BMW X1 (F48) Rear Brake Pad Replacement

 So the CBS for my BMW X1 indicated that the rear brakes pads were up for replacement. The pads were last replaced at 58k kms and the odo currently stands at 82k kms. Which means I got about 24k on the pads. From what I read this is average with a general life of the pads being about 25k. The last time I changed the pads I got it done at the BMW service center as I did not have the pads and not enough research completed to attempt a DIY.

I sourced a set of AKEBONO pads for around $100. Ordered an extra couple of sensors just in case. The pads however come with a brake sensor and springs that fit onto the pad.

Every DIY comes with it's own set of peculiarities. All manufacturers have specific approaches regarding design of bolts. fastenings etc. For the X1 here is what stood out for me:

• The electronic parking brake. The X1 comes with a electronic parking brake which means that there is a motor that is actuated to push the pads against the rotors. This means that pushing the piston back to get clearance for the new pads doesn't quite work. There are multiple ways to do this:
• the standard practice is to achieve this through BMW's service software ISTA. In ISTA there is a routine that puts the brakes into service mode which essentially pull back the motor from the piston so that you can push it back. This is what i used. It also means that you need to reset the brakes to normal operating condition using ISTA once the service is done. ISTA provides a clear step by step procedure to get this done and is pretty easy to follow.
• another option is to remove the motor from the calipers entirely so that the piston can be pushed back
• the third option is to apply reverse polarity to the motor to and spin in in the opposite direction to retract it.
• When you remove the dust covers over the caliper bolts you might be excused for expecting a 12mm bolt like most of the other vehicle. BMW however uses a hex bolt that needs an 7mm Allen key (H7) to unscrew the caliper guides. Picked this nice toolset from Flipkart that included a star allen key that helped with the X1's oil filter drain cap, the filler nut for the Aisin transmission as well.

I used the ISTA software to set the parking brake to service mode, jacked up the car and removed the tyres. The first step is to unplug the socket to the parking brake motor. This is the plug that you see dangling at the bottom of the image below. It has a small tab that you have to depress while pulling out the plug to unlock the lockinging mechanism. While pushing it back just push till you hear a click of the locks engaging.

Unplug the brake wear sensor from the socket which is located behind the fender lining towards the rear of the wheel well. I was able to access this by folding the lining back but you may have to pull out one of the fasteners to access the socket. Just following the wear sensor cable to locate the socket. It sits in a plastic holder along with the ABS sensor socket. You can see the wear sensor cable in the right of the image below.

Next I removed the spring that holds the calliper agains the caliper assembly. If you don't have this the you will get a rattle as you push against the callipers even with the calliper bolts fixed. No guesses for how I figured this one out. Let's just say I had changed the pads and bolted back the wheel on one side before the figured this one out.😐 To remove the spring just push down on the top with your thumb and use a flat head screwdriver to pry out the portion that goes into the two holes on the face of the calliper itself.

It other vehicles I've owned you had to remove only one of the calliper bolts and loosen the other and the calliper could be swung up/down to access the pads themselver. However in the X1 you need to remove both the bolts and lift the calliper off to access the bolts. These kind of aspects create a new appreciation on how simple things lend themselves to easy service procedures and less mistakes which make Japanese cars much cheaper and faster to service. In the image below you can see the calliper with the spring removed.

I used a box to place the calliper on, once I removed it from the assembly to avoid straining the brake lines and ABS cables. You can see the piston in the middle that I pushed back using a socket extension so that the increased thickness of the new brake pads could be accomodated.

Comparing the thickness of the old and new pads. Maybe another 1000 kms left on the old pads. However the wear sensors were pretty worn out and indicated I was 400km over the replacement warning. Give the amount to programming these cars have I am not sure how much this would cause the control modules to adjust associated setting and performance so I generally follow the CBS (Condition Based Service) warnings.

Installed the pads next which just hook on top of the calliper assembly requiring the calliper to hold them in place. This makes it a bit fiddly while installing the calliper. Another aspect that I dislike over the Japenese cars that have a pad profile that just locks into place which makes installing the calliper much easier. You can also see an additional spring peeping out in the middle of the picture. Got new ones along with the Akebono pads. I think these help the calliper push down on the pads and maintain them in place. Maybe ensure that the wear sensors are held tight in place to but not 100% on this one. Anyway they slot into the grove for the wear sensor. You need to install new wear sensors as the old ones will be pretty worn down and useless.

New pads in place with the callipers fixed and the spring installed. Did it in perfect order on the second wheel after all the learning on the first one. 

Some additional observations. The hex bolt is access from the rear face of the wheel and it helps to have a longer Allen key or a ratchet extension. 

The plug that goes into the socket of the parking brake motor. The socket is just above the plig in the diagram and located towards the bottom of the assemble. You can also see the wear sensor cable coming out through an opening in the calliper. I installed the wear sensor at the end after installing the pads and bolting the calliper in place.

