Proper following distance to reduce windshield damage, and other related concerns.

S

S

Hi All!

OK, I give up. I can't keep a new windshield on a car. Two weeks on
fresh glass in my old GL, and it's already cracked beyond legality :p

So. Howzabout some discussion on the subject.

It seems to me that the only "safe" distance behind those darned
SUV/PUT/SEMI things, at least as far as your windshield is concerned,
is dreadfully close; two to three car-legnths at most (at highway
speeds). At a reasonable following distance, you catch every pebble;
if you really back off, some one will inevitably fill the gap,
spraying you with debris as they change lanes.

How about mandating effective mud-flaps on those high-clearance, big
tired beasts?

Does anyone besides me notice that aftermarket windshields tend to
crack more easily then the OEM glass? Maybe due to unusual stresses
induced during handling and installation?

Do the spiffy looking deflector shields actually help, or do they
merely move the damage up into your line-of-sight?

Are the 15 minute windshield repair outfits worth the money?

Burning questions, no doubt. Anyone?

ByeBye! S.
Steve Jernigan KG0MB
Laboratory Manager
Microelectronics Research
University of Colorado
(719) 262-3101
 
OK, I give up. I can't keep a new windshield on a car. Two weeks on
fresh glass in my old GL, and it's already cracked beyond legality :p

So. Howzabout some discussion on the subject.

It seems to me that the only "safe" distance behind those darned
SUV/PUT/SEMI things, at least as far as your windshield is concerned,
is dreadfully close; two to three car-legnths at most (at highway
speeds). At a reasonable following distance, you catch every pebble;
if you really back off, some one will inevitably fill the gap,
spraying you with debris as they change lanes.

How about mandating effective mud-flaps on those high-clearance, big
tired beasts?

Uh.. I've never experienced a cracked windscreen. In any of the cars I've
driven, ever.
Closest I've come is getting two tiny stone chips in the screen in one day.
(<2mm)

The quick repair places wouldn't be suitable if your screen is actually
cracked. They're only legally allowed to repair small chips (at least in
good ol' convict land) as cracks greatly reduce the structural ability of
them in a crash.

We have more suv's on the roads now than ever, hell, even I drive one...
Forester...
Maybe it's your shit roads? Hell, taking corrugated dirt tracks at 80kph,
not even 10m behind a Landcruiser, rocks, dirt, dust, shit on the road...
Not a single scratch or chip. Plenty of dirt though. Sealed roads, only
windscreen cracks i've heard of have been caused by B-double semitrailers
goin the other way, throwing up large chunks of bitumen when running over a
pothole... Fist-sized bits of rock hitting you at a closing speed of 200kph
ain't fun.

-mark
 
Mark said:
Uh.. I've never experienced a cracked windscreen. In any of the cars I've
driven, ever.

Hi,

Hope you were knocking on wood while you typed that! I'd say you're
about the luckiest guy I've heard of... come on out here to SoCal and
interview drivers who commute on two particular local freeways to see
who HASN'T had a busted up windshield! Covering the loads, flaps,
nothing seems to stop the rocks from gravel haulers that run 24/7. :(

Anyway, in answer to Steve, I think aftermarket glass is somehow a bit
less "sturdy" than factory, but I've been told that's not true: most
current factory glass is pretty fragile, too. My glass guy told me
they're making it thinner to save weight, and owners pay the price. My
Subie's on its second windshield that I know of, and considering the
condition of the trim around it, the former owner may have gone thru
more than I'm aware of. The car's due for at least its third one...

If you want bad luck stories... I had glass replaced in a Toyota truck
some years back. Picked it up from the glass shop about 4 p.m. and
headed toward the freeway. At 4:20 p.m., I was hit by a rock thrown up
from an unknown vehicle. I didn't even see who chucked the rock, so
"proper following distance" would be impossible to guess. Nice bullseye!
Rats.

I went five whole days on my Subie from the day I bought it used (dealer
had JUST replaced the glass) before I hit a sand storm that blasted the
glass. Didn't bother replacing it, I just curse every time I'm driving
toward the sun. Since then, it's picked up two bullseyes, a star and a
LONG crack. They were all repaired. The bullseyes and star came out
fine, the crack is still noticeable though theoretically it's "legal"
here in CA cuz it's on the passenger side.

OTOH, I bought my Camry from a friend who'd had the glass replaced
twice, and it had a coupla chips when I got it. Made it almost six
months before getting hit by a rock that yielded a nice crack. It's on
the driver's side, and while I don't look thru it, I was told it can't
be legally fixed cuz of the area. It needs to be replaced, so that will
be No. 4!

So... don't feel alone: there are others of us out here who are rock
magnets!

As for the 15 minute "repairs" I can recommend them for bullseyes and
stars, but once you get a growing crack, I'm not impressed. Guy who did
my last one said they're very effective on cracks only up to about 2",
but he'll work on 'em up to about 15" to cut the glare and prism
effects, as well as make the glass "legal." So you kinda take your
chances...

