Splitting brake calipers

Disaster Area

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Hello everyone,
Now that the seal kit and new pistons have arrived and I have some time off coming up, it's time to think about refurbishing my rear brakes.

Motorworks say not to split the callipers as they warp and leak afterwards. The YouTube tutorials that I've found don't mention this at all.

Does anyone have an opinion on the best way to replace the pistons and seals?

Thanks in advance.

DA
 
All the advice is not to split them, however I did before I read the advice. One thing you have to be careful of is the two very small 'O' rings which seal the fluid passages; I didn't notice them until after the rebuild (which leaked) and after I'd poured the bucket of water into the gutter. 30 mins searching found both and the were quickly and successfully refitted.
 
I’m struggling to understand how something as stable as an aluminium casting can warp when it’s separated from a similar component :nenau

Having said that, there’s no reason for the small O rings between the casting galleries to need replacing so leave well alone. As for removing the pistons, the best was is to fit a grease nipple to the brake fluid inlet port and use a big grease gun to pop it out.
 
I split my calipers on the rebuild and had a bit of a problem with leakage afterwards. Pulled them apart a second time and all good now . Inhind sight as Andy B said if I was redoing them again I'd wouldnt split them and it's perfectly manageable to get the seal pistons etc out without splitting
 
I split a set of 1100 brembos and had big problems with one caliper... I thought the o rings were too small to compress properly and you also find surface corrosion which once cleaned may leave the surfaces slightly out of level... I'd avoid if I did it again but I guess people have been successful as well...
 
Split Brembo calipers maybe 1/2 dozen times over the last 20 years, never had a problem, fitted new o rings each time, cleanliness and even tightening recommended :thumb
 
as a mechanic , i have done many , the only time they have leaked is when you get the o-ring out of place .

the square seals must be square ...... trapezoid = unserviceable you'll know when you see it.

clean everything , spray off with brake cleaner , blow dry , run a "stone" over them if needed , again clean them , assemble with supplied grease or " red rubber grease ( RRG) " . add copperslip or alu paste to bolts ,little dab of RRG , to hold o-ring in place, screw together , nip everything up , bolt to bike and torque up. add pads and hose , and bleed.

normally i take 1hr per caliper , from seized , to back on the bike working , some take longer , some take less.

the rear brake on my GS MY2000 doesn't need to be split , the fronts do .

if you aren't sure ....get an adult to do it.
 
theoneandonly said:
if you aren't sure ....get an adult to do it.
Click to expand...

That's the problem: None of the brake specialists around here will touch bike brakes, claiming that they're too small/difficult/they can't get the parts etc...

edited to add: I had to buy the refurb kit from the UK because nobody had the seals in NZ or Australia. Or so they claimed. If the square seals aren't square then I'm stuck as I doubt I'll be able to get any replacements.
 
The potential for distortion probably arises from a caliper having been subject to extreme heat at some point.

I simply pumped the pistons out with the brake leaver prior to detaching the hydraulics, I was going to be replacing the fluid anyway.
 
Easyrider5258 (Mark) said:
Split Brembo calipers maybe 1/2 dozen times over the last 20 years, never had a problem, fitted new o rings each time, cleanliness and even tightening recommended :thumb
Click to expand...

I did 3 last summer but only because I wanted them cerakoting. The original O rings were perfect but if you’re not supposed to replace them why are they in the seal kit :nenau

As I said before, unless they’re leaking there’s no need to split the caliper unless you want to paint them which I suspect will be one reason Mike has done so many.
 
AndyB_11 said:
I did 3 last summer but only because I wanted them cerakoting. The original O rings were perfect but if you’re not supposed to replace them why are they in the seal kit :nenau

As I said before, unless they’re leaking there’s no need to split the caliper unless you want to paint them which I suspect will be one reason Mike has done so many.
Click to expand...
Years ago,
With the 4pot and 6 pot tokico calipers,fitted to nearly every Kawasaki,the o ring fitted between the two halves wasn’t available separately. At all:blast
Bit of a bugger if you lost it somehow

And as Andy points out,if the caliper is not meant to be split,why supply the new o ring?
 
Disaster Area said:
Hello everyone,
Now that the seal kit and new pistons have arrived and I have some time off coming up, it's time to think about refurbishing my rear brakes.

Motorworks say not to split the callipers as they warp and leak afterwards. The YouTube tutorials that I've found don't mention this at all.

Does anyone have an opinion on the best way to replace the pistons and seals?

Thanks in advance.

DA
Click to expand...

I’m guessing that you don’t have the same issues with corrosion due to gritted roads in NZ.?
You also don’t mention the brand of brake caliper.
The reason I always split them is to ensure there is no corrosion at all in the machined seal recess.
If they are not completely clean they compress the seals causing the the pistons to jam and binding brakes.
The deformation of the square section seal is what releases the piston,pulling it back slightly.
For this to happen the piston needs to be completely free.
I always use a bent scribe to scrape the corrosion away,
You cannot do this if the caliper is not stripped.
If you have access to an ultra sonic tank it could be used to help clean the halves of the calipers but be aware,any alkaline solution will wreck the anodised finish on a brembo unit,and won’t do the mating/internal surfaces of any caliper any favours.
 
A couple of things occurred to me:

Firstly the calipers are Brembo. But then I was thinking: The seal kit has got four round O seals, which I am assuming go on the piston. There are no other seals, hence the reticence to split the caliper.
The other thing is that about taking it to the bike shop/specialist to have it done. If there were no seal kits in the whole of NZ it's obviously not a job that gets done that often.

Am I better to try it myself? To be honest, I'm at the 'the bikes been off the road for so long what does it matter' stage, so I might as well try doing it all myself.
After all, what's the worst that can happen?
 
Nippy Normans supply Touratech, Wunderlich, Desert Fox and many other makes of accessories.
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