Subaru Forester (up to 2005)

ateixeira

Someone paid under $800 for a 7/70 on an Outback, that's dirt cheap IMO. Subaru warranty, too, not one of those insurance companies.

My tires are also much quieter than the Duelers, again Touring tires like yours. The Duelers have at least a theoretical advantage off road. They were better in snow, for instance, but that's all.

Yesterday my sister asked me what that torx driver was for, I had to show her.

-juice

joseph50

I do not use the roof rack either, and thought about removing the bars. They look rather substantial and heavy.
My quick second thought was that if I ever ended up going roof side down, I would probably appreciate having a couple of cross bars above my head.

ballistic

The roof crossover bars are nowhere near strong enough to provide any meaningful added support in a rollover. Their manner of attachment to the rails, while adequate for their intended purpose, would immediately give way under any significant lateral load. They would collapse like a defeated politician.

joseph50

If Subaru ever rolled one to find out for sure.
If not, wouldn't it be worth the try?

speterson1

The roof bars are pretty light, they felt like plastic.

Interesting comment; my wife says she doesn't like the way the Subie looks quite as much now that the roof rails are gone. I'll admit it does take away some of the SUV look and push it more towards the station wagon realm, but I don't care about looks that much. Combine that with my new blackwall tires, and you could make the claim that our Subie has an identity crisis and wants to be a car (it sure drives like one, which is one reason why I love it)!

Thought another benefit of removed cross bars may be better gas mileage, but I'd be surprised if I actually can see a noticable difference. Shouldn't make it worse, at any rate!

subkid

interestingly enough, my wife didn't like the looks of it when I took them off a couple weeks ago.

The way I see it, the major benefit of not having them on when not needed is easier snow removal, car washing and waxing. I did get a couple of painful bruises on my hands last time I tried to wipe/wax/polish underneath the bars and especially close to rail attachments.

K

ateixeira

JB: and since when can we recall politicians here....oops! Never mind! LOL

There are reinforcement beams at the B- and C-pillars. The Forester is registered as a car and by default has to withstand 150% of its own weight on the roof.

The only roll over I've ever heard of was this guy from Australia who had a nasty lift kit and tall springs. He showed pictures and all. The unibody held up AMAZINGLY well. It was a total loss but the passenger compartment was completely intact. He walked away from it.

I keep the cross bars on. I use them occasionally at Home Depot, and you never know. If it took them off I'm sure I'd wish I had them the next time I went shopping.

-juice

ballistic

There are reinforcement beams at the B- and C-pillars.

I'm sure that's true for the closed-roof versions, but how can there possibly be a B-pillar crosswise reinforcement beam on Foresters having the huge sunroof? There's nothing but air between the tops of the B-pillars!

It seems to me that sunroof-equipped Foresters almost have to provide less structural integrity than those without. This would affect not only rollovers, but probably also side impacts, because the tops of the B-pillars would be more easily moved/dislodged without a crossbeam tying them together.

Which raises a question: In the recent side-impact tests where the Forester scored so well - were they testing sunroof-equipped Foresters, or closed-roof versions?

mckeown

In BOTH Frontal AND Side, It was an X Model, No Sunroof.

http://www.nhtsa.dot.gov/NCAP/Cars/2533.html

ateixeira

The MT XT doesn't have one. The rest of the models are not important.

just kidding!

I'm sure they brace and reinforce the roof; it still has to meet the same 150% weight standard.

These agencies typically test the cheapest model available, so it was the X. They'll only do a 2nd test if the manufacturer pays for the vehicle.

For instance, the CR-V and Escape both scored poorly in IIHS side impact tests. Ford gave them a 2nd, with optional side air bags, to re-test. Honda did not. So Ford got better scores for those models (still not as good as the Forester), but the CR-V keeps its not-so-good score, even though the EX models with side air bags likely would have done better.

-juice

bsvoller

Cars are designed with computer-assisted design and manufacturing systems today (CAD/CAM). The entire beast down to the last nut and bolt is modeled on the computer first. Size, form, thickness, material used, fastening points, fastener types for every part - it's all in the model. They can optimize the required thickness of a part down to thousands of an inch to provide precisely the strength required without adding unnecessary weight. They can test deforming and failure under predicted loads in an accident. How do you think they determine how much impact energy a crush zone can absorb ? The models are verified with real-world tests.

These models are then converted into blueprints for the manufacture tooling and programs for the cutting and assembly robots.

