Want to upgrade front discs, any tips?

JOC · 01-19-2001, 12:49 AM

As you may know, I've had persistant probs with warping of the standard Brembo discs. On my 3rd set, which now cause heavy vibration. BMW don't want to know anymore, and garage reckons they're al within tolerance. Any tips on a good upgrade, any producers of aftermarket discs for the S you can recommend?
JOC

Malc · 01-19-2001, 01:51 AM

JOC,

The Ally Pally show starts in a couple of weeks. It might be worth having a look there to see what's around.

In the "Power increase work at San Jose BMW" post JPF has some interesting comments. Also, there was an item in MCN a few months ago where they had an S with a PFM setup which they rated quite highly. Motorworks (http://www.motorworks.co.uk) list the full disk and caliper kit at £850.

Malc

roger albert · 01-19-2001, 06:11 AM

Hi all,

Its worth considering that there are a few possibilities here.

1) you just use the brakes very hard and that an aftermarket brake may be required to handle the stress. Its possible, but note that the same basic disc/caliper setup seems to work fine for much heavier, and typically much more heavily loaded RTs, or for that matter, Ks. Something doesn't add up. At any rate, you'd need to spec an aftermarket one that was meant to be more durable and handle higher thermal loads, not lighter, the parameter which some aftermarket discs target.

2) a wheel or hydraulic problem is causing this. This seems much more likely. Never say never, but I've not seen a good disc setup (one proven on more heavily loaded bikes) that has failed three times, when something else wasn't wrong.

I'm not saying something else is wrong, but I'd seriously, meticulously examine that possibility before coughing up a set of expensive aftermarket discs, which might themselves warp. Has runout of every mounting pad been checked both hot and cold?

Any aftermarket system that needs an intermediate carrier will be heavier, but that alone will assist you if the issue is primarily thermal loading and stress.

Best of luck. This sounds like its been a tough one for you.

regards
roger

Chris Canning · 01-19-2001, 02:01 PM

There is also a similar kit from AP brakes in the pipe line due for release in the next few weeks i've had a prototype set on my S for the last 12 months fantastic sorry i'll rephrase that FANTASTIC!!! there's a picture on the boxertrix site.

Chris C

Greg G · 01-19-2001, 02:54 PM

It would seem to me there would be little advantage in an aftermarket setup since the Brembos on the bike now works fine for the vast majority of BMW models. People put zillions of miles on those brakes with few problems across a range of models (including my K1200RS).

I suspect whatever is the problem will just warp the new setup at considerable cost to you. It might be cheaper to purchase new front wheel bearings, the minor wobbling of which may be your culprit. My understanding is that disk warpage is usually the result of uneven wear on the disks from wobbly wheels. In fact, the brakes themselves may have absolutely nothing to do with the problem more than being the place that "takes the hit" from wheel alignment gone awry.

Greg Girard

JOC · 01-21-2001, 11:01 PM

Noted - thanks for yr comments. Much as I expected. I'll get them properly checked out - again.
Cheers
JOC

DavidSoine · 01-22-2001, 07:54 AM

JOC:

I am with Roger on this one, of course - there is something wrong, most likely wheel/runout related...

The fact is, the manufacturers are fully aware of what causes this condition - but will not deal with it unless there is serious warranty cost associated with it. The least they could do is help diagnose and solve, even if we pay for it. You certainly need to keep complaining to your dealer!

If you do upgrade - I'd like to know if Spiegler's new SiCom rotors are available yet (for any bike, much less the S...)

In theory, and because with motorcycles we can choose from different materials, I think we want the hardest, most wear resistant rotors to help reduce this problem (all other things being equal).

best,

Dave

JPF · 02-01-2001, 05:23 PM

I have just completed a major rebuilding of my front brakes on the S and am super pleased by the results. I went ahead and did everything from the master cylinder down and boy did it make a difference.

The lines are SS from galfer and are chromed fittings on clear coated silver SS with teflon lining and rubber coating. Very nice and work great with the ABS which was a real concern as my last S was a non-ABS model and I have generally been wary of ABS since I race.

The new calipers are 6 piston, 6 pad Harrison Billet 6's. These calipers rock. My TZ has a $4,500.00 set of killer Brembo monoblocks that can slow you down so fast you feel like your eyes are going to pop out of your head and these new Harrisons kick thier ass!

The Harrison's put 8 more leading edges onto the rotor and have almost double the total pad surface of the stock brembos and make the stock set feel like a wimpy old bicycle brake.

Now I can easily raise the rear wheel off the ground in heavy braking with just one finger and they are lighter than stock.

the new rotors are from Braking in Italy (although the Galfer guys have the same stuff). The new rotors are "wave" rotors and require special mounting assemblies but save 4 lbs over the Brembo rotors. The dissapate heat far better than the brembos due to the design of the rotor and make a pretty big difference over the stock pair. all told the brakes were about $900 for the calipers, $600 for the rotors and the mounting assemblies and $150.00 for the lines. The master cylinder is a spare I had for my GP bike and the little sucker was almost $500 but the difference that made was minimal compared to the other upgrades so I wouldn't bother with that if i didn't already have one kicking around.

Another friend of mine with the exact same bike (save for the exhaust which is two-brothers not staintune as on mine) rode it the other day and he claimed the difference in braking power and feel was "mind blowing" so he's already ordered a set of Harrison's for his bike.

Why spend almost 2,000.00 bucks on brakes some might ask? well the answer to that is pretty simple, last year i did the brembos on my TZ and in one weekend I was able to chop almost 3.4 seconds per lap off my lap times which had all but stagnated for the past 3 years. it was the only change in the bike from the past week and the results spoke for themselves.

the only thing to watch here is the shimming of the calipers relative to the rotors. you have to be really, really, REALLY careful to make sure that the calipers get totally centered on the rotor or you'll be chewing up $600.00 sets of rotors like so many graham crackers. there are lots of shimms that come with the calipers and i suggest you be super patient and take this part of the installation very seriously.

have fun!

JPF