Another new project - the COVID pandemic Fifth Wheel RV Recreation Plan - Ford F250 and Glendale Titanium 27EXB

Just when I thought I had enough on my plate, my wife and I decided to finally execute on the RV project we've been thinking about for years. We've rented C class motorhomes a couple of times now - I always liked that when you rent an RV - someone else takes care of winter storage, repairs, license, insurance, and all the rest. The only downside is the availability of a suitable unit that fits your family. The last C class rental we did, the arrangement of the bed didn't fit well with our family and schedule. The kids are too old now to share a bed, so that means one kid is down on the couch in the middle of the RV, and if that kid is a late sleeper, you have a problem when trying to get going in the morning in the kitchen. And so on.... 

The other issue with the C class is that you need to tow a vehicle if you plan on setting up camp and sightseeing - not impossible, lots of people do it, but this is impractical with a rental. 

So - we ended up going with a pre-owned 2012 Ford F250 4x2, and a pre-owned 2001 Glendale Titanium fifth wheel - 27EXB with bunk beds in the back for the kids. We made the purchase in January and are getting things set up and organized for this summer. 

2012 Ford F250 4x2 Gray Metallic with 2001 Glendale Titanium 27EXB

The truck is well suited for towing the RV - full crew cab so everyone has lots of room, and full 8' box for 90 degree turning capability with the fifth wheel. I'm happy with rear wheel drive - we don't plan to use the vehicle too much in the winter, and it has the electronic locking rear differential to put power to both rear wheels when traction is limited. The lack of 4WD saves some weight and complexity. 

I found a used Reese Titan 16K fifth wheel hitch which I installed with new rails. No need for a sliding fifth wheel hitch. Installed this myself on a Saturday, pretty straightforward. 

Installing the universal bed rail kit for the Reese Titan 16k Hitch

There were plenty of used fifth wheel hitches for sale in January - I ended up going with the Titan because of the urethane bushings which help isolate trailer motion from the truck frame. On my initial haul returning home with the fifth wheel, I was really impressed by how quite and stable everything was. Other than the weight, you really don't notice the trailer unless you're on rough pavement. 

Reese Titan 16k Fifth Wheel

The hitch will need a bit of love, the grease fittings were seized, the jaw bushings were ungreased, and there is some rust on the frame to touch up. 

On the trailer - we got it for a good price, however there is some water damage and structural issues to take care of due to a few years of neglect. The RV is booked for the structural / water damage repairs in March, more on that in future posts. 

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Hydro Quebec Flex D Rate - Controlling Clothes Dryer with Insteon EZIO relay

We're just over half the peak demand season in Quebec, so far, so good. Will write up some articles on what I've done so far. On one demand management period a few weeks ago, someone in the house started the clothes dryer, I caught it after it had been running for about 10 minutes. One of the problems with the whole energy management / peak demand implementation is that it is difficult to get everyone in the house on the same page. I understand that at $0.50 per kW-hr - running the dryer for an hour ends up being an expensive proposition. It's harder to get the two 12 year olds in the house to understand. 

LG Clothes Dryer - Cover Off, Control Board back left of the photo. Relay will go close to control board

For avoiding future problems with the dryer, I decided to implement an interrupt to prevent the dryer from starting during a peak demand event. We have an LG dryer with an electronic control board. I didn't want to get into switching the power feed to the dryer - it's a large circuit. I decided to try interrupting the door open switch, effectively putting a second switch (relay) in series with the door open switch. 

Opening the cover of the dryer exposes the wiring and control board. Cut the power before opening the dryer cover for obvious reasons. The wiring diagram was attached to the inside sidewall of the dryer, and still quite legible. 

LG Dryer Wiring Diagram

The dryer switches 120V (one leg of the 240V), and it switches the connection to neutral. When open - it provides the neutral connection for the lamp inside the dryer, causing the lamp to come on. When closed, it provides the neutral connection for the control board. I decided to interrupt the neutral connection to the control board, in a fail safe fashion. My relay will be normally closed on the neutral circuit to the control board, so that if there is no control system, no connection to the relay power - the dryer will function normally. The interrupt feature will require 24VAC from my control system. 

Wiring in the relay with a relay base was quite simple - 4 connections. 

Relay with base installed on a short braket - no interference with top cover

The wire to the control board was a yellow wire according to the wiring diagram - very easy to identify. I simply cut the wire, crimped in two extensions to take the connection over to one of the relays normally closed pair of terminals. I use heat shrink crimp connections for a neat installation.