Rick
 
Rick said:
Hope you were knocking on wood while you typed that! I'd say you're
about the luckiest guy I've heard of... come on out here to SoCal and
interview drivers who commute on two particular local freeways to see
who HASN'T had a busted up windshield! Covering the loads, flaps,
nothing seems to stop the rocks from gravel haulers that run 24/7. :(

What two particular local freeways are you referring to?
 
Guy said:
What two particular local freeways are you referring to?

Hi,

91 between Riverside and Anaheim Hills, and 15 between the 60 and
Temecula are my favorites (along with most everybody else I know) for
playing "rockhound!"

Hope you don't have WORSE stretches in mind!

Rick
 
OK, I give up. I can't keep a new windshield on a car. Two weeks on
fresh glass in my old GL, and it's already cracked beyond legality :p

You appear to have very dirty roads. Never suffered anything worse
than minor stone chips in 40 years motoring...and then only two or
three times. (Does worry me when driving cars without full windscreens
though, when I always wear flying goggles rather than just wrap-around
sun glasses.)
It seems to me that the only "safe" distance behind those darned
SUV/PUT/SEMI things, at least as far as your windshield is concerned,
is dreadfully close; two to three car-legnths at most (at highway
speeds).

Which is more important, your windscreen or your life? Only a fool
breaks the two second rule.

David Betts
(e-mail address removed)
 
Are the 15 minute windshield repair outfits worth the money?

Absolutely.

Mature technique and technology; had a "star"
fixed in 1983 and sold the car for four years
later, with no problems.

Most Ins Co's waive the deductible for repairs,
as it's so much cheaper than a full windshield...
$50-75.

You do have to get it done before it spreads
beyond a working limit.
 
No precise answer to your safe following distance question. A few
years ago, I was in my Cherokee following a Mercury Villager minivan,
when the Villager kicked up a rock and cracked my windshield from top
to bottom.

The glass in my Subaru is still crack free, but I've had all manner of
vehicle throw rocks at me.

You could certainly improve your odds by avoiding semis and stearing
clear of anyone that's wandering outside their lane onto the median
where there's rocks.

IMHO, 15 minute repair kits are not worth the money. If you have a
salvageable windshield, take it to the dealer or a glass shop for a fix.
 
David said:
You appear to have very dirty roads. Never suffered anything worse
than minor stone chips in 40 years motoring...and then only two or
three times. (Does worry me when driving cars without full windscreens
though, when I always wear flying goggles rather than just wrap-around
sun glasses.)


Yeah, well S is posting from Colorado, so I assume he lives there. It's
a lot drier there than in the UK. Perhaps all the moisture you have
there keeps the dirt and pebbles mixed onto the ground, whereas it rolls
around in Colorado and California, which are two fairly dry states.

Which is more important, your windscreen or your life? Only a fool
breaks the two second rule.


Indeed!
 
Rick said:
91 between Riverside and Anaheim Hills, and 15 between the 60 and
Temecula are my favorites (along with most everybody else I know) for
playing "rockhound!"

Hope you don't have WORSE stretches in mind!

I drive the 91 Buena Park to Riverside fairly often, as well as most
other SoCal freeways, and have never had rock damage to my windshield.
 
Guy said:
I drive the 91 Buena Park to Riverside fairly often, as well as most
other SoCal freeways, and have never had rock damage to my windshield.

Hi,

Now that you've said "never..."

Glad to hear you've been more fortunate than all the commuters I've
known. Good luck!

Rick
 
Yeah, well S is posting from Colorado, so I assume he lives there. It's
a lot drier there than in the UK. Perhaps all the moisture you have
there keeps the dirt and pebbles mixed onto the ground, whereas it rolls
around in Colorado and California, which are two fairly dry states.

This observation seems to hold true for me in western New York, where
I haven't experienced any serious windscreen chip/crack problems. I've
got 3-4 chips that my sister acquired during her ownership of the car,
and they haven't grown in the 4 years I've had the car, nor have I
acquired any new ones myself.
 
S said:
Hi All!

OK, I give up. I can't keep a new windshield on a car. Two weeks on
fresh glass in my old GL, and it's already cracked beyond legality :p

Stop tailgating! ;-)
So. Howzabout some discussion on the subject.

It seems to me that the only "safe" distance behind those darned
SUV/PUT/SEMI things, at least as far as your windshield is concerned,
is dreadfully close; two to three car-legnths at most (at highway
speeds). At a reasonable following distance, you catch every pebble;
if you really back off, some one will inevitably fill the gap,
spraying you with debris as they change lanes.

How about mandating effective mud-flaps on those high-clearance, big
tired beasts?

Does anyone besides me notice that aftermarket windshields tend to
crack more easily then the OEM glass? Maybe due to unusual stresses
induced during handling and installation?

