulls the mist off the tires as high as the trunk, but no higher

The slipstream on my wagon (Shooting Brake?) and Minivan, (MPV?) however, pulls the mist from the tires all the way onto the rear window. Necessitating the rear wiper.

Sadly, both the Wagon and Minivan now live in a junkyard. I wrecked both of them.
 
My car doesn't have a rear wiper, but the JDM version does, as with most cars that were offered in both market places.
I noticed this a long time ago when my moms minivan had a rear wiper with only a 1 1/2' tall window and my car didn't with its huge 2 1/2' tall window. One thing I did notice though was the way water sat on the windows. On my moms it runs over the window in layers, distoring the vision, and in mine, it runs over the window and off smoothly, distorting little vision.
 
The rear wiper isn't limited to hatchbacks -- it's also found on some fastbacks (such as the Mazda RX-7)...

I have no idea why it is or is not available on certain models. As ferrari_chris said, it may very well just be a visual style thing. :indiff:
 
It's because of the trunk on a 3-box sedan/saloon vs. the 2-box shape of a hatch or wagon. The trunk allows for a smoother slipstream and consequently spray tends to be whipped over the back window and trunk deck, without collecting so much on the back glass.

But the angled back glass of a hatch or wagon creates a vacuum without the decklid to direct airflow. This void attracts and collects a lot of spray which is then deposited on the back glass. You'll see a lot of older wagons (like c. 1970) that had a little deflector across the rear edge of the roof to direct airflow down over the backglass and prevent this low-pressure area from forming.
 
I skimmed through the topic, but wouldn't it be due mainly to IF the person chooses the option of having on OR not?

I know here it usually is an option on cars..
 
Duke
It's because of the trunk on a 3-box sedan/saloon vs. the 2-box shape of a hatch or wagon. The trunk allows for a smoother slipstream and consequently spray tends to be whipped over the back window and trunk deck, without collecting so much on the back glass.

But the angled back glass of a hatch or wagon creates a vacuum without the decklid to direct airflow. This void attracts and collects a lot of spray which is then deposited on the back glass. You'll see a lot of older wagons (like c. 1970) that had a little deflector across the rear edge of the roof to direct airflow down over the backglass and prevent this low-pressure area from forming.
Click to expand...

That's pretty much what I said, 'cept you say it a lot prettier.
 
This topic is of great interest to me. In October last year on a car ride, all of a sudden, I began to see that there were tons of sedans with rear window wipers. I honestly had NEVER noticed that before in all my 17 nearly 18 years of life. It was quite possible the oddest day of my life, how can something like that just completely go over me like that? I guess I'll never know.
 
STLbarcelona5
This topic is of great interest to me. In October last year on a car ride, all of a sudden, I began to see that there were tons of sedans with rear window wipers. I honestly had NEVER noticed that before in all my 17 nearly 18 years of life. It was quite possible the oddest day of my life, how can something like that just completely go over me like that? I guess I'll never know.
Click to expand...

...I think you need to get out more ;)
 
gibus
I skimmed through the topic, but wouldn't it be due mainly to IF the person chooses the option of having on OR not?

I know here it usually is an option on cars..
Click to expand...

On some cars it is an option. On most, the car either comes with it or it doesn't.
I know on Mercedes, the wagons and trucks, it is standard. There is no option of having it or not (at least not in the US)
 
I've never seen a rear window wiper on any options list in my entire life. A car has it, or it doesn't, that's the only options I know.

Regards
the interceptor
 

Latest Posts

Back