With more power now available (see the series that starts at Powering up the 1.9 litre TDI, Part 1, it was time to upgrade the Skoda Roomster’s front brakes.
Said quickly that sounds easy, but what form should the upgrade take?
ApproachesAs described in Upgrading Brakes , basically four different approaches can be taken to brake upgrades:
1. Fit new pads and discs (eg slotted standard-sized discs with performance pads)
With the Roomster, all options but Number 2 above were on the table. Number 4 (taking parts from other manufacturers) was likely to be the most difficult, although if the standard braking components from larger and heavier cars were used (here in Australia, read: Commodore and Falcon) the parts acquisition cost could be kept low. But that advantage was more than outweighed by the difficulties in making new caliper mounts, potentially sourcing (and then mounting) a new master cylinder, altering brake bias and so on.
That left Number 1 (changing discs and pads) and Number 3 (using components from sister cars) as the best bets.
I posted a question to a Skoda forum and got back the suggestions that the best upgrade to the standard 288mm front brakes (pictured) would be to fit Audi TT caliper mounts and TT 312mm discs. This, the suggestion went, would allow me to mount the standard calipers further outwards from the wheel centreline, so increasing the leverage being applied. Furthermore, the larger discs would better store and then dissipate heat, so improving fade resistance. This approach, if matched with aftermarket slotted discs and better pads, seemed to tick all the boxes – it was going to be easy!
I did some further web research and found that the upgrade from 288mm discs to 312mm discs with the TT caliper mounts (and it appeared, the same mounts and discs are used on some other VW products) was very common. In fact, I found some step-by-step coverage of this upgrade – and it looked dead-easy.
The caliper mounts I needed were part number 8N0615125 (a pair needed, same part number for left and right) and a web search found a pair of brand new ones on US eBay – and at a good price, about AUD$160, including freight.
I used the DBA catalog to ensure the availability of VW / Audi / Skoda discs that had the same centre hole diameter and offset dimensions as standard Roomster, but which were the required 312mm diameter, and then sat back waiting for my eBay parcel to arrive.
When the caliper mounts came (brand new, just as advertised) I raced out to the car to see how they fitted. If they bolted to the cast uprights (knuckles) and the calipers bolted to the mounts, I’d be laughing.
Except I wasn’t: laughing, that is.
The caliper mounts bolted to the uprights fine – but the standard calipers were the wrong bolt pattern to fit the mounts. Pictured here are the Audi TT (top) and Roomster caliper mounts. Note how the upper bolt spacing is the same (that’s where the mounts bolt to the upright) but the lower bolt holes for the calipers are quite different in spacing.
So, it turns out, there are two completely different calipers used on VW / Audi / Skoda products on 288mm discs….. not what anyone had said!
Now what? It seemed I needed front brake calipers from an early Audi TT (or Audi S3, or possibly a range of other cars from VW / Audi / Skoda – I was no longer quite sure). In addition to sourcing these calipers, questions now arose about the required master cylinder – if the Audi TT calipers used larger diameter pistons, more fluid flow would be required, so resulting in greater pedal travel or the required use of the Audi TT master cylinder.
In other words, the potential complexity (and cost) of the brake upgrade had just increased significantly.
I started looking at the front brakes of every VW / Audi / Skoda I could see on the street. To my eyes, at least, this showed that quite a few models use the larger calipers that would match my caliper mounts – but without actually taking off the wheels and making some measurements, I couldn’t be sure. Certainly not sure enough to start trying to source the calipers from, say, a Golf GTi for example.
Instead I looked around for an Audi TT being wrecked (very uncommon here in Australia) and watched eBay and the various forums where people were selling VW / Audi / Skoda parts. And then, unbelievably, I saw some Audi TT / S3 calipers being sold.
They were bare of pads (and also, although I didn’t initially realise, the anti-rattle springs) and were being sold for AUD$200. They were variably claimed to be new or reconditioned – this pic is of the same design calipers but aren’t the examples that were on sale. I looked very closely at the pics and decided that these were the calipers that would match my mounts, so I bought them.
