strange disc wear
Discussion
First of all check for any run-out on your hubs with a DTI, once you've eliminated this start looking a the wheel spacers because if there's a weak link with this conversion its the use of wheel spacers, at best these wheel spacers should be viewed as a necessary evil. There's a reason no OEM manufacturer fits wheel spacers, in this case the wheel spacers are there to solve a calliper clearance issue, a clearance issue no manufacturer would let past the pre-production design stage, check your wheel spacers in every way!
Make 100% sure your wheel spacers are deep enough, if they bottom out on the hub flange even slightly they will splay, as little as 0.5mm of insufficient depth here and the spacer flange won't sit perfectly flat to the disc. It's also essential the hub face is scrupulously clean & free from corrosion. Check the inner face of your wheel too where it sits against the spacer, remove any powder coat here and or ally corrosion, flat by hand with file if necessary.
Basically all faces (wheel, hub, spacer) must be perfectly flat and meticulously cleaned, keep in mind a spacer is just a packer that's only there because you're forced to use it, no engineer would fit wheel spacers by choice. Only use hub centric spacers and consider having your discs skimmed on the car, a professional disc skim job actually re-faces the disc to the true axle line, not the hub as you my assume.
Be wary of anything other than brand name high quality discs from a trusted source, there are a lot of very poor quality discs on the market and sadly price is no measure of quality, be especially wary of the drilled variety which attract buyers who mistakenly believe drilled discs give them an amazing braking advantage. The truth is if you use your car on the road buy OEM brand name quality plain discs not Carlos Fandango drilled items from EBC or Ebay sellers, you're normally way better off fitting good quality road pads too.
OEM quality brand name discs are accurately machined so you can just fit them quickly without issue because brakes are consumable components that need frequent and so convenient replacement, but even then if you really wanted to do a proper job you would have the discs ground to the car so they were perfectly true to the axle of your specific car because minute dimensional variations from car to car are unavoidable.
On the topic of alignment I found my Brembos sat extremely true from day one just using the spacer bushings supplied in the kit and a couple of thin shim washers, the brackets are clearly very accurately cut and well designed, our hubs are mass produced Ford items so accurately cast and the opposing Brembo pistons should easily compensate for any very slight calliper misalignment. Where it can go wrong is when cheap (especially not hub centric) wheel spacers are used or there's even slight run-out on the hub, the mating faces of the spacer, hub and wheel must be completely clean, flat and free from any corrosion or debris.
Then there's the quality of your discs and pads to consider, basically everything needs to be perfect and only perfect is good enough. On my conversion the hub centric spacers weren't quite deep enough, just 0.5mm was suer easy to miss but tightening the wheel was enough to splay the spacer by a tiny amount, we're talking microns here but its multiplied by the size of those big discs so eventually and only after a few thousand miles I started to feel some very slight pulsing through the pedal.
After a lot of head scratching the issue was located and a quick spin on the lathe had the spacers sorted, with the discs skimmed properly to the axle line too the pulsing was gone and all I was left with was astonishingly good brakes. If you think about it spacers are not only a bit of a bodge they're also sold as a universal fit... which clearly they can never be.
Watch those wheel spacers chaps
Make 100% sure your wheel spacers are deep enough, if they bottom out on the hub flange even slightly they will splay, as little as 0.5mm of insufficient depth here and the spacer flange won't sit perfectly flat to the disc. It's also essential the hub face is scrupulously clean & free from corrosion. Check the inner face of your wheel too where it sits against the spacer, remove any powder coat here and or ally corrosion, flat by hand with file if necessary.
Basically all faces (wheel, hub, spacer) must be perfectly flat and meticulously cleaned, keep in mind a spacer is just a packer that's only there because you're forced to use it, no engineer would fit wheel spacers by choice. Only use hub centric spacers and consider having your discs skimmed on the car, a professional disc skim job actually re-faces the disc to the true axle line, not the hub as you my assume.