I can't imagine that there's a significant difference in the structural integrity of the Forester unibody with or without the moonroof. They modeled both, built tooling for both and tested both on the computer and in steel as well.

Although it may seem intuitively stronger to not have a gaping hole in the roof, the reality is that little bit of sheet metal in place of glass isn't going to matter much. The strength is designed in elsewhere.

As to the roof rails helping out in a roll-over, don't count on it. That's not what they're there for. The lateral forces on the rail will sheer it off the roof as you roll in a lot of cases. The cross-bars appear to be made out of some kind of carbon reinforced plastic (aka "carbon fiber"). They are very strong for their weight, but not designed to withstand the kind of load you're talking about. If overstressed, they'll crack or shatter.

Hope this helps,

-brianV

ballistic

Although it may seem intuitively stronger to not have a gaping hole in the roof, the reality is that little bit of sheet metal in place of glass isn't going to matter much. The strength is designed in elsewhere.

The point isn't that a little bit of sheet metal has been removed. The point is that the hole includes the space between the tops of the two B-pillars. Few sunroofs extend rearward past the B-pillars. On Foresters without the sunroof (and on normal vehicles with normal sunroofs), there is undoubtedly a structural roof beam welded solidly between the two B-pillars, connecting them. On the sunroof-equipped Forester, that becomes impossible. It may be that the sunroof models surround the opening with very stout reinforcing loop, and that the two B-pillars might tie into that; however (all other things being equal), it's tough to imagine how that arrangement would be as strong as the direct, straight-across connecting roof beam of non-sunroof versions.
 

envyabull

Removing the rack eliminates much of the wind noise, especially with the big moon roof open or closed. Turning up the sound system gets rid of rest.

If you plan on using a roof rack often, consider getting the optional Cross Bar Set-Square. This rack goes on and off very quickly without tools. It is compatible with all Thule components which are more varied than Subaru's offerings. This option is about $100 at subaruwrxparts.com. There may be an equivalent Yakima compatible rack.

In my opinion the factory Subaru rack with its Torx fasteners and proprietary cross bar shape is a blatant attempt to sell proprietry Subary rack accesories. These may not be as good as what Thule or Yakima makes. Your garage full of proprietary Subaru equipment will then give an edge to Subaru when you are considering you next car purchase. I like Subaru, but this is a rather blatant method of forcing brand loyalty on the customers they have already won over.

$100 for the square bar rack is a cheap way of not falling for this ploy while giving you a more verasatile rack that is fast and easy to take on and off. It is a no-brainer, especially if you already have Thule accesories.

I am a structural engineer. Any rack will provide some additional structural reinforcement during a rollover. Whether this will be enough to reduce injury or more serious damage depends on many factors too complex to predict. It will certainly absorb some impact energy even if it breaks away. If you knew you were to be involved in a rollover accident and had a choice, you would be a fool to do it without the rack. All this being said, I drive around most of the time without my rack on because the chances for a rollover accident in the Forester are not that great. Wearing seatbelts and having side airbags will provide the most significant benefits during a rollover.

bsvoller

-ballistic: Do you know for a fact that there's a crossbar at the B pillar, or are you assuming that because it's the most logical place to put one ? Assuming that you're correct, it still doesn't mean that the moonroof design is weaker, you can reach the same strength factor with other methods, such as you mention, at the cost of additional weight.

The moonroof does add more weight - about 50 lbs more as I understand it - so perhaps this is the explanation. I've been told that the Premium package changes the spring rates and track width to counter the additional rollover risk due to the added weight, as well, but I'm not sure I believe that...

Stating that the moonroof necessarily makes the unibody weaker, however, requires more evidence than I've heard to date. I think we're speculating, sorry.

-envyabull: I don't doubt for a second that the roof rack adds *some* strength, or that it would absorb *some* energy no matter the circumstances in a roll-over. The question is whether its presence is enough to make a statistically significant difference, and that I strongly doubt. The other factors you mention will overwhelm whatever impact the roof rack might have, don't you agree ? "At the limit" you might see some benefit, but what are the odds of encountering just that situation ?

I wouldn't want people reading this board to conclude that their Subie is "less safe" without a roof rack on it. While it may be technically true, the difference isn't enough to matter.

Any more than we should be stating unequivocally that a Subie with a moonroof is "less safe" unless we have compelling reasons to believe that beyond mere speculation.

As to the OEM roof rack parts, they're manufactured by Yakima and fully compatible with their entire line. The crossbar cross-section is not a proprietary Subaru design. It's Yakima's.

