Greetings all

 

I am in the process of upgrading my brakes on my 1.2 TSI petrol Yeti due to their "barely adequate" level of braking.

 

Rear wise has been a pretty simple case of finding some CR170 caliper brackets for 282mm discs, the discs, pads and backing plates . All very straightforward.

 

The fronts are a whole different kettle of fish to deal with. Firstly the hubs on the 1.2 petrol  have built in carriers for the 280mm discs. These cannot be removed and therefore an upgrade to a hub with bolt on calipers is required - i.e from a 2.0 or 2.0 4x4 . This brings its own issues as the diesel hubs use a 55mm damper , the 1.2 petrol is 50mm . Easy enough to sort, but a bit of a pain none the less.

 

I'm looking to install 340mm front discs (the biggest that will go under the standard 17" rims) from a 2021 VW Tiguan.

 

However the diesel flanges have a different spline arrangement than the 1.2 petrol ones , the petrol ones are smaller. 

 

So that leads me to two potential solutions 

 

1. Use 2.0 diesel front driveshafts with the correct splines for the hub flange

 

2. Use the 2.0 diesel hub but fit a 1.2 petrol bearing and flange into it (the more simple solution)

 

So the question is does the 1.2 bearing fit into the 2.0 diesel hub?? If not, do the 2.0 diesel driveshafts bolt up to the 1.2 DSG gearbox without issue??

 

Advice most appreciated , especially from someone who may have already done this conversion

 

Jonathan

Edited 3 March, 20251 yr by Joff-Monty-Yeti

The brakes on my 1.2 are perfectly up to the job so rather than 'upgrading' I'd suggest you find out why yours are so poor, I've not heard of it being a thing?

What do other 1.2 owners think?

Never a problem with the 2 1.2 DSG Yetis I owned. Brakes were excellent.

I would suggest you take a look at your current brakes first. What do you mean by 'barely adequate'? Do they not cycle the ABS?

Talking about 340mm discs is pointless - even if you could fit them (the appropriate calipers will fit only on very specific 17s with a healthy offset) you wouldn't be able to use more than 50% of the braking power before cycling the ABS. That is, of course, not mentioning the fact you'd need to tell the ABS system about the extra (and I suspect uncodable) sizing. You'd also have issues with the master cylinder, in addition to the huge increase in unsprung weight and the fact I highly doubt you'd be able to physically fit calipers that large - you'll need new carriers and shields at a minimum. The only reason for going to brakes that large is for better heat resistance during braking, and if this is the case, you have the wrong car.

My previous car had 180bhp and with some upgraded pads I did several track days with no issue (288/253mm). I currently have a 340/310mm setup, but I'm also running over triple the power of a 1.2 Yeti.

I've heard of people upping their 312mm discs to 340mm (e.g. older vRS TDI's) but I've never heard of anyone attempting to go from 288mm to 340mm. The limiting factor of braking in any car are the tyres. I would suggest putting some PS5s on the front and reporting back, but I doubt they even make them in the size you want. You have something wrong with your brakes!

Not sure what you mean by "barely adequate".

Even tiny discs would be able to take the ABS to the point of intervention on a single stop, and braking ability is ultimately determined by the tyres and the road surface. The only difference with larger discs is the ability to cope with multiple stops from high speeds and/or a heavy vehicle (or one towing) without heating up excessively.

Maybe you drive down alpine passes in a spirited way ?

A full brake service plus a change of pad formulation and possibly higher performance standard sized discs might be an awful lot easier.

5 minutes ago, Austin 7 said:

Maybe you drive down alpine passes in a spirited way ?

Which, again, is having unrealistic expectations of a budget compact crossover.

Bottom line is the standard braking system is completely adequate. It will cycle the ABS more than happily, and provide more than enough heat resistance for anything you can reasonably expect to do in a Yeti.

Swapping out the pads comes with issues too - increased noise, dust and, depending on what you go for, a possible degradation of braking performance from cold.

OP gone into hiding?

If the mods to the rear have been done, which seems the case, then he has already upset the brake balance of the car potentially making it at the least unpredictable and at worst dangerous.

