Mercedes SL - Fitting Parking Sensors

With winter upon us I decided to fit parking sensors to my 280SL as the rearward visibility of this car isn't fantastic at the best of times, so with frosty windows a scrape is inevitable.

I'd like to start by thanking Stevitee for posting his photo sequence on the Mercedes Club forums. Without those pictures I'm sure it would have taken me a lot longer as I didn't have to figure everything out, I simply had to go through the motions. So here goes:

Before

Here are some quick "Before" shots for later comparison

The kit

I bought one of the multitude of kits available on the internet (or eBay). These came branded as Gadgetman, but the sensors are identical to those in a kit I bought for the ambulance so expect it's the same factory in China making them all.

I chose the 6 sensor (2 front 4 rear) kit with a buzzer as I didn't want to mess up the interior with an after-market display (I had one in a cheap runabout I'd bought and it didn't suit the interior).

I took the time to quickly test the kit and all the sensors before taking my car apart. Just in case I needed to return anything.

Bumper removal

Rear bumper removal is up next. The bumper is held in place by 2 bolts (13mm nuts) which come through the rear of the vehicle. These nuts need to be completely removed. The following two pictures show the location of the these nuts (right and left side of the vehicle respectively).

In addition the side extensions of the bumper slide over a plastic fittings which are held on with 2 x 10mm nuts each. The two on the side where the battery is located can be loosened without removing the battery, but it would be much easier with the battery out. These don't have to be removed entirely (in fact I'd advise against it), but loosening them helps with wiggling the bumper about. Again pictures of the right and left sides respectively.

Before removing the bumper I stuck on some masking tape (see picture below) and figured out where I thought the sensors would go. I centred them vertically on the bumper "insert" (it isn't really an insert but it looks like one), and initially measured them out to be evenly spaced across the back of the bumper (see later why I say initially).

The second picture below is of the wheel arch liner. This is easy to prise out gently when the 2 x 10mm nuts hold the extensions tight have been slackened. Also be very careful as there are lugs (you can just make the one out if you know what to look for in the picture below - which you probably won't if you're reading this) at the top front of each extension which hold the bumper in place. (Thanks to numerous posts on the forums I knew about these and didn't break mine as many did).

Bumper off

My 9 year son was helping me with this job. We carefully pulled the bumper off and laid it on an old blanket. Some pictures below of the bumper off and the grommet (middle right of the car) that I chose to put my wiring through. In retrospect I should have put it through the one at the middle left as the wiring runs along the left hand side of the car, but there was ample length in the wires.

Let the holes begin

Here you can see that I followed Stevitee's suggestion of drilling a pilot hole. The supplied hole saw has a 4.5 mm centre bit so I used the same to drill the pilot holes. Here you will also be able to see that at the rear of the bumper are 4 recessed in the polystyrene packing which appear factory made for parking sensors. This is why I earlier mentioned having marked out evenly space holes. when I noted these recesses I moved the sensors so that they would be centred in these recesses.

Fitting the rear sensors

I fitted the supplied angle rings to the sensors and fitted the sensors with the thin side to the top. this angles the sensors away from the ground. This decision was made based on the instructions talking about the sensors not pointing at the ground. I suspect that in this bumper the rings cold be omitted, but better safe than sorry.

If you look at the pictures below you will note that I was able to thread the sensor wires behind the plastic backing which makes quite a need job. I also took the time to fit some heat-shrink sleeving over the 4 sensor wires so they would go through the grommet as one. Subsequent re-fitting of the bumper truly followed the Haynes principle of being a reversal of the removal procedure. I did however make sure that it was properly lifted and pushed in before tightening, so an assistant does come in handy.

Stripping the interior

having followed Stevitee's approach I knew that it would be possible to route the front sensor wires through to the boot from the engine compartment via the sill, so I proceeded to take the interior apart.

The following pictures are of the sill cover fixings; when these 2 have been removed the cover simply pulls off.

You don't need to remove the carpeted cover under the dash. I wasnt' sure and loosened the 2 8mm screws and discovered that someone had been there previously and actually broken it. I put the 8mm screws back and it isn't noticeable, but now I'll never forget it.

To feed the wires through from the engine compartment the easiest is to feed them through the grommet that the bonnet release cable goes through. To get at this you need to remove the left side kick board. Once the sill cover has been removed, this is held in place by the 8mm screw that holds the bonnet release handle in place. Remove that and then slide the kick plate backwards (I didn't realise this so damaged the tab on mine as I thought it would be held in by the standard press fit panel fasteners).

