bad disk brake performance

4onthefloor · Jul 16, 2011

First of all, i want say thank you to all guys 'n girls who gave my a lot of tips tricks, to finish my bike. I passed the federal test for motorbikes without any troubles.
It starts with one kick ( hot and cold )performs very well, it's a very nice bike to ride!
But the braking performance of the bike is horrible, it's equal to a 50cc motorcycle (puch maxi )of my son. The master cylinder and the caliber are rebuild, brake pads are new but unknown and the disc looks like new ( i think it has a lot chrome ). The brake pressure feels fine. The brake has no bite, it feels like i use a ice block instead of the brake pads! Any ideas to improve the braking performance? I want to keep it stock locking, so a brake swap to hp parts is not welcome. I don't want to make stoppies! I don't want to kiss the ass of a truck that has better brakes :mrgreen:

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Greetings from switzerland
Marco

Matt Spencer · Jul 16, 2011

Hold the bars so youre first two fingers get the end of the lebver at the ball .

And exercise the wrist / finger mussles .
Should be lockable up to 30 mph , but dont fall of trying doing it . :wink:

L.A.B. · Jul 16, 2011

4onthefloor said:
The brake has no bite, it feels like i use a ice block instead of the brake pads!

Yes that's a fairly typical description of the standard Norton disc brake.

4onthefloor said:
Any ideas to improve the braking performance? I want to keep it stock locking

If you really must keep it stock looking, then the RGM Motors 13mm master cylinder re-sleeve is about the only option available.

EBC pads seem to work well.

4onthefloor · Jul 16, 2011

or are there any cast brake rotors on the market/ better brake pads? I was talking to a old honda guy, they had the similar problems with high chrome rotors, no rust and no braking power!
Resleeving could be a option...

Marco

L.A.B. · Jul 16, 2011

4onthefloor said:
or are there any cast brake rotors on the market

You could have the chrome plating ground off the disc, as that often improves braking performance....but it wouldn't be stock then?

gtsun · Jul 16, 2011

Do the Reslieve, bead blast the rotor, use a steel braided line and it will be 100% better. That gets you to a place where you can live with it if you must keep it stock looking. I don't know what the best pads are. Need more experiance to tell but as L.A.B. Said I think Ive heard good things about the EBC pads. You can talk to the guy at vintagebrake.com

pommie john · Jul 16, 2011

There are a number of ways of upgrading the terrible performance of the original disc. As mentioned there is the master cylinder upgrade, or replacing the whole system with a better master cylinder and calliper and disc. I went for a cheap option of getting a Brembo calliper from a wreckers yard and using a Brembo master cylinder ( 12 mm) .
The calliper cost about $50 , I can;t remember how much the master cylinder cost, but I bought it new.
I also had the chrome ground off the disc which makes a big difference to wet weather braking.

A simple bracket is all that's needed to mount the calliper.

steveyacht · Jul 16, 2011

I used some pretty aggressive sand paper on my rotor, cleaned it with Brake Cleaner and put on a set of AP Racing brake pads.... Made a HUGE difference. I am very happy with the performance of the brakes now, as compared to before.

http://www.apracing.com/info/index.asp? ... e+Pads_977

daveparry · Jul 16, 2011

The one thing that will make a huge improvement immediately will be to sleeve-down the master cylinder (or replace with something else of a smaller bore,

Dave.

Flo · Jul 16, 2011

The Disc brake was actually quite a good brake in it's day, but well lacking by todays standards. People can't be able to squeeze very hard today, even me.
If you really want to keep it looking standard, the only options are sleeve reduction or squeeze harder.
I went for the Andover Norton upgraded Master Cylinder myself & am very happy with it, but for the wopping aluminium block that attaches it. I shall reshape this in the winter.
The caliper is in fact extremely good & can't really be improved on unless you go for a four potter.

ashman · Jul 16, 2011

Who cares if the brakes look standard, myself would rather have brakes that work, whats more important, your life or if your bike looks standard, I went for the Grimica 12" floating disc, caliper, master cylinder and braded line, the Norton nows stops with 1 finger operation, I think my life and safety is more important than keeping my Norton standard, but then again my 850 Norton does live in a 57 Wideline Featherbed frame, so keeping my Norton standard went out the window 31 years ago now, for the better.