When they arrived I found to my relief that they would in fact bolt-up to the TT caliper mounts I’d bought out of the US. I already knew these mounts would bolt to the Roomster - so that meant the brakes would fit. Or would they: was there clearance under my larger-than-standard 16 inch ex-Vento wheels? Yes, there was…
With the TT caliper mounts test-bolted to the Roomster, the standard 288mm discs looked correct in all aspects except for their smaller diameter. This confirmed that a disc with the same offset and centre hole diameter, but 312mm instead of 288mm, would fit.
I measured the standard disc very carefully (after the caliper experience, I didn’t want more mistakes!)…
… and then ordered a set of RDA slotted discs. They were part number RDA 7214V to suit an Audi S3 1.8 (154kW), 1999 – 2004. These retail at about AUD$370 a pair.
I also ordered EBC ‘Red’ pads part number DP31330 to suit the S3 – retail is AUD$384.
Inspection of all those front brake systems on the street had shown I needed some anti-rattle springs – these are part number 4A0 615 269, with two springs needed. These cost about AUD$24 from a local Australian Volkswagen dealer.
So I now knew that the calipers and discs would fit – but what about the brake hoses? Without actually assembling the new brake system on the car, it was impossible to tell if the standard hoses were the right length - and would also connect straight to the different calipers.
I painted the calipers and caliper mounts (VHT brake caliper paint – about AUD$15) and then fitted the new discs and caliper mounts….
…followed by the calipers, pads and anti-rattle springs.
Much to my relief, I found that the standard brake hoses were fine – they were the correct length and, while the fitting attaches to the calipers at 90 degrees to the original, the hoses are still a straight bolt-up.
Next, would the master cylinder have the required fluid delivery? I’d measured the TT calipers cylinders as having a 53mm diameter piston (but there must be an internal step in it, as the number in the casting is 54) and the standard Roomster calipers measured at 54mm as well, so that looked positive. After bleeding the brakes the pedal travel felt fine – another positive sign. In fact, with the new calipers, brake pedal travel proved to be unchanged.
On the Road
So was the upgrade worthwhile? In short: yes…. on the road the results are excellent.
The brake bias is clearly more to the front, but this is noticeable only when reversing down a steep gravel driveway, where the fronts will ABS earlier than before.
The ability of the brakes to pull the car down from high speed with progression and feel is superb – vastly better than with the standard brakes. On a back road (hmm, I mean the track) you can drop from 150 to 60 km/h with literally a gentle push of the centre pedal – and do it corner after corner. In an emergency stop the ABS operates as it did with the standard brakes.
Downsides? There are some.
When the brakes are dead cold (in my normal daily drive I arrive at a roundabout after 30 kilometres of country driving that has had literally no brake applications at all) the pedal needs a distinctively firmer push. [Note: this downside disappeared after a few thousand kilometres.] In normal urban braking this greater pedal effort doesn’t occur (the brakes must retain some heat) and in spirited driving the pedal effort is clearly lower than with the standard brakes.
Each new disc has a mass that is 1.4kg greater than standard (interestingly, the new calipers and pads are 200 grams lighter than the old ones) and the Roomster is a car where the 1.2kg increase per side in unsprung weight can be clearly felt. When I went from 15 to 16 inch wheels, the latter fitted with larger tyres, I could feel the increase in unsprung weight, and the same has occurred with the new front brakes. The result is that over lumpy bitumen, the car does not ride as well.
In retrospect, the front brake conversion is quite simple: buy the caliper mounts, calipers, discs, pads and anti-rattle springs. Then just bolt it all up and bleed the brakes! And someone with a Roomster can do just that.
But this story is also a good example of how what appears to be a straightforward upgrade (remember, everyone told me that I could retain the original calipers and pads) can actually turn out to be much more complex. To put this another way, the cost was about double expectations.
Luckily, the results are outstanding…