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Front brake calliper rusted - rebuild or upgrade?

3K views 18 replies 11 participants last post by  Macdesmo 
#1 ·
Hi all,

As you will see in the photo the front brakes are a little worse for wear on my 95 900SS that’s being rebuilt. Full rebuild kits including seals and pistons are not cheap, I wonder am I better off spending the money on something slightly newer as an upgrade?

If so, what would you suggest that would work with my stock forks? I do have an 848 front master cylinder but I believe this should work with any callipers I can use from earlier Ducs.

Thanks in advance for any advice.
 

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#3 ·
I definitely don’t need to upgrade, it’s purely a street bike. I am just hoping to find the most cost effective way to future proof the bike.

I did find a full rebuild kit from a mob in the UK (Powerhouse) for around $350AUD, which isn’t too bad. It’s not a Brembo kit though so I’ll do some research on them.
 
#4 ·
Are the mounting bolts 40 mm apart?
Then there's little choice in brake calipers, afaik. Some unobtainium billet Brembo race thingies.

I have tried your calipers with a radial master cylinder like the one on the 848. Liked them a lot.
 
#5 ·
It is pretty hard to rust Aluminum and that is what you should have in those calipers for pistons. A good clean and fresh seals should make them as good as new or go out and find a better set off of a lower mile bike. I have been working on these bikes since the 1990's and have not seen caliper issues that a good cleaning did not take care of.
 
#8 ·
Better 40mm calipers are hard to find, and adapters to the more common 65mm cost more than newer forks. Of course, just about any good option for fork legs with 65mm caliper mounts will require a 25mm axle which means a new front wheel, then you gotta figure out the fender and tachometer drive and next thing you know there's a picture of your bike in the wikipedia page about "project creep".
So yeah if these really can't be cleaned up (and that does look exactly like decade old brake fluid), I'd just get some replacement ones of the same kind.
 
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#9 ·
I just finished rebuilding mine. I cleaned all the years of grime off with a degreaser, off gassed them in the oven for 30 minutes at 350, and then had them powder coated. Here's a link to the kit I ordered.
Photograph Automotive engine gasket Wood Gas Circle
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#10 ·
Thanks for the replies all, looks like I’ll go ahead with the rebuild. This is the kit I mentioned earlier from the UK I reckon I’ll go with: Ducati 900 SS Supersport 1995 front brake caliper piston seal repair rebuild kit | eBay

As to how they got that bad - good question. My father and I are restoring the bike, we bought it with some damage from a low side, and are giving it a big birthday. I imagine it’s just 30 years of infrequent bleeding/maintenance and some water in the brake lines causing the amount of rust. The bike has also been parked post the incident for over 6 months so potentially it’s gotten worse since the fluid was drained out.
 
#12 ·
Sorry if I was unclear there is nothing inside your calipers to rust, the pistons are aluminum as is the caliper itself. What you likely have is simply old contaminated brake fluid , if you have steel pistons (which can rust) I would change the calipers for a different set as someone has installed non-oem parts of unknown origin.
 
#13 ·
Simply as a point of reference, I'm rebuilding the front brakes on my 1976 Triumph Spitfire. The calipers are original and I have no reservations about using them.

The braking began to decline and last week I needed to stop quickly and couldn't! Nothing bad happened other than I nearly shit my pants! Anyway, I completed a frame off resto of the car about 7 years ago. At that time the front calipers were rebuilt. I'm doing it again only this time I'm putting in new stainless steel pistons, new seals all around and new EBC Green Stuff pads. Should solve the breaking problem.

Here's a photo of one of the bound up pistons and the caliper bore it came from. Found rusty water, some bad looking brake fluid and a lot of crud in both calipers. Some cleaning and these should work as new. Oh, and I plan to change the brake fluid in 2 years which should prevent this from happening again.
 

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#14 ·
Rebuild should be fine. I wouldn't bother with replacing the pistons unless you have some visible flaw or wear, generally just he seals and a good clean and fresh fluid is sufficient. When you get the seal kit make sure it includes the o-ring that goes between the caliper halves :)

Cheers
 
#17 ·
Doesn't really answer your question, but I had the same problem years ago and ended up doing the rebuild without splitting the calipers. It is possible to get all the pistons and seals out and back in, just obviously more awkward to clean them out.
 
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