Connections made on the NC relay terminals - interrupt yellow wire (neutral to control board)

I ran a control wire down into the basement next to the dryer vent line - very easy in my case - and over to an automation panel where I had a pair of existing Smartenit EZIO 4x2 Insteon relays. I just selected one of the relay output terminals, and used 24VAC from the transformer in the cabinet. When going through the dryer case - I was careful to run the cable through a rubber grommet to avoid any shorts in the future, and ensured my cables were well attached to the dryer frame with zip ties. 

I just finished testing the connection. It works perfectly. When interrupted - the electronic control panel stays powered up, all the control lights are illuminated, but when you press the start button, nothing happens. The control board thinks the door is open and won't initiate the drying sequence. All good. This project was surprisingly quick and easy - took about 2 hours in total. Feel free to ask any questions down below. 

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Hydro Quebec Flex D Rate - Peak Demand Project

Hydro Quebec, my provincial electricity utility, is trialing a dynamic pricing model this winter. It hasn't been rolled out to all residential consumers yet, it's in a trial phase. I applied for the trial and was accepted to participate. I figured that dynamic pricing is inevitable with Quebec's push towards electric cars, so I might as well jump in and see how it goes. My home is already extensively automated, so I should be able to come up with protocols to deal with the peak demand events with a minimum of manual intervention.

The base electricity rates in Quebec are tiered. The first 40 kWh per day are charged at 6.08¢/kWh (1st tier). The remaining energy is charged at 9.38¢/kWh (2nd tier).

The "Rate Flex D" is a dynamic rate where electricity is cheaper than the base rate in winter, except during peak demand events, when it’s more expensive. From December 1st to April 31st of the following year, outside of peak demand events, the price of electricity is below the base rate, so you can save money (4.28¢/kWh for the first tier of 40 kWh/day, and 7.36¢/kWh for the 2nd tier). During peak demand events, electricity is billed at a high price (50¢/kWh). The day before a peak demand event, you receive a notification.

I've been through three days of peak demand events so far. In this post, I'll describe some of my preparation, and how things are going so far. 

First, here are some characteristics about my house.

• Large, two story house with full basement. Electrically heated garage on an elevated concrete slab, with basement space below the slab. 3/4 of the basement is finished, 1/4 is utility space housing the fan coil, most of the zoned ductwork, the electrical entrance, and storage space under the garage;
• 400A electrical entrance, with three 200A breaker panels. One panel is designed for critical loads and is connected to a generator transfer switch. There was a generator installed at one time at the house, it has since been removed. 
• Principal heat source is a Carrier Infinity Greenspeed 4 ton heat pump with variable speed indoor fan coil, with three stages of backup electric resistance heating. The heat pump can maintain a constant temperature in the house, without electric backup heating, down to about -14C. Below that temperature, the heat pump needs help. The heat pump thermal efficiency drops to 1 at about -20C, where it no longer is effective.
• The forced air ductwork is zoned, with a separate zone for each level of the house - basement, main floor and 1st floor. I upgraded the Infinity system to full zone control this year, and can now control the temperatures on each floor independently. 
• There are supplemental electric resistance heaters in most of the rooms in the basement for comfort. These are controlled by programmable thermostats. Now, since the zone heating upgrade, I haven't bothered turning those circuits on since I can effectively control the basement temperature from the principal heating system. Our offices are in the basement, and with COVID confinement, a comfortable working temperature in the basement was one of the prime drivers to do the zone heating project.
• I have extensive Insteon control over lighting. Virtually all lighting in the house, on all levels, is controlled by insteon switches and dimmers. 

More to follow in this series on Rate Flex D Peak Demand.....

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Franke Sink Stopper - Leaky Seal Repair

We did a kitchen renovation about 10 years ago, and installed two side-by-side Franke stainless steel sinks. Total cost was substantial. Only three years after installation, the stoppers started leaking - if you filled the kitchen sink with water and walked away, it would be empty in about an hour. I did a bunch of research, and found that you could purchase a replacement rubber seal for the stopper, you could only purchase the entire stopper. Not particularly cost effective. 

Franke 1145 Strainer Assembly - Expensive way to replace the stopper seal

Note how the new seal on the stopper looks

So - I had a close look at the stopper and seal design, to try to determine why the stoppers were leaking. The seal is in the shape of a tee - with the base of the tee set into a groove on the stopper, and the sealing surface protruding perpendicularly from the base of the tee. When the stopper is set in place, the sealing surface is pushed laterally, and causes the base of the tee to rotate. If the seal rotates enough, you get metal to metal contact between the stopper and the drain fitting, and water can escape past the rotated seal. 

