BSM compatible Road Armor bumpers on sale

On thinking more about this, and how MW works, I am not really worried.

Sidewalls to the sensor are irrelevant as far as signal restriction goes. If the side walls weren't there then any "excess" signal width (And we don't know if there is any to begin with) would just be caught on the back/inside of the bumper anyway. If the signal were that wide that early you would get alarms from the bumper itself. Going out on a limb and saying that's not the case because they sell the bumper with the option for the BSM, and they wouldn't do that if it threw nonstop errors. The only issue the sidewalls might pose would be in signal reflection, but, again, unlikely because it would constantly throw errors.

The beam is going to start very narrow and then expand as it travels further away. If the beam were wide enough to hit any part of the bumper it would be reflected and set off the BSM. If it did that when they tried it out, then it wouldn't have gone to production.

Looking at some of the images of Tacos with the bumper removed and then the C4 Fab bumper I linked, no, they are not any closer to the surface of the bumper than the Road Armor one would be. They are recessed several inches. They look closer because C4 put a flat plastic panel on the bumper instead of building the little tunnel to the sensor. The opening isn't any bigger either.

The only actual problem I could see would be restricted signal coming back to the sensor, but with the way MW works I don't think it'll hurt it. See pic below for reference only. The beam expands as it moves away from the sensor right up until it hits something. Then it is reflected back, and also continues to expand on its way toward the sensor. If any of that ever expanding signal makes it back to the sensor your BSM/RCTA will work as intended. It doesn't have to thread the needle back to the sensor because it's blasting a wide beam back at it.




It SHOULD all work in theory.




@Motor71 have you had a chance to use/test the BSM and RCTA features in your bumper? Real world experience is worth more than any speculation we can do here.

 

The bumper is all prepped just waiting for a nice day to throw it on.

 

Didn't say everyone would utilize the winch. Everybody that has a lift and bigger tires doesn't use the extra capability and clearance. Doesn't mean the lift/tires are basic just because they aren't using it.

You may not like the product/company, and that is fine. You may even be right that no one who NEEDS a rear winch would every stoop so low as to buy a Road Armor, but that doesn't change the fact that it has the option that a lot of basic bumpers lack. Best execution? Nope. But the option does put it a bit above basic bumpers. Couple that with the discount of half off.... are there any other BSM friendly, winch capable rear bumpers for the Tundra for less than $800? Is it still overpriced when it's cheaper than lots of non winch, no recovery point, no BSM bumpers that are out there?

 

You’ve had this bumper? If so, what makes it crappy. As an engineer, the design looks normal. Supports BSM, which is rare, Uses 3/16 steel, which is normal and weighs ~200 lbs. May not be to your liking but doesn’t have the specs of a “shitty” bumper.

 

Well, I looked at the install guide, and the chopping of the hitch is the deal breaker for me. Thank you for pointing it out early so I didn't have my hopes up too long.

 

Have you already done the to the hitch for it? If so, do you have any pics? Their guide has mediocre pics and nothing that shows the hitch after the cut.

 

This weighs on me as well, but still keeping an open mind about it. Considering if I go with this bumper and want to return to factory, I can always have a local shop tac weld it back on.

 

Post #14 has pics of the bracket that gets cut.

https://www.tundras.com/threads/looking-at-this-bumper-install-question-on-hitch-trimming.81141/

 

THANK YOU! That's not as bad as I had worried. Dammit. Back on the fence.

 

The only pic I have been able to find with it on the truck is the one on the Road Armor site. Looks pretty good, but I'm not 100% sold on the sensor cut out. Kinda wish they had done it like C4 Fab with a plastic panel. I think that's just because the hole in the corner that I can see light through pokes at my OCD.



Link if you want to look at the pic on their site. https://roadarmor.com/stealth-rear-...n-m8000-or-9-5xp-2014-2020-toyota-tundra.html

 

I see that you don't have the Road Armor badge on yours. Did you remove it, or did the previous owner? How did you fill the holes? Can't quite see for sure in the pics.

 

I filled them with black button head screws.

 

The sensor working and the sensor working optimally are too different thresholds. Testing systems like this isn't a one and done endevour were we cut a hole in the bumper and we call it good. It's also more than making sure you don't throw a fault when you remount your sensor. It's tedious to verify and validate a system works according to spec. There is no way this supports OEM spec.

The Toyota sensor doesn't start as a pin point as in your example. It starts off as a wide beam and attenuates the lobes depending on what mode it operates in. It's a cone with the tip cut off.

