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Offline monkeycabbage

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Quick ranting session!! Warped brake discs
« on: September 24, 2013, 02:57:59 PM »
Hi all, sorry to bend your ears.... just feel like I need to get this off of my chest!!


About 3 weeks ago, my fork seals gave up very abruptly on my old 900 Trophy. I've never known seals to skip the mild leak and go straight to dumping the oil so quickly, but I just chalked it down to wear and tear - and possibly bad maintenance from the previous owner... just like every other problem I've had since I bought the bike.  :087:

Naturally, the pads and discs got soaked in the stuff. So new seals, new oil, new pads, new discs... and back on the road!  :001:

However, after breaking the new discs in (about 700 miles), the front brakes seemed a tad squidgy last week. They were still working fine and biting so I decided to carry on with the mindset that I would need to keep an eye on them and get them looked at.

I like to use engine breaking and keep a good breaking distance... so yesterday morning, I got from home down to the A2, traffic was moving so well that I got about 20 miles before I actually needed to use my breaks. Then I caught up with the traffic as I got closer to London. In fact, the traffic ground to a halt quite abruptly. Even with good breaking distance, the distance you have is only good to you if you have working breaks!!  :005:

I swear I couldn't have physically pulled the right lever any tighter and even had the rear wheel locking up!  :172: All I had from the front brakes was a huge pulsating feeling.

By the time I came up to the rear of the stopped cars, I was still doing about 45 mph and had to very quickly pull onto the white lines and ride out the speed with some very tight filtering (and a very tight sphincter!!).

Needless to say, I'm surprised I didn't soil myself!! SCARED THE CRAP OUT OF ME!! And when filtering, you always plan to move through cars, and you have the choice to hold back if it gets too tight - well, not yesterday!!

I managed to very carefully totter the bike back to the garage and the mechanic took it straight for a test ride - and refused to pull out of the car park! In short, my new discs are seriously warped. Although he used the phrase "THEY'RE F :172: D!"

Ok, so rant over...

Does anyone know what can cause a set of new discs to warp after they've been worn in by several  hundred miles?
...on an old 900  :164:

Paranoia is a survival mechanism!


Offline Trophy Bike

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Re: Quick ranting session!! Warped brake discs
« Reply #1 on: September 24, 2013, 03:11:56 PM »
Let me think of a few:
Poor quality discs
possibly wrong pad material for the discs (not sure about this)
Bad installation - i.e. maybe the discs were not affixed correctly (poorly torqued down)
Brakes are hanging up on the discs causing heat build up as you ride and ultimately warping?
That's all I got. 

Offline john348

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Re: Quick ranting session!! Warped brake discs
« Reply #2 on: September 24, 2013, 03:22:46 PM »
on the sprint the bobbins get seized up and make the discs warp or feel warped.  It was part of the service routine to spen and clean the bobbins to free them up.  Not sure if the discs are floating?

Offline Trophy Bike

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Re: Quick ranting session!! Warped brake discs
« Reply #3 on: September 24, 2013, 03:48:55 PM »
*Originally Posted by john348 [+]
on the sprint the bobbins get seized up and make the discs warp or feel warped.  It was part of the service routine to spen and clean the bobbins to free them up.  Not sure if the discs are floating?

That would be a nice inexpensive solution. 

Offline seadog

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Re: Quick ranting session!! Warped brake discs
« Reply #4 on: September 24, 2013, 04:58:14 PM »
Looking at the previous posts. Agree but recessive heat is usually a good cause for warping.
As mentioned badly or wrongly fitted.
Are they triumph approved parts.
Was it an approved triumph garage/dealer.
Could have been the wrong disks for that year bike.

Glad you got out of the incident safely. Could have been more than warped disks.

Seadog
seadog

Offline john348

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Re: Quick ranting session!! Warped brake discs
« Reply #5 on: September 24, 2013, 09:51:37 PM »
I had to spin the bobbins about once every month.  I changed the discs for EBC ones as I got fed up with it.  Of course you have to grease the brake pistons Avery couple of months as well.

Definitely the siezed bobbins caused a warped feeling.

John

Offline Saaz

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Re: Quick ranting session!! Warped brake discs
« Reply #6 on: September 25, 2013, 02:34:36 AM »
Could be dragging pads if the pistons were not properly cleaned before pushing them in to fit the new pads.  They might start sticking if grit gets in.  I have had this happen a few times when I have changed pads for others and the person who previously did the work must have done a quick job that took me a lot longer to fix up.

Offline cropbiker

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Re: Quick ranting session!! Warped brake discs
« Reply #7 on: September 25, 2013, 06:26:41 AM »
Yes, assuming you didn't buy cheap dodgy parts then they were probably fitted badly. The pistons probably weren't cleaned properly of grit and grim causing them to stick on and warp the discs from the heat generated.

Glad you are OK, that must have been a nasty experience!
Triumph Trophy! Not for every Tomaz, Dieter or Herman!🇬🇧

 



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