Also the insurer should be notified of such modifications, preferably before implementing. They will not be happy if their is an accident and this comes to light - as it surely will.

It certainly sounds like there is a fundamental problem with the braking system and poorly thought through modifications can never be a correct response to that.

On the topic of insurance and modifications, there was a recent case of an insurer who initially declined a large claim because the insured car had a towbar fitted which had not been declared. The towbar had no bearing on the accident/claim, but logic and insurance companies don't always go hand in hand. Worryingly, the insurance ombudsman initially decided in favour of the insurer.

No, still here - just mulling over options at the moment - given that it had brand new brake pads and discs (Brembo) last August, with all sliders cleaned and greased (with silicone grease) and the brake fluid changed and brakes bled (twice) , I'm still wondering why the performance is so poor.

I will be doing some further investigation once the weather gets a little more conducive to working outside.

Thanks for all in the input so far, and yes I am fully aware mods need to be declared to the insurance co's, given I built a Meriva with an Astra VXR engine, and have a Nova with a C20LET conversion.

Cheers all

Jonathan

8 minutes ago, Joff-Monty-Yeti said:

No, still here - just mulling over options at the moment - given that it had brand new brake pads and discs (Brembo) last August, with all sliders cleaned and greased (with silicone grease) and the brake fluid changed and brakes bled (twice) , I'm still wondering why the performance is so poor.

I will be doing some further investigation once the weather gets a little more conducive to working outside.

Thanks for all in the input so far, and yes I am fully aware mods need to be declared to the insurance co's, given I built a Meriva with an Astra VXR engine, and have a Nova with a C20LET conversion.

Cheers all

Jonathan

Without wishing to sound like an angry person on a forum - as three of us have asked, what exactly is wrong with the braking? 'Poor performance' can mean lots of things!

As for the causes - an ungreased caliper slide won't case poor performance, it'll just make it a tiny bit worse.

If it's had a bleed and fresh fluid, it could still be an issue with the lines, bad booster/servo unit, bad master/slave cylinder, etc.

FYI - Brembo doesn't mean much these days. Most of the time it's knock-off stuff from ECP. Even if you get genuine, their performance isn't brilliant. I had genuine discs and pads on a previous car, and while the performance wasn't that bad, the pads glazed and squealed like something else.

3 hours ago, Occy245 said:

Without wishing to sound like an angry person on a forum - as three of us have asked, what exactly is wrong with the braking? 'Poor performance' can mean lots of things!

As for the causes - an ungreased caliper slide won't case poor performance, it'll just make it a tiny bit worse.

If it's had a bleed and fresh fluid, it could still be an issue with the lines, bad booster/servo unit, bad master/slave cylinder, etc.

FYI - Brembo doesn't mean much these days. Most of the time it's knock-off stuff from ECP. Even if you get genuine, their performance isn't brilliant. I had genuine discs and pads on a previous car, and while the performance wasn't that bad, the pads glazed and squealed like something else.

To explain further, you press the brake pedal , first there is an inch of travel when nothing happens, then the brakes start to work, but feel like they just can't slow the car down. The harder you press they start to bite a little, but even with a really hard press I cannot get the fronts to lock/abs kick in.

As I have mentioned I have bled the brakes twice, once via a pressure system from the top, and the other via a vacuum bleeder from the caliper. Put probably about a 1.5 litres through the system (full bleed all the way round front and rear) - zero bubbles coming out at the end of both bleeds.

As I said before they just feel "adequate" and thats with just me in - 4 up with adults and the feel is just worse, like it just doesn't want to stop at junctions. Its a DSG and previously I have used cars with manual boxes using engine braking as well as the brakes.

Hence the reason for considering bigger discs to help provide more braking force to give more confidence when coming to junctions or the end of slip roads.

I don't drive like a hooligan, but I like to keep up a decent speed and not dawdle along , to me the brakes are just so mediocre.

2 minutes ago, Joff-Monty-Yeti said:

To explain further, you press the brake pedal , first there is an inch of travel when nothing happens, then the brakes start to work, but feel like they just can't slow the car down. The harder you press they start to bite a little, but even with a really hard press I cannot get the fronts to lock/abs kick in.

