Author Topic: Drumming soft top  (Read 532 times)

Merc_Girl

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Drumming soft top
« on: February 21, 2021, 10:04:12 »
Hi folks

Turning again to you knowledge folk for advice

I know there has been a previous thread on the subject, but maybe ‘knowledge’ has moved on?

https://www.sl113.org/forums/index.php?topic=18185.msg126863#msg126863

So, when driving along with the hood up, there is a horrendous drumming of the roof between the windscreen and the first cross member of the soft top. Even far worse than I remember my old triumph spitfire being (albeit with all the other rattles and knocking noises, the roof noise may have been drowned out!).

Obviously when I put my hand on the inner lining, the drumming significantly reduced, but the police don’t like folk to have only one hand on the steering wheel for some reason!

I could I guess keep an old towel in the car, and when the roof is up, jam it along the leading edge to tightened up the canvas, but that doesn’t really go with ‘the look’.

Previous discussion mentioned something about making sure the ‘front edge is curled down’. What is meant by that? There is also mention made of a piece that is often missing, but the link no longer works.

I’ve been told by the garage, not the I’ve looked yet, that rubbers etc are ok.

Any thoughts, or do I resort to a towel?

Many thanks once again for your invaluable advice

Katie
230SL

Garry

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Re: Drumming soft top
« Reply #1 on: February 21, 2021, 11:16:32 »
There appears to be two solutions to this problem. 
Firstly it is usually the front of the soft top that has lifted/curled up slightly.  See photos on link to an earlier discussion on this.

https://www.sl113.org/forums/index.php?topic=15211.msg104418#msg104418

The solution appears to be to strip off the top and stretch and re glue it down at the front when refitting or alternatively fit a new soft top that are not all that expensive to buy.

Garry Marks
Melbourne/ Kyneton, Australia
1965 MB 230SL Auto RHD Lt Blue 334G, Top 350H, 213 Leather, Tourist Delivery
2005 MB A200
2008 MB SLK 55 AMG
2016 VW T6 4x4 pop top Camper
2021 Volvo XC40 Electric Recharge, on order.

Iconic

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Re: Drumming soft top
« Reply #2 on: February 21, 2021, 16:33:49 »
Garry,
You brought a smile to my face this cold February Sunday AM.
As on most Sunday AMs, I'm reading the forum, what a surprise.
So, Garry posts this link to help out Merc_Girl, and lo and behold, I follow the link and see pictures of my old Pagoda and my Camaro in the background which was posted 10 years ago.
These Mercedes Pagodas and the people who are interested in them have brought so much joy to my life.
Now I've got a newish blue softop on a different Pagoda, this one was installed by Gernold at SL-Tech, so I'm confident it was done like the factory did it. I could take more pictures if you want, but it looks just like my old factory top.
Merc_Girl, I sure hope you get it straightened out .....  or you just drive with the top down.  ;-D
Take care,
Mark
1970 280 SL Automatic, USA version, Grey-Blue (906G/906G), Blue leather (245)
1968 SS396 Camaro Convertible (owned since 1977 -- my first car :D)
1984 Porsche Euro Carrera coupe, LSD, SlateBlueMet/Blue
1998 BMW M-Rdstr Estoril Blue
1970 280 SL Automatic, Anthracite Grey-173G, Red Interior-132 - sold

Merc_Girl

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Re: Drumming soft top
« Reply #3 on: February 21, 2021, 20:17:58 »

Merc_Girl, I sure hope you get it straightened out .....  or you just drive with the top down.  ;-D
Take care,
Mark

Mark

I go topless as often as possible you will be glad to hear 😉. My usual theory is that if it rains, if you keep over 50mph, you are usually ok even if it is raining. Unfortunately the UK has traffic jams, a lot of them, and that kinda ruins my fluid dynamics theory 🤣🤣
230SL

DPreston

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Re: Drumming soft top
« Reply #4 on: February 21, 2021, 21:10:18 »
Katie,
This probably a long shot but I had the same problem. The cloth was vibrating excessively with the top up.
When I attended the 2017 PUB in Charlottesville I asked around about my noise. A couple of the guys asked me to release the top from the windshield.
After a few minutes the guys said that there was a rubber washer around each post going the windshield. No washer is supposed to be at the latch.
I removed the washers and the noise was reduced by 90%. So check the latch for incorrect washers.
Good luck,
David
190SL 1960
280SL 1969
280SE 1969 cabriolet
Vette 67
Porsche 912 67

Iconic

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Re: Drumming soft top
« Reply #5 on: February 21, 2021, 21:57:40 »
Mark
I go topless as often as possible you will be glad to hear 😉. ......
As you might have guessed, I wanted to say that and knew I shouldn't  ;D, ..... but you could !!! LOL
And yes, I have driven top down in my Camaro for literally hours at a time in the rain..... but I was much younger and my Camaro was not as nice as my Pagoda (at the time). I was completely dry unless I needed to slow down for a toll both or something. I loved the look on peoples faces as I passed them.
I hope you get your soft top straightened out.
Mark
1970 280 SL Automatic, USA version, Grey-Blue (906G/906G), Blue leather (245)
1968 SS396 Camaro Convertible (owned since 1977 -- my first car :D)
1984 Porsche Euro Carrera coupe, LSD, SlateBlueMet/Blue
1998 BMW M-Rdstr Estoril Blue
1970 280 SL Automatic, Anthracite Grey-173G, Red Interior-132 - sold

Garry

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Re: Drumming soft top
« Reply #6 on: February 21, 2021, 22:15:29 »
Mark,


i think it was probably ten years ago i saw your garage with the Camero, a Porsche and the anthracite Pagoda. i was very envious of your set up. 😲😲😎
Garry Marks
Melbourne/ Kyneton, Australia
1965 MB 230SL Auto RHD Lt Blue 334G, Top 350H, 213 Leather, Tourist Delivery
2005 MB A200
2008 MB SLK 55 AMG
2016 VW T6 4x4 pop top Camper
2021 Volvo XC40 Electric Recharge, on order.

