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What do you use on your dashboard to help prevent cracks?

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Old 10-12-2017, 11:32 AM
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Socal_Tom
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Default What do you use on your dashboard to help prevent cracks?

Has anyone found anything that works without being too shiny?

Thanks
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Old 10-12-2017, 01:33 PM
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Originally Posted by Socal_Tom View Post
Has anyone found anything that works without being too shiny?

Thanks
I have always had great experiences with 303 Protectant on vinyl. I have the same question for leather as my new 928 has an almost perfect leather dash that I am keen on protecting. For now, I used Leatherique to moisturize it but I would like additional protection. I think 303 can be used on leather but I don't know for sure. I would like to know for sure before before trying it myself.
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Old 10-12-2017, 01:42 PM
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Originally Posted by Vandalizer View Post
I have always had great experiences with 303 Protectant on vinyl. I have the same question for leather as my new 928 has an almost perfect leather dash that I am keen on protecting. For now, I used Leatherique to moisturize it but I would like additional protection. I think 303 can be used on leather but I don't know for sure. I would like to know for sure before before trying it myself.
I use both on my leather dash, and here in Las Vegas, the trick is to keep the car in the shade, and outta the sun, and heat.

My problem is the Pod, the original, will be going to Rob Budd, at Classic 9 , to be recovered in Alcantara. My Pod has cracks, where as the dash looks great. Plus the center console is starting to lift up on both sides. So because of cost it one thing at a time.
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Old 10-12-2017, 02:06 PM
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Bertrand Daoust
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Protect the car from the sun as much as you can.

If this can't be done, always use a car sun shield.

With age, they all cracked.

My pod and dash are still intact.
The car is always inside the garage.

But I know, It will happen some day...
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Old 10-12-2017, 02:31 PM
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When the car first acquired me 20 years ago, give or take a day, I immediately shopped for a dash mat to keep the pristine dash and pod pristine. I put it on then, and now two decades later I think it's been off for a total of maybe 24 hours, always just for washing. The sun has faded the black to a medium grey, so it probably deserves to be replaced. I tried dip-dying it black again with Rit fabric dye but it didn't really help much.

I'll echo the advice of the others on keeping the dash (and the rest of the car...) out of the sun as much as possible. Until a few years ago, mine was doing regular duty in SoCal. It lived in the garage at home with a cover on it, and was in underground parking at my office usually with the cover on it. Anytime it is parked out somewhere else, even for just a few minutes, the windshield sunshade is on duty. If it's going to sit out for any length of time greater than a shopping stop, a set of Nicole's fitted window sun shields pretty much seals off the interior completely from the sun and a lot cooler inside too.

For a few interesting cars that had giant greenhouse windscreens and poor or no AC fitted, (think Lotus, Ferrari, de Tomaso) I used to use what was described as a "cockpit cover". It's a heavy-duty reflective car cover piece that covers the roof and windows, pretty much everything above the beltline. It had straps that would drop into the door openings, securing it in place. Those cars had such small luggage boots that there really wasn't room to carry a full car cover.

Oh... The payback: I've never had a car with dash or pod cracks. Ever. In forty-plus years in SoCal sun, dash covers and the religious screen-or-cover program actually delivered results. Seats, rugs, and virtually everything else inside the car lasts longer without the sun exposure. Paint on the outside hates sunlight too.


So where are good replacement dash mats these days? In black velour, to replace the old one I have. It's done all the fading so the dash and pod underneath haven't.
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Old 10-12-2017, 10:31 PM
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Isn't there a coating you can put on the windows that keeps the harmful UV rays and heat down? I think Andy Kay mentioned this when we were all in Monterey at Werks
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Old 10-13-2017, 02:57 AM
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Originally Posted by vanster View Post
Isn't there a coating you can put on the windows that keeps the harmful UV rays and heat down? I think Andy Kay mentioned this when we were all in Monterey at Werks
There is, I have it. But sun & heat will still cook it.

Get a dash mat.
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Old 10-13-2017, 03:35 AM
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I use a dash cover and a retractable sun shade from these guys in AZ in my GTS.
https://www.dashdesigns.com/

My GTS is a German model and comes with an all leather interior (except pod). No cracks no issues.
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Old 10-13-2017, 08:17 AM
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This has worked for me over the past 20 years of 928 ownership:

1. Minimize sun exposure: keep the car in the garage, except when driven once every few weeks.

2. When the car has to be parked in the sun, use Heatshield window coverings on all sides that could get sun exposure while the car is parked (anticipate movement of the sun)

3. Choose a 928 with a light colored dash - classic grey doesn't get nearly as hot as black. Avoid burgundy interiors, if you can - this color fades the fastest.
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Old 10-13-2017, 09:14 AM
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If your vinyl dash starts getting cracks drill tiny holes at the ends of the crack to prevent them from spreading.

Also, ceramic tint on windows works wonders at blocking UV and heat, it really helps the AC out. It does have its limits though and the car will still get heat soaked.
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Old 10-13-2017, 09:31 AM
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Originally Posted by Nicole View Post
This has worked for me over the past 20 years of 928 ownership:



3. Choose a 928 with a light colored dash - classic grey doesn't get nearly as hot as black. Avoid burgundy interiors, if you can - this color fades the fastest.
Schocki's GTS: "AmazonasgrŘn" with "Klassikgrau Lederausstattung"
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Old 10-13-2017, 10:14 AM
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My guess is that it is heat (not UV) that causes cracking - it's more of a bulk than a surface phenomenon. It probably degrades the material, but the direct cause is thermal stress from expansion/contraction when an article is constrained from moving freely.

