A few brake and tyre questions

[hedges88]

I had a squealing noise from the rear of my W169 A class recently but only at motorway speed or after driving at motorway speeds. An inspection revealed that the rear backing plates had corroded and warped slightly causing the noise. I was also recommended new discs and pads all round.

They wanted £500 which was a bit much IMHO so I called someone else willing to do the job for approx £400 but I was then asked when pricing the job over the phone if my car had vented or solid front discs, id always assumed that most cars have vented front discs and solid rears but after checking part numbers, sure enough my front discs are solid. I asked about changing them to vented which involved changing calipers etc which pushed the price up a lot. However I was then told by the mechanic to my utter suprise that solid discs actually have better stopping power, at least for average driving in such a light car (1210KG) for average driving. Is this true? I thought most cars had vented at the fronts and solids at the rear for the reason that the rears did much less work.

Also I finally found a set of 16" OEM alloys to replace my 15" steelies but like most urban cars, A class alloys are never perfect and they certainly need a light refurb. They are 195/55/R16 as opposed to my current 185/65/R15. There are even larger OEM wheels available all the way up to the 215/45/R17 but most owners agree they are hard to live with and that the 16s are the sweet spot. Two questions here, is an extra 10mm tread all round even noticeable and will they be quieter than my current 15"? I just can't help but think that the large sidewall of the 15s must carry a lot of road noise through the body of the tyre.

I also need to clothe my 16s when they are refurbed and having a look around for a premium tyre two keep popping up, Bridgestone Turanza T005 but they are pretty pricey (nearly £80 a pop) and just wondering if anyone has real experience with them. Toyo Proxes TR1 are super cheap though (£54) if they are any good?

[Scrump]

I would think that the 16 inch wheels will be slightly noisier and have a slightly harsher ride than your 15 inch wheels. They certainly will not be quieter (for the same tyre type).

I would not worry about spending any money trying to fit vented discs on the front, unless you do track days/carry a lot of load/do repeated hard braking from high speed then your solid discs will be fine. Vented discs have better cooling so should run cooler under hard or repeated braking (As this is PH I expect this statement to spark some debate )

[hedges88]

Scrump said:

I would think that the 16 inch wheels will be slightly noisier and have a slightly harsher ride than your 15 inch wheels. They certainly will not be quieter (for the same tyre type).

I would not worry about spending any money trying to fit vented discs on the front, unless you do track days/carry a lot of load/do repeated hard braking from high speed then your solid discs will be fine. Vented discs have better cooling so should run cooler under hard or repeated braking (As this is PH I expect this statement to spark some debate )

So the A class guy told me that 16s were the best compromise, especially with the comfort suspension like I have. 15s have too much sidewall play to be fun and anything larger than 16 is just horribly jarring so I settled for the 16s.

I won't be upgrading to the vented ones. I was just incredibly surprised that they used solid ones at the front. I was tempted at one point to fit the larger front discs found on the diesels and the a200 turbo. But to be honest, the amount of work involved just pushes the price way too high.

I am surprised that the 16 in would be more noisy. I just thought the noise would travel through the carcass of the tire a lot more? Either way, I feel I made the right choice by plumping for the 16s in terms of a balance of comfort and performance. I am thinking of replacing my dampers at some point and that is going to be a huge expense as they are Bilstein B4 damp matic systems. They say they "drive like the first time every time" But after 97k I reckon that might be stretching things a little

[E-bmw]

hedges88 said:

Scrump said:

I would think that the 16 inch wheels will be slightly noisier and have a slightly harsher ride than your 15 inch wheels. They certainly will not be quieter (for the same tyre type).

I am surprised that the 16 in would be more noisy. I just thought the noise would travel through the carcass of the tire a lot more?

Noise is just vibration, a taller wheel/shorter sidewall combination is more solid & therefore transmits more noise/vibration from road to cabin.

[Dave Brand]

hedges88 said:

However I was then told by the mechanic to my utter suprise that solid discs actually have better stopping power, at least for average driving in such a light car (1210KG) for average driving. Is this true?

Total garbage! All other factors, such as disc diameter, pad material, etc, being equal, the stopping power will be no different.

[ARHarh]

Dave Brand said:

hedges88 said:

However I was then told by the mechanic to my utter suprise that solid discs actually have better stopping power, at least for average driving in such a light car (1210KG) for average driving. Is this true?

Total garbage! All other factors, such as disc diameter, pad material, etc, being equal, the stopping power will be no different.

Unless you manage to get them really hot, which should not really happen on normal road driving. The vented will then perform for longer than solid disks.

[hedges88]

Dave Brand said:

Total garbage! All other factors, such as disc diameter, pad material, etc, being equal, the stopping power will be no different.