As I have mentioned I have bled the brakes twice, once via a pressure system from the top, and the other via a vacuum bleeder from the caliper. Put probably about a 1.5 litres through the system (full bleed all the way round front and rear) - zero bubbles coming out at the end of both bleeds.

As I said before they just feel "adequate" and thats with just me in - 4 up with adults and the feel is just worse, like it just doesn't want to stop at junctions. Its a DSG and previously I have used cars with manual boxes using engine braking as well as the brakes.

Hence the reason for considering bigger discs to help provide more braking force to give more confidence when coming to junctions or the end of slip roads.

I don't drive like a hooligan, but I like to keep up a decent speed and not dawdle along , to me the brakes are just so mediocre.

If you can’t get the ABS to cycle you don’t need larger discs - you need to get the system repaired.

If it’s not air in the system or contamination then next best guess is the servo.

FYI - increased pad/disc surface area won’t make you stop any faster. They might give you a bit more bite, but going from 288mm to 312mm is pointless, and 340mm won’t be possible. As said before, all you’d be gaining is heat resistance - not an issue in a Yeti.

Certainly, I wouldn’t be driving it all that far until you have it sorted.

Only you will know if the pedal is spongy and there is air in the system, very difficult to decide from your comments, if there isn't then you have glazed discs and pads which has happened regularly to me on modern vehicles since I stopped driving like the road was my personal racetrack and since asbestos was removed from the pad formulation.

I can normally tell by the disc scoring or by kickback, other times I become aware when I do have to do an emergency stop, the solution is not for the faint hearted, it involves abusing the brake system doing repeated full on emergency stops from 80+ mph downhill (away from traffic bien sur) until the brakes are smoking and the pedal is spongy, then driving without breaking to initially cool them and leaving it overnight to properly cool without applying the handbrake.

I bought bigger discs and calipers from a Golf GTi because I have remapped the car and tow trailers more than double the weight limit albeit only locally now, I found out the hard way that my struts being 50mm dia body were too small for the GTi steering knuckles, adaptors are available, I was going to fabricate mine.

Someone spoke of unsprung weight, thats what put me off, the box with the brake discs and calipers is so heavy that I can barely lift it, the brakes work very well in standard form (if maintained as above) but do lack feel somewhat, I no longer even notice that.

I will investigate the servo situation, which sounds like it could be the route of the issue so far

With the engine switched off press the brake pedal several times to empty the vacuum accumulator, the pedal should then be rock solid and remain high when pressed.

Then with your foot remaining on the brake pressing moderately hard start the engine, the pedal will move further downwards under your foot pressure showing the servo is working correctly.

From what you have described I think the servo is working however there might be a split on one of the hard plastic vacuum lines reducing its efficiency.

Reading with interest.

OP, You mention the brakes dont seem to retard the speed, and if you press harder then you start to get some retardation etc,

Question, what type and spec of pads are you using? Sound like it may be "track pads or fast road pads or some type of performance pads" from someone like EBC (green, yellow, red, black.)

IME these types of pads are not really suitable for road use, they generally need to be warmed and used very hard to get the "performance" the manufacturers claim and IMO, you cant really get that from just normal day to day driving, you will get squeel, glazed pads/discs and that worrying foot on the brake nothing happening sensation until you brake much harder ... why? thats the way they are designed.

I dont know what pad and friction material you are using, but maybe its a step for a hint.

Hope it helps 🙂

I agree with @J.R. regarding the vacuum lines - if it was the servo itself, I think you'd know about it.

From memory the weight difference between 312mm and 340mm is just over 2kg per side, without pads or calipers included. A 288mm disc is about 1kg lighter than a 312mm, so you're adding around 3.5kg of rotational unsprung mass each side - that's a lot - about 50% the weight of a 17" wheel. You'll also find a hefty weight penalty at the rear, going from solid to vented.