Left Stopper - normal seal. Right stopper - seal flipped down and leaking

I researched possible replacement seals - o-rings, or similar shaped seals and didn't find anything that would fit or seal. You can not purchase just the replacement seal from Franke - you can only purchase the entire replacement stopper. 

Seal removed from stopper - not available as a replacement part

Then, I figured maybe there's another way to prevent the failure mode - the rotation of the seal. What if I could add some support for the perpendicular sealing surface, prevent it from rotating. I found that a very small diameter o-ring stretched around the stopper, just above the seal, supports the seal and keeps it from rotating, and allows the sealing surface to do its job. I've had this fix now for over a year, and is completly reliable. 

Large o-rings, small cross section

Simple stretch the o-ring over top of the seal, snug it up against the metal body, and it will prevent the large stock seal from rotating and leaking water.

Look closely - note the o-ring avove the stock seal

Another view - O-ring above the stock seal

Works well. 

I picked up some extra o-rings - if you would like to purchase a pair to repair your leaking sink, just click here. 

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Shop-Vac is going out of business

 You may not have heard, but Shop-Vac is in receivership. This was announced on September 18, 2020, but I only realized it when I needed a part that I accidently discarded after cleaning my large Shop-Vac. I went to their website and found all of their manuals and customer support information was offline. 

I've had one or two Shop-Vacs for as long as I can remember. As soon as I realized that getting a part might be difficult, I went to Canadian Tire and managed to find what I needed, however I was surprised to find the shelves almost bare of Shop-Vacs, parts and accessories. So I picked up a few spare dry pickup bags. 

Shelves are almost bare of Shop-Vacs at my local Canadian Tire

This company is an icon, and their components drove standardization in wet/dry pickup vacuums. Knock-offs abound, and accessories tend to be universal fit across brands now. Maybe this is the reason that they're in financial difficulty. Hopefully someone comes in and rescues the brand and the North American manufacturing facilities based in the Eastern United States. 

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Multiple Zone Retrofit Carrier Infinity Residential HVAC System

I upgraded my residential central heating system three years ago with a new variable-speed Carrier Infinity Greenspeed 4 ton heat pump and fan coil. The previous system was about 22 years old, and had some upgraded components, but ultimately, the 22 year old fan coil developed a refrigerant leak in the coil, and replacements were no longer available. I looked at having a custom coil fabricated, but ultimately, decided to go with a full variable speed system for efficiency, low temperature capability, and greatly reduced outdoor noise with the variable speed heat pump.

Close duct - basement supply. Far duct - main floor supply with Belimo Damper Actuators

My house has three levels - main floor, basement and first floor. The house was originally constructed with three ductwork branches, one for each level, and each branch had a bypass damper installed. The bypass dampers allow excess air from any one zone to recirculate within the mechanical room back to the furnace. In my case, the bypass was open to the room and not ducted, for this reason, the large mechanical room in the basement was always very warm in the heating season, or very cold in the cooling season - a tremendous waste of energy.

At one time, the dampers were controlled with an industrial PLC which was also connected to thermostats on each level of the house. By the time I purchased the house, the PLC controller was no longer functioning and the system was operating as a single zone system, however, the thermostats were still installed on the walls, and the dampers could be controlled manually with toggle switches on the original PLC panel.

Manual Damper Controls on Legacy PLC Panel Cover

With the Covid-19 lockdown, my wife and I were working from home full time, from our office in the basement. In the summer time, the basement was too cold, and I began manually modulating the dampers to heat the basement in the summer for better comfort. This was laborious, especially considering the dampers had a 45 second full cycle time - you had to manually hold the spring loaded control switch for 45 seconds to make the damper position change. I quickly scrapped this idea and thought about upgrading the Carrier Infinity system with its Damper Control module and retrofit damper actuators. 

Components required for the retrofit - 2 Zone Thermostats, 3 Zone Actuators and the Zone Control Module

Researching how the Infinity Damper Control module controls its dampers, I learned that it expects the damper actuator to have a 15 second cycle time from full open to full close. If the Damper Control module needs to modulate damper position partially open or partially closed, it will simply actuate the damper for a fraction of 15 seconds - for example, half open - it will power the actuator for 7.5 seconds from full open or full closed. It also has a current limit of 1A at 24VAC. My Belimo dampers would not be compatible, so I would have to replace them. Carrier sells two damper actuators which are compatible with the Infinity system - standard damper actuators complete with the damper for new installations, and a retrofit damper actuator designed for round shaft dampers - in two versions - 90 degree rotation and 45 degree rotation. I needed the 45 degree versions. 