-brianV

ateixeira

There is. I've seen cutaways and engineering drawings.

Also, when I had a moonroof installed I asked about it, they said indeed it gets removed but other bracing is installed in its place. Whether that makes it weaker is hard to say, you'd have to test the new bracing.

It's not factory installed, but the OE moonroof's bracing is, so who knows...

-juice

johnb2251

There is. I've seen cutaways and engineering drawings

Where? Do you have a URL?

ateixeira

Oh, sorry, I meant at Auto Shows. They had a new XT cut away, it was really cool.

You could see the aluminum bumper beams, plus the roof reinforcements.

paisan took pics of the NY Auto Show, though.

-juice

gmginsfo

Just ended a few days of hell down here in SDiego, with the fires threatening to roar down my canyon last Sunday and engulf my new house - until the winds changed, thankfully! Took my '03 Forester X Premi out for a closed window drive to test the air filter and it seemed to work pretty well. Didn't remove all the smoke from the air, but kept things breathable in the car, when they were barely that on the outside. Can't wait to see what that filter looks like when replcement time comes, which I may move up a bit in light of this extra duty it got.

I checked the pressure on my stock Yokohamas the other day and was surprised to discover they were, at 6400 miles, overinflated by 4-6 pounds front and rear, respectively. I had the shop bring them down to the proper levels as shown on the door frame tag, but I wonder why the dealer overinflated them so. Any thoughts as to mileage and handling issues? Which controls, tire mfr's or Subaru's instructions on proper pressure?

I see roof racks are in the news again - mine came off before I drove off the dealer's lot and have been lodging in my garage ever since. While I don't know that they improve mileage, their absence can't hurt it, and that's fine with me, since I like the cleaner look of the car w/o them.

Finally, I ended up taking my Power Acoustic 4-ch amp back for a refund. I found that it had apparently been blown by the installers in the installation process, which explains the problems I had with balance and sound. But their installation of an RCA plug kit to connect the new speakers to the stock AM/FM-Tape-CD appears to have improved sound measurably, and there's more than adequate power to crank out the tunes. So, my advice: forget adding an amp, put in some decent speakers, including the OEM tweeter kit, make sure your connections are proper and of good quality and you're set.

ateixeira

Subaru's numbers are fairly low, so I'm sure no harm was done. In fact, see if you like the lower pressure as much. I run about 32psi in mine.

-juice

envyabull

Bsvoller,

I agree with you that a Subie is safe either with or without their roof racks. I feel comfortable driving mine without its rack attached and I have the huge sunroof. More on that below.

However, increased structural adequacy due to the presence of a roof rack could likely be proven if enough testing was performed. I would stand on my roof rack, but I would never stand on my roof. So I do think for some types of impacts, the rack could make a difference to occupant safety.

I briefly checked the structure around my moonroof on my XT while going out for lunch. There is some additional compensating steel around the opening. I suspect the frame and sliding roof assembly also add quite a bit of stiffness. And lets not forget the glass itself. While not resilient, the sunroof glass is stiffer than the sheet metal used on the rest of the roof. It could be just as likely that the reinforcement around the sunroof is there to protect the sunroof from damage and leaking due to normal flexing of the rest of the roof while driving.

It would be shortsighted to assume that the presence of the factory sunroof results in a roof that is somehow weaker than a roof without a sunroof. There very well may be some incidents where the additional sunroof structure located more uniformly over the passenger compartment provides better protection than a B-Pillar roof beam made of formed and spot welded sheet metal.

Based on what I see, the aluminum roof rails and surrounding fairing/connecting structure on the new foresters will likely provide the most protection in rollovers. They are intimately connected to the A, B, C & D pillars creating two strong longitudinal roll bars.

So it is probably safe to assume that the roof of the Foresters are structurally adequate either with or without roof racks or sunroofs. I don't think there are any safety games being played by the Subaru engineers. If the roof racks were required, they would not be removable. The accident tests show that the new Foresters are at the top of their class. I suspect that the new dynamic rollover tests will show that the Forester has one of the lowest probabilities of rollover in its class. Certainly its car-like handling suggests that to me.

njswamplands

on this b-pillar issue as i have a sunroof on mine.

ateixeira

You'd just get the company line. All our products exceed the pathetic government minimums blah blah blah.

Be glad it's not a truck, those have loopholes big enough to drive...a truck through.

