Rainsensor is loose, need cheap glue idea!

[GaryG]

What else can I use. Windshield was replaced, now the black box is just hanging from the wires. What a useless gizmo! What should I glue it back on with?

[JimD]

Go after the folks that installed the windshield. You want to insist they use the correct GM adhesive as anything else will either fail (as you have seen) or interfere with the operation of the rainsensor.

Hardly useless when installed properly.

[JohnnyG]

If you think it's useless, just cut the wires and get it out of your face.

[MAC]

I agree with JimD. I would first go to Cadillac and ask them if it’s possible for the black box to fall off if the proper adhesive is used. In other words, what are the chances of the box falling off if installed correctly? They’ll probably say “never” or something like 99.99% of the time a properly installed black box will not fall off. Then I would go back to the people/company that installed the windshield and insist they make the repair. As an alternative, I suggest asking them to reimburse you the $54 to buy the kit. As a consumer, you have every right to expect professional repairs to be done properly.

[adallak]

The sensor uses an infrared LED array to sense the refractivity of the windshield glass as it changes due to the presence of water droplets. It has to be attached with the correct adhesive so as to be transparent to the LED output. Otherwise it will not work correctly.

I am pretty sure such a thin layer of adhesive (transparent for visible wavelengths) will be transparent for IR as well (say super glue)

[adallak]

Refractivity is the problem...not just the transparency. You do not want to create an artificial refractive layer for the LED array with the wrong adhesive. Simple transparency is not the clue.

bbobinsky, I know a little bit about refractivity, reflectivity etc. It is I believe you ment "reflectivity" not refractivity. 50 micron layer cannot change the direction of light rays. As far as I understand the LED sends light out and a portion of it REFLECTS back to the IR detector. The main REFLECTIVE surface is windshiel external glass/air surface. Its reflectivity depends on the difference between refractive inecies of air and flass (I guess some 1.5). When it rains the difference changes dramatically since water refractive index is about 1.33 for near IR of the LEDs. So instead of the light directly reflected back to the detector you have light spreaded by water drops in wide angle of possible directions. It will result in drastic decrease of the signal detected by the rain sensor. A THIN LAYER of super glue cannot absorb a lot of near IR and will not create additional reflective surface since its refractive index is pretty close to the glasses. The rest will work jus like with GM glue (gosh... sounds like HODA ANTIFREEZ ). Peple (even smart GM engineers love to make thigs complex ) please do not take this personally

[adallak]

What else can I use. Windshield was replaced, now the black box is just hanging from the wires. What a useless gizmo! What should I glue it back on with?

GaryG,

Here is what I would do. There are many so called optical adhesives which are transparent for near IR (infrared light). I did not see the rain sensor, I believe it has some plastic or glass surface to be glued directly to the windshield right? Good! Adhesives will not cure in seconds (unless it is cyanoacrelate "SuperGlue" BTW it was created for surgery to join human tissues say skin, bons etc.). Many optical glues are UV cureable say Loctite 349, Norland 61, 68 etc. They cure in minutes depending on the intensity of UV radiation or even sun light. Put a thin layer of an optical adhesive ( I'll ship to you if you cannot get some) on the sensor and press it to the windshield. Make sure there is NO air gaps (it is important) . Ask your wife or GF (if you do not have one I'll ship mine to you ) to immitate rain ...with a sprinkle . Watch the reaction of your wipers. If it works leave it alone, sun light will cure it in a coule of hours, and send me some beer. If it does not work take it off immediately and wipe the glue off with some swabs and alcohol (use only high quality Vodka, I recommend SWEDKA). Then try another adhesive or even five minute epoxy. You need less than five minutes to see whether it works or not. Do not be afraid of experiments, that's what I do for more than 20 years, still insane and in pretty good shape BTW.

Good luck,

Armen

[adallak]

Sounds like a lot of work for a $50 repair avoidance. You are going to eat up a lot of the savings even IF you find something else that works because you are going to have to buy several different products.

My advice is to get the GM kit because you know that it works....the testing and experimentation has been done for you.