Reagarding the 80mph emergency stops - a far easier thing to do is to just re-face the pads (and chamfer the edges too). Of course, this only works if you've glazed the pads through lack of 'proper' use, rather than cooking them. I've never really seen this on OE pads though - I did it on some Yellowstuffs, but that's a different thing altogether.

By the sounds of it @TruckbusUK OP just has regular replacement Brembo discs and pads - aside from being a terrible combo (IME) they're just standard pads. I run DS2500s at the front, and aside from being a bit dustier than standard pads, they work very well on the road. FYI, Greenstuff/Redstuff are road use only - you'll cook them on a track! I would be interested to know though if they are Brembo Brembo, or ECP Brembo. Of course, if they are some sort of fast road pad, then not only is that problem solved, but sounds like OP needs to find a new garage!

Either way, this is all inmaterial - you do not need to be thinking about upgrading brake size/compound/etc in a car with 100bhp, unless you are modifying it (with an engine swap) to be a track toy. For the benefit of thoe coming across this in nine years time after a "288mm to 340mm" google search -

I know OP said that 17" wheels will clear 340mm brakes, but from what I've seen, it will be very close (the sort of close that the wheel weights could contact the caliper, which is daft). They'll need to be quite a nice offset to give some space between the inner barrel and caliper, the only ones that Skoda makes are the "Crystal", which AFAIK didn't come on Yeti's. Therefore, you'll be needing new wheels, tyres (if doing the smart thing and going up to 18"), discs, calipers, carriers, shields, sensors, hubs, master cylinder (the standard Yeti one will not be up to it) and a fair bit of time - all of which to ruin the ride, balance and performance (especially with a rigid rear end), without adding any tangible benefit. I'm also reasonably sure the ABS pump would have a fit, and that you wouldn't be able to make the ABS system understand you've gone for 312mm discs, let alone 340mm.

Certainly, this seems to be a similar thing to those intelligent people that paint their drum brakes red, or buy fake caliper covers.

This topic has been brought up numerous times -

https://www.briskoda.net/forums/topic/492764-bigger-brakes-for-14-140hp/

https://www.golfmk7.com/forums/index.php?threads/brake-upgrade-for-1-4-tsi.339282/

https://www.golfmk7.com/forums/index.php?threads/swapping-golf-r-brakes-to-base-golf.346027/

The standard braking system is perfectly adequate for a fully loaded Yeti, in wet conditions, with a completely worn-out system and tyres, on a poor road surface. It has to be, otherwise VW wouldn't be allowed to sell it!

@Joff-Monty-Yeti TLDR - you are correct. Please post back here once you've had a look, and go from there. It's nice when threads have a solution to them. As has been said, you've got an issue somewhere. I drove around on pads that were absolutely glazed to sh** for a week (thank you, Thruxton), and while it wasn't the quietest or smoothest experience, I had no issues with stopping.

Edited 8 March, 20251 yr by Occy245

Glazing is a strange phenomenon that I dont fully understand, yes the easiest way to deglaze pads is on the bench but it's also the discs that become glazed which other than machining only abrasive pads or abusive braking as I described can remove.

Glazing from a track day, yes I have experienced that but I believe its actually the pad material degrading through overheating, its only happened to me with the wrong compounds, OTOH for road glazing a few hot laps works wonders, well the next day that is when everything has cooled down, never apply the handbrake after returning to the pits!

An anecdotal story which first brought me to abusive deglazing of brakes.

I bought a Ford Galaxy as a write off rebuild project, it was one of the very first made and caught fire very early on, it had been driven by a mother of children judging by the amounts of sweets and toys wedged between and under the seats etc, I would say in hindsight that she had driven it very gently, all 4 tyres were equally under-inflated and gave a very smooth but unsafe ride, the brake discs were scored to hell, the brakes juddered like mad and hardly slowed the vehicle at all, at 20mph the steering judder nearly tore the wheel from my hands.

I resolved to replace all 4 discs and pads as soon as I could but being busy with my own business it took a couple of weeks, I was commuting to and from sites in London every day with the seats out and the back heavily loaded with tools and materials, I drove like an absolute maniac back then, the road was my personal racetrack.