New Carrier Retrofit Damper Actuator DAMPACT45DEG-R on the Left - Old Belimo Actuator on the Right

So - I ordered all the parts and got started. The first order of business was replacing the actuators. I could take my time with this without affecting the normal system operation. 

First step before removing old actuators - mark shaft with damper blade orientation

And for each damper - mark the blade orientation - Damper Open and Closed

In my case - the damper opened with counter clock wise (CCW) rotation, but the markings on the Carrier actuator are for clock wise (CW) opening. So - I simply relabled the actuator cover with open and close positions reversed, both for the electrical connection and for the orientation sketches. Not only does this help yourself keep things straight during installation and cabling, but it will really help the next guy that comes along sometime in the future and has to figure out what you've done. 

Carrier DAMPACT45DEG-R Damper Actuator Cover Relabelled for CW Opening

I expected this to be fairly quick and straightforward and it was - until I tested the actuator with 24VAC. The actuator could not supply enough torque to move the damper for the basement or main floor dampers which were installed horizontally. The first floor damper, which was installed in a vertical duct, was properly balanced and the Carrier actuator had no problem with it. 

Measuring torque required to move damper blade

So - to check to see how much trouble I was in, I took a pair of vice grips and gripped the damper axle. Then, I took a digital fish scale and hooked it on the vice grips at a measured distance from the axle (8") and pulled the damper open - careful to keep the scale oriented exactly 90 degrees to the radius to the axle. I measured approximately 2lb of force required at 8" - which works out to 16 in-lb of force. The Carrier Actuators are rated for 10 in-lb of force, and the old Belimo actuators were rated for 133 in-lbs. So - the new Carrier actuators were 13 times weaker than the Belimo actuators, and half as strong as what I needed. What to do now..... 

The axles did not protrude from the other side of the duct, so I would have to come up with a solution on the actuator side of the axle. I checked out counterweights - some are available online, and the principle is that you have a weight on an arm that is fixed to the axle at a particular orientation - with the weight at a particular distance from the axle to balance the damper blade. I didn't have enough space to use a balance weight because I had ductwork above each actuator installation - I only had about 3" of clearance above the two horizontal duct actuators. 

I thought about using springs to assist with opening the actuator, to reduce the torque required. Luckily, I had a mixed kit of Power Fist extension and compression springs from another project. I realized that I could simply replace the short shaft lock screw with a longer lock screw - the screw thread is 5/16" diameter, and I had some 2" bolts in my hardware stores. 

Damper actuator assist first attempt - extension spring attached directly to 2" bolt

First I tried connecting an extension spring directly to the 2" bolt - however, very finicky to retain the other end, and I found that the spring yielded easily because of the relatively long travel of the head of the lever (2" lock bolt) compared to the relative short length of the extension spring (about 3" compressed). So, I selected some additional extension springs and cobbled together a spring assembly using zip ties. 

Prototyping an assist spring for the damper

I ran out to the local home improvement store, and found some 3" fully threaded 5/16 bolts to allow me to use a washer and nut to attach the spring assembly near the head of the lever bolt. 

2nd Try - 3" fully threaded lock bolt with spring assembly

Upgraded with small turnbuckle for Tension Adjustment

I was able to get these adjusted to reliably assist the opening and closing of the dampers. In my case, if the furnace fan was running - it greatly impacted the torque on the axle. I adjusted the dampers to reduce the opening and closing effort without the fan running, because I expected that the Damper Control module would only actuate the dampers at a reduced fan speed. I turned out to be correct. 

With damper actuators resolved, I moved onto installing the remote thermostats. You have the option of installing 2 wire thermocouples, or 4 wire communicating thermostats. I went with the thermostat option, which Carrier calls a "Smart Zone Temperature Sensor", Carrier part number SYSTXCCSMS01. Luckily, I had a 4 conductor cable already in the wall from a Legacy home automation system - so I just reused the existing cable. 

Smart Zone Temperature Sensor baseplate and 4 wire communicating cable connections

Smart Zone Temperature Sensor installed in the upstairs master bedroom

With the actuators and zone thermostats installed, it was now time for installation of the Zone Control module. Before undoing any connections, shut power off to the furnace, fan coil and thermopump, to ensure that the 24V control transformer is powered down. 

