NC24 Front Brake Caliper Rebuild

[speedfreak87]

Hey folks,

yesterday I wanted to replace the front brake discs and pads on our NC24. Unfortunately I had to notice that I may be the first person after 25years of this bikes life who had his hands on the calipers.... This is what I have done / tried to do:

- Because they are too thin I had to replace the brake discs with new ones from TRW-Lucas (www.trwmoto.com/de/). Those have a one MM thicker minimum TH than the ones which were fitted.

- I bought new brake pads from TRW as well.

During installation I noticed that the front left caliper pistons are kind of stuck because I can not push them properly back. Therefore the new discs wont fit between the new pads......So now I will have to disassemble the whole caliper to replace the seals and clean/replace the pistons

My question to you is if anybody can tell me a good shop to get new seals (and maybe pistons) for the brake caliper?
Or can I trust/buy those seals offered on Ebay?


- Furthermore on the right caliper one "cover screw" has no "head". Sorry but I dont now the right translation. Im talking about this little screw which is screwed right on top of the brake pad secure pin. Im not able to use a screwdriver, it gets no grip. So I was thinking of drilling it out? Our has any of you maybe a better solution?

regards

Kai

[Neosophist]

Hello!

the little cover screw (flat head) often gets broken, to drill it out is usually the only way, you could try a punch and hammer to knock it around.

The NC24 uses plastic pistons so i doubt there will be any issue with the pistons themselves, just the seals and dirt.

You an buy from the uk from davidsilverspares or maybe cmsnl from the Netherlands might be cheaper for your location.

[newtothis]

I bought pistons and seals from powerhouse-uk on ebay. Might be worth a look

[Suzuki416]

I am also almost doing the same job on one of my NC24's.

I got 1 x set of seals from David silver spares - worked perfectly. So I caliper is excellent.

Looked at the next caliper & it was awful. Think 30 years this hasn't been touched - was missing both dust seals and really seized. 100psi wouldn't move the pistons...
150 psi got it though - lol
Ordered a set of seals from eBay and they are s**t...
So going back to DSS today to finish it.

[speedfreak87]

I am still waiting for the parts from cmsnl and will give you a feedback on the quality asap.

So far I had the same issues as you mentioned Suzuki. It seems that no one ever touched the calipers. The right hand caliper must have had a big amount water in the brake fluid because its has started to rust inside the ventilation screw. Furthermore the dust seal screws on brakepad pins where corroded and pretty tight.
The dust seals are broken (or better not present any more) on ALL pistons. The oil seals looked good but i decided to replace all.

Furthermore the "slide-pins" for the right hand caliper are rusty. I dont now the correct translation and hope you know what I tried to described. So You should have a look at them as well.

PS: I had to use very much air pressure as well to shoot the pistons out!

[speedfreak87]

Hey guys,

finally we were able to rebuild the front brakes on the nc24. The parts from CMSNL are pretty good.
But were in some kind of trouble now. After bleeding the air out of the brakes the caliper on the left side seems to be some kind of loose.
We are pretty damn sure that there is NOT any air left in the brake lines.
The brakes kind of work but we can pull the lever right onto the handlebar.
We took a closer look on the left caliper and noticed that there was missing a washer which was secured by a little snap ring. We did replace it but the caliper is slightly moving each time we pull the lever.

Has anyone a hint what we can check or does anyone know what this problem is?

Once again, the brakes are working but we think we dont get enough brake pressure because we can pull the lever onto the handlebar. It seems that the left caliper is slightly moving (the smaller mounting screw on the bottom of it).

greeting

kai

[Neosophist]

That is part of the anti-dive mechanism, It is OK if its a little loose, it won't alter the brake feel.

If you can pull the lever to the handlebar then unless you have brake fluid leak then you still have air-lock in the brakes.

The lever should be very hard if bled properly. they can sometimes be troublesome to bleed the air out as it gets trapped.

It is common for air to get trapped in the master cylinder, so that even if you bleed until no bubbles come out the hose you still have air in the lines.

Try turning the handlebars so that the side of the master cylinder that the brake hose connects to is lower than the other end.. this can force trapped air out.. be careful you might spill fluid and the master cylinder wont hold much fluid at an angle but it can help bleed it out.

You can also try holding a cloth around the brake hose bolt.. get somebody to pull the lever slowly and open and close the bolt a little to force fluid and air out of this gap.. tighten the bolt before the lever reaches the bars.

Keep going, you will get the air out of it.

[speedfreak87]

Thanks for your hints. We almost tried everything now.
Can it be just normal the the lever has a "weak" start if you begin pulling?

Im asking because were using adjustable after market levers (pazzo).
The lever has 6 Positions. 6 has the biggest distance to the lever and position 1 is the nearest.
You still can put a more than a finger betwenn lever and handlebar on pos 1.

The problem is, that on pos 1 - 3 the lever can be pulled almost onto the handlebar. The break pressure is good but in case of an emergency it would not be enough delay to block the wheel.
Even with the original lever mounted the pressure has "to build" up. The breaking begins as soon as youre beginning to pull but to get a hard break you have to pull the lever several centimeters.

Do you think its still air in the system?

[Suzuki416]

Yep you definitely have air trapped.. I have just got my 2nd caliper rebuilt however having a lot of fun (not) bleeding it too..

I think I'm going to partially fill it from bottom to top & see how that goes.

[Neosophist]

Thanks for your hints. We almost tried everything now.
Can it be just normal the the lever has a "weak" start if you begin pulling?

Im asking because were using adjustable after market levers (pazzo).
The lever has 6 Positions. 6 has the biggest distance to the lever and position 1 is the nearest.
You still can put a more than a finger betwenn lever and handlebar on pos 1.

The problem is, that on pos 1 - 3 the lever can be pulled almost onto the handlebar. The break pressure is good but in case of an emergency it would not be enough delay to block the wheel.
Even with the original lever mounted the pressure has "to build" up. The breaking begins as soon as youre beginning to pull but to get a hard break you have to pull the lever several centimeters.

Do you think its still air in the system?

yes 100% air..

get it setup with the original lever first to elimate lever problem.

You are displacing / compressing air. a few pumps of the lever and the lever should be almost rock solid and not compressible...