Experimenting is fine and fun....if you are getting paid for it and someone else is footing the bill for the various materials and such.....LOL If it it your dime I would take the surest and quickest approach as any potential cost savings will probably be superficial and false and will take a lot of time and effort to learn about. Worst case is you give up and THEN go buy the GM kit after spending a lot of time and money to learn what I am telling you....the GM kit is specified for a reason as there are no common adhesives that allow the system to work correctly....whether it is because of refractivity, reflectivity, transparency, etc....LOL

GaryG,

What if I send you an adhesive (just a couple of dollars from my pocket) and I am pretty sure it will work right away! You'll spend nothing and it will be a good lesson to GM! I saw many arrogant corporations which had to give up and use my inventions (sometimes paying nothing in other words stealing ) Could you please post the picture of the sensor so that I would know better what adhesive would be more appropriate?

Sorry bbobynski, but you have challenged me and I am going to prove I am right despite all the respect for you

[phillydude]

What else can I use. Windshield was replaced, now the black box is just hanging from the wires. What a useless gizmo! What should I glue it back on with?

GaryG,

Here is what I would do. There are many so called optical adhesives which are transparent for near IR (infrared light). I did not see the rain sensor, I believe it has some plastic or glass surface to be glued directly to the windshield right? Good! Adhesives will not cure in seconds (unless it is cyanoacrelate "SuperGlue" BTW it was created for surgery to join human tissues say skin, bons etc.). Many optical glues are UV cureable say Loctite 349, Norland 61, 68 etc. They cure in minutes depending on the intensity of UV radiation or even sun light. Put a thin layer of an optical adhesive ( I'll ship to you if you cannot get some) on the sensor and press it to the windshield. Make sure there is NO air gaps (it is important) . Ask your wife or GF (if you do not have one I'll ship mine to you ) to immitate rain ...with a sprinkle . Watch the reaction of your wipers. If it works leave it alone, sun light will cure it in a coule of hours, and send me some beer. If it does not work take it off immediately and wipe the glue off with some swabs and alcohol (use only high quality Vodka, I recommend SWEDKA). Then try another adhesive or even five minute epoxy. You need less than five minutes to see whether it works or not. Do not be afraid of experiments, that's what I do for more than 20 years, still insane and in pretty good shape BTW.

Good luck,

Armen

I also recommend the Swedka vodka... but I'm partial to the vanilla.

[GaryG]

You guys are great! A more tremendous response than I ever hoped for. bbobynski, when I called it useless, I meant that it's just hanging by the wires, and therefore, it's no good to me like that. It worked great when it was working! I don't like not having it.

You are right about the silly concept of wanting to save a couple of bucks on an expensive car that by its very nature is high-maintenance, (kind of like the beautiful trophy wife some guys have!) I've had my trophy wife 35 years, and now she's really a treasure, and I'm glad I've had her all these years! This is her car, so I want her to have it in good working order.

The glass installer (whole other story here, better left alone for the time being) says "stick it on with some 2-sided tape"!!!! Ummm, no thanks, I'll take care of it myself, so that's why I put it on the discussion board. I feel kind of like Adillak, I think of a little tube of sticky stuff costing a couple of bucks, so when they quote me over $50, I've got a lot of Scotchman (no, not scotch!) in my blood, and that just takes a little time to adjust to that shock.

I usually have a lot of fun seeking out little projects I can do myself, rather than just paying somebody and letting them do it. That's why I like the direction Adillak's going with this. My common sense is in a conflict with itself, first, I could just buy the kit, and get it over with. Then I think, hey, dab a little of this other stuff on there, stick it back up there, and have a great dinner with the money I just saved. Sounds like a formula for trouble doesn't it? (But I just had a thought --- I can use duct tape! Probably not one of my best ideas??)

We're getting ready to be out of state for the next week, not taking the car, so I'll ponder the words of wisdom from you guys and we'll see what happens. Thanks a million, you guys! Later!!

[Logan]

I'm with you Guru. Try to jusify the cost/time.

Same thing on the brakelights. Silicone material is a big repair favorite. Wont hold water. It just destroys the lamps. It simply does not work.

The 'stuff' used has to work as well in Canada as it does in the middle east. 99% of over the counter materials at Home Depot or Ace hardware etc fail already in that requirement.

