jimq

the wipers in my TT work a whole lot better in the Florida monsoon rains we get compared to my 964. On rain sensing mode they move as fast as in any other car i have owned.

Macster

My experience -- and this is the point I was trying to make in an earlier post and failed horribly -- is that the limit to how fast I can drive in the rain is not the wipers ability to keep the windshield clear, but (I suspect) the tires and their ability to deal with heavy rain.

I've driven my Turbo in some pretty heavy downpours -- the worst is a couple of years ago one early Sept on my way to Fredricksburg TX to attend a gathering of Porsche owners and their cars. I made my way to the town driving through some of the worst rain I have ever driven through. This was the year a low pressure system settled on over TX and it rained inches over the normal amount of rainfall.

I slowed down, way down, not because of the wipers but because the tires (relatively new (Continental) tires too) were simply not up to the task of dealing with the huge amount of water on the roadways. While the roads were ok in some places, I encountered places where water had puddled and the tires had I been going any faster would have hydroplaned.

Anyhow, I tested my Turbo this AM and on high speed (using the stalk not the rain sensing mode) I counted 20 full cycles from the wiper low position to full over and back again in just about 20 seconds, using my cell phone's stop watch feature.

It is hard to believe there's a faster speed.

In the OP's case, I wonder if the wiper blades are the right blades or the blades are installed wrong or even the arms are weak, damaged, worn, or are not adjusted properly?

Sincerely,

Macster.

"02996ttx50

this thread needs to be archived. this place is great

harris

Macster

you wrote...and this is the point I was trying to make in an earlier post and failed horribly

this is not true..

all posts add up something in order to reach a point which at the begining of the post is not known...and this is the magic in this forum...

concerning now the fact that tires cannot deal with very heavy rain..or in other words there is a limit for the tyres when the car is driven in the rain...in which limit wiper arm can do the job I would like to add up something....

964 + uk rain + early 90's technology car and tyres... = never had any problem...never had aquaplanning or any other issues before wiper arms could do the job...

996 TT + greek rain ( i.e. deffinetelly less than u.k. amount of water ) + early 00's technology + 4wd system...never had any had aquaplanning or any other issues ...but almost always wiper arms cannot deal with the rain...I always end up to a point where I cannot see due to the fact that rain ia on my windscreen...


and this is the total opossite of what you wrote...
I slowed down, way down, not because of the wipers but because the tires (relatively new (Continental) tires too) were simply not up to the task of dealing with the huge amount of water on the roadways. While the roads were ok in some places, I encountered places where water had puddled and the tires had I been going any faster would have hydroplaned.

harris

so I assuming that ...since there are no issues with the tyres...and wiper arms cannot deal with the rain at a certain speed..it would be nice-practical that I had one more scale on the wiper arm's speed.

thanks for the reply all of you

harris

jury_ca

The fastest wiper speed on the 911 is relatively slow when compared to a modern BMW. With wider rear tires making the 911 more prone to hydroplaning, this is probably done by design. Faster wipers would give drivers a false sense of security.

It wouldn't be difficult for the engineers to provide a faster wiper speed if they wanted to.

harris

by saying that you almost accuse BMW for giving drivers a false sense of security.

i totally disagree...

harris

harris

and again why they did it (provide a faster wiper speed) on a 964???

Dock

The windshield on that car is more vertical and not as curved as the windshield on the 996. More vertical and flatter = harder for wind speed (fast driving) to move the water off the windshield and = the need for faster wipers.

That's my best guess and I'm sticking to it

harris

I will write something but I have to say that I am not the expert to justify what I will write...so just read it...


More vertical and flatter = harder for wind speed = easier to move the water on the windshield since the resistance of the car would be bigger which means that it is much easier to move the water..

(this is my opinion , and of course it might not have any thing to do with physics or reallity)

harris

Dock

Airflow around a flat surface produces a null in the airflow in the middle area of the surface. Water would essentially "pool" there. See the bottom left illustration in the picture below.

Macster

It was not my intention to imply that modern Porsches, in this case the 996 Turbo, have slow/inadequate wiper speeds in a crude attempt to limit the speed of the car in the rain because modern tires not up to dealing with the rain.

I was trying to get across that in my experience with my modern Porsches the tires' ability to deal with the water is what limits my speed in the rain, not the wiper speed. I've never encountered rain that overwhelmed the wipers and were I so inclined I could have certainly driven faster in this rain but in the situations I have felt/sensed the tires were borderline hydroplaning so I slowed down.

So, getting back to your situation, I assume the wiper speeds posted agree with what you are seeing from your car?

If so and assuming the wipers are in otherwise acceptable condition, then for some reason you need a faster wiper speed.

Whether there exists a wiper motor that can be adapted to your car and which will operate the wipers at a sufficiently and suitably faster speed I have no idea.

Your issue is a new one to me. Since this is Turbo related and I have a Turbo I'll bring this subject up to some techs the next time I'm at a dealership and see if they have any ideas. I'll be happy to pass along to what if anything of interest I learn.

Sincerely,

Macster.

harris

Macster & Dock

thanks for the reply...

harris

kkswow12

sounds a bit like abbott and costello