Jump to content

Rust on brake disc


Robi55

Recommended Posts

 

Now I know this is a common issue with lots of bikes, but today I noticed the start of rust on the front disc of my NC750X on the braking surface itself, not the inner rotor. The bike is less than than a year old. I do ride in winter but it gets cleaned every week and generally wrapped in cotton wool relative to some bikes. Has anyone got any tips on maintenance/removal and good product to use to prevent it spreading? Thanks!

Link to post

Never seen that stuff before, thanks for the tip Argyll. Not cheap but then diluted at 2% I guess it will last plenty long enough.

Link to post
jeremyr62
46 minutes ago, Argyll said:

I use Bilt Hamber's Atom-Mac on both the bikes and the cars as (according to the blurb) it's one of the very few rust preventatives safe for use on wheels/brakes.

 

https://bilthamber.com/product/atom-mac/

Does it work?

Link to post

Yes, it works but you have to learn how best to apply it. Some disagreement about applying on dry/wet surfaces and I can't remember what I found best. I think that both were ok.

 

There are also aerosol sprays from Germany which work well. Kent is one brand but I have never used that one. Can't remember the name of the one I had, unfortunately.

 

http://www.litalex.at/article/16123

Link to post
Mr Toad

If I don't use my car for a few days the disks start to rust, as soon as you brake for the first time it's gone. On cars nobody cares because it's pretty much hidden and hardly noticeable. On a bike it's more in your face. 

 

Brake disks can do one of two things, they can stop you or they can shine like a shiny thing that's been polished. Motorcycle brake disks are a balance between the two.

 

I know which I prefer.

 

I'm sure Andy M will be along shortly to explain it much better than I can.

 

  

  • Like 1
  • Thanks 1
Link to post
Andy m

For those of you who don't know me, I've been working in brakes for 25 years. I am currently key account manager for the one the worlds top two commercial vehicle brake system suppliers working with the UK's trailer manufacturers. I used to be a test track engineer doing type approvals on DAF's, Foden, Dennis, Landrover etc. These are my opinions not my employers. 

 

A brake works by having two rough surfaces touch under pressure and using energy to destroy each other. Think of a run away mountain railway suddenly being able to drop an anchor into the sleepers but on a microscopic scale. The energy converted is movement to heat. 

 

We want the surfaces to be rough, heat resistant and to stay rough, not polish to smooth. 

 

Cast iron is perfect. Under a microscope it looks like aero chocolate, it glows cherry red at 700 degrees and if you then squash it, it crumbles to leave another rough surface. 

 

What we do not want is lubricants like chrome or oil in there. Apologies @Argyll but I'm sure you'll understand why I don't like the idea of sprayed/painted on gunk.

 

Rust is good, it shows the material is nice clean running steel with a good iron content. To get rid, go ride the bike. 

 

If you want to paint the bits outside the rubbing patch fair enough. 

 

Andy 

  • Like 3
  • Thanks 8
Link to post
jeremyr62

Can't disagree with that but for long term storage they could be useful.

Link to post

Yes I love it Andy  

Best one we had, a customer came in "brakes are crap"  rode it  Yes CRAP  what you done recently "just cleaned it"  clean all three disks with brake cleaner and a Gental rub emmery paper ride again with hard braking  3 goes and brakes are fine

Customer would not say what he put on disks! 

 

  • Like 2
  • Sigh 2
Link to post
Andy m

ACF-50 will result in a dry cleaning bill. I know because I got ahead of my self and started spraying before I put the covers on 😓😞🤕🤐

 

Andy

  • Like 1
  • Haha 2
Link to post

Yes my suspition on the customers bike was ACF50  I did it once by mistake, careless spray now very carefull with ACF50 !

Link to post

When disc brakes first appeared on road going, not racing, motorcycles it was partly because they were easier to make than drum brakes, partly fashion and partly for performance, probably in that order. Some Japanese ones rusted, those in the US because they weren't used in the wet but sat on a drive or in a garage, so the Yanks complained. The Japs being very customer aware started making discs out of materials that didn't rust and the Yanks didn't mind because they didn't ride in the wet. UK riders did (and still do) ride in the wet, so unless you had cast iron discs (usually made by Brembo and on Italian bikes) you had no wet weather brakes, it was so much fun -not. Eventually the Japanese manufacturers got the message for UK riders and we got more iron based discs, which incidentally boiled the brake fluid more readily, but they eventually cured that too, so now our discs rust a bit but work all year round.

As Andy says you can have shiny or you can have stoppy but you can't have stoppy shiny brakes. :)

No biker looks at a rusty disc and thinks anything other than, needs to brake harder 😂

  • Like 3
  • Thanks 1
Link to post
Steve Case
On 17/01/2022 at 13:02, MatBin said:

When disc brakes first appeared on road going, not racing, motorcycles it was partly because they were easier to make than drum brakes, partly fashion and partly for performance, probably in that order. Some Japanese ones rusted, those in the US because they weren't used in the wet but sat on a drive or in a garage, so the Yanks complained. The Japs being very customer aware started making discs out of materials that didn't rust and the Yanks didn't mind because they didn't ride in the wet. UK riders did (and still do) ride in the wet, so unless you had cast iron discs (usually made by Brembo and on Italian bikes) you had no wet weather brakes, it was so much fun -not. Eventually the Japanese manufacturers got the message for UK riders and we got more iron based discs, which incidentally boiled the brake fluid more readily, but they eventually cured that too, so now our discs rust a bit but work all year round.