-juice

bsvoller

-envyabull: Great post and eloquently stated. The roof rack on my '01 may not be as intimately attached to all 4 pillars as the new design. It's hard to tell without knowing where the attachment points are located. Note that my '01 appears to use structural plastics for the rails as well, not aluminum.

While I'm not a structural engineer, I am somewhat familiar with structural plastics, as my family has been in the molding and plastics forming business for over 50 years. Although the roof rack can no doubt handle static loads such as you describe, I am doubtful as to it's ability to handle violent impacts. I think you'd see abrupt catastrophic material failure in many rollover scenarios (especially in the cold), which would limit the rack's ability to absorb, deflect or dissipate the impact energy.

Most of the plastics that I'm familiar with experience a pretty steep increase in brittleness as temperature falls, and have relatively poor sheer strength to begin with. I'm envisioning a "rollover" as having a fairly large "slide" moment, which would induce large sheer forces that the rack would not tolerate. You'd just rip it off. YMMV, especially with aluminum rails.

I could be wrong though... Perhaps a rollover shouldn't be characterized as an "impact", and they might typically have more "rotation" than "slide". If so, I see your point. Regardless, the internal structure supporting the moonroof mechanism is an entirely different matter. That's a factor I hadn't considered.

It's entirely possible that the roof with the moonroof is actually "stronger" in some senses than the standard roof.

-juice: I agree. Not being a truck is a major selling point to me, and not because I'm just biased against trucks !

-brianV

stever

Chat starts in ~40 minutes. Link is on the left.

We'll excuse Juice this time :-) Happy Anniversary!

Steve, Host

njswamplands

that had a commercial that showed them dropping a volvo on its roof? is that a good test. seems like a roll over is just that, a roll over. cant the IIHS create a machine that flips autos out of it to test this or just get it on a steep ramp and roll the thing down? speaking of that i dont even really know how the us government tests roofs. does anyone?

ballistic

You bet it's a good test. Cars almost never just roll over onto their roofs. They typically flip, landing on the roof from at least some airborne distance. Moreover, rollovers often involve more than one roll. To provide adequate safety, the roof supporting structure needs to withstand quite a bit more than just rolling onto the roof.

speterson1

I second what Juice said. Tire pressure is a balance between comfort/softer ride (lower psi) and fuel economy (higher psi). If you do a search through this thread I'm sure you'll come up with many hits as I know we've discussed tire pressure a lot. I run with 34 psi for the front tires and 32 psi for the rears, the difference because most of the weight of our Forester (which usually has an empty hatch) is in the front w/the engine & passengers. Run the numbers printed on your door panel and you will probably notice a softer ride but I bet your mileage may get dinged by 2-3 mpg. Check it out and see what you're comfortable with.

Steve

lark6

Opened my browser this AM and came across this report:

http://moneycentral.msn.com/content/Insurance/P63955.asp

What happened to the Forester? I was under the impression that it was highest-rated among small SUVs.

I still need to test drive an XT Premium to gauge the differences in handling between it and the regular XT. Hopefully I will not get the opportunity to test its safety ion a rollover.

Ed

tincup47

In my opinion the first line says it all, the list was compiled by Consumer Reports. They have no problem letting their opinions obscure the facts.

ken_from_nj

here's the link to the rating on CR site,
http://www.consumerreports.org/main/content/display_report.jsp?FO- LDER%3C%3Efolder_id=340571&ASSORTMENT%3C%3East_id=333137&- bmUID=1067615535434
 
don't know if it will go thru or if you have to have a subscription to the site.

rsay777

The Intermountain West has gone from summer to full blown winter in less than 48 hours. The X is digin in just fine. I only wish there was position on the heater control to direct defrost air to the windshield without the AC comp coming on. Bob L.

gmginsfo

Bob L, the only way around this I know of, short of installing a relay switch to preclude the A/C from kicking in at all unless you want it to in any mode, is to set the airflow control to blend heat and defrost, turn off the whole system, and then jog the airflow control again to blend. But - since the fan stays off, this only works if you're going fast enough to pull air in, although cracking the right rear window helps a bit.

Foreign cars used to avoid this dumbed-down Detroit "innovation" which is really unnecessary, since weather conditions calling for dehumidification occur much less often than those that don't. But the idea caught on overseas as well, despite its wastefulness, as another sort of "convenience" for drivers too brain dead to figure out how to run the A/C when required. Some justify it by claiming the A/C needs to be run periodically to keep it limber, but that can be accomplished much more economically with a few minutes of A/C idling every few weeks in the off season. But providing that intelligent option is apparently too hard for automotive engineers to handle, with the result that its absence ranks as my number one all time pet peeve of car design.