DaveB

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Re: Drumming soft top
« Reply #7 on: February 22, 2021, 01:40:20 »
My usual theory is that if it rains, if you keep over 50mph, you are usually ok even if it is raining.

I was completely dry unless I needed to slow down..

That is great! So the air flow carries all the raindrops away above and behind?
DaveB
'65 US 230sl 4-speed, DB190

mrfatboy

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Re: Drumming soft top
« Reply #8 on: February 22, 2021, 02:07:03 »
It’s true. As long as you keep moving while raining you  are usually good 😜.  It’s the stop lights that kill you🤣. It’s the longest 60 seconds of your life 🤣🤣🤣
1969 280sl (Aug 1968 build)
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mnahon

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Re: Drumming soft top
« Reply #9 on: February 22, 2021, 02:51:38 »
You can show it's more a matter of relative velocity of the water droplets relative to the moving car. Seen by an observer in the moving car (the driver), the droplets are not falling downward, but rather at an angle. The faster the speed of the car, the shallower the angle---for an infinitely fast car, the droplets move horizontally.

For example, if the car is moving at five times the speed of the droplets, the angle is twelve degrees to the horizontal, which is pretty shallow. If your head is even a bit below the top of the upper edge of the windshield, they won't touch you.

I've also spent lots of time driving top down in the rain on the highway. As others have mentioned, it works great till you hit traffic...
Meyer Nahon
Montreal, Canada
1968 MB 280SL Auto Euro LHD Silver
2007 MB C280

DaveB

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Re: Drumming soft top
« Reply #10 on: February 22, 2021, 04:52:01 »
Ah ok, that is a better explanation than how I envisaged it. Hence still need the wipers of course.
DaveB
'65 US 230sl 4-speed, DB190

Merc_Girl

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Re: Drumming soft top
« Reply #11 on: February 22, 2021, 22:17:55 »
It’s to do with air turbulence

You may find this article of interest
https://www.carthrottle.com/post/how-fast-do-you-have-to-drive-a-convertible-with-the-top-down-to-stay-dry/

Relative velocity is what you think is happening (ie how your brain interprets what Igor ‘see’)

http://www.lon-capa.org/~mmp/kap3/cd057.1.htm

However, not getting wet doesn’t appear to happen, it doesn’t happen (bar tolls and traffic jams)

Would love to live where traffic lights only stay red for 60 seconds 🤣

Katie
230SL

mnahon

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Re: Drumming soft top
« Reply #12 on: February 23, 2021, 02:37:09 »
Hi Katie,

Relative velocity is more than what you think is happening; it's actually happening. In the example in your second link, the rear window doesn't just stay dry because it 'thinks' the raindrops are moving at an angle. They actually are---albeit, yes, relative to the car, but that's all that matters.

Though I don't deny there's also some aerodynamics at play. So both contribute to the effect of staying dry, and figuring out their relative importance will have to wait for the right researcher to get an appropriately large research grant.

As far as practical application, in the US and Canada, once you get away from big cities, it's relatively easy to go for long stretches at uninterrupted high speeds.

Meyer
Meyer Nahon
Montreal, Canada
1968 MB 280SL Auto Euro LHD Silver
2007 MB C280

RAY

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Re: Drumming soft top
« Reply #13 on: February 23, 2021, 08:51:54 »
So as our windscreens are more vertical than the MX5 we should be dry at less than 50 mph.

Merc_Girl

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Re: Drumming soft top
« Reply #14 on: February 23, 2021, 09:52:42 »
I’m interested in the ‘high speeds’ Meyer is doing!!!!!

Thought in most part of the states one was only allowed to do 50mph? Mind you, in UK, we are only meant to do 70!!!

I still believe aero dynamics is the main reason for keeping dry’er’ than relative velocity, although as Meyer says, both contribute to the overall precept of keeping one dry 😁

230SL

mnahon

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Re: Drumming soft top
« Reply #15 on: February 23, 2021, 14:16:07 »
In Canada, limits are 100-110 kph. In the US, mostly 60-70 mph. But as has been said, it doesn't need that much speed to stay dry.  In most rain, above 70 kph will do it. In a hard downpour, you'll need more speed. As Mark mentioned in his post, you get some pretty surprised looks from people when it's raining hard.

Meyer Nahon
Montreal, Canada
1968 MB 280SL Auto Euro LHD Silver
2007 MB C280

neelyrc

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Re: Drumming soft top
« Reply #16 on: February 24, 2021, 02:56:33 »
.....Thought in most part of the states one was only allowed to do 50mph? Mind you, in UK, we are only meant to do 70!!!....

There are some 50 mph zones but on open freeways (limited access interstate highways) posted limits of 70 are the norm.  I have found that in the Southeast USA, the cruising speed of  most traffic in these zones is at the 80 to 85 level!! 
Ralph
USA
1969 280SL, 4 Speed Manual, Dark Olive (291H), Parchment Leather (256), Dark Green Soft Top (747)
2007 BMW 328xi (E90)
1995 Jaguar XJS Convertible
1988 Mercedes-Benz 560SL
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