brake question for 78 gs550

[dalknob]

Last spring I picked up a 78 gs550 w 5K miles, new tires, brake pads, professionally tuned up & carbs cleaned for $900. i love the bike, it has been a great bike to learn on. I've decided to keep it stock, because from reading posts it seems that any performance mods would take too much time & $, for not too much gain. The one thing I would like to improve on is braking, from a safety standpoint, I am not sure if I should get better rotors, or simply replace the breaklines with braided lines, or swithch out the whole fork assembly for one with dual rotors. Any advice would be greatly appreciated.

[Tom MLC]

Replacing the old rubber brake lines with stainless steel lines would be a sensible improvement. Also, converting to dual front brakes would definately be worth the time & money.

Good thinking.

[dalknob]

As far as converting to a 2 rotor system, is that something I can do with the stock forks, or will I have to replace the forks as well?

[Nessism]

Right hand side lower fork leg does not have caliper lugs so you need to change at least that part of the fork. Also, you will need new master cylinder, lines, caliper, etc.

[dalknob]

I read a post earlier that stated that using the master cyclinder from one rotor setup with a two rotor setup was preferable. As far as changing the fork setup, I am curious about how interchangeable the forks are. For example, will front forks from an 81 gs 750 fit on my 78 gs 550?

[tkent02]

I think the fork tube diameter is different...

Not sure about the 550, the '78 750 fork is 35mm. Perhaps the 650 or a later 550 fork would work?
Performance pads with steel lines may be enough of an improvement, without too much effort.
The drum brake on the back should be plenty too.

[dalknob]

Actually, I've got rear disks, which goes back to my earlier question, would it be worth the investment to replace my stock rotor(s) with aftermarket drilled & slotted rotors, as well as replace the lines & get high performance pads.

[jimcor]

Actually, I've got rear disks, which goes back to my earlier question, would it be worth the investment to replace my stock rotor(s) with aftermarket drilled & slotted rotors, as well as replace the lines & get high performance pads.

Probably not worth the investment, if you can find them at all. New brake lines are a worthwhile investment. A complete rebuild of your master cylinder and calipers to replace old rubber might be a good idea too.

[Tom MLC]

Nessism, I wonder why you think the master cylinder needs to be replaced? Actually, Billy Boy may be interested in hearing this. He's converting his '78 GS1000C to dual front brakes.

[Nessism]

Nessism, I wonder why you think the master cylinder needs to be replaced? Actually, Billy Boy may be interested in hearing this. He's converting his '78 GS1000C to dual front brakes.

The dual disk bikes have a different master cylinder - with larger piston I think so they pump more fluid for any given amount of hand lever travel. I'm not sure if it's critical but there must be a reason or Suzuki would not have bothered.

[dalknob]

this is from a previous post about a gs 850 brake upgrade:
One my '78 750 I put dual discs...
Braided brake lines and decent pads. Two fingers now for a panic stop, one for normal riding. Mucho better. Kept the single disc master cylinder, gives more pressure for less effort.
Stops as good as the '83.
Tires aren't sticky enough for stoppies but the brake power is there.
__________________
so now I'm curious, according to this post, not only will the brakes work with the single master cylinder, they may actually work better.....
Ah, what to do!

[Nessism]

The smaller master will result in lower effort at the lever but it will also be more spongy. Take your pick.

[8trackmind]

The smaller master will result in lower effort at the lever but it will also be more spongy. Take your pick.

The "spongy" feeling at that point is line flex due to the higher pressure, or air trapped in the system.
You will have more lever travel with a smaller bore, but if it's done correctly it shouldn't feel "spongy".

[Nessism]

The "spongy" feeling at that point is line flex due to the higher pressure, or air trapped in the system.
You will have more lever travel with a smaller bore, but if it's done correctly it shouldn't feel "spongy".

Yes, air will create a spongy feel but I was refuring to the leverage ratio difference between a large bore and a smaller one. Small bore = more spongy than large bore. It's a matter of choice. For me, I hate feel of a spongy lever and would rather have a firmer feel that requires a little more hand force. Suzuki choose the larger bore for a reason.

[Billyboy]

Interesting stuff.

My stock GS1000 brakes are spongy at the best of times. I'm thinking its the lines because I've bled them way too much for it to be air. Once I get the twins on I'm going to have to see how they feel.

Jeff. On your "C" to twin brake conversion did you use a different MC?