Brake Pads

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IanB
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Re: Brake Pads

Post by IanB »

The VFR800 master cylinder arrived, it's perfect for the job, thanks for the tip Cadbury. The breaker also has the matching clutch master cylinder, also with a built-in reservoir - do you happen to know if the plunger is the same diameter as the VTR1000's? If it is, I'll complete the set. Both will then get rebuilt, new seals.

Ian
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IanB
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Re: Brake Pads

Post by IanB »

The VFR800 MC arrived, nice condition. Stripped it, minted it up, polished all the casting lines off (personal fetish) and now it's ready for painting and new seals when they arrive. So far, so good.

Stainless braided hoses will be the next thing, although I'll have to get the repositioned handlebars in place to know the length. Awaiting arrival of a lump - er, sorry - billet of aluminium for that.

Two ways of piping the calipers: One line from the MC to a splitter just above the mudguard and then 2 short lines to the calipers (stock setup), or what I see referred to as a "racing" setup - 2 full length individual lines from the MC, one to each caliper, longer banjo bolt on the MC.

I can see that the second method means half as many joints & gaskets, which sounds attractive. Apart from having to route 2 hoses around the steering head, are there any other pros & cons? I don't think it'll make much difference pricewise.

Thanks,

Ian
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sirch345
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Re: Brake Pads

Post by sirch345 »

IanB wrote: Thu Jul 29, 2021 7:38 am Thanks Chris, those pics really help, they give me almost everything I need to know.

I think that loosening the multipoint bolts while the calipers are still on the forks might be a good idea - they are probably pretty tight, and calipers are awkward things to hold. Same goes for final torqueing up. 32Nm according to the manual.

I've ordered a used VFR800 front master cylinder, so I'll keep the 14mm MC / 27mm/30mm caliper area ratio. I did some calcs. If I compare the total area of caliper pistons to the area of the MC plunger, I get a ratio of 12.9:1. Doing the same for a CBR600F, I get 12.8:1, virtually the same. It looks like braking force on the discs for any given MC lever force should be the same. It does mean that the VTR system operates at a higher pressure though, another good reason to go for stainless hoses. Whatever, with new pads, it'll brake hard enough for me.

Ian
Not a bad idea to loosen off the caliper joining bolts before removing them :thumbup:
IanB wrote: Thu Jul 29, 2021 5:08 pm The VFR800 MC arrived, nice condition. Stripped it, minted it up, polished all the casting lines off (personal fetish) and now it's ready for painting and new seals when they arrive. So far, so good.

Stainless braided hoses will be the next thing, although I'll have to get the repositioned handlebars in place to know the length. Awaiting arrival of a lump - er, sorry - billet of aluminium for that.

Two ways of piping the calipers: One line from the MC to a splitter just above the mudguard and then 2 short lines to the calipers (stock setup), or what I see referred to as a "racing" setup - 2 full length individual lines from the MC, one to each caliper, longer banjo bolt on the MC.

I can see that the second method means half as many joints & gaskets, which sounds attractive. Apart from having to route 2 hoses around the steering head, are there any other pros & cons? I don't think it'll make much difference pricewise.

Thanks,

Ian
I think most go for the "racing set-up" when replacing the front brake hoses with aftermarket ones.

There is a third option some suppliers offer, and that is one long hose from the M/C to one caliper (the right-hand side caliper), then a short hose to link the left-hand caliper. Double banjo bolt is then fitted on the right-hand side caliper.

I can't really say there is any pros or cons to which is best, although some may say different :wink:

Chris.
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Cadbury64
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Re: Brake Pads

Post by Cadbury64 »

The leading pistons are smaller as the disc is cooler at the point it enters the caliper. Friction heat causes the trailing piston to have to work harder to generate even force, hence the larger piston. Without that I understand you'd have excess wear on the leading edge of the pad.
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IanB
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Re: Brake Pads

Post by IanB »

Cadbury,

Yes, that does make sense. The first double poston calipers must have had equal sized pistons, and that then changed when wear patterns were observed. I checked on 6 pot calipers - not 3 different diameters, the front 2 are the same smaller size, the back one is larger.

The aluminium arrived for the steering yoke mods, off to start carving it now.

Cheers,

Ian
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IanB
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Re: Brake Pads

Post by IanB »

I tried my existing front brake lever to see if it fits the VFR800 master cylinder - it does, perfectly. Microswitch works, no probs. Obviously there was no change in design.

So anyone looking for a same size front master cylinder with a built-in reservoir, this is the answer. Thanks Cadbury!

Ian
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sirch345
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Re: Brake Pads

Post by sirch345 »

IanB wrote: Fri Jul 30, 2021 4:58 pm I tried my existing front brake lever to see if it fits the VFR800 master cylinder - it does, perfectly. Microswitch works, no probs. Obviously there was no change in design.

So anyone looking for a same size front master cylinder with a built-in reservoir, this is the answer. Thanks Cadbury!

Ian
Handy to know, thanks to you both :thumbup:

Chris.
IanB
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Re: Brake Pads

Post by IanB »

Clutch master cylinder; I just found this: https://www.ebay.co.uk/itm/282812259916 ... Sw9jNgEmx3

The same rebuild kit fits the VTR1000 and the VFR800, which I take to mean that both have teh same 14mm diameter pistons - same as the front brake. I'm presuming that my existing clutch handle will fit just as the brake handle did, so I'm ordering a VFR800 clutch master cylinder with integral reservoir.