In my installation, I had a Carrier Network Interface Module installed to control my whole house air exchanger. This ended up greatly simplifying my installation, because all system cables already ran to a location just above my fan coil, so I didn't have to move any cables. 

Carrier Network Interface Module

As I removed the cables from the Network Interface module, I labelled each cable with 6mm Brother TZ tape, with clear heat shrink to protect the label. This provides a durable label that won't fall off or become illegible over time. Helps avoid errors during installation, and greatly assists the next guy that has to come along and maintain or modify the system. 

As I disconnected cables from the Network Interface Module, I labelled them

The new Zone Control module installed on the ductwork above the fan coil in place of the old Network interface module. I labelled all the new thermostat and damper actuator cables and brought them into the Damper Control module enclosure. Zip ties help keep the cabling neat. In my case - the master thermostat (what Carrier calls the "User Interface") connects here, as well as the 4 wire communication cable to the fan coil. 

Damper actuator cables connected to the terminals on the Damper Control module

Cabling complete - Thermostats, Damper Actuators, Air Exchanger

Once all the cabling is complete, double check all of your connections, and then reapply breaker power to the fan coil and thermopump, this powers up the 24V system transformer and powers up the User Interface (Master Thermostat) and the Zone Thermostats (Smart Zone Temperature Sensors).

The first thing you need to do is program the Smart Zone Temperature Sensors with the correct zone number. This is done at the Zone thermostat - because it is a communicating device and the commications cable connects to a common interface ABCD bus, and not a particular terminal on the control board. 

Program the zone number on the Smart Zone Temperature Sensors

With the zone sensors programmed, you then need to reset the installation at the User Interface. This will force the User Interface to query the Carrier communication bus and identify all connected components - the fan coil, the thermopump, the two smart zone temperature sensors, and the zone control board. 

Carrier User Interface queries the communications bus and identifies connected equipment

Carrier User Interface identifies the Zone Control Module, and 2 Additional Zone Thermostats

With all equipment identified, the system automatically starts a duct assessment, and checks the flowrate (duct sizing) of each zone.

Duct Assessment in Progress

When the duct assessment is complete, it displays the results. In my case, I have relatively high leakage and I later realized that the humidifier bypass duct is open - this will cause air recirculation that appears as a leak. I intend to redo the duct assessment with the humidifier bypass duct closed and see what effect this has. 

Results of duct assessment

Then - the setup process finishes, and you can now control all three zones independently from the user interface / main thermostat. You can control the remote zones using the Smart Zone Temperature sensors as well. This worked perfectly from initial startup, and I really like the new capability. 

System status - temperature control screen - shows setpoints and temperatures of all zones

System status - temperature control screen on the Carrier iPhone app - Same information

System has been running for 2 days now - I've programmed the the first floor where we have our bedrooms for cooler temperatures at night to promote better sleep, and the basement during daytime hours to be warmer for comfortable working temperature from home. I'll be fine tuning the programs going forward to optimize energy consumption. Stay tuned for an update once I have some operating experience and data. 

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Quickjack Hydraulic Fluid Contamination and Quickconnect Fitting Failures

I had the BMW wagon in the garage up on the quickjack for a few weeks at the start of September, fixing a Low Boost Pressure code, oil pan leak, replacing rear drive axles, and treating some underbody and rear bumper corrosion. 

I've had the Quickjacks for two years now - they've been a great tool, really useful to quickly get all four wheels in the air for doing seasonal tire changes, or drivetrain maintenance. Halfway through the last job, the hydraulic hoses began to get difficult to reconnect, there was residual hydraulic pressure in the hoses. I was in a hurry, so I tried forcing the connectors onto the pump. The next time I hit the lift control, I started losing a lot of hydraulic oil from the quick connector. 

Quickjack hydraulic pump releasing its schmoo

It didn't take long to figure out the problem - forcing the connectors cut the o-rings in the face of the connectors. I trashed two connectors of the four female connectors. 

Notice the protrucing piece of O-ring left of the center pin

I was in the middle of raising the car and I wanted to get the next step of the job done, so I simply removed the bad connectors and made fixed hose connections, using 3/8" NPT unions, and a 3/8" bulkhead fitting to replace one of the pump male quick connectors. However, I had lost a lot of fluid. I went to my automotive fluid bin and grabbed a bottle of brake fluid. Big mistake. The spec is for automatic transmission fluid, and I added about a pint of brake fluid and got back to business. 