Be wary of anything other than brand name high quality discs from a trusted source, there are a lot of very poor quality discs on the market and sadly price is no measure of quality, be especially wary of the drilled variety which attract buyers who mistakenly believe drilled discs give them an amazing braking advantage. The truth is if you use your car on the road buy OEM brand name quality plain discs not Carlos Fandango drilled items from EBC or Ebay sellers, you're normally way better off fitting good quality road pads too.
OEM quality brand name discs are accurately machined so you can just fit them quickly without issue because brakes are consumable components that need frequent and so convenient replacement, but even then if you really wanted to do a proper job you would have the discs ground to the car so they were perfectly true to the axle of your specific car because minute dimensional variations from car to car are unavoidable.
On the topic of alignment I found my Brembos sat extremely true from day one just using the spacer bushings supplied in the kit and a couple of thin shim washers, the brackets are clearly very accurately cut and well designed, our hubs are mass produced Ford items so accurately cast and the opposing Brembo pistons should easily compensate for any very slight calliper misalignment. Where it can go wrong is when cheap (especially not hub centric) wheel spacers are used or there's even slight run-out on the hub, the mating faces of the spacer, hub and wheel must be completely clean, flat and free from any corrosion or debris.
Then there's the quality of your discs and pads to consider, basically everything needs to be perfect and only perfect is good enough. On my conversion the hub centric spacers weren't quite deep enough, just 0.5mm was suer easy to miss but tightening the wheel was enough to splay the spacer by a tiny amount, we're talking microns here but its multiplied by the size of those big discs so eventually and only after a few thousand miles I started to feel some very slight pulsing through the pedal.
After a lot of head scratching the issue was located and a quick spin on the lathe had the spacers sorted, with the discs skimmed properly to the axle line too the pulsing was gone and all I was left with was astonishingly good brakes. If you think about it spacers are not only a bit of a bodge they're also sold as a universal fit... which clearly they can never be.
Watch those wheel spacers chaps
Edited by ChimpOnGas on Sunday 23 October 22:39
When I did my E38 Brembo upgrade I had barely any wear on the outside edge of one disk.
I used 0.5 mm shims to centre calipers as the hubs are not particularly square.
This persisted for over 500 miles but eventually everything levelled off and then the brakes became fantastic.
How many miles have you done with the new brakes, I thought I had a serious problem but after extensive bedding in they are wearing very nicely.
Got any pics
I used 0.5 mm shims to centre calipers as the hubs are not particularly square.
This persisted for over 500 miles but eventually everything levelled off and then the brakes became fantastic.
How many miles have you done with the new brakes, I thought I had a serious problem but after extensive bedding in they are wearing very nicely.
Got any pics
I am using 17 inch rims no spacers ,on the back of the disc in question is a strip on the outer edge of 5mm which is not touching the pads makes me thnk that the disc must be running true to have even none contact areas on both sides, going to try brembo pads and if the problem persists I suspect naff discs cheers
keith-vznby said:
I am using 17 inch rims no spacers ,on the back of the disc in question is a strip on the outer edge of 5mm which is not touching the pads makes me thnk that the disc must be running true to have even none contact areas on both sides, going to try brembo pads and if the problem persists I suspect naff discs cheers
Good choice as the Brembo (branded) pads are very effective once bedded in, it may take sometime to wear them to the discs mind. I beleive this is simply because the Brembo's would normally be doing a lot more work on a BMW so even with regular use and even serious stopping tests it can take hundreds of miles to achieve this, well it did with mine
What another Pistonheads member noticed with mine was that the offending nearside pads contacted the disc a couple of mm closer to the bell than on the offside, I removed my calipers and checked the brackets and they were drilled identical to eachother so decided it was the hubs that were drilled slightly differently,
What this seemed to suggest was that the pad contacted the inside edge of the disc before the outer, because the Brembo disc and pad are so good at braking force this just meant that I was Not applying enough pressure to get the outside edge working.
I just bided my time and eventually the pad wore enough to sit flat and then the outside edge started wearing more evenly and now the disc and pad wear as you'd expect.
I get the feeling my pads will last for many thousands of miles before needing to be replaced (bonus) because they still appear almost as new!
Once this bedding in is done you should then be getting roughly the same amount of brake dust either side as mine now do.
Hope this helps
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