You get told a lot of rubbish I find.

I took took off my back wheel today, prized the backplate away from the disc a little with a screwdriver and the noise is gone. Discs at the back were also fine, no glazing, not lipped or anything. Pads were starting to get a little low.... Fronts were about the same. Some people take the biscuit

I might brave my first home disk and pad change, lots of YT videos that are so helpful. If Ethan from carthrottle can do it then I can ??

[ARHarh]

hedges88 said:

You get told a lot of rubbish I find.

I took took off my back wheel today, prized the backplate away from the disc a little with a screwdriver and the noise is gone. Discs at the back were also fine, no glazing, not lipped or anything. Pads were starting to get a little low.... Fronts were about the same. Some people take the biscuit

I might brave my first home disk and pad change, lots of YT videos that are so helpful. If Ethan from carthrottle can do it then I can ??

One of the easiest jobs to do on a car hence why every garage / dealer wants to change the brakes. Make sure you have a spare M8 bolt, as there will almost certainly be a threaded hole in the disk for said bolt. Wind it in and the disk will free its self from the hub. They are often stuck.

[E-bmw]

ARHarh said:

hedges88 said:

You get told a lot of rubbish I find.

I took took off my back wheel today, prized the backplate away from the disc a little with a screwdriver and the noise is gone. Discs at the back were also fine, no glazing, not lipped or anything. Pads were starting to get a little low.... Fronts were about the same. Some people take the biscuit

I might brave my first home disk and pad change, lots of YT videos that are so helpful. If Ethan from carthrottle can do it then I can ??

One of the easiest jobs to do on a car hence why every garage / dealer wants to change the brakes. Make sure you have a spare M8 bolt, as there will almost certainly be a threaded hole in the disk for said bolt. Wind it in and the disk will free its self from the hub. They are often stuck.

Spare M8 bolt to wind the disc off, never seen that in over 30 years of working on cars.

What car have you seen that on?

[AgentZ]

E-bmw said:

Spare M8 bolt to wind the disc off, never seen that in over 30 years of working on cars.

What car have you seen that on?

I've seen this on a number of YouTube brake videos. Specifically Toyota's on The Car Care Nut's channel where he shows this using a M8 bolt from the exhaust manifold heat shield.

[ARHarh]

E-bmw said:

ARHarh said:

hedges88 said:

You get told a lot of rubbish I find.

I took took off my back wheel today, prized the backplate away from the disc a little with a screwdriver and the noise is gone. Discs at the back were also fine, no glazing, not lipped or anything. Pads were starting to get a little low.... Fronts were about the same. Some people take the biscuit

I might brave my first home disk and pad change, lots of YT videos that are so helpful. If Ethan from carthrottle can do it then I can ??

My mx5 and my Lexus rd have them, as did my previous jag x type, and cavalier sri. Not needed the hole on any other cars.

One of the easiest jobs to do on a car hence why every garage / dealer wants to change the brakes. Make sure you have a spare M8 bolt, as there will almost certainly be a threaded hole in the disk for said bolt. Wind it in and the disk will free its self from the hub. They are often stuck.

Spare M8 bolt to wind the disc off, never seen that in over 30 years of working on cars.

What car have you seen that on?

[hedges88]

Before people start debating about some bolt , what tools would one need for doing this job at home? I have basic sockets, wrenches etc but with brakes you need a thing to retract the caliper yes?

Would something like this on eBay fit the bill:

https://www.ebay.co.uk/itm/124338910584?mkcid=16&a...

I know with my XENTRY diagnostics I have the options to do a brake bleed and also an "exceptional" bleed, whatever that means.

I just want to be prepared before I go ahead and do this, since I drive this car on a daily basis. The current discs/pads from what I can see are made by Ferodo, I have no idea if that's good or bad. I know EBC make brakes that's a name that's stuck with me but I ended up ordering Brembo discs and pads because that's a name I recognize and associate with brakes the most. They are just normal OEM level replacements nothing special or anything.

A lot of the YT videos I've been learning from are American and I know they call many things (tools included) different words than we do.

If worse comes to worse and I chicken out I'll get a local garage to do the work, but I'd really like to have a go at doing it myself. I got loads of satisfaction just from stopping the squealing noise by adjusting the backplate. I need to save as much money as I can with home repairs because when my clutch goes my car has to be disassembled to an incomprehensible level

[GreenV8S]

hedges88 said:

I might brave my first home disk and pad change, lots of YT videos that are so helpful. If Ethan from carthrottle can do it then I can ??

There's more to servicing the brakes than replacing the pads and discs. If you're going to do it, make sure you do it properly.