(No. 2 is fog lights that come on only with headlights as well, and not on their own or with parking lights.)

ateixeira

Very, very simple explanation, Ed. They are basing that info on the previous generation Forester. They've labeled the 2003 a "face-lift" and have not tested a new one.

That means that they are not factoring in the IIHS Best Pick in front offset crash tests, or the IIHS class-leading side impact tests. Or the NHTSA quadruple 4 star results. Overall scores are now better than the Vue's or CR-V's, in some cases *far* better.

So basically that study is using outdated information. All those scores are better than the previous Forester. The side air bags also protect the head, before it was just the chest *and* they were optional, not standard.

Add to that EBD technology on the XS, better tires on the X model, bigger brakes on all models, the list of improvements for 2003 goes on and on and on. There's even one for 2004 - collapseable pedals.

I am confident that the Forester will easily climb to the top of that list once they re-test a 2003 or later model.

Want to feel even safer? How about heated mirrors, to keep those clear in rain and snow. Wiper de-icers. Front *and* rear? Guess who offers this, class-exclusive?

I'd tell you but you already know...

-juice

subkid

Hi,

that's the topic I'd like to discuss more. This dumb set up exists on the CRV also, but there is a way to de-program it. It involves setting climate control dials in specific positions and starting the car while pressing recirc button (check CRV forums for the specifics). I was hoping something like that might exist on Forester too.

Besides, if heater control is set to "feet", certain amount of warm air goes towards the windshield. So, defrost position doesn't have to be used all the time.

For people concerned with the Forester's rating on CR, what's it to you? You know that our Forester is very safe vehicle, and who cares how CR or any other car critic rates it.

K

lark6

juice: I had no doubts or concerns about that, just curious as to how they missed all that newer info.

For reasons many others here have gone into in greater detail, I take anything CR says re autos with a grain of salt.

Ed

jim259

My dealer wants $223 to install the tweeter kit. $90 for the kit and $133 for installation. How easy is this to do it yourself? Do the side panels come off easily? Does the sound from these speakers make a nice improvement?

thanks,
Jim

subkid

that's what I'd call a rip off.

It's 15 minutes job, done with just a screw driver.

Look here:

http://www.subaruparts.com/guides/Forester_2003MY_Tweeter_IxI.pdf

now when I re-red it, I stand corrected. It's a 5 minutes job. They should be doing it for free, as a courtesy to their customers.

K

joseph50

You wrote:
"For people concerned with the Forester's rating on CR, what's it to you? You know that our Forester is very safe vehicle, and who cares how CR or any other car critic rates it."

At the risk of sounding thin-skinned, please understand that the feeling around here is one of being family.
Whenever the family name is besmirched, or is made the subject of misleading info, or is not given due credit as in the present case, it sort of riles.

c_hunter

Yep, it's a 5 minute job, don't even need to pull the door panels. Just pull off the little plastic triangle piece on there now, and the wires should be there waiting for you. New tweeters plug in and snap on. I've seen the tweeters for about $75 online.

Craig

lfdal

ditto on the tweeters - the dealer is after an absolutley obscene profit.

Larry

jms338

I recently took my Forester with 12,000 miles on it to my local dealer for what I believe is engine ping. I was told by the mechanic that rode with me the the noise I was hearing was air moving through the tumbler valve.

I am not completely convinced that I received a correct diagnosis so I was hoping someone might be able to provide insight into whether this makes any sense or not.

This noise occurs regardless of gas brand or octane level. It occurs on acceleration and when climbing hills primarily, but has also been noticed when cruising at highway speed. I can only describe the sound as a rapid fire knocking noise from the engine compartment. The noise apparently is not loud enought to trigger the knock sensor.

The dealer was not able to find any diagnostic problems. Is it possible that this something I am just going to have to live with? The owners manual states that you should not be concerned if the engine knocks occasionally on hills or acceleration, but how severely or persistantly does an engine have to knock to cause piston damage?

raybear

Hey!

We have to make an obscene profit somewhere!

stever

Just not off educated Town Hallies :-)

Steve, Host

raybear

Not a chance, Edmunds shoppers are among the most educated I run across.

joseph50

It is no consolation to you, but I have had "cruise speed pinging" since day one with my 2001 S.
Can you, or anyone else, please describe the location and explain the operation and purose of the "tumbler valve"? I never heard of such a item before.
Thank you.

bsvoller

Never had it, even once on my '01. I'd say something is amiss if you regularly hear it - bad gas...?

