Warped Disc :(

[robbie09]

Morning all,

Just a quick question sprouting from an annoyingly pricey service. They tell me a disc is warped and needs to be changed. When i put it in there i'd been riding the bike every day for 2 weeks and noticed nothing (wobbling really). Im going to give it a ride round today and see if theres an issue.

Basically if i get 'pulsing' i guess it means a new disc.

My question is...is it likely to be one ****ed disc? or both? anddd can i replace the one disc without having to buy two new discs?

cheers buddys

[barwel1992]

both "can" warp but one or the other can warp as well and yes you can replace the one disc but it replace all the front pads at the same time

[andrewsmith]

as barwel

but it worth checking the other too.
on top of replacing the pads, a caliper service should be done incase its a seized brake piston causing the warping

[speed3racer]

Warped discs can sometimes be wrongly diagnosed.
I also have a Triumph Speed Triple and one MoT was given a warning for warped discs. I attacked the bobbins with brake cleaner and a toothbrush and gave them all a jiggle and rotation by hand to feel that they were free of crud.... job's a goodun! Discs are bloody expensive to replace, especially if they don't need to be!

[embee]

Personally I think truly warped discs are much rarer than often bandied about, any sort of inconsistency in braking is just called "warped discs".

If you can't measure anything they aren't warped.

More likely to be floating bits not free (as described above) or inconsistent surfaces and material transfer from the pads.

You can clean the braking surfaces with coarse abrasive paper as long as you clean them well afterwards to remove all abrasives from the drillings and bobbins. This then allows the surfaces to re-condition with pad material and can sometimes cure such issues.

I know a courier who had typical "warped disc" syndrome on a Honda, and after cleaning the discs they were slightly better. He then fitted Carbon Lorraine pads and it cured it completely.

[robbie09]

So from the above posts the consensus is --> give the whole front end a good once over.

As this is the first proper bike ive had i'm not sure what to expect but i can only describe the brakes as 'spongey'. They work but it takes a good squeeze to get any real brake power out of it. I know power is somewhat subjective but i would have thought i'd have to be pretty light on the brakes, when really im giving it a good squeeze.

Sorry i dont really have a clue :D *edit* ive just realised this may be already answered - going to run a search now just incase!!

[barwel1992]

spongy brakes means there could be air in the system, if you are used to cars though it will feel spongy even when theres no air in the system

where about are you located, people might be able to come and help then :)

[robbie09]

Yeah after a quick search sounds like a common issue. Big issue seems to be air in the system :). I'm in St Albans, Herts but this forum seems to be enough! So much information and i guess since the bikes been out a few years, theres a lot of people with serious experience with the old horse :)

Time to spend more money i dont have! ;)

[barwel1992]

rofl, bleeding the brakes is a easy job even for the inexperienced (like i was when i first did it)

this forum is pretty damn good for tech stuff, id say if i had never gotten a sv and come on hear i wouldn't be training to do the job i want to do because i wouldn't know a throttle body from a spark plug :lol: a year down the line and im putting race cars and bikes together with some competence ;)

[DavieSV]

Warped disc may not give a 'pulsing' feel.

they may take a longer first pull on the lever to bring the pads back in, the second pull will be much shorter.

The wobbly disc will push the pistons further away so they will have to travel more to apply the same pressure

[yorkie_chris]

Classic sign is when the lever is rock solid at standstill but goes slightly squishy when you are moving. Or pulsing in the lever.

Shuddering when braking also.


Warped discs will cause first symptoms, some other things as well as discs may cause second... like pad spring being wrong behind caliper.


If in doubt measure the discs. If they feel fine when riding they probably are. Badly warped discs are f'in terrifying!

[zadar]

Warped disc may not give a 'pulsing' feel.

they may take a longer first pull on the lever to bring the pads back in, the second pull will be much shorter.

The wobbly disc will push the pistons further away so they will have to travel more to apply the same pressure

Warped is usually referred to disc that has bad surface, dips from heat and wear. This will give you pulsing in lever or vibration.
Everything else is bent rotor which does what you say, inconsistent lever travel.

[punyXpress]

Warped disc may not give a 'pulsing' feel.

they may take a longer first pull on the lever to bring the pads back in, the second pull will be much shorter.

The wobbly disc will push the pistons further away so they will have to travel more to apply the same pressure . . .
. . . as will slack wheel bearings.