Thats why there are OEM suppliers. They make stuff the general public has no idea about....fantastic stuff......but oh well....

I guess its their car. I bet new sensors are available if they mess up.......But...I bet a new sensor is a bunch more then the glue.

[GaryG]

Here's what the wife says about it, she's with you. Buy the GM kit and do it right, and stop fiddling around with it. Like the man says, it's her car. Seriously, thanks for the input and wisdom.

[Logan]

I agree....the company that fixed the windshield should of had at least ....some limited information about this.

Sounds like every one they do they use double sided tape. INOP....wipers.

Its a little bit like the heated windshields 5 years ago. Crackkkk. No, just install a standard window please. This is just the opposite. Hanging sensor? Hello....in this case it needs to work.

[adallak]

Great GaryG. Wives are always wiser than we Now I'll leave alone the GM engineers with thei unique glue and concentrate on my leaking and fontaining radiator tanks . I am sure that the GM engineers experimented with tank material painstakingly before bringing them to market!

[Logan]

I will add...I am not a fan of the plastic water systems connections.....you touch them .....they fail......

[Logan]

Sound like the $54 kit is the bargin....here a post from another site..

http://www.cadillacforums.com/forums/showthread.php?t=17745

[Greg P.]

bbobinsky, I know a little bit about refractivity, reflectivity etc. It is I believe you ment "reflectivity" not refractivity. 50 micron layer cannot change the direction of light rays.

Hmmmm... interesting. I guessing Guru was referring to refractive index as that would be quite relevant here.

As far as 50 microns goes, I would say that is plenty enough. Why wouldn't it be? Consider a simple optical fiber. A relatively small difference in refractive index between the core and cladding (both glass) causes a near perfect internal reflection. All done in much less than 50 microns. And as I'm sure you know, the delta in refractive index required to produce a reflection decreases as the angle of incidence increases.

I'd guess that they run this sensor somewhere near the hairy edge to make it work as well as it does. Therefore a small difference in refractive index could make a large difference in performance.

Without knowing the precise principles of the sensor operation, it's hard to say for sure, but it sounds like GM knows from both design and experience that superglue won't work here.

[Regis]

Aside from Greg's rather "simple" response (heh), why would GM spend money to develop a special glue if an equivilent could be had OTC? Simple economic logic should at least prevail here. OTC glues and adhesives are incredibly cheap considering the amount used per application. Next to nothing in cost if you think about it. Just a guess but I'm betting the GM rain sensor adhesive is really good at minimizing the possiblity of trapped air bubbles.... unlike most otc adhesives and glues. Just a thought.

-kg

[adallak]

Hmmmm... interesting. I guessing Guru was referring to refractive index as that would be quite relevant here.

As far as 50 microns goes, I would say that is plenty enough. Why wouldn't it be? Consider a simple optical fiber. A relatively small difference in refractive index between the core and cladding (both glass) causes a near perfect internal reflection. All done in much less than 50 microns. And as I'm sure you know, the delta in refractive index required to produce a reflection decreases as the angle of incidence increases.

I'd guess that they run this sensor somewhere near the hairy edge to make it work as well as it does. Therefore a small difference in refractive index could make a large difference in performance.

C, but it sounds like GM knows from both design and experience that superglue won't work here.

GregP,

It's nice to know someone here knows the proncipals og waveguide operation

Unfortunately if ine follows your logic it apears GM rain sensore detects rain in the car not out How the hell 50 microne layer of anything transparent for IR is going to change the direction of nearly NORMALLY reflected (by the glass/air boundary) from the external surface of the windshield. That's what I assumed if you red my post carefully and undestood what it was about.

But you are right -"Without knowing the precise principles of the sensor operation, it's hard to say for sure..."

Again, if you red my post I did not insist on superglue and offered special commercially available OPTICAL adhesives. The GM enginners do not develop adhesives, they just tried a few of known adhesives and have chosen one of them.