OEM vs this bumper would look like this if the beam was only going straight out perpendicular to the sensor; the box is the sensor and the line is the surface of the bumper. The cone is just an example and is not to scale of the OEM signal:





Notice how the cone on the right is covering less detection area, the bumper channels are casting a "shadow". Not only is the signal going out covering a smaller area its able to detect even less return signal as a result.

The picture you posted isn't exactly how these sensors work, there isn't a singular cone bouncing back. In reality there are many cones bouncing back from the whole surface of the scanned object. With a smaller window, less of this spacial information is able to come back into the sensor. This creates blind-spots along similar angles as the shadow areas in the second example. It's important to note we don't know how sensitive the sensors are and how large object need to be to throw an alarm. It certainly doesn't help to restrict the information coming in. Comparing the two you could say the OEM bumper is capable of sensing 180 degrees of information while the aftermarket is covering a max of 90 degrees but could be as low as 30.

According to the manual the sensors operate differently in BSM mode vice RCTA mode.

BSM mode's range is limited to 11.5ft max (less width than a US lane). It can detect vehicle 9.8 ft behind the vehicle and 3.3 feet in front of the rear bumper line.



RCTA wouldn't be useful if it was limited to 11.5ft so it's detection perpendicular detection ranges are 18ft for slow movers (<5 MPH) and 65ft for fast movers (<18 MPH). It is supposed to be able to detect vehicles in both lanes so it can detect objects up to 24ft behind the vehicle.



The point is these lobes are big (especially the RCTA) and they aren't just fanning out perpendicular to the vehicle. They are scanning towards the rear up to an estimated 24 ft. There is no way this bumper's geometry supports what these sensors need to operate effectively. The easy fix is to push the sensors as close as possible to being flush with the surface of the bumper. If the sensor fits through the hole you probably don't even need to mod the bumper just the cover

 

That is an assumption based on an assumption... it requires the assumption that the spread of the signal is rapid enough for the 2-3 inch channel to be an issue. We don't have a known pattern for the beam. Also, if the signal were hitting the channel it should be setting off the alarms. Apparently it doesn't, so I would actually be more inclined to assume that the signal beam is narrower than your diagram would indicate.

Again, all of this is assumption without actually having a bumper to test, or a technical diagram of the sensors actual beam pattern.

 

It's based on what is clearly stated in Toyota's owner's manual.

The sensor head is only ~3x~3. To transmit a lobe as described in the manual it has to spread out more than the channel allows and in directions the channel doesn't permit. Precise amount of spread doesn't matter, it's a non sequitur. Anything other than a beam is diminished. The angles of detection matter more. We know 100% its not a narrow beam and we know 100% its not purely perpendicular. This can be observed and proven easily.

Negative. We do. Its not a lobe diagram but an estimate bases on the dimensions described by Toyota. You can look at the manual snapshots to figure out roughly what they are. You can easily observe them as well.

No. Not necessarily. What the channel will do is mess with the timing making the sensor think parts of the objects are further away. Signals hitting the channel will travel a longer distance along this path. It will also make object look smaller, less return information coming back.

Note there is a "no detection area" close to the vehicle within 2-3 feet. Any signal returned is immediately rejected. Based on this feature alone we would not expect a sensor fault as you pressume.

Even without the signal rejection the cross section of the channel is tiny enough were it would appear as a very very small object; significantly smaller than the objects Toyota states the sensor will reject/not detect.

False premise, documents say otherwise and observation say otherwise. You can disprove your beam premise by driving your vehicle and observing when BSM kicks in and when it doesn't. So no it's not a beam.

 

You are assuming the signal has to travel in a straight line, and that the entirety of the sensor surface is used to transmit it. What if the pattern is similar to the one above? It blooms more as it moves away, but is extremely narrow in the first 5-8 inches. This would work fine, wouldn't it?

What if there is only a half inch square right in the center of the sensor that transmits and the rest of it is for receiving return signals? That would make the beam patter start out at a fraction of what you are proposing in the diagram.

The type of signal matters too. I'll use telecom tech and how it has changed as an example because it is something I work with. The newer tech (3G, 4G, and 5G) has to have more line of site so a mountain can cause you to lose signal, but older TDMA tech flowed over obstacles in a more fluid fashion. It had better coverage in mountains and valleys than the new stuff. What kind of signal and tech is used in the BSM?

We DO need the technical diagrams and more info before we assume anything about how this bumper will affect/not affect the BSM sensor. My point is that there are too many variables to make a conclusion right now.

 

Here's an image from a toyota manual. Using your rigid assumptions on function based on "documents" this vehicles BSM sensor must be huge. It starts at the back door and goes to the middle of the bumper... Owner manuals are NOT technical. They are useless in determining if something will interfere.