As mentioned at the start DO NOT FORGET to set your parking brake back to normal operating mode using ISTA. Test that all is well by activating and deactivating the parking brake a couple of times.

That's it. As usually the achy joints and muscles notwithstanding, the sweet feeling after a DIY is priceless.

Links - Automotive

https://www.e90post.com/forums/showthread.php?t=1517476

The Future of AI

 The Future of AI

To say that Artificial Intelligence is taking the world by storm is an understatement. It's projected to be that all conquering technological advancement in the coming century. Depending on what streams you are employed in this triggers a wide range of emotions ranging from gut wrenching fear to euphoric excitement.

I am more of an observer at this point, interested enough to read more or less anything related to AI that crosses my feed. I satisfy myself with being able to understand that transformers has nothing to do with Autobots and Decepticon and stochastic gradient descent is not a mountaineering technique.

It the last one week I read two articles that for me gave a great perspective on AI as a whole. The first was an article by Rob Toews on Forbes.com. This was about the work of AlphaFold by the DeepMind team in predicting with considerable accuracy how proteins are folded into a 3D architecture. The complexity of proteins are covered in the article but let's just say that the combinations are humungous and the combination determines whether you are a mouse or a human being. Normally the structure of a proteins takes years of experimentation and specialised equipment to arrive at. However as of July 2021, a library of 350,000 protein structures predicted by AlphaFold has been published. 

To me the article was fascinating from the point of view that is showed how AI was helping us gain more knowledge and insight into previously unsurmountable problems. Of course this means that the added insight also means that we gain more understanding about what we actually do not know. For a "glass half empty"perspective it also showed how DeepMind was fast gaining in terms of intelligence that could one day threaten my precarious existence as a knowledge professional or even more depressingly take away my ability to commandeer the helm of an automobile through all that self driving blah blah, a skill that I consider existential.

In the midst of this came an article from IEEE Spectrum written by Neil C Thompson which sheds light on the computational limitations faced by Deep Learning. Apparently deep learning models are fast approaching limits of computational capabilities and more importantly incurring huge costs in training deep learning models to achieve the necessary accuracy. This cost is a critical factor in deciding the return on investment of Deep Learning projects and correspondingly their viability. The article touches upon the various work arounds and techniques used by the leading AI research teams to mitigate the cost of training and also CO2 emmissions. 

This places the value of human capital in context and illustrates how much ground technology has to cover to match up to a human brain. Again as mentioned about it also shows the frontiers of knowledge remaining to be explored and conquered. All the talk about machines replacing humans is a bit far fetched. Yes, just like the tractor replaced the oxen certain skills will become obselete. As much as I love driving I do see driving as a skill becoming obselete in the next 50 years if not earlier. However my skill as a software architect will still be relevant assuming I use my natural deep learning mechanism (my brain) to discover the great unknown.

Yuval Noah Hariri in his book "Sapiens" says that great progress started in societies who realised that they knowledge that they possessed was but a small modicum of the vast mysteries that the world had to offer. This realisation and the subsequent drive to gain more knowledge and consequently riches hugely spurred human development in the next 750 years to where we are today. In the same way both articles expose the exciting frontiers that remain to be conquered in which AI is but a welcome aid and not necessarily something to be feared.

P.S : the initial outline of this frontier seems to be the Metaverse but more of that later.

Book Review : The Phoenix Project

The Phoenix project

An excellent read for anyone in the Information Technology space irrespective of your role or position. It clearly calls out why IT is a differentiator and why IT risk is a business risk. For developers it puts perspective around why things like faster deployments, smaller packages matter from a busines perspective. It clearly elucidates why DevOps is not just something that start when you check in code but right from the requirements phase. 

Suddenly the hulabaloo around the "Shift Left" mantra makes all the more sense to you. In the midst of all this it left me with the Theory of Constraints which provides yet another weapon in your arsenal to approach IT delivery.

Ten deployments per day! Audacious in 2013 when the book was released but today it's much more common place. The book shows the need for automated testing, a focus on security right from the design stage.

DevOps is a culture

Yes it is and this book makes it clear why it's so. It makes it clear why all arms of the IT and business should work hand in hand to achieve goals and why for instance business KPIs should be reflected in application monitoring KPIs. Return on R&D spend, prioritising features that bring business value, paying down technical debt are all aspects that need to be considered in a DevOps culture.

Musings on the Iterator Design Pattern

Reading about the iterator pattern sparked a few thoughts. The Iterator pattern is used in conjuction with Collections. It abstracts the traversal methods out of the Collection. This has the advantage that the code of the relevant collection is not congested with the logic of traversing the list. In addition the responsibility of traversing the collection is offloaded to a separate class. Collection have a factory method called getIterator that provides the Iterator implementation for the collection.

