drilled brake rotors for airhead GS?

[crarchitect]

Hey Gringo,

Thanks for chiming in. Let me clear things up by saying I completely recommend the MAP disc. Yes, I have had repeat problems with these buggers but as far as stopping a GS goes, good luck at finding a better option. Bigger is better. However, your comments give me a new idea; could it be as simple as the brake pads? I started with the recommended Galphers (sp?) a few years ago, but I thought they were too grabby- which they are! But holy sh!t do they stop you. I went back to stock just for a more relaxed and metered brake feel. Kinda silly when I think about it.



Do you folks think the stock pads could be the weakest link? What pads do you run? Anyone heard of a stock pad burnishing a MAP disc and causing problems?

I think I need to go with the Tokiko...


Thanks for the help,

C man

[MotorMike]

Originally Posted by crarchitect

Hey Gringo,

Thanks for chiming in. Let me clear things up by saying I completely recommend the MAP disc. Yes, I have had repeat problems with these buggers but as far as stopping a GS goes, good luck at finding a better option. Bigger is better. However, your comments give me a new idea; could it be as simple as the brake pads? I started with the recommended Galphers (sp?) a few years ago, but I thought they were too grabby- which they are! But holy sh!t do they stop you. I went back to stock just for a more relaxed and metered brake feel. Kinda silly when I think about it.



Do you folks think the stock pads could be the weakest link? What pads do you run? Anyone heard of a stock pad burnishing a MAP disc and causing problems?

I think I need to go with the Tokiko...


Thanks for the help,

C man

I always ran the Galpher Green. They are soft and don't last very long, but the grab really well and don't tear up the rotor.

Michael

[Ron Seida]

Originally Posted by Gringo

The Brembo is a single-piston caliper, like a C-clamp - one side pushes, the other side just sits there, so the whole thing has to slide itself back and forth to center over the disk, and if the contact area where this sliding happens gets crudded up, it stops sliding, the fixed side starts dragging, the drag creates heat on one side of the disk only, and if this goes on long enough, you may get warpage... that's my 2 cent theory anyway.

Gringo, i just checked the caliper on my '89 gs/pd, both sides have a piston. They each have their own bleeder also. I'm just curious, what year are you talking about.
Also, i'm wondering if anyone is preforming the proper break-in procedure for new brake-pads? Failure to do this creates cementite, or "hot-spots" on your rotor. This creates a spot on the rotor with a different friction than the rest, which causes pulsing. I'll try to find a link to give you better info...

[Ron Seida]

...okay, try this: http://www.stoptech.com/whitepapers/...otors_myth.htm

[Frank Warner]

Originally Posted by Gringo

o my ' 92 PD

my stock Brembo caliper

The Brembo is a single-piston caliper,

The standard caliper is a two piston Brembo caliper. I don't know what you have but it is NOT standard on an airhead GS or even a G/S (covers 1980 to 1996).

(At least some, possibly all) Oilhead rear calipers are single piston. As are some older airheads ... but not on G/S or GS airheads.

[Paragon]

I haven’t read all the postings in exact detail, but the following is my experience, which I hope contributes to the debate;

There are various alternatives, some of which are as follows:

The “upgrade� 320 mm rotor works with the original 2 pot paralever Brembo - you may have to get a slightly bigger "metal pipe" to connect the flexible bit to the calliper, but the new rotor works on the 80GS/100 GS PD a lot better than stock.
This is a cost effective solution at around £160, and also has another benefit in that most airheads need a new caliper sometime and the BM OEM one is more expensive than the after market 320
It is also a PROGRESSIVE way to look at an upgrade as it uses the original 2 pot Brembo and can go on to use the 4 pot oilhead Brembo.
The ones I use are from HE in Germany, they are well made, look neat and the company is quick to deliver and responds well

Ferrodo pads are good

Before I go on to the next point I want to say that riding an Airhead in modern conditions is more about planning your ride, vis-ê-vis brakes, than with a modern Oilhead; this is a big brake improvement if you take in onboard.

If the above does not satisfy you, move onto use an oilhead 4 pot Brembo with the 320 set up. The 4 pot Brembo from the later Oilheads need a little machining but the cost is just a few £s and the beauty of this is that you are still within the realms of a “stock� set up.

Onto the Harrison - 6 pot - is it expensive? - yes - are the pads expensive? - yes - is it OTT off road? - yes – does it overbrake the RHS? – you tell me - is it OTT on the black stuff? - well maybe on the 80 but not as much on the 100PD.

IMHO, save your money, think about your riding a fit a 320 to start with

Just my opinion – I have Bikes with a 320 and 2 pot Brembo, I have a Bike with a machined 4 pot and I have ridden a Bike with a Harrison, although never had the nerve to part with that much cash to buy one.

(another alternative – you can also fit twin disks and twin Brembos – need another LHS fork stanchion but they are around second-hand and easy to fit).

The Holy Grail – the airhead front brake – confuses all but that is the beauty of an airhead – character, style and interest.

Cheers

[Wirespokes]

Here's something that hasn't been mentioned yet in this thread. And this is something that finally hit me after having several bikes with this problem all at once. I've got bikes that have been sitting for years. This spring I also picked up an R65 that hadn't been ridding much in the last several years. But I know the PO had had a problem with pulsing brakes. It's got the dual disc set-up with floating rotors. The PO had removed the stock discs due to warpage to put them on. When I rode the bike the brakes pulsed. I transferred the discs to another bike and the brakes didn't pulse, but the discs that I swapped to the R65 DID pulse.

Another one of my bikes was having a problem with pulsing brakes (getting it going again after sitting many years) when it hadn't had a problem before.

I've got to say that I don't use the brakes hard as a rule. I like to go and not slow down. So it didn't make sense I'd warped the discs.

The pads were also screeching.

I tore into the calipers since that seemed like the only thing left. The pin that the pads slide on needed a little cleaning, but no more than usual. What I found was that the caliper piston itself either needed cleaning or there was pitting and corrosion that prevented it from retracting.

The way the caliper works is there's a square section o-ring for the outer seal. When the piston is forced out by fluid pressure, this o-ring gets deformed. Then when pressure is off, the o-ring returns to it's original shape, pulling the piston back with it. I could see this warping a disc, but there is some wobble to all discs and isn't a problem. A little run-out is actually beneficial as it helps push the pistons and pads back away from the rotor.

So either the o-ring is worn, or there is grunge on the piston preventing it from returning into the bore of the caliper.

When I got the pistons cleaned up, the screechy, pulsing brakes returned to normal. No pulsing. Nada! Any more, unless the disc is really really bad I assume there's something wrong with the caliper if I've got pulsing.