Ian
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Re: Brake Pads

Post by MacV2 »

Making up since 2007, sometimes it's true...Honest...
IanB
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Re: Brake Pads

Post by IanB »

The new front caliper seals arrived today, so I'll start the rebuild.

Had the bike out for a run yesterday (the sun actually deigned to show its face). I checked the rear brake. I was really surprised how little braking it gave - clutch pulled in, I had to apply what seemed like a lot of force to the brake pedal to get pretty minimal braking. Nowhere near locking the wheel. I wasn't trying to lock it, but I had expected a lot more braking force than this.

Do others have the same feeling? The disc was dry, enough fluid in the reservoir, nice hard pedal and it gave *some* braking, so it looks to be in good mechanical condition.

Ian
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sirch345
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Re: Brake Pads

Post by sirch345 »

IanB wrote: Fri Aug 06, 2021 8:35 am The new front caliper seals arrived today, so I'll start the rebuild.

Had the bike out for a run yesterday (the sun actually deigned to show its face). I checked the rear brake. I was really surprised how little braking it gave - clutch pulled in, I had to apply what seemed like a lot of force to the brake pedal to get pretty minimal braking. Nowhere near locking the wheel. I wasn't trying to lock it, but I had expected a lot more braking force than this.

Do others have the same feeling? The disc was dry, enough fluid in the reservoir, nice hard pedal and it gave *some* braking, so it looks to be in good mechanical condition.

Ian
How you discribe the rear brake is how they are. The main problem IMHO is due to there being only one piston in the rear brake caliper. I believe some have swapped the rear caliper for a more efficient unit, although I'm not 100% sure which one that is. May be someone will see this and give us the required information?

Chris
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8541Hawk
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Re: Brake Pads

Post by 8541Hawk »

Have you checked to see what type of pads you have? I ask that because I have found with a set of HH pads, the rear brake is very easy to lock up. For this reason I run GG pads in the rear. They do act a bit like you have described, in that you do tend to need a bit more pressure on the brake lever to get them working and are a bit difficult to actually lock up the rear wheel. :thumbup:
Loud pipes don't save lives, knowing how to ride your bike will save your life.
IanB
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Re: Brake Pads

Post by IanB »

Chris,

It's indeed no surprise that the rear is less effective than the front; single (ie. 1 pair of opposed) pistons, only 1 disc, smaller disc at that. But even then, I was surprised how feeble it felt.

Good point on the pads, I hadn't thought of that. Changing pad material is the easiest upgrade. I don't want to lock the back wheel. I'm buying new GG pads for the front (one disc has oil / brake fluid on it), so I may as well get the complete set. I read up on the difference between GG & HH pads, found this: https://www.wemoto.com/info/brake_pads_ ... ck%20brake.

So in any case, GG's for the rear. The bike won't be seeing a racetrack whilst in my (not very capable) hands, so GG's all round looks good.

Now making a paddock stand. Being from Yorkshire, I wasn't going to buy one. The first fun came with those black swingarm end caps. Seeing 6 holes, I thought, special pin spanner, they'll unscrew - easy turning & indexing job. A bit of looking on Ebay showed a pic of the back of the caps - they just snap in. Why the $%*& do Honda then make it look as if they unscrew?

Anyway, I had a lump of 2" diameter steel bar laying in the dust, so the extensions are machined up now, I have a length of M8 threaded rod (largest size that'll fit through the hole in the pivot pin), just need to fab up some bits of 1" box section. Tomorrow's job.

Ian
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IanB
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Re: Brake Pads

Post by IanB »

On upgrading the rear caiper, I found this: https://www.ebay.co.uk/itm/265248000339 ... SwbhthBL6-

A piston that fits a whole range of rear calipers, from CBR900, CB600F, CB1300 and the VTR1000. It would seem they all share a common rear caliper.

As you said Chris, the rear caliper only has one piston (not an opposed pair as I'd wrongly assumed). To accommodate pad wear, the caliper floats. I might be wrong, but I think that a single piston floating caliper arrangement gives exactly the same braking force as would a fixed caliper with two opposed pistons. I don't think that adding an opposing piston increases the clamping force on the disc. All that having opposing pistons does is it lets the caliper and disc be solidly mounted.

Is this correct? If so, then the solution to more rear braking would be:
- A larger diameter disc
- Higher pressure (reduce the MC diameter of change the pedal leverage ratio)
- A caliper with a larger diameter piston (1 or 2, makes no difference I think)
- Twin pistons, like the front brakes
- Heavier boots!

It'd be great to hear from anyone who has uprated the rear brake. It seems that 1993 - 1997 CBR1000's went the twin (or maybe triple) piston route: https://www.boonstraparts.com/en/part/h ... 0000070243

Ian
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tony.mon
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Re: Brake Pads

Post by tony.mon »

The rear can lock up if you downshift aggressively downshift, so the amount of braking force from the rear that you need us less than you might think.
But it's easy enough to fit a Brembo caliper and MC if you want better rear braking.
It's not falling off, it's an upgrade opportunity.
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