Braking upgrades for GT750A

[Evans Ward]

I find the stock dual disc braking system on my 76 GT750A to be lacking even with the stock master cylinder changed out to a 14mm unit from a Suzuki V- Strom. Reading about the concerns over wet weather braking conditions has me in the process of upgrading the braking. For the time being, I want to retain the stock GT750A forks and front fender. I did purchase some nice used cross drilled and balanced GT750 disc rotors. I have searched and have done a lot of reading on this subject but it’s not all 100% clear to me. I’m now looking at other Suzuki calipers that will bolt up to the stock forks in the stock position. I will totally disassemble whatever calipers I purchase to restore and rebuild with all new parts and pads. The first pic are the cross drilled/ balanced rotors I purchased. The next 2 pics are 1981 Suzuki GS650G calipers, pics 4 & 5 are Suzuki GS750/1000/1100 calipers, and the last 2 pics (pics 6 & 7) are calipers from a 1982 Suzuki GS1000. Which of these 3 different brake calipers will bolt up in the stock position on stock GS750A forks? Down the road, I want to replace the stock forks with those from a GS650G and use some Kawasaki EX500D calipers in the lower position but don’t want to change front fenders. Can anyone answer my question about which of the 3 caliper types I referenced will bolt up and which would be best? I also already have stainless steel braided brake lines. Much appreciated on any help and feedback!

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[daxman]

I can't answer your question about the calipers There must be some known upgrades but perhaps they will need adapter plates? Have you posted on Kettle Clinic? I don't like the look of those discs though - they look seriously weakened with those large holes in. Liable to cracking I'd think. Who did them?

[Evans Ward]

I’ll post up on Kettle Clinic too. Bought the discs used off eBay- seller guarantees them to be straight and free of warpage. Don’t know who modded them?

[jabcb]

Lots of options. Depends on how correct you want it to look & your budget.

For a simple caliper upgrade, SmokeRiders recommended GS1000EC calipers mounted in the stock GT750 position.
http://smokeriders.com/Technical/Suzuki ... ocket.html

Also, early & late GT750 rotors look different. They can be used interchangeably, but the early rotors are a good bit heavier. Those are early rotors in your pic 1.

The GT bikes have two different disk sizes. The GT250 & GT380 use the smaller disk & the larger bikes use the larger disk.
Suzuki GS-series bikes also used different disk sizes. GT & GS disks can generally be used interchangeably, but you need to have the correct disk size for your fork + caliper combo.

Later GS-series forks use top out springs & lower fork inner-tube bushes. Those forks perform a lot better. My red 75 GT750 has stock forks & the gray 75 GT750 has GS1100GK forks. The GS forks were too long for the GT750 & have too much travel. With a lowering kit, new springs & correctly-set sag, you get a really good ride without bottoming as happens on the stock GT750.

It’s pricey, but for max brake performance use a modern disk, modern brake pads & twin-piston calipers. This upgrade is popular on GS-series bikes but is a bit complicated. Our GT250 cafe build has stock forks & this upgrade.
viewtopic.php?f=21&t=12998&start=30
Cafe-GT250-0576 by jabcb, on Flickr

Our T500 cafe build has the fork upgrade & twin-piston calipers. But I haven’t gotten far enough to know how well it works.

[Evans Ward]

Thanks jabcb! That helps a lot and I’m going with the simple Smoke Riders caliper upgrade to start with. Hoping it will yield stronger front braking performance. I ordered 3 sets of the 78-79 GS1000 calipers and a quality rebuild kit. Should be able to assemble one really nice set from all parts ordered.

Your T500 cafe build has some serious brake components and should be top notch in braking. Are those Kawasaki EX500D calipers on it? I run those (one on left side) with the machined adapter on my 72 Kawasaki H2 and it stops very well. I’m well versed in those calipers and refurbish and resale them loaded with pads. I also do the same with Yamaha Blue and Gold Spot calipers which is a popular upgrade with the vintage RD and RZ owners. Personally, I run a set of front Gold Spot calipers (again with machined adapter) along with modern R1 disc rotors on my RZ350. Tremendous brakes! If anyone is looking to purchase the Kawasaki EX500D front calipers (left and right) as well as Yamaha Blue Spot front calipers (full set too) please contact me as I always have a few sets ready to go. They are cleaned ultrasonically with new rebuild kits installed along with HH sintered pads loaded.

Does Salty Monk on the GS Resources site still sell the adapter kits for the Kaw EX500 front calipers to GS650G front forks? That’s the eventual route I’ll take with my GT750A but running a non stock front fender doesn’t excite me.

[jabcb]

Salty Monk sells a lot of those adapter kits.

That twin-piston caliper was used on lots of different models. Salty Monk has some GS Resources forum posts that list the details.
The GT250 caliper was originally on a Kawasaki Ninja. And the T500 caliper was on a 1991 Suzuki VX800.
http://www.thegsresources.com/_forum/sh ... &p=2236887

Per the EBC website:
The GT250/GT380 & GS650G use the smaller 276mm disk, EBC VMD3014.
The GT500/GT550/GT750 use the larger 296mm disk, EBC VMD3019.
https://ebcbrakesdirect.com/motorcycle/ ... 1977/37081

You need to use a larger disk with the twin-piston caliper + Salty Monk adapter kit.
The GT250 cafe build has the larger GT750-sized disk — it’s an EBC VMD3019.
The T500 cafe build has a larger disk that’s actually for a Honda NT650 Bros.
For the GS650G forks + Salty Monk adapter + twin-piston caliper, you will need the larger 296mm disk.

[Evans Ward]

Why is another GT750 triple tree/ steering stem needed when going the Salty Monk all out brake upgrade?

[jabcb]

Not sure why you are asking that question.

The SaltyMonk adapter is a little plate that allows you to mount the twin-piston caliper on the stock forks.
The adapter positions the caliper a little further away from the axle, so you need a larger-than-stock brake disk.