Ashley

daveparry · Jul 16, 2011

I still say start at the m/cylinder first, I done mine in completely reverse order! I put a Grimeca caliper on with the RGM mounting plate, better but still not good, then I fitted the braided line which had no noticeable effect. Lastly, I sleeved down the master cylinder using the RGM kit (which was probably the cheapest part of the whole job) and this worked wonders, so much better. This was all about 15 years ago when we'd all had much less experience of trying to get a decent brake performance, it's all down to mechanical theory really, the original ratio of m/cylinder to caliper piston size/area was wrong,
To put in engine terms it's a bit like trying to move off in 3rd gear!

Dave.

pete.v · Jul 16, 2011

This is a system. All aspects need to tip top to function optimally. Rebuilding the master cylinder is good but onlly part way there.

The caliper is very ofter crudded up and stuck and It doesn't take many heating and cooling cycles to bring moisture into it.

Not much can be done with the disk but it can be cross sanded with emery to remove glaze.

MC+cal+dsk=op.brkng. Decreasing the condition of any of the three and you will lose op.brkng.

The OEM system works well it all parts are well.

A chain is only as strong as its weakest link.

Fishheads can be a delicacy.

daveparry · Jul 16, 2011

The OEM system works well it all parts are well
-------------
I agree with most you said except the bit above! I've had my 1973 850 Interstate since 1975, it had about 10,000 miles on when I bought it and I can say the brake performance was never good, because the fundamental design was wrong for the reasons I stated above.
Even if you put a new original type of master cylinder, caliper, hose and disc on it would still be a poor brake and i'm not comparing it to a modern system, even for it's time it was poor,

Dave.

Guido · Jul 16, 2011

pvisseriii said:
This is a system. All aspects need to tip top to function optimally. Rebuilding the master cylinder is good but onlly part way there.

The caliper is very ofter crudded up and stuck and It doesn't take many heating and cooling cycles to bring moisture into it.

Not much can be done with the disk but it can be cross sanded with emery to remove glaze.

MC+cal+dsk=op.brkng. Decreasing the condition of any of the three and you will lose op.brkng.

The OEM system works well it all parts are well.

A chain is only as strong as its weakest link.

Fishheads can be a delicacy.

I have to agree with you 100%. Fish heads are a delicacy! :wink:

But on a more serious note. Going fast is only half the fun,,being able to stop and live to brag about it is the most important part.
I have been running a drilled rotor and stock setup and it stops fine, or so I thought until I rode a modern bike and hit the brakes and nearly went over the handle bars.
I'd like to try a new master cyl but have heard issues about the sleeved ones having the holes not being lined up right or something like that.
I'll have to do some more research.

pete.v · Jul 16, 2011

Now let's be fair here. I never said it was GREAT. I myself have added a Magura MC to bring it to very good, not great but very good. Get to stopping too good and no telling what may fall off the old girl, including me. Although I would love to take a few laps around Grattan, I will never be competitive.

rvich · Jul 16, 2011

I would consider the following:

1.) Sleeve the master cylinder
2.) Buy the best pads you can find
3.) Grind the chrome off the disc, paint it silver anywhere the pads don't contact it and ride it often to keep it rust free.
4.) Stainless line. I have never seen one that is black, which wouldn't be impossilbe considering that you can get them with clear tube over them. If I had to have it black, I would put shrink tube over it, paint it, get the liquid vinyl tool grip, or figure out some other method of disguise.
5.) Put as much effort into the rear brake. (which never seems to get mentioned in these threads)

Good luck with it,
Russ

daveparry · Jul 16, 2011

I often think the rear brake is a bit too good as it is, very easy to lock-up!

Dave.

Flo · Jul 16, 2011

I have led a closeted life. When did Norton start chroming their discs?
Only seen cast iron ones.

4onthefloor · Jul 17, 2011

Well, i will grind the brake rotor and put in custom build brake pads ( for hill racing ) they should bite excellent cold and warm.
If it doesn't satisfie me, i will resleeve the master cylinder. I don't want a killer brake, but a brake that performs well ( like on my old cars ).

Thanks
Marco

bad disk brake performance

4onthefloor

Matt Spencer

L.A.B.

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