1000H brake fluctuation. Is it .....
#1
04-05-2009, 11:33 AM
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1000H brake fluctuation. Is it .....
Hello fellow CBR owners.
This question may be aimed at the UK guys and galls but please wherever your from answer if you have any input.
Ive just had an MOT (UK yearly vehicle conformaty check) and it failed on brake fluctuation. Now they suggested to me that the brake discs/rotors are warped. So today I stripped of the fromt wheel ready for the discs/rotors that I havent ordered yet, only to find that the front wheel spindle is not totally straight and true, there is a slight bend in it of about 1-2 mm. Would this cause an inaccurate reading on a brake test machine??
Im think im going to change the discs/rotors and pads anyway but seeing as the cost of decent parts ( ie you pay for what you get) are quite high without changing this part am I going to get the same problem. Theres not to much info that I can find on this after trawling through pages of google.
The discs/rotors and pads that I have on now seem ok, there is no blueing around any parts, the calipers are free moving. Would I be able to measure any run out on the discs/rotors with basic tools?
Thanks for any replies but just be called away so I be back on later.
Cheers Riders.
This question may be aimed at the UK guys and galls but please wherever your from answer if you have any input.
Ive just had an MOT (UK yearly vehicle conformaty check) and it failed on brake fluctuation. Now they suggested to me that the brake discs/rotors are warped. So today I stripped of the fromt wheel ready for the discs/rotors that I havent ordered yet, only to find that the front wheel spindle is not totally straight and true, there is a slight bend in it of about 1-2 mm. Would this cause an inaccurate reading on a brake test machine??
Im think im going to change the discs/rotors and pads anyway but seeing as the cost of decent parts ( ie you pay for what you get) are quite high without changing this part am I going to get the same problem. Theres not to much info that I can find on this after trawling through pages of google.
The discs/rotors and pads that I have on now seem ok, there is no blueing around any parts, the calipers are free moving. Would I be able to measure any run out on the discs/rotors with basic tools?
Thanks for any replies but just be called away so I be back on later.
Cheers Riders.
#2
04-05-2009, 12:27 PM
Very difficult to check with a run out gauge on the bike.........it would depend on where the spindle is warped, but it only takes a couple of thou to throw the discs offline - I had it from two coats of paint on the rear of discs on an XJ900.
Check my post above on cheap UK spares - you may be able to replace the spindle and/or discs cheaply.......
Check my post above on cheap UK spares - you may be able to replace the spindle and/or discs cheaply.......
Last edited by Shadow; 04-05-2009 at 12:30 PM.
#3
04-05-2009, 12:47 PM
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Can I ask if YOU can feel a pulse when you brake ?
The reason I ask is that is that it is an easy score for a garage to claim fluctuation for an MOT failure.
I have had it done to me (Twice) the first time one of my discs WAS warped (And TBH I could feel a pulse on braking) so I bought a used pair of ebay - which were perfect - no pulse at all, but when I took it back to the garage (A very big posh workshop) they told me they were still warped - well the boss did. The 20 something mechanic walked outside with me and told me to drive a couple of miles down the road to another garage (He was readlly embarased about it)
So I went down the road with my failure certificate and told the guy there the story - he looked at my discs and gave me a pass straight away!
Trouble is for the MOT there is actually NO defined limit for warpage - The actual guideline is something like "Excessive runout" - but they dont say what excessive runout is - its all down to the garage doing the test.
a good way to test is to put the disk on a glass top table - they tend to be perfectly flat - my warped disc would wobble on the table top - my good discs were perfectly flat.
Ebay will get you a spindle fairly cheap and ask this guy if he has any discs available
http://stores.ebay.co.uk/Zone-Products-Shop
I bought a pair of these to use when I refurbish my wheels (£50)
http://cgi.ebay.co.uk/ws/eBayISAPI.d...m=400021929838
and you can see that VFR750 discs fit
The reason I ask is that is that it is an easy score for a garage to claim fluctuation for an MOT failure.
I have had it done to me (Twice) the first time one of my discs WAS warped (And TBH I could feel a pulse on braking) so I bought a used pair of ebay - which were perfect - no pulse at all, but when I took it back to the garage (A very big posh workshop) they told me they were still warped - well the boss did. The 20 something mechanic walked outside with me and told me to drive a couple of miles down the road to another garage (He was readlly embarased about it)
So I went down the road with my failure certificate and told the guy there the story - he looked at my discs and gave me a pass straight away!
