Warped Brake Disc

Hi Guys,

My recently aquired 4th genVFR is coming along nicely now, although there are a few more problems I'm discovering as i get to know the bike. I recently rebuilt the rear brake caliper as it was seized on when i bought the bike as a non runner.

I found that one of the pistons had a bit of corrosion on it stopping it from returning into the caliper, so i cleaned it up and disassembled everything for a thorough clean and rebuilt with red rubber grease, and all was well.

How ever i noticed when i wheeled it out of the garage to clean down the bike that it was still binding a little when wheeled forwards, but not backwards. I started it on the centre stand to see everything moving, and noticed the caliper was visibly moving along it's sliders in a cyclical fashion.

My thoughts are that i probably have a warped rear brake disc, but i ran out of time at that point so i can't strip it down 'til later to find out what's going on. I would be interested in hearing the thoughts of the rest of the community, has anyone else had a problem like this? Could i have simply pieced everything back together wrong? I hope so as the brake discs look expensive and those loctite bolts are a devil to get out

 

I thought this might be best explained with a video http://tinypic.com/r/14tldgl/9

 

This seems to be an open and shut case, I braved the elements and took apart the rear end tonight, where I discovered a crack in the disc.

I thought I'd investigate a slight blow from the exhaust while I was out there, and I opened a can of worms! I ended up pulling the entire system, as there was a small leak someone had tried to plug with a jubilee clip at some point.

One of the exhaust studs also broke off while I was in there. So now on my shopping list I need a reasonable chain, a rear disc, some replacement studs (these were rotten!) And any advice on how to get the stubborn bit of stud out of the front cylinder. There is about 1/4 inch exposed, and enough thread to half screw a nut on.

Any advise is appreciated guys

 

A good penetrating lube is a mixture of acetone and ATF - Automatic Transmission Fluid - Mix 50/50. The acetone evaporates, leaving the atf to lube the threads.

I like...I don't like to, but when I have had to do this, here is how - I heat the surrounding material gently and evenly, and not too hot. I spray the mixture on the stud until it is cool to touch. Then grip the stud with Vice-Grip type pliers and try to turn stud. Keep repeating until loose. Don't turn too hard, just repeat until loose.

Use anti-seize on the new stud,

Good luck,

 

I bought some left handed drill bits that work good for drilling out things like that. By turning left there is a chance that stud/bolt will come out as you are drilling it.


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You stated that you still had some tread to thread a nut onto. The best way that I have found in this situation is to thread a nut onto the stud, and weld the inside of the nut to the stud. after it cools turn it out with an impact driver.

 

Did the same, used it for removing a broken rotor bolt. As you said, just drilling the bolt in the reverse direction got the bolt to come out.

 

Thanks for the advise guys, i have some kit to tackle this coming later in the week, I'll let you know how i get on

 

We have a result on the stuck engine stud! A friend with a mig welder came and welded a lump on the end of the stud so the nut couldn't come off and the stud unscrewed fine with only the heat from the welder applied I put all new studs in there now with some copper grease in the hope of avoiding a repeat performance the next time i have to take the exhaust off.

Just waiting on a used disc I have on order now then it'll be nigh on ready to head back onto the road. After standing for a long time the chain is pretty ropey, and i thought the safest thing to do would be to buy another. It comes with a split link though, which worries me a little on a bike with a 100bhp. What are other peoples thoughts on using a split link on this, I've only ever seen rivets used on anything over 125cc so i'd be interested on hearing if people think it's safe?

 

Hi Guys,

Just wondered if i could pick the brains of anyone who has dismantled the rear end on the RC36, my replacement disc has arrived and i will probably tackle fitting it at the weekend when the temperatures get up to plus figures out there. I've had a look at how to get to it in the manual, and it looks like i might have to dismantle the whole hub assembly to get to it. I just wanted to make sure that this is what I will have to do and if i'll need any special tools, i think i only have sizes 4mm-20mm sockets with one random 25mm socket in my inventory so i might have to go and buy a new socket if this is the case.

Your comments are appreciated guys

 

I’ve done mine 2 years ago, but don’t remember if you have to take hub out or not. If you do then you will need 46mm socket, which I only found in 3/4” so I needed to get adapter to 1/2”. I used my electric impact gun as that big nut is super tight. You will also need big snap ring pliers, bigger than 8”, which I couldn’t find locally, so I tortured myself with too small pliers. The rest is pretty easy.


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Not sure if the 4th Gen has the same size axle nut but the 5 & 6 Gens use a 46mm and requires 148 ft.lb torque value when installing it. I bought this little goodie to work on my friends Ducati but works for the VFR as well. It's 41mm on one side and 46mm on the other and uses 1/2' drive.

https://www.amazon.com/gp/product/B005CW9TWG/ref=od_aui_detailpages00?ie=UTF8&psc=1

 

Thanks guys, looks like i'll have to invest in a few new tools for this. The brake disc saga continues

 

I just checked the socket and yea it’s actually 46mm. Sorry for wrong information before.


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No problem, I’m glad of all the help these forums have provided I’m pleased to report that the brakes are now fixed, I couldn’t find an oem rear disc at a decent price near me so won’t with a nearly new 98 800 rear disc, works just fine, only downside is you need to remove the spindle to replace the disc.

I think you can just about get the 750 disc off with the wheel and calliper off but the 800 disc doesn’t have that cross shape removed from the centre so you have to have one of those great big 46mm sockets. Tbh it would be a real pain to remove those threadlocked disc bolts on the bike anyway so it was no great hardship, and of course parts for the 800FI seem to be numerous by comparison.

Thanks for everyone’s assistance with this project so far