/6 disc brake upgrades?

[billpayne]

Just took delivery of a well-maintained R90/6 with single disk on the front and master cylinder under the tank. I was shocked at how poorly it pulls the bike down from speed. I'll change out pads, freshen the brake fluid, and fit a stainless set of hoses; what else can be done to make them bite? Anyone done an upgrade to real brakes (as in, larger discs and modern calipers?). Open to suggestions (and yes, "slow down" is a valid suggestion ).
thanks--

 

[20774]

Welcome to the forum! A critical aspect of the ATE front disk is to make sure to position the internal eccentric pin to get flat contact with the disk. People mention using a sharpie to make streaks across the disk surface, then find the position where the pads wipe clean/evenly once the brakes are applied light. I've found that I can find that spot by using an appropriate screwdriver in the slot from below, I can turn the eccentric back and forth and feel the point where it makes contact with the disk. I find those limits turning it one way then the other...I then position the eccentric in the middle of that range. I like the way my front brake is on my /7.

A common thing to do is to convert to a handlebar master cylinder...you'll need to find an internal diameter that works well enough...I don't remember the sizes. Another more expensive option is to add the other slider which accepts another caliper...like the R90S. At least one of the threads in the similar threads pane below addresses that upgrade.

Snowbum discusses brakes and upgrades on this page:

https://bmwmotorcycletech.info/brakes.htm

 

[ccolwell]

It wasn't feasible for me when I had my R75/6 but now I would mount a second disc and a handlebar mounted MC. And I'd start with the MC. One of the main reasons I gave up the R90S was the (lack of) braking. I don't think my R100 had much more in the way of calipers/discs than the R90S but the brakes were a lot better. At least in my rose tinted memory spectacles.

 

[stevenrankin]

Upgrade

So how much do you want to spend? Can you do the work yourself or will you have to find a shop to do the work for you?

As Kurt says, one of the first things to check is the caliper is set up properly. Changing the brake hose may make a small change in braking.

Adding a second fork leg and caliper will help more. You will have to also change the master cylinder to a two brake one.

Moving the Master cylinder to the handlebars not so much. The only reason to move the master cylinder to the handle bars is to eliminate the cable actuating. Frankly in my experience as long as the cable is properly adjusted, there is little or no difference in master cylinder performance between the under tank or handle bar units.

The most bang for your buck would be to get rid of the ATE brake calipers altogether and switch to Brembo units. This however requires completely changing the front forks and most of the front end hardware. It is not a difficult job but can be expensive as well as hard to find used parts if you choose to go that way.

I swapped out the ATE calipers on my 78RS for Brembos, I left the Master cylinder under the gas tank and in all performance comparison, the bike braked the same as my 84 R80RT which was stock with the Brembos and MC on the handlebars. If I had found a good reason to move the MC to the handlebars, I would have done so as I had the parts on hand. There was no reason to do so.

I can't give you any idea as to cost of the conversion as I squirreled away parts over several years as they came up used for good prices from various sources. St.