Note that the tensile stresses that start and grow cracks occur upon cooling, and rise the colder it gets. I'm not a plastics guy and don't have the details, but if the temperature drops below a ductile-brittle transition temperature - boom. I'm suggesting that new cracks will be found in the morning, after a cold night.

In engineering parlance, mind your delta T's.

Related question: How many have experienced new cracks in an uncracked dash, for a car mostly kept out of the heat and cold?
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Old 10-13-2017, 10:08 PM
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It's the heat...and the shrink-swell stuff Curt said.

It's an inherent property of glass that prevents most UV from passing through it. So dark tinting mostly stops visible light - which absorbed by the dash (or black pavement) is converted to thermal energy (gets hot) and then reradiates this energy as infrared (heat).

The physics of how even clear glass blocks almost all UV is a bit of a mind bender....but it's a good thing to understand generally before trying to get a sun tan in a greenhouse. It's explained in Hewitt's Conceptual Physics (with some of my own analogies)...

"Warm" Infrared light (longer wavelength than red) vibrates the electrons around the atoms in glass - and the entire structure of glass, dispersing the energy as heat and causing the glass to warm up. Visible light (all the colors) has frequencies that vibrate the glass atoms less dramatically such that each atom can transfer the vibration to its neighbor efficiently (think of it kind of like a energy transfer bucket brigade) - thus transferring the visible light from one side of the glass to the other. This process is why the speed of light is lower in the glass than in air. It's very weird..this isn't transparent like we imagine...rather, the visible light hits the top surface of the glass...vibrates the glass atoms..bucket brigade transfer between atoms ensues...then the last "buckets" vibrate that exact frequency and wavelength (color) back into the air....and we perceive this as transparence (so this is like the "telephone" game, except in this case the electrons around atoms don't screw up the message like people do). UV has a shorter wavelength than visible or infrared and matches the natural resonant frequency of the electrons around glass atoms. It's a higher frequency (and higher energy) vibration than infrared vibrations mentioned above and causes the the glass atoms to resonate kind of like a bell that continues to ring after it is struck...this energy retention allows the electrons around glass atoms additional time to transfer energy to neighboring atoms as heat...thus filtering the UV and also warming the glass.

The above is a greatly simplified description of what's going on at the atomic scale. A classic wave propagation model and a separate quantum mechanics model, both involving constructive interference in the forward direction for either visible light waves or photons, and complete destructive interference for IR and UV waves or photons within the glass may also work.


So... glass filters IR and UV The dash is heated by absorbing visible light (and a dark dash will absorb the most).

Last edited by Captain_Slow; 10-14-2017 at 12:27 AM.
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Old 10-14-2017, 11:36 AM
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Originally Posted by Captain_Slow View Post
It's the heat...and the shrink-swell stuff Curt said.

It's an inherent property of glass that prevents most UV from passing through it. So dark tinting mostly stops visible light - which absorbed by the dash (or black pavement) is converted to thermal energy (gets hot) and then reradiates this energy as infrared (heat).

The physics of how even clear glass blocks almost all UV is a bit of a mind bender....but it's a good thing to understand generally before trying to get a sun tan in a greenhouse. It's explained in Hewitt's Conceptual Physics (with some of my own analogies)...

"Warm" Infrared light (longer wavelength than red) vibrates the electrons around the atoms in glass - and the entire structure of glass, dispersing the energy as heat and causing the glass to warm up. Visible light (all the colors) has frequencies that vibrate the glass atoms less dramatically such that each atom can transfer the vibration to its neighbor efficiently (think of it kind of like a energy transfer bucket brigade) - thus transferring the visible light from one side of the glass to the other. This process is why the speed of light is lower in the glass than in air. It's very weird..this isn't transparent like we imagine...rather, the visible light hits the top surface of the glass...vibrates the glass atoms..bucket brigade transfer between atoms ensues...then the last "buckets" vibrate that exact frequency and wavelength (color) back into the air....and we perceive this as transparence (so this is like the "telephone" game, except in this case the electrons around atoms don't screw up the message like people do). UV has a shorter wavelength than visible or infrared and matches the natural resonant frequency of the electrons around glass atoms. It's a higher frequency (and higher energy) vibration than infrared vibrations mentioned above and causes the the glass atoms to resonate kind of like a bell that continues to ring after it is struck...this energy retention allows the electrons around glass atoms additional time to transfer energy to neighboring atoms as heat...thus filtering the UV and also warming the glass.

The above is a greatly simplified description of what's going on at the atomic scale. A classic wave propagation model and a separate quantum mechanics model, both involving constructive interference in the forward direction for either visible light waves or photons, and complete destructive interference for IR and UV waves or photons within the glass may also work.


So... glass filters IR and UV The dash is heated by absorbing visible light (and a dark dash will absorb the most).
Science!
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Old 10-14-2017, 02:01 PM
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Wow!

I usually condense this down to something simple like "ultraviolet epoxidation" if "... the sun cracked it!" is too simple.

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