Two days later I went to lower the car - and the cylinders wouldn't hold the car raised without the buttons pressed. I had difficulty removing the lift locks so that I could lower the car. Fluid was bypassing the check valve that holds the car in the air when there isn't any button input. I removed the check valve, and found little bits of white plastic jamming the check valve open. 

Quickjack check valve - marked with a CV on the valve body.

Not good news - but I immediately realized the contaminated fluid was the probable cause. Once I was done with the Quickjacks, I drained all the fluid from the system - removed the reservoir, removed the quick couplings from the hoses, and stood the jacks up to drain the cylinders by gravity. 

Draining fluid from hoses and jack cylinders by gravity

When I opened the reservoir, that's where I encountered the real mess. Bits of white plastic suspended in hydraulic fluid. Larger chunks in the bottom of the reservoir. The inlet strainer was detached from the inlet elbow, and just lying in the bottom of the reservoir.  

Inlet strainer (round) detatched from inlet elbow.

Bits of white plastic in the reservoir

Inlet strainer missing its attachment hardware (likely made of the white plastic which dissolved)

White plastic in the inlet port of the pump

More white plastic in the pump inlet port

I don't have a replacement inlet strainer yet. I have seen all metal inlet strainers and inlet elbows on the internet - but I'm having difficulty getting my hands on them. For now, I've replaced all the fluid with clean ATF and I'm running the jack without the strainer, just the inlet elbow. I'll drain and flush the fluid a second time once I have an inlet strainer to install. 

A few recommendations from what I've learned the hard way.

1.    Put a label on your quickjack hydraulic reservoir near the fill port - "ATF Only"

2.    Always hold the "down" button for 5 to 10 extra seconds when descending the quickjack, to release as much pressure as possible from your hoses before disconnecting them. This helps prevent residual pressure buildup in the hoses. 

Not my finest hour - but hopefully the information in this post helps someone else avoid the same issue in the future. 

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BMW E60 / E61 Rotor Repair - COVID Lockdown Parking Rust and Brake Vibration

 When the COVID lockdown hit back in March, daily commuting stopped, kids were pulled from school, shopping essentially stopped except for weekly trips to the grocery store, and the BMW wagon went from use 4 to 6 times a day to a couple times a week. The drop in use was dramatic, and one result of this was a couple of instances of the brake pads bonding to the rotors with corrosion. You would go to use the car, all the brakes would be stuck, and after a few seconds of throttle, eventually the corrosion bond would break and the car would start rolling normally. 

BMW E61 535xi Front Rotor

Use of the car has gradually returned, and we did a local road trip in August. The brakes in the car were completed replaced when I did the turbo project 2 years ago, since then the car has only travelled about 20,000km. During the road trip I noticed minor brake pedal vibration - more apparent during light braking, less apparent with a bit more force on the pedal. 

When I brought the car into my garage in September to look at the low boost pressure issue, this was on my list of issues to repair. 

Rust ridges on front rotor left from pads freezing to rotor

I thought about purchasing new pads and rotors to sort out the issue, but 20,000km is next to no use, and I wanted to avoid the cost and the waste. I got onto google and looked for brake rotor turning services. At one time this was common, now, almost impossible to find. There was one machine shop in east Montreal that gave me a reasonable quote for turning the rotors, but when I went to drop them off, the machinist had sufferred an accident and would be off work for a month. No go. 

Frozen brake pad prints on the front rotor

So - if a part is broken, you can't really break it any more trying to fix it. I decided to try sanding the rotor surfaces with a Dewalt 5" orbital sander with 200 grit paper, to try to remove the ridges. 

Frozen brake pad prints on the front rotor

I sanded the complete surfaces, front and back, of both disks. I did two passes, not wanting to remove too much material and creating a bigger problem than I already had. I was careful to spend the same amount of time and pressure as equally as possible around the surface of the disk, just spending slightly more time on the ridges left by the various brake pad prints on the rotor surface. I didn't try to completely remove the brake pad prints, but smooth them out and hopefully reduce the pedal vibration. 

Front disc following sanding - pad outlines are still visible.

The sanding removed some of the ridges left during the pad bedding into the rotors. I knew that the pads would have to bed in again, so I was patient for the last month and tried to modulate my brake pressure to allow that to happen gradually. 

I would say that this has largely solved the problem, although, with very light application of the brakes there is still a slight vibration. With normal stopping pressure, the vibration is not apparent. It seems to have improved the braking feel, but it's not perfect. It seems to be improving with time however, so I'll let it go for another month or two and report back whether the problem resolves itself. For now - I've saved the cost of a pair of rotors and pads. So far, so good. 

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