Trouble is for the MOT there is actually NO defined limit for warpage - The actual guideline is something like "Excessive runout" - but they dont say what excessive runout is - its all down to the garage doing the test.
a good way to test is to put the disk on a glass top table - they tend to be perfectly flat - my warped disc would wobble on the table top - my good discs were perfectly flat.
Ebay will get you a spindle fairly cheap and ask this guy if he has any discs available
http://stores.ebay.co.uk/Zone-Products-Shop
I bought a pair of these to use when I refurbish my wheels (£50)
http://cgi.ebay.co.uk/ws/eBayISAPI.d...m=400021929838
and you can see that VFR750 discs fit
#4
04-05-2009, 05:22 PM
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Now see this is why im here, good info.
Thanks Shadow, Harry_T_Hamster.
Luckily ive just won a new/used front spindle on fleabay. I may very well go down the new disc/pads route as I dont want the MOT guy having a chance to say its out again as ive heard some stuff about them a few years ago, however saying that I dont always believe everything I hear. As the braking system is up there high with staying alive on the biking scale I dont really want to take chance ( too many other varibles when the lids on your swede), Just hope the spindles true !?
Lez
Thanks Shadow, Harry_T_Hamster.
Luckily ive just won a new/used front spindle on fleabay. I may very well go down the new disc/pads route as I dont want the MOT guy having a chance to say its out again as ive heard some stuff about them a few years ago, however saying that I dont always believe everything I hear. As the braking system is up there high with staying alive on the biking scale I dont really want to take chance ( too many other varibles when the lids on your swede), Just hope the spindles true !?
Lez
#5
04-05-2009, 06:15 PM
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The discs/rotors and pads that I have on now seem ok, there is no blueing around any parts, the calipers are free moving. Would I be able to measure any run out on the discs/rotors with basic tools?
but if you would like to check them on the bike... you can do it pretty easily.
This is a touch primitive , but it works
Whack your ride up on its center stand.
Drop the calipers of to allow the wheel to spin freely .
Turn the steering to one side and use a tie down or similar to lock it over firm.
Get a solid box or something that is about the same height as the disc center and put it close to the disk..(about 50mm away)
Get yourself a straight tool like a socket extension bar or similar and just pin it real close to the disc
( near the outer edge!! not on the braking surface!! ) and spin the wheel..
Move the tool that you use closer and closer slowly till you hear it touching the rotor while shes spinning ..If you hold the tool firm and when the rotor spins it should either touch all the way around or it will make an intermittent scraping sound indicating a warp somewhere.. Whallar
SOME Road worthy stations have dual agendas... if they find an issue , it may be for your own good ,. or it may be because (if they are a shop) they want the work and more of your money ? Trying 2 places is a good idea if you are sure nothing is really wrong ..
As was the case with Pete's rotors ....remove yours and check for anything like paint , rust or dirt on the mating surfaces ..
Replace the spindle/axle before you check anything ...
BTW- have to checked your wheel bearing in case they are allowing the wheel to wobble a touch ??
Last edited by CBRclassic; 04-05-2009 at 06:21 PM.
#7
04-05-2009, 06:36 PM
just slightly different names for things like brake disc/brake rotor.
#8
04-05-2009, 06:43 PM
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just j/k ing
#10
04-05-2009, 11:55 PM
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Classic, there is an easier way to to exactly what you did (did it to my last Hurrican 16 years ago). Take a piece of wire, like a coat hanger, wrap it aroudn the borrom of th efork, near the brake rotor/disk. Then do what you did, spind the wheel and slowly move the end untill it touches the rotor. Stop as soon as it makes contact, then rotate the wheel where the gap is the larges and measure it.
If the rotor is warped, mark the rotor and use a plastic hammer or a wood and a steel hammer and give it a slight whack. Then re measure it. Slowly you should be able to get the rotor back to spec but be easy with the hammering and have a really good look to make sure the rotor is not actually cracked.
If the rotor is warped, mark the rotor and use a plastic hammer or a wood and a steel hammer and give it a slight whack. Then re measure it. Slowly you should be able to get the rotor back to spec but be easy with the hammering and have a really good look to make sure the rotor is not actually cracked.