Fitting the front sensors

Again following Stevitee's procedure I decided the fit the front sensors without removing the bumper.

Some careful measuring and drilling later I had two holes in the bumper, right into the polystyrene packing (picture 1). Removal of the plastic air duct (picture 2) and slacking off the bumper retaining nuts (picture 4) allowed me enough room to shove a piece of coat hanger wire through the polystyrene from the back (picture 3). It goes through OK, but needs a bit of time.

I then tape the sensor wire to this and pulled it back through. Having learnt my lesson on the first one (I damaged the wire), on the second I first pulled through a double piece of coat hanger wire to force the hole bigger before pulling the sensor wire through.

Routing the wires

Routing the front wires back to the boot starts in the engine bay by feeding them along the left side of the engine compartment. There is a convenient plastic wire trunking fitting here. In the second picture you can see the coat hanger wire having been pushed through bonnet release cable grommet from the passenger foot-well. I then used this to pull the wires through.

Stripping the rear seat area

My car has rear seats, so the whole base and back rest on the left side of the car have to come out. This then allows the carpeted panel to be removed. (I noted that the plastic screw cover had been glued in on mine so broke on remove). This reveals more plastic trunking that the wires can be threaded through into the boot. At the same time I threaded the buzzer wire through and hid the buzzer behind the panel so it is inside the passenger compartment.

Control box

The final step was to wire up and install the control box. The sensors and buzzer all simply plug in, but I had to solder the power leads to the brake and reversing light fittings for the front and rear sensors respectively. I was able to wire the earth lead an existing earth point near the aerial.

You will note from the pictures that I stuck the control box to the inside of the wing and also fitted push in connectors the wires so that I would easily remove them if I needed to. All that remained was refitting all the trim.

After

Final, here are some "after" shots to show the sensors in place.

Camper Part 34: Cosmetic Quicky

Yesterday was a 'camper' day as I decided to start trying to improve the cosmetics a little.

As is evident in this picture from last year when I was removing the stickers, some paint had lifted off the passenger door.  (look carefully in the crease line).  As I recall it wasn't on the latest stickers, but some time earlier in the life of the vehicle.

This made the vehicle look tatty, so having located a better door, I went and collected and fitted it yesterday (picture when I manage to download it off the phone).  This had the advantage of not waiting for paint to dry and the new door comes off a much newer vehicle so hopefully less time before rust sets.

Opto Issues

The issues with the optos are ongoing.  I replaced the connection pins with wires on all three my opto circuits, but it appears the one I damaged last time is fubar.

As for the other two:

• The TechZone optos have the LED enabled until the opto is blocked then it switches off
• On mine, they're never turn off, no matter what I block them with.

Help!!

Mendel Mayhem: Completing the bot

Having gotten the X-axis running last time, the job tonight was to finish off the job.

I started by wiring up the Y & Z stepper motors. Luckily with the Zapp Automation stepper motors and the Azdle mounting for my TechZone electronics, I was able to wire the steppers directly, no extending of cables. (The extruder stepper will be another matter).

I then starting playing with moving the axes around using the RepRap host software. This reminded me that I had tweaked the config for the ScrapStrap (which had a belt drive for the Z-axis), so I set about trying to remember how to reset the config. I decided that the best was to get the latest from Sourceforge (now at 20100806 - I had previously installed 201000702).

Upgrading RepRap Host
As I wanted to reset my config, I upgraded as follows:

• Extracted the latest software 20100806 to a temp folder.
• Replaced the raprap.bat with the one I modified last time (to make it work in a different sub-folder)
• Copied in my RepRap.ico file I had created
• Deleted the contents of my install folder (having backed it up)
• Copied in the new installation (and deleted the temp folder)

This means that I reverted by firmware config as well, so I had to reprogram the firmware. This was achieved as follows (any folder locations refer to sub-folders off Reprap\mendel\firmware\FiveD_GCode):

• Copied configuration.h.dist to configuration.h in the FiveD_GCode_Interpreter and Extruder folders (I compared to my old config and was reminded that I commented my changed with my initials - glad I followed a guideline I insist all my coders at work follow)
• Load the FiveD_GCode_Interpreter/FiveD_GCode_Interpreter.pde sketchbook
• Modified the configuration.h tab to match my setup (guessed most of it as I don't know what applies yet - it seems to be pretty much setup for the v3 electronics which the TechZone stuff is - For the hardware, I left it as standard for now, as it should be) and saved.
• Selected the Tools->Board->Sanguino board and then Sketch->Verify/Compile
• Connected the board to the PC.
• Selected Upload to I/O Board and done!!

