Brakes drum vs disk for 380

[CowboyX]

Hey guys! Got a parts bike to help rebuild my 380. It has disk brakes as opposed to my project bike that has the original front drum brake. Is it the worthwhile upgrade that I think it is? Also I read somewhere recently that disk brakes function better with the caliper mounted behind the fork. Anybody got opinions? How would that be accomplished? Is it as simple as swapping the forks right for left or some such thing. Also, please recommend any other worthwhile brake options or upgrades.

[Alan H]

The original GT380 with drum brake are quite rare nowadays and tend to fetch decent money to enthusiasts in original condition. The later disc models less so.
The drum brake wasn't really up to the weight of the 380 and the disc option was much better - until it rained. 70s discs were made of a higher stainless content and had to warm up before they worked really well. Modern pads help, but if you need modern braking, you really need a modern bike.
These are a GT, which stands for 'Grand Tourer' not 'great thrash'. The engines are torquey, not highly tuned. They are quick without being particularly fast, but very enjoyable to ride. If you want balls out performance with pin sharp handling and brakes, the GT triple range may not be for you.
If a caliper works, it shouldn't make any difference whether it is at the front or rear of the forks, Suzuki knew what they were doing when they designed the bike don't you think? If you still intend going to the rear, then you will need a left caliper from a GT750 as they are handed differently. (And good second hand ones are like rocking horse sh1t!)

[jabcb]

The 1972 GT380J front drum brake was essentially the same as the front brake on the T250/T350, which were much smaller & lighter bikes.
As Alan indicated, it really wasn't up to the additional weight of the GT380.
So Suzuki switched over to a disk brake for the 1973 GT380K.

Easy improvements to the disk brake:
1) modern aftermarket pads
2) a slotted brake rotor from a GS-series bike
3) stainless steel brake line (obviously doesn't help with wet braking issue)

Let us know if you want to upgrade to a GS-series rotor & we'll lookup which ones work on your bike.

[Coyote]

hen you will need a left caliper from a GT750 as they are handed differently. (And good second hand ones are like rocking horse sh1t!)

I stand to be corrected, but you can reverse the fork legs for a caliper behind design. All the GT wheels from 73 on were designed for 1 or 2 disks on either side of the wheel.
You can turn the wheel over or you can swap the disk and dust cap side for side. Everything is symmetrical.

[Alan H]

hen you will need a left caliper from a GT750 as they are handed differently. (And good second hand ones are like rocking horse sh1t!)

I stand to be corrected, but you can reverse the fork legs for a caliper behind design. All the GT wheels from 73 on were designed for 1 or 2 disks on either side of the wheel.

True, but the forks weren't on the 550 down.

The single disc fork legs are different as far as I know. left and right are definitely different and only the 750 had twin discs which is why you need a 750 left leg bottom to fit twin discs to the 550. The calipers are different right and left which is why I had to buy a left caliper to twin my discs on the next 550 I do. I must have a dozen right calipers and they dont fit on the left, trust me. No double discs on the 380 but I suppose either a 380 right leg bottom could be fitted to the left fork and have one caliper in front and one behind.
(Unless I'm missing something completely - I have been wrong in the past, but I divorced both mistakes, so they don't count anymore!!)

You'd need a master cylinder off a GT750 then as the piston in the MS is a bigger diameter - underneath the cylinder a D is cast in. The 380 forks are different diameter to the 550/750 forks, but the 550/750 are the same.

You can turn the wheel over or you can swap the disk and dust cap side for side. Everything is symmetrical.

Don't turn the wheel over or the speedo will go backwards, unless you go everywhere in reverse!!!

[markush]

Hi!

The only difference between left and right caliper is the caliper holder. If you get a left holder, you can use the other parts of your right calipers to build a left one.

No double discs on the 380 but I suppose either a 380 right leg bottom could be fitted to the left fork and have one caliper in front and one behind.

True, but who would want to ride it ...

I did it so at my 250-racer (same fork as 380): fitted a right outer tube to the left fork side with the caliper to the front. It takes some modifications on the bores/threads of the fender mounting.
The bottom clamp isn't in the middle of the tube, so the distance piece at the wheel axle has to be changed, and the speedometer drive had to be omitted. No matter in this case.
I use the master cylinder of the single disk brake (smaller piston diameter) with two calipers. This entails less manual force but greater lever travel. It works well, but steel flex brake lines are required.
In double brake master cylinder the "D" is bashed, not cast. The cast signs are not of interest in this case.

Markus

[CowboyX]

Great feedback! So this is what I am hearing. If I want to upgrade to disks there are some easy things to make the brakes perform better for the size of bike. Altering the position of the caliper is a job for someone with more skills and better tools than I. So the real question now is should I stay with the drum brake due to it's relative scarcity? Can better braking be coaxed out of drums with modern pads? Or are the drums worth more to sell? I'm not really going for a restore so much as making it just a daily rider.

[Alan H]

'Back in the day' a friend had a 1971 Gt380 with a drum front brake and it was well poor. Suzuki's remedy was to fit Ferodo green racing linings and have them and the drum skimmed to fit correctly. They were a vast improvement until the disc option was available, but the drum will never be more than adequate unless you only intend to ride 'defensively'. I understand they do fetch decent money, but maybe the entire bike will be worth more to a collector/restorer and a later model would be easier for your project? There were more of them (and cheaper!) and spares would be a bit less of a problem. Spares don't always fit between different models - carbs, side panels, filter box, exhausts and others were different.

[CowboyX]

Yeah perhaps it would be worth more as an original but I have already disassembled the engine and bought parts to revive it. I am starting to like the idea of better braking with disks. So how much are the drum brakes worth?

[Alan H]

Only as much as someone will pay! Obviously they are worth more if still attached to the bike.
If you decide to make mods to the bike that can easily be changed back to standard, then keep the drum parts for when you sell it. It will then be 'putbackable' by the new owner if they want to go back to original and the bike will be worth more in the future. Depends what you want to do with the bike really.

[husky99]

Check out these guys for drum brake service. It will stop better than a 1st generation disc brake.

http://www.vintagebrake.com/drum.htm" onclick="window.open(this.href);return false;