It's the answer for the next guy. I think it's better to end this discussion because it is not worth posting. What do you think? I believe thee are dozens if not hundred rain sensors in patent database. GM bought one of them or just has stolen some one elses idea and used it on Cadillacs. That's it. And as i said to Guru in a private message the rain sensores have not been around for a long time and nobody knows how long they will last on Cadillacs.

[Greg P.]

My assumption is that in dry conditions, they DO get a reflection from the glass/air interface and that the sensor picks up reflected wave at a specific point that is calibrated based on the thickness of the glass. At least that's how I might have designed it. But like I said I don't know. If this was so, any false reflection from the sensor/glue/glass interface might throw off the readings by returning the reflected wave sooner and to a different point. Just my guess though. Like I said, it's hard to know for sure without knowing the specifics.

What we DO know, is that if you use the wrong adhesive, the system will not work. I have seen a few firsthand reports of that on here.

I'd guess that in any case, the adhesive you would use would want to have the same refractive index as the windshield glass. Which could be interesting, now that I think about it since the windshield glass is laminated isn't it?

It's worth mentioning that the rain sensor (at least mine) works amazingly well at what it does. I was initially skeptical but was well pleased with how well it functioned.

a mildly interesting ancedote... the 2nd day I had my 1999 STS, I took a couple or friends to lunch who are both instrumentation engineers and of course I was explaining all the nifty features including rainsense.

Both of them expressed doubt as to how well the rainsense would work. As luck would have it, it started to rain on our return to the office. Both my friends and I were impressed at the performance of rainsense, not only at how it detected the rain, but at how well it modulated the wiper speed in accordance with the intensity of the rain.

But not to be outdone, my one more skeptical friend said something like "but how can they account for personal preference of how fast YOU want your wipers on?" I then showed him the sensitivity adjustment. He replied with something "Okay I'll just shut up now."

[adallak]

I am going to buy a new Caddy just to take the f... sensor off and conduct a couple of experiments. I'll report the results

[Scotty]

My assumption is that in dry conditions, they DO get a reflection from the glass/air interface and that the sensor picks up reflected wave at a specific point that is calibrated based on the thickness of the glass. At least that's how I might have designed it. But like I said I don't know. If this was so, any false reflection from the sensor/glue/glass interface might throw off the readings by returning the reflected wave sooner and to a different point. Just my guess though. Like I said, it's hard to know for sure without knowing the specifics.

What we DO know, is that if you use the wrong adhesive, the system will not work. I have seen a few firsthand reports of that on here.

I'd guess that in any case, the adhesive you would use would want to have the same refractive index as the windshield glass. Which could be interesting, now that I think about it since the windshield glass is laminated isn't it?

It's worth mentioning that the rain sensor (at least mine) works amazingly well at what it does. I was initially skeptical but was well pleased with how well it functioned.

a mildly interesting ancedote... the 2nd day I had my 1999 STS, I took a couple or friends to lunch who are both instrumentation engineers and of course I was explaining all the nifty features including rainsense.

Both of them expressed doubt as to how well the rainsense would work. As luck would have it, it started to rain on our return to the office. Both my friends and I were impressed at the performance of rainsense, not only at how it detected the rain, but at how well it modulated the wiper speed in accordance with the intensity of the rain.

But not to be outdone, my one more skeptical friend said something like "but how can they account for personal preference of how fast YOU want your wipers on?" I then showed him the sensitivity adjustment. He replied with something "Okay I'll just shut up now."

I want RAINSENSE! Your description of it has me wanting it! Mike

[adallak]

I want RAINSENSE! Your description of it has me wanting it! Mike

Mike, it seems to be a good option. Changing wipers' mode may become annoying and distracting. The question is how much GM charges for having it..

[KevinW]

I was successful in repairing a Rainsense module that had been RTV'd to the windshield of an STS. I used the GM kit and followed precisely the directions; I believe the location of the adhesive layer is just as important as its thickness. Those contemplating 'irreversible' means of attachment might consider that the windshield may require replacement (again!) at some point.

[TDK]

"Rainsenser" ?

The heck with it...

Just live in Nevada with 5" per year average rainfall. Who needs wipers at all !

For that matter, considering the relatively low angle of the windshield - I just drive faster when in rain (in California) and it just scoots over the top.