[hedges88]

GreenV8S said:

There's more to servicing the brakes than replacing the pads and discs. If you're going to do it, make sure you do it properly.

Well I know for sure that the back plates need doing as they are rusty and warped, The people who assessed it said that one of the calipers might need replacing, but then they said a lot of things needed replacing that it turned out were fine!

Given that brakes are vital to safety, this is something that I might let someone else do. Thankfully, unlike everything else on the w169, I think the braking system is straightforward and conventional!

I just don't want to pay someone to do something that it turns out is just a bit of a pain in the ass for a few hours but perfectly doable by someone with basic mechanical skills!

[hedges88]

Also something I wanted to add. If you use the brakes hard because you've come off a slip road or stopped from high speed, the handbrake is probably less than half as effective as it usually is, like it needs to be pulled almost to the max. I'm aware this is normal to an extent and I believe it may be Subaru's or some other high performance cars that have a separate drum brake for the handbrake because it's expected their rear discs will be heavily used but it's not something I've ever experienced in average driving with many other cars I've had with rear discs. Thankfully the hill hold helps

Is this another sign of wear or a symptom of low pads?

[Smint]

Thankfully all of our cars have the superb and seldom any bother drum inside disc park brake design, one of them being a Prado which you would hardly call high performance, though it does have vented discs all round and a 'sport' setting on the electronic damper control

Its an expensive system to engineer in having lots more working parts at manufacture stage, cost cutting (and a very expensive fix when it does fail and it will) is the only reason for electric parking brakes car makers want you to think you can't cope without.

Haven't worked on a W169 or any FWD MB, are the rear brakes drums or discs with mechanically self adjusting calipers that double as park brake?
Every RWD MB i've owned has had the excellent drum inside disc park brake, itself operated by the foot pedal, the only trouble they give is that most owners never gently apply the park brake whilst moving so the drum doesn't get cleaned off and corrosion on the drum friction area can cause deep grooves in the shoes, not expensive to replace (DIY) just a fiddly job to change if you don't have the spring clip removal tool.

By the way, having tried swapping wheels on MBs before, stick with the original size but fit good quality tyres, increase wheel size and all you do is destroy the ride and make it easier to kerb wheels and/or damage tyre sidewalls.

Edited by Smint on Thursday 5th May 01:33

[hedges88]

Smint said:

Thankfully all of our cars have the superb and seldom any bother drum inside disc park brake design, one of them being a Prado which you would hardly call high performance, though it does have vented discs all round and a 'sport' setting on the electronic damper control

Its an expensive system to engineer in having lots more working parts at manufacture stage, cost cutting (and a very expensive fix when it does fail and it will) is the only reason for electric parking brakes car makers want you to think you can't cope without.

Haven't worked on a W169 or any FWD MB, are the rear brakes drums or discs with mechanically self adjusting calipers that double as park brake?
Every RWD MB i've owned has had the excellent drum inside disc park brake, itself operated by the foot pedal, the only trouble they give is that most owners never gently apply the park brake whilst moving so the drum doesn't get cleaned off and corrosion on the drum friction area can cause deep grooves in the shoes, not expensive to replace (DIY) just a fiddly job to change if you don't have the spring clip removal tool.

By the way, having tried swapping wheels on MBs before, stick with the original size but fit good quality tyres, increase wheel size and all you do is destroy the ride and make it easier to kerb wheels and/or damage tyre sidewalls.

Edited by Smint on Thursday 5th May 01:33

As I see my car only has discs at the back and nothing else to hold it, although I guess it could be hidden somewhere? It does have hill hold control which works very well thankfully but I assumed the ESP system operates that function? Both w169s I have had, the handbrake doesn't seem to self-adjust very well at all so I might have a go at tightening it up or get my A class guy to do it for me because he's retrofitting my cruise in a few weeks

W169s all come as standard with Bilstein B4 dampmatic dampers, either with standard, BlueEfficiency, performance or off-road damper and spring setups. Then the wheels range from the 15-in 185/65, 17-in 195/55 and also even larger and wider ones for the A200T, Avant-garde specs and the more potent diesels. I think a lot of people deleted the sport springs and dampers on Avant-garde models because it's bad!

Apparently comfort dampers and 16s is a good combination but everything else is difficult to live with. 15s like mine are comfy but a little too soggy as that's a fair old bit of sidewall They handle great and are huge fun just a bit too much body roll on my spec. Easily upset by rough surfaces and naturally the wheelbase is very short

The rear axle is parabolic (like an old pick up truck) but with coil springs instead of leaf springs. This means the rear coils are very small because they don't go up to the body of the car. They handle brilliantly because the weight of the engine and gearbox is behind the front axle, i can only think of the Citroen Maserati SM doing that too?