 

@AzureNightmare @Saltyhero13, this is actually the most technological and presentable information known to mankind on a truck thread and I submit you both to @Squatting Pigeon and @ColoradoTJ for a monthly award for your research and explanations. I say they purchase you both the bumper and we “f around and find out!”

 

Every time I see one of your posts I realize how utterly appropriate your avatar is. You trot about giving the bird and spreading rainbows in your wake!

 

What I find to be very interesting is how did Road Armor determine that the bumper is compatible with the BSM sensors? The only way to know is either thru hit or miss when alarms trigger (or not?) and hope it sort of complies or contracting an expensive certified 3rd party testing facility that has the required test equipment that costs literally tens of thousands of dollars, the knowledge on how to use the test equipment to measure super low level noise, gain, cross section, patterns, etc, and........ a large enough RF anechoic chamber to perform the testing. You would need to know Toyota's actual specs for the BSM system. CW or pulsed specs, RF level at what freq specs among other things? (Keep in mind that the BSM emitted energy is kept purposely low for obvious reason. Quite low and does come into play big time in regards to sensitivity.) This is the only the way to truly test the actual sensor sensitivity to interference from external EMI's or a physical interference caused by the bumper's design. Obviously alarms will go off when the sensors have too much interference but I'm not into the hit or miss concept with sensor sensitivity because there are so many variables to take into account. Sensitivity to interference has always been critical with RF components/systems even more so today. BSM is a good example. Both Rohde & Schwarz and Keysight analyzers have phase noise specs down to 170 dBc. My Keysight E4440A I use at work is spec'd to 160 dBc. Overkill in this scenario. Crazy and unheard of only a few years ago. 1st world bumper issues.....lol

 

I did, hoping to put the bumper on this week.

 

Seems like minor trimming anyways compared to BMCs which actually alters the frame. Definitely a good deal for a USA made winch bumper. Although not completely sold on the BSM compatibility claim. We shall see soon enough!

 

@Squatting Pigeon @ColoradoTJ

Before you kick me off this thread allow me to present one last post after this or peel off my discussion with Mr. Nightmare to a separate thread. My intent is not to derail a sales thread with non-related info. I see what I think is a safety issue. I sincerely appreciate the healthy skepticism but I cannot in good conscious stay silent in what I see as a design flaw that will diminish the sensor's ability to do it's job as designed by the OEM. I do not believe the manufacture did this intentionally. I think they tried to preserve the sensor's exact location on the truck with a bumper that is much thicker than OEM hence the recessed design. Since the sensor doesn't throw codes they considered it G2G. If I am wrong I am wrong. So be it. I will present my final findings either way.

Addressing @AzureNightmare retorts: As far as EMF signals bypassing steel bumpers, its not going to happen with the physics on this Earth using technology currently known to man. Certainly not with a 24Ghz signal (1.2cm wave). Now is it possible at all? Interestingly enough, yes! Quantum Tunneling and Gravitational/magnetic Lensing are two phenomena that exist but I do not think these apply to or describe anything related to this situation.

I understand that user's guides are not technical manuals; that doesn't discount the useful information they offer to help build a better picture of the problem space. We can extrapolate much of the information to a degree that is close enough for this thread. In reality we don't need a precise model when approximations and reasonable assumptions will do given the info we have so far. The missing piece is the angle of the sensor which I already have. The arc of detection would be helpful but we can accept that it won't be less than what Toyota states in its manual.

Regarding the sensor TXing from a pinpoint or the whole pad surface. The point argument makes the geometry even worse for this bumper and is actually an argument in my favor. I was giving the manufacturer the benefit of the doubt and working my approximations in their favor.

Following up with a trig thread.

 

The cut

 

This forum is probably the last bastion of hope for grown men to speak to one another in a civilized manner with a touch of cheeky humor (the mods allow) and not get into online fights or battles that amount to nothing. So I always try to keep it clean but I, like you, am a very sarcastic bastard. But only in good fun.

In your posts above, I just learned more about how our system “actually works” then anywhere else I’ve ever read. I also have to appreciate the depth of knowledge that lurks on this forum waiting to be unleashed by people about the most random things. I know to add white vinegar to make pancakes more fluffy and now I know all this data as well so one day when the mechanic is BS’ing me I will pull this up, reread it and say “oh really? You sure about that?”

 

F**king unicorn

 

Excellent.....

 

Whether bsm works or not, I'll know once this bumper is up and running, and I'll post updates. I don't understand half of the scientific explanation that was written, but the earth is still spinning, biden will be president in a few days, and if my bsm doesn't work, I'll be pissed!!!

 

BSM will work but I suspect it is being clipped. I hope I'm wrong.

How much is being clipped? I'm working out the math.

 

3 inches in