View Full Version : MoT advisory - brake discs. Pointy
scotty217
10-11-14, 11:07 AM
Just had Suzy, my SK6 MoT'd - got an advisory for slight fluctuation in front brakes. The guy says I should be ok but to think about changing the disks. Sooner rather than later! £300 for disks then pads too! I'll just have to spread the cost over a couple of months.
Red ones
10-11-14, 11:15 AM
Mine does that.
Surely if the discs don't get any worse then it remains only an advisory?
scotty217
10-11-14, 11:21 AM
Mmm I get your point. I do need to get pads though, they are getting close to limits. I'm not sure if the disks would get worse over time. I can change them myself though, so some costs saved.
Sent using a crayon cos they won't let me have anything sharp!
When you start to notice it then it's time, rather than the surprise advisory.
Look at it this way.
You can update to flashy wavy disc's.
jetfire1383
10-11-14, 12:47 PM
have you checked the bobbins are not stuck, they need to be able to move.
https://www.youtube.com/watch?v=1qoPqN2GBdw
scotty217
10-11-14, 01:27 PM
I'll check the bobbins, I think I've seen that vid before, but I've forgotten about it. I don't think I'll get wavies ntec. Unless they make any difference.
Sent using a crayon cos they won't let me have anything sharp!
Waveis just look flash I believe.
Armstrong Web site say otherwise but they are trying to sell them after all.
Nutsinatin
10-11-14, 06:00 PM
Can't remember which manufacturer it was that sold round disks because they dissipated heat better than wavy disks. Then the next year they released wavy disks and claimed they were better at dissipating heat! I'm sure I didn't imagine it! Zilch difference on the road anyway.
Well when the bsb and WSB blokes start using wavey then I'll believe the hype.
Still I think makes the bike look trick
maviczap
11-11-14, 09:15 AM
Check out Garynorthest's review of his Chinese discs, which are very good for the money.
I know he's got a curvy, but I'm sure they'll do pointy ones
If not Blackshadow discs, made in the UK. Bibilo has them on his pointy
http://www.blackshadow-uk.co.uk/
Or ABE
http://www.allbikeengineering.co.uk/discs.php
OEM are the best, but at a price
In fairness to Suzuki, thier OE discs are not outrageously expensive compared to the competition. I was once quoted about £280 per disk by Kawasaki...
A look up on Alpha sports suggests an OE disk for a K6 SV650 is part number 59210-08F11
If that's so, Robinsons foundry quote £103.74 per disk. It's hard to feel that's bad value.
Jambo
If that's so, Robinsons foundry quote £103.74 per disk. It's hard to feel that's bad value.
I went for stock when I replaced mine. They were the cheapest I could find at the time.
Why are car discs so much cheaper? I could replace all 4 of the discs on my car for that money, and there's a lot more metal in them.
Look at the way a car disc is made up and materials.
Then look at your fancy semi floating discs on the bike...
Why are car discs so much cheaper? I could replace all 4 of the discs on my car for that money, and there's a lot more metal in them.
Look at the way a car disc is made up and materials.
Then look at your fancy semi floating discs on the bike...
The machining involved in a bike disc is clearly more involved. I suspect that production volumes play into it as well, look how many cars are made and how many use the same discs, helps spread the cost.
Jambo
I'm probably wrong but, could car discs be moulded? Most standard ones I have seen look more moulded than machined.
Whereas bike discs all look machined....
Which could explain the disparity in cost, along with the production numbers as Jambo said
???
ChrisCurvyS
11-11-14, 09:05 PM
I think it's mainly about production volume as has been said. As well as keeping production costs high for manufacturers, it means they're not pushed to find ways of doing things more cheaply because it's not worth anyone's while setting up in competition.
Red Herring
11-11-14, 10:26 PM
Are car discs (or at least the run of the mill ones) cast then machined. Bike discs are forged and then machined I believe?
maviczap
12-11-14, 09:13 AM
H'mmm let me see, here's an informative video :p
MAzbbID6BZ0
And another
4VV6Ra3fkHk
Without even playing the videos, the brembo is 5 mins long and the JDM is 1 min. That's gotta explain the cost difference right there :)
Red Herring
12-11-14, 10:30 AM
And they are both car discs. The best I've found is this EBC video and at 3.30 in it shows a motorcycle disc being cut out of a sheet of stainless steel with a laser cutter, so not cast as the car ones are.
http://www.youtube.com/watch?v=I2SOf2WCoR4
So not forged. I wonder what the advantages of that method are? Forging gives greater strength and durability as it aligns the grains of metal. I can't imagine a cut steel sheet having the same benefits.
Think how much unsprung weight having two cast disc's on the bike would be.
If they were cast in the same shape and size as they currently are, I can't see it adding any weight. I don't think cast steel is significantly denser than sheet steel. Might be a wee bit brittle though.
Red Herring
12-11-14, 01:11 PM
I'm no expert on metal processes but I'm pretty sure sheet steel is produced from a forging process where the steel is put through a series of rollers to get to the desired thickness. This process results in a more uniform alignment of the metals elements (I don't know the technical terms, I'm sure someone on here will correct me if needed) which gives it a far greater strength than the casting process where they are still in an unworked random order.
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