Visit our Popular Forums

Roadtech · 08-13-2015, 09:01 AM

I have an crack on my curb side plexiglass curved rock guard. The L shaped crack is about 1 inch horizontal and 4 inch vertical crack. Should I replace the rock guard now or wait until I have more cracks? I wonder if another rock hits the cracked area, whether it will go through.

A W Warn · 08-13-2015, 09:25 AM

I have a few cracks in mine, from three different rocks on the Excella and one on the Safari. I have no plans to replace them.

dznf0g · 08-13-2015, 09:32 AM

I have several, when it gets bad enough, I'll replace with polycarbonate.

Morgan guy · 08-13-2015, 09:39 AM

One thing you might try to delay replacing the rock guard is to obtain some liquid acrylic (or acrylic cement) and slowly squeeze it into the lines of the crack. It will seal the crack and minimize problems if you are hit with another rock.

mandolindave · 08-13-2015, 09:40 AM

You could put a cool sticker over the crack. It might slow down the spread of the crack if you drilled small holes at the ends of the crack.

spclkaz · 08-13-2015, 10:40 AM

Is it just me that has aluminum rock guards on my old Excella...? when did Airstream move to a pexiglass (?) rock guard... was that a cost-saving move for them?

dznf0g · 08-13-2015, 10:51 AM

Quote:

Originally Posted by SKP46015

Is it just me that has aluminum rock guards on my old Excella...? when did Airstream move to a pexiglass (?) rock guard... was that a cost-saving move for them?

We're talking about the window guards, not the corner protectors.

dames7 · 08-13-2015, 11:54 AM

We just return from a 6000 mile trip to the Northwest and thank GOD I got a
ROCK TAMER MUD Flaps on my TV and did not see one ding on the AS or crack window guard. Well with the $200+

I camp next to another AS in Montana and he had all 3 windows guards broken from rocks on the road over the last 2 years.

dznf0g · 08-13-2015, 12:08 PM

Yeah I have rocktamers. They don't help with stones thrown form passing or oncoming vehicles.

GammaDog · 08-13-2015, 12:30 PM

I took a rock to one of my plexi wraps on i90 in SD in July. Went right through leaving a hole the size of a dollar bill. It saved the glass underneath. That part new from airstream will set you back almost $500. You can install it in 10 min with minimal effort. The window underneath is almost $1,000 and must be rerivited.

I'd live with cracks for $500 but replaced mine given the hole and a personal belief that sometimes lightning does strike twice.

dznf0g · 08-13-2015, 01:33 PM

Gamma, I assume you replaced frame and all? You can, with some cutting and riveting get plexi (or polycarbonate) stock and replace the plastic only. I understand, however, that plexi has to be heated to make the curve of the side guards....could be tricky.

dwightdi · 08-13-2015, 01:50 PM

To have the best strength Plexi window guards need to be formed by what is called slump molding. You have a wood male form mold and then heat the plexi up to the point that it droops over the form to make the curve. This results in no molded in stress and the window guard is best at resisting stones. If you cold bend plexi you have a high stress and it will crack if impacted with a small stone. Poly carbonate (Lexan) is somewhat subject to the similar limitations. It must be heated slowly to dry it out and not cause bubbles to form.

dznf0g · 08-13-2015, 01:55 PM

Quote:

Originally Posted by dwightdi

To have the best strength Plexi window guards need to be formed by what is called slump molding. You have a wood male form mold and then heat the plexi up to the point that it droops over the form to make the curve. This results in no molded in stress and the window guard is best at resisting stones. If you cold bend plexi you have a high stress and it will crack if impacted with a small stone. Poly carbonate (Lexan) is somewhat subject to the similar limitations. It must be heated slowly to dry it out and not cause bubbles to form.

Dwight, I keep getting mixed info on the poly. Some say that with thicker sheets, heating is necessary but not thinner sheets. I don't remember thicknesses mentioned, nor what is OE in our plexi guards. Thinner and more crack resistant may be better than thicker plexi????? If it is thinner, I'd just have to find extra thick spline material (they already use special order thick spline with the OE setup.

Can you shed light on the thickness debate?

amaier7771 · 08-13-2015, 10:07 PM

Subscribing, this is interesting....

acstokes · 08-14-2015, 06:45 AM

I got a star-shaped crack in one of mine. It was repaired by a mobile windshield repair guy and my insurance paid for it. Your's may be too large large for such a repair.

GammaDog · 08-14-2015, 01:15 PM

Response to Dznf0g...

The airstream replacement part is the complete unit (almost) ready to install. If your trailer uses the same approach as mine, the wraps are mounted on hinge posts on the rear of the panel. When the locking pins on the front are both turned 90 degrees, the panel swings back and lifts directly off the hinge post (no screws, nuts, etc.). The replacement unit is complete (frame, gaskets, hinges, etc.) and drops in place of the broken one. The only installation I had to do was to install the two twist lock fittings, each of which is held in with a snap ring. The alignment between my trailer and the new unit was off just a bit. A quick adjustment of the slot on the new window using a round file was enough to complete the installation.

Shoot me a PM if you need pics, part numbers, etc.

dwightdi · 08-14-2015, 02:24 PM

The more you cold bend a plastic the higher the stress is present. Thin materials you can bend by hand. Thick materials require considerable force. Either is bad for the plastic. Heating the material to its softening point causes the material to deform easily and will result in low stress. Keeping it bent for a time at that temperature will allow the material to anneal and remain in that shape when the force is removed. In this state, the material will have its best impact strength. Polycarbonate (Lexan)(if not exposed to a chemical crack agent (like gasoline) will have 20 times the impact resistance of acrylic (plexiglass). Polycarbonate is available as an upgrade on some guards and skylights. I have corrugated Lexan for one skylight on my 63 and it was undamaged by hail up to 2.5 inch in diameter, while all other skylights on RVs in that park were destroyed. I lost two glass side windows in that storm.

Thinner is easier to cold form, but has poor impact resistance. Thicker is better, but you may need to heat form it to stay in the frame and keep the curve.

Foiled Again · 08-14-2015, 03:14 PM

Dwight - would someone who works with Corian Countertops be able to slump mold Plexi or Lexan?

I've seen Corian bent to 90 degrees under heat, and even watched a man make a pencil box out of 3/8 corian by bending it around a circular wooden mold.

Paula

dwightdi · 08-14-2015, 03:57 PM

My guess would be that they had the proper equipment. Lexan needs to be heated to about 345F to do the job. Plexiglass is workable at 280 F. An oven or IF heating is usually used. People who do vac forming like acrylic sign people frequently have equipment necessary.

Inland RV Center, In · 08-15-2015, 01:15 PM

Rockguards are for windows.

Segment protectors are for the front sheet metal quarter panels.

The cracks happen usually from rocks.

Call your insurance company and submit a "Comprehensive Loss".

A comp loss usually has a much lower deductible.

A comp loss settlement will save you many dollars.

A comp loss cost for a typical rock guard including shipping is about $ 600.00 for a one piece rockguard, and about $ 750.00 for a wrap window rock guard, which is a part of the 3 piece rockguard.

Parts stocking dealers may have them in stock.

Andy