Upgrading 750 SF2 front brakes

TeddyG

TeddyG

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Location
Portland Oregon
My 74 750 SF2 came with 7mm thick Malcolm Cox solid rotors mounted on 6-bolt Brembo carriers with Brembo labeled calipers that have @ 26mm opening for the pads. The Brembo master cylinder fluid container is the classic round shaped that I'm assuming is OEM. The rotors 7mm thickness limits pad choice to narrower pads and I'm currently using "shaved" EBC organics- normal thickness pads are a very tight fit into the caliper.. The brake lever feel is extremely tight with no modulation and the lines have been bled. Actual braking feel is wooden with no real "bite".
So I'd like to install thinner/lighter stainless/semi-floating rotors, and a previous Forum post lists EBC# MD609LS. I've contacted EBC USA with no reply yet, and am wondering if anyone has used these rotors and their opinion of them.
Regarding the master cylinder, I'm thinking of upgrading to a newer Brembo unit, unless there is a re-sleeving that can be done to improve the brake lever feel with more modulation.
I've seen rotors (brand unknown) listed on a Laverda parts supplier, but they are very expensive at $500 each.
Thank you for your input
 
You might contact Mercury Morris at vintagebrake.com
He's helped me a lot over the years, really knows his compounds, and most recently set me up with a better ratio master for my SF2
 
Are you using 40-year-old original rubber brake lines? There are much better options. The best for buck fix after braded lines I found was swapping to a 16mm Radial Master, sadly, they don't look very standard though.
 
Malcolm's thicker than normal discs are not the problem. It will be pad material, or hoses if as Vince suggests may be original old rubber ones that should be swapped for braided, or master cylinder. I never got the original all alloy master cylinder working as well as the newer plastic reservoir one (which I raced with for many years), even though they should be identical in working. Today there are radial master cylinders that are really effective. If the callipers have not been stripped and cleaned it is also an easy job. It all adds up. Even moving the master cylinder as far inward as possible on the handlebar helps as you have more leverage the further out on the lever you squeeze.
 
Early on, I had an annoying front brake lever issue. I spent lots of money trying for a fix. Braided lines helped, 4 spot calipers helped, but it's hard to find adaptors for Ceriani forks and radial master also helped. But just before fitting that radial, someone noticed I had a lump where my brake lever touched the original master piston that caused the non-smooth brake action. 2 minutes smoothing that with a file made a huge difference. In the end, just maximising the original kit made a huge difference. One issue is finding modern brake pads that maximise both wet and dry grip on the standard cast-iron Discs. Lots work on modern Stainless discs, but Cast not so much.
 
Hi Teddy.

Don't get too wound up about discs and pads. Almost the entirity of your 'wooden' problem is down to the hydraulic ratio between your master and slave (caliper) pistons. Reduce the diameter of the master cyl and you will be a happy-chappy. Then start to look at more bite via pads, if you want more brake.

Paul (Using a Ø12,7mm master and chuffed).
 
CDHE said:
two piston brembos off a bmw are also a bolt-up option
Click to expand...
Plus one on that fix.
Much improved feel with these calipers. Confident braking on loose surfaces and increased pad area. Better still, they were cheap to buy and, with the addition of a couple of spacers and longer bolts to suit, fit straight on.

Four Pot Shims (arrowed).jpgFour Pot on Bike.jpg
 
Thanks guys,
I neglected to mention that it came with stainless Speigler brake lines. The brake lever has almost no travel before the brakes are engaged, so it's like a switch. I'll look into 4 pad Brembos, thinner rotors, and try re-sleeving the master.
Another question- why are there the thin metal tubes connecting to the calipers, instead of the hydraulic lines simply extended and attached directly to the calipers?
 
TeddyG said:
Another question- why are there the thin metal tubes connecting to the calipers, instead of the hydraulic lines simply extended and attached directly to the calipers?
Click to expand...
Because that's the best way to do it.
The shorter a flexible hose is the better. If Goodridge hoses, end to end, were really better then that's what would be fitted on six figure priced sports cars.

If you fit the four pots, you won't need the thinner rotors or the sleeving, Teddy.
 
Of course, this is. Jota, but these are 4 potters too, needing fork legs swapped and a longer Speedo cable to get them being the legs, which some prefer.
 

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TeddyG said:
Thanks guys,
The brake lever has almost no travel before the brakes are engaged, so it's like a switch. I'll look into 4 pad Brembos, thinner rotors, and try re-sleeving the master.
Click to expand...
That sounds like the master cylinder is your problem, master cylinders are cheap and plentiful. Up to you.
 
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