As Andy says you can have shiny or you can have stoppy but you can't have stoppy shiny brakes. :)

No biker looks at a rusty disc and thinks anything other than, needs to brake harder 😂

Ooo blimey Matt your getting all racey here, what next stoppies down Harpenden high street

  • Haha 1
Link to post
Steve Case

I had one of those cast iron rear disks Motorworks used to sell on the R1100GS, it wasn't grabby but the power just kept increasing the longer you held it.

 

I could stop 350Kg of pig iron and pie eater easily with just the rear it was that good

  • Like 2
Link to post
1 hour ago, Steve Case said:

Ooo blimey Matt your getting all racey here, what next stoppies down Harpenden high street

I would need a broom handle to assist the NC brakes I think.

  • Haha 1
Link to post
Grumpy old man
On 19/01/2022 at 16:04, MatBin said:

I would need a broom handle to assist the NC brakes I think.

I've not had a lot of  experience on other bikes other than the Nc but I find the Nc brakes very adequate in fact on one occasion on braking hard into a corner ( miss read it) I had the back wheel up and the Abs cutting in, I presume the abs was cutting in because the bike wheel was hopping. Baring in mind I'm no Rossi so it doesn't happen often.

Edited by Grumpy old man
  • Like 1
Link to post
41 minutes ago, Grumpy old man said:

I've not had a lot of  experience on other bikes other than the Nc but I find the Nc brakes very adequate in fact on one occasion on braking hard into a corner ( miss read it) I had the back wheel up and the Abs cutting in, I presume the abs was cutting in because the bike wheel was hopping. Baring in mind I'm no Rossi so it doesn't happen often.

Compared to abs assisted large twin discs on the front on say a big Sports Tourer e.g. Triumph Sprint 955i the NC shows less initial 'bite', but yes you can lock them if required and have enough time. They are perfectly adequate for the bike, especially if you use the rear brake too. Trouble is old farts like me need re-education to use a rear brake in anger without worrying the rear wheel will lock and swing round, as they did in the 70/80's, so I tend to rely on the front to a very large extent, on all bikes on tarmac, and therefore reckon the NC could do with a bit more front.

Tbh my comment above was tongue in cheek and much like never doing a wheelie I rarely brake hard enough to lift the rear wheel.

The NC is fine for what it is.

  • Like 1
Link to post
40 minutes ago, MatBin said:

Compared to abs assisted large twin discs on the front on say a big Sports Tourer e.g. Triumph Sprint 955i the NC shows less initial 'bite', but yes you can lock them if required and have enough time. They are perfectly adequate for the bike, especially if you use the rear brake too. Trouble is old farts like me need re-education to use a rear brake in anger without worrying the rear wheel will lock and swing round, as they did in the 70/80's, so I tend to rely on the front to a very large extent, on all bikes on tarmac, and therefore reckon the NC could do with a bit more front.

Tbh my comment above was tongue in cheek and much like never doing a wheelie I rarely brake hard enough to lift the rear wheel.

The NC is fine for what it is.

I find that the brakes on my NC750X are adequate, nothing more. They work but both together are needed to stop quickly from high speed. My Moto Guzzi is very similar in this respect, having a similar single front disc setup, albeit without the trendy moth-eaten look, and also being relatively heavy. I would imagine both would be a bit marginal two-up or with a completist pie-eater on board.
Prior to these bikes most of mine in the last twenty or so years have had twin front discs that were sufficient on their own to stop the bike from high speed, usually with relatively little pressure and very controllable, leaving the rear brake for gentle braking in slippery conditions or for trail braking to aid cornering or just to operate the brake light to put off a following vehicle from driving into me. It’s a long time since I‘ve had bikes on which the rear brake is more effective than the front, usually because of the inadequacy of drum front brakes (though not all of them) and the usual long rear brake lever affording huge mechanical advantage. I don’t think the rear brake on my NC would lock if I stamped on it on a road with good grip and without ABS - it’s not that great on its own. The Guzzi one works better, but tbh I’ve never triggered the abs on either bike other than to see if it works.

  • Like 1
Link to post
Andy m

The ABS on the V7-850 is pretty smooth. If I wanted to be critical I'd say too smooth, could feel like brake seal failure rather than a loss of adhesion. Weirdly, the typical reaction by Giuseppe Publico is to release the brake control at that point. My preference is a more agricultural cycling that is obviously ABS, but if I couldn't tell the difference and hold the control you'd all take the ****. Its a lump to do stoppies on. 

 

I'm no fan of twin discs, change the master cylinder if you want more decel for less lever travel. Two cold and glazed brakes, both still limited by the tyre size is just weight and cost. 

 

Andy 

  • Like 3
Link to post

I had my Pajero serviced @Mitsubishi a couple of days ago and got the below written on the bill:

 

IMG-20220121-084829150.jpg

 

(Ignore the spelling pls, not their first language)

 

About the shocks, roll bar bushing, drop links I will check myself with pry bar/ borescope/bounce check later...before spending any money...

Edited by Jamesco
Link to post

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
×
×
  • Create New...