Decoupling the Iterator also provides an additional advantage of being able to apply a wider variety of iteration techniques like Filtered Iterator etc.

Now extending this thought process a bit we can use this decoupling technique to provide Pagination techniques for instance for a list where the paging logic is abstracted from the list itself and handles the paging requests. This can be combined with a session cache so that the paging request does not go down to the db server.

This general approach can potentially be used to declutter a class from responsibilities that do not form it's primary objective.

Improving the handling of the Baleno RS

The RS has clocked up a little over 17000 km so far and it has been great so far. Typical Maruti ease of ownership coupled with an eager, peppy engine that has so far handled all that it has been thrown at. The daily grind, inching traffic, highway cruising and a few trips to the hills, it's delivered on all of them. Sure, the couple of crucial upgrades have really helped in ironing out the few compromises that Maruti has made in the interests of cost and appealing to a wider audience. Yes, very rarely there are nostalgic memories of the mid range of the GT but those are few and far between.

Of the compromises that Maruti made, none bothered me so much as the handling. It was stiffer than then regular Baleno and was fine as long as you were smooth on the throttle and did not push it too much into corners. However get ready for some aggressive cornering and I found myself having to wait while the car settled on it's springs before plugging on. Not good. To me it seemed that the springs were still too soft. Hunting about for a solution and at the same time not willing to make a huge investment this early, I decided to give RogerAb buffers a try.

Got the buffers in quick time. Decided to tackle the front first as this was the end that was giving me the most problem. The buffers were easy to fit, requiring nothing more than jacking up the car. However their circumference was a bit too much, so that they overlapped. Cutting a bit off would solve this but I haven't gotten around to it. The problem is that when the lower end of the buffer overlaps the upper, it fouls with the fender lining.

However the results were very good. It really firmed up the front suspension such that the wheel felt much more planted. The floatly feeling at triple digits speeds was also sorted out to a huge extent. There was a bit more heft to the steering wheel and the car felt much more planted when cornering.

The rear buffers were a bit more difficult and it seemed that I would have to undo the shocks to get enough extension on the spring to push the buffers in. So decided to shelf it for now and see how much of the handling was sorted out with the front buffers. Good, but not enough. The rear was a bit too soft and there was considerable weight transfer during accelerating and braking. Braking more so as the rear seemed to stand up when hard on the brakes. Not an issue if you were smooth on the brakes, squeezing them slowly so as to ensure a more gradual shift. Took another couple of weeks while I freed up some time to install the rear buffers. I took the car out for a drive and instantly felt a world of difference. The front axle seemed even more planted and high speed composure is so much more. The stance of the car also seemed to change a bit and the rake felt a little bit less. So much so that I feel it is a shame that Maruti opened itself up to so much brick bats on high speed composure just because of a softer suspension. The weight or the lack of it rather does play a part but primarily because of the absense of a suspension tune that matches the character of the car.

Even better was the braking feel or rather the improvement of the braking performance. I had earlier experienced this on my GT when I used Koni sport shocks on the rear. I feel much more confident braking hard rather than having to baby the brake pedal to ensure that the braking is smooth. The car holds it line very well now with acceptable (to me) roll. The front end does not dip so much when pushed into a corner. The best part is that the ride has not become so much more stiff kneed especially at the back. At this point I am pretty satisfied with what I have been able to achieve with the RogerAb buffers.

The second change that made a big difference was the tyre pressures. Thanks to an incorrect fillup at an alignment shop I am now running with 32 PSI against the company prescribed 29 PSI. With 29 PSI there used to be quite a bit of road noise (a fact I came to realise after running with 32 PSI) along with a bad rubbery vibe on the brakes especially when braking and cornering together. The change in pressure lightened up the front end and helped to tighten everything up together in a very nice way. I am pretty satisfied at where the entire package is at now to the extent that I am in no hurry to invest more anytime soon.

A few other things that I looked into an discarded on the way:
1. H&R springs - The 30mm lowering was not something I was willing to ake a chance on given our roads.
2. Swift Type 1(2008) Rear Springs - these were too tall for the rear.
3. Swift Type 1(2008) Front Springs - cooling off in my garage as the current setup has me pretty happy.

I think if I add on to this it would be a set of dampers. However I cannot seem to find any options on the Koni or Bilstien sites.

A couple of point on the Swift springs though. They are considerably thicker and heavier than the Baleno's, a reminder of what an excellent handling package that version of the Swift was.

CES 2016 - What does the future hold?

CES 2016

This year I will be following the CES at Las Vegas closely. CES 2016 promises a lot of new futuristic tech that gives us an insight into what we would be upto in the future and how we may be interacting with our environment at large.

Driverless cars, wireless speakers, electric vehicles, rollable displays they are all there. Check out a nice update at Day 2 coverage from the Verge.

See you on the other side of the show and I should have a few posts out.