After a few days I noticed the braking improving and the juddering reduced, after a week or so it had gone completely and when I looked at the discs which were rusted and grooved beyond redemption they looked as smooth as brand new discs fresh off the grinding machine!

They remained that way all the years I owned it.

Its only when I eventually grew up and drove normally that I started to suffer brake glazing but I knew then what the solution was.

The Yeti suffers less than the preceding Octavias, possibly because it has the smallest brakes and has been remapped so they get more of a work out, I'm using the same Ferodo Eco Friction material that I have for a decade which I find is the best all round for road use.

Yes, it is a bit confusing. As a rule of thumb, glazing occurs when the pad material is pushed beyond it's thermal limits - for example, heavy use on track. Glazing can also occur when the brakes are dragged (or driven with very softly) - this is partly due to the constant friction causing gradual but continual heat build up, but also because the surface of the pad naturally becomes hard and glassy due to oxidisation, exposure to moisture and heat. When braking with force, this glassy layer is removed by friction with the disc (hence why you never see glazed pads on grooved discs), but with slow, gentle braking, it isn't worn away. Hence why, like I said, if the glazing is due to lack of use, you can re-face the pad, whereas if it's cooked, then bin them.

Glazed discs/rotors are a bit different, and occur when the glassy/hard surface of the pad sort of polishes the metal surface.

I'm a keen mountain biker, and poor braking is 99% of the time due to organic pad compound, which has melted and glazed (due to a lower heat tolerance). I've run sintered/metallic pads for years now, and while they do make a bit of noise, work like a charm.

I'd personally only resort to heavy braking for bedding brakes in - any glazing and I prefer the bench. That said, any glazing and I generally replace the pads anyway, so it's less important.

I use Ferodo DS2500 pads on the front, and stock OE VW pads on the rear. The Ferodo have a little less bite than OE, but can take a fair bit more heat. If set up correctly (somehow mine are, pure luck) they can be pretty damn quiet on the road, and take some beating on the track.

Brake pads are a tricky thing to balance. You can have plain discs and eco pads, which will last a while, produce no dust or noise, but won't brake all that well, or you can go for some metallic track pads with grooved discs that will always bite hard and stop you dead, but will also eat pads and discs like they're going out of fashion.

Its been over 20 years now since my racing days so I'm only concerned with road brakes now.

You might be right in that it was the pads and not the discs that were glazed but when the braking force became reduced the discs would always be in a right 2 and 8, dressing the pads on the bench never seemed to yield results for me.

It' strange that the Yeti has yet to suffer although it does a lot of towing.

No, no - it sounds like those discs were glazed! I was just saying that a glazed pad occurs before (and causes) a glazed disc. If they’re both glazed then in theory re-facing the pads should work, but as you say 99% of the time, they just glaze up again, especially if the discs are nice and shiny/grooved with uneven wear.

It is strange, but also serves to reinforce my point that the stock braking system is perfectly fine! People say to use cleaner, alcohol or even abrasive paper on glazed components - in my experience, unless it’s very mild, sack them off and get new ones.

On 07/03/2025 at 20:10, Joff-Monty-Yeti said:

even with a really hard press I cannot get the fronts to lock/abs kick in.

Had you come here with that observation earlier you probably could have saved yourself whatever cash and effort you've already expended on what is now even more evidently an unnecessary 'upgrade'!

Have you had a scan done on the car for faults?

Any fault on the ABS system or any of the sensors it uses will bring up the ABS warning light permanently.

If the braking system does not develop enough pressure (weak servo or weak driver) or if there is a lack of friction (glazed pads, pads through to backing) it will not illuminate.

Regardless of what shows up, not being able to cycle the ABS means the car is not only unfit for the road, but also dangerous.

How OP has been driving around for a year like that, is a bit of a suprise!

My ABS has not cut in for the last year aside from when I have tested it.

Somewhat of a contrast to when I was 30 with a company Sierra XR4x4 when it would be solicited multiple times during my 20 minute journey to and from work.

Plenty of older vehicles do not have ABS, that does not make them dangerous or unfit for the road.