Note that we typically shift early (3000 rpm) when driving around town, and routinely drive through hilly terrain in 5th going 40-45. Yes, I have burned premium (91 octane in these parts) in the past, but I've just switched to 87 with no ill effects.

I've also been known to drive cross-country at 85 for hours on end, to tow a 1 ton camper a couple of times a year into the mountains, or to push the Forester rather enthusiastically through the mountain twisties (not all at once, of course !).

Never a ping, and I'm watchful for any sign of trouble, mind you...

I'd get a second opinion. The 2.5 should purr like a kitten at idle, and growl pleasantly when challenged.

-brianV

ateixeira

If I had to guess I'd say it's a faulty knock sensor.

FWIW, reset the ECU to see if that resolves it.

-juice

rangerron7

I was going to wait to weigh in on the pinging issue, at least until we had another tankfull experience after our latest visit to the dealer.
As a refresher, I'm the guy that complained about pinging on my wife's 2003 Forester during medium acceleration. It was diagnosed last year by the dealer as "spark knock" due to bad gas. After rotating gas stations and occasionally using mid-grade, the problem persisted.
I took it back to the dealer about 3 weeks ago. They reprogrammed the ECU and I have only heard pinging one time since. More importantly gas mileage over these last two tankfulls (I know, limited data points) has improved to 21 and 23mpg respectively. Right now I'm optimistic that the reprogramming has fixed the problem.
If in addition to what you describe hearing, you also notice a rotten egg smell and poor gas mileage (our average had been 18-91mpg), then it could be an ECU problem like Juice said.
Ron

envyabull

bsvoller,

I too am in the plastics business. I went from steel in nuclear submarines to aluminum for jet airplanes and now am in plastics for buried structures. While not as glamorous, buried plastic structures is the most complex and interesting of these disciplines.

I will need to look at the new factory bars on the XT to see what the materials are. Mine were never on the car since taking delivery. They are stashed in my garage. The optional square bar racks are painted steel, maybe galvanized in places. Their pillars are taller than the factor racks and probably more likely to buckle under compression or side force. Still they could help keep the longitudinal roof rails in column under some loads.

The plastic material you seemed to be describing was polypropylene (PP). PP is known to be more brittle than other more common plastics like high density polyethylene (HDPE). PP can become even more brittle at colder temperatures and some types even transition to a glass phase at colder temperatures not uncommon in colder climates. Despite these apparent shortcomings more PP is being used in automobiles including Subarus.

As you know, selecting the right plastic usually involves a compromise on properties. Even with the PP family there can be large differences in stiffness (flex mod), impact strength (Notched Izod), tensile strength and melt rate. I suspect automobiles typically use impact-copolymer polypropylenes. Furthermore, they probably blend in additional impact modifiers to increase the materials impact strength at lower temperatures. This will also lower the point of glass transition to temperatures well below those experienced by autos. Much of the plastic interior of cars is high impact PP. Also most battery cases are made of PP.

I just received my optional splash guards in the mail. These things will be in the cold getting pelted by rocks ice and snow. Those with just a basic understanding of plastics would never use PP for this application. However, they are indeed made of PP blended with EPDM, a common propylene rubber impact modifier. The splash guards felt more like a firm rubber rather than typical PP. The use of PP - EPDM was not the big surprise for me. I would like to know how they are able to spray on paint and make it stick. Paint and adhesives do not readily adhere to HDPE or PP.

bsvoller

-envyabull: PP is indeed one of the plastics I was referring to, although we've molded HDPE, polystyrene, and polycarbonate, among others. We've made everything from parts for an electrophoresis experiment on the shuttle to hospital supplies to liners for football helmets.

One of our most successful products is dunnage bags for restraining shifting loads on a truck or train. The forces involved when a train is "assembled" in the yard are considerable - they roll a car down a slight incline and let it slam into a standing train to couple. I've seen multi-ton loads shift 3 feet.

It's amazing what they can do with plastics by adding modifiers as you describe. The early attempts to adopt plastics in cars resulted in a lot of cracked dashboards, if you recall. Today it's used in various formulations all over the place. Laminating various materials together is another option in some applications.

I think I've been underestimating the strength of the roof rails - you're probably right, they could offer additional (and in many scenarios significant) stiffness/strength to the roof structure.

-brianV