For the Extruder controller:

• Copied the configuration.h.dist to configuration.h in the Extruder folder
• Moved the USB board to the extruder controller, remembered to invert it (ground is on the opposite side). Mine is now marked with a black marker.
• Loaded the Extruder/Extruder.pde sketchbook.
• Modified the configuration.h tab to match my setup (left it all standard as I didn't see anything relevant to change) and saved.
• Checked the temperature.h tab as I am running a thermistor. I wasn't sure is the default table is correct or not, so I left it be for now.
• Selected the Tools->Board->Arduino Diecimila, Duemilanove or Nano w/ ATmega 168 board and then Sketch->Verify/Compile
• Connected the USB cable to the PC
• Selected Upload to I/O Board and done!!!
• Disconnected the USB and moved it back the main board

Next step, testing the config. I reloaded the RepRap host software and it all worked fine.

Next step was to get on with mounting the end-stops and checking that it can home itself. This is when I discovered one of the issues with the TechZone electronics. In their efforts to reduce the size of the components, they gave no consideration to the retention of the standard mounting locations and as such I managed to damage one of the circuits while trying to make this work. This caused me to suspend work for the evening as I now need to get into some soldering etc, which is a change of focus so will be done on another day...

Mendel Mayhem: Frame continued

I got bored inside, so here I am again. My wife popped out to the shed to see what was happening, and got a guided tour of the assembly to date.

Installing the Y-axis
It took very little time to get the Y-axis installed, completed with belt. I then quickly installed the X-axis belt while I thought I knew what I was doing. As said before, the bed is going in later.


Fitting the electronics
Having a moving cartesian frame and a seperate set of mounted electronics will only drive one insane, so the next step was...

And it works!!!! Well ok, I only connect the X-axis, but at least I'll be able to sleep tonight (sort of).

Mendel Mayhem: Frame

As I have previously assembled my TechZone electronics on a thick sheet, the next step is the frame.

Frame sides

The lower vertex pieces supplied by Nophead have feet so I needed to ensure I took heed of this from the off (I don't know which he used, so no link, sorry These are Nophead's own design, frame-vertex_with_simple_foot_4off located in the alternative-parts repository).

I did a loose assembly initally, but tightened one end of each threaded bar. Then laying the assembly flat on the worktop I adjusted them to the jigged value. For locating the Z-leadscrew brackets, motor bracket & tensioner, it is useful to note that the lying the assembly flat on the worktop allows you to have these pointing up perpendicularly.

So another hour got me from this:

To this:

I also decided to use these 3M stick on rubber feet that I found somewhere (I'm a bit of a hoarder if you hadn't realised yet). The picture on the right shows one fitted to the Mendel's foot. They should help a bit with regard to the reduction of noise/vibration transmission to the worktop.

Frame ends (i.e. the bits that join the two sides together)
Starting to read this I just see that they recommend feet like the ones I fitted. Great minds and all...

In reality this is the assembly of the main framework (without axes), so quite time consuming with all the calibration. As you'll see if you look carefully at the first picture, I was so happy to be done after 1.75 hours that I had forgotten to align the Y-axes motor and idler brackets.

This is going to be an epic segment as I need to get all the cross pieces in.

On sorting these out I found that my large mudguard washers on the motor bracket were preventing the M8 washer from getting past. Loosening the M4 bolt a bit so the washer could 'wiggle' allowed the two to pass each other. Another 15 minutes had passed, so 2 hours in total for the frame assembly.

X-axis installation

Following the instructions on the 'Mendel Frame' page of the wiki, I noted the following (depicted in the pictures below):

• The cap screws for the Z-lead screw bearings are easier to fasten if they point upwards. The picture will show that I only switch to this for the 3rd screw on each side as the bolts for the Z-bar bracket prevent my socket from fitting.
• The instructions mention that that X-axis should be approximately levelled before adding the belt. I achieved this by using the J3 measuring jig as shown.
• I double checked the spacing of the top brackets by measuring and comparing to the leadscrew brackets at the bottom. (Still need to test full travel).

That was another hour, I think I'm calling it a day for now. The next step in the instructions is the lower circuits, but that doesn't apply with the Techzone electronics, the next instalment should see the Y-axis, bed and electornics (on the side) installed.