Is your windshield cracking because of impacts or on its own? If it's
cracking on its own, that could caused by improper installation.
Do the spiffy looking deflector shields actually help, or do they
merely move the damage up into your line-of-sight?

I find mine helps.
Are the 15 minute windshield repair outfits worth the money?

I wouldn't know, I have a deflector... :)
 
Do the spiffy looking deflector shields actually help, or do they
They help on some cars, and not on others, its really hit or miss :D .
On the otherhand $20 for a shield might be worth a try.

In Oregon you have to have mudflaps. not sure about elsewhere. I have
begun to see a coating you can put on your windshield (not sure if its
a film, spray, or what exactly) that is suposed to help prevent
cracks. I’ll lookout for where they sell it and get back to you. I
dont know if it works, but a windshield every 2 weeks... somethings
gotta be worth a try.
 
In Oregon you have to have mudflaps. not sure about elsewhere. I have
begun to see a coating you can put on your windshield (not sure if its
a film, spray, or what exactly) that is suposed to help prevent
cracks. I'll lookout for where they sell it and get back to you. I
dont know if it works, but a windshield every 2 weeks... somethings
gotta be worth a try.

Get it replaced with 6mm bulletproof glass. You might get chips in it from
the major impacts, but good luck smashing the thing. Combined with some good
high-quality 3m strengthening film on the inside, you'll never replace one
again.

Would save probably 20kg in weight but cost a fair bit to have custom made
;)

-mark
 
Your OEM windshield weighs more than 44 pounds??

Ever tried picking one up?
It's a 2 square metre piece of reinforced tempered glass, prolly 8mm thick!
Fuckin' heavy.

-mark
 
Hi All!

Yeah, well S is posting from Colorado, so I assume he lives there. It's
a lot drier there than in the UK. Perhaps all the moisture you have
there keeps the dirt and pebbles mixed onto the ground, whereas it rolls
around in Colorado and California, which are two fairly dry states.

Sorry I'm late getting back to this; been on vacation.

Ya, I live in Palmer Lake Colorado, on what is termed the Front Range;
loosely the Colorado Springs-Denver corridor. And locally, our paved
roads vary from merely OK to down right awful; some of what passes for
pavement would be better off ripped up and replaced by graded gravel.
Colorado Springs is notoriously bad; tire-swallowing pot-holes seem to
appear overnight, and the city is months in repairing them.

Even tho I frequently travel back-country dirt/gravel roads, and often
drive pretty fast on 'em, all of the windshield damage I've
experienced has been on the interstate, and usually on the commute
to/from work. I don't think the problem is mine alone; everyone in the
region seems to experience it to a greater or lesser degree. Part of
it may be related to the explosive growth we are experiencing; there
always seem to be sand and gravel trucks out on the highway. And altho
Colorado has been moving away from the traditional sand/gravel/salt
mix, in favor of Magnesium Chloride (yuk), there still seems to be
plenty of gravel being dumped onto the highway in the winter.

Furthermore, at least locally, there are an inordinate number of large
SUVs and full-sized pickups; some days, it seems like 50% of the
vehicles on the road fall into these categories. Most of these run
either snow tires, or the deep-lugged off-road tires, and most do
_not_ have adequate mud flaps. This results in a high percentage of
vehicles with the capacity to loft fair sized gravel; anything from
pea-sized to marble-sized and larger. And while I generally try to
allow plenty of distance between myself and the next car, it simply
isn't always possible, as I'm sure that those of you who commute thru
"rush-hour" traffic understand.

Ummmm, I _will_ comment that the problem was less severe (to the point
where I don't recall it even being a problem) back when the speed
limit was 55MPH, vs 65-75MPH in most places these days. Not that I'm
recommending going back to the "good ol' days", mind you, but surely
the higher speeds (75MPH limit = 85-90MPH traffic at times; yea, yea,
me too . . .) contribute to the size of the airborne debris, and the
severity of the resulting impact.

Finally, someone jokingly suggested a bullet-proof (Lexan) windshield.
I've actually considered this, but friends who are required to have
them on their "street-legal" (yea, riiight) race cars experience very
short usable lifetimes; their wipers scuff the plastic into murky
translucency almost immediately. Plus they're awfully expensive
($400-500+); thru contacts, I can generally get a windshield done for
about $150. Guess I should stop complaining, and simply budget for new
glass once a year, but since the first of this year, 3 new
windshields, in 3 different cars, all have rock damage. The last one
didn't last two weeks before a golf-ball-sized stone (big enuf that I
actually saw it coming, and _ducked_) cracked it badly enough that it
is probably illegal to drive with. Guess I'll try again; what's $150;
4-5 tanks of gas? . . . :p

Sigh.

ByeBye! S.

Steve Jernigan KG0MB
Laboratory Manager
Microelectronics Research
University of Colorado
(719) 262-3101
 

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