Firestorm Brakes/VFR750

[Zen Dog]

So, I've fitted a Firestorm front end to my VFR750. The forks/mudguard/spindle/spacers/brakes/MC are all Firestorm. The front wheel and disks are from the 750. Thread here - https://www.bikechatforums.com/viewtopic.php?t=333972

Problem is, after fitting it, the brakes are shit. They do stop the bike OK with a good squeeze of the lever, but there's no initial bite. They also don't seem to be fully contacting the disk, even after riding 20-30 miles. I don't know how well you can make it out in the pics, but they still have a ring of light surface rust in places (just from getting slightly damp over the winter). Obviously, my first thought is the lines still have air in them. So I've bled them multiple times at the calipers and the MC banjo, ziptied the lever back (this never seems to work for me but I tried it anyway), and reorientated the MC a load of times to try to get any bubbles to the top. No change. It has a 2-line "race setup" from the calipers and they have an upward path the whole way, so I don't think anything is being trapped there.

So the question is this. Before I get further into bleeding it (pushing the pistons in fully in case there are bubbles trapped behind them etc.), and given the changes I have made, are there any other possibilities? I serviced the MC, cleaned up the calipers, refilled the fluid, fitted new pads, and copper greased the tips of the pads before fitting. Could I have contaminated the disk with copper grease somehow? Is that consistent with the symptoms? Given I've changed the front end, could messing that process up in some way have caused this?

Or do they just need more bleeding? I expected the pads to have bedded in enough to be contacting the surface of the disk fully by now even if they did need more bleeding. The disks really aren't badly grooved or anything. I even rolled the bike down a really long hill near me (we have plenty), using the front brake the whole time (and varying pressure) to see if it would help. It didn't, obviously.

Got any ideas?

https://i.imgur.com/4OEtkAfl.jpg
https://i.imgur.com/NM2rg1Hl.jpg
Full Quality Versions -
https://i.imgur.com/4OEtkAf.jpg
https://i.imgur.com/NM2rg1H.jpg
____________________
Current - '94 VFR750FR (Dead), '00 VFR800FI, 2011 CBF125 Previous - '10 Street Triple R, '92 MZ ETZ301, '05 TTR250, NSR125R, KMX125, "Honda" Win (chinese copy of an old Honda design with a C90 engine)
My bike trip around S.E. Asia 2010/2011

[stinkwheel]

I suppose you could check the discs are central and square in the caliper by measuring the distance from the disc to the casting at both sides of the leading and trailing edge of the calliper. You can shim under the caliper mount if it isn't. Even my pretecs needed shimming slightly.

I can't see why it would cause that wear pattern though.
____________________
“Rule one: Always stick around for one more drink. That's when things happen. That's when you find out everything you want to know.”
I did the 2010 Round Britain Rally on my 350 Bullet. 89 landmarks, 3 months, 9,500 miles.

[Robby]

Are the pads moving freely?

Quality control on lots of parts is shit right now. I've had a few sets of pads where the powder coat on them made them too thick, so they wouldn't move smoothly. A bit of filing sorted it.

Bent or notched pads pins is also a possibility. They're surprisingly expensive.

[Bhud]

Bleeding brakes is a pig. Tedious job.
I've found the zip-tie trick has some limited use when there are tiny air bubbles in the system. I'm doing it overnight right now (new HEL line).

Just some thoughts and I'm not saying you haven't already thought of this, (also, I haven't read your other posts about this project):

- whichever MC you're using has to be man enough for the Firestorm brakes, i.e. shift enough volume of fluid into them
- if there's air in the system then the main giveaway would be the lever (being able to pull it too far back)
- if you can bleed them and make the brakes grab tight, but they go loose again later, then there's a leak somewhere
- if your pads are dirty or greasy, that's no good

Why the copper grease on the tips of the pads?

[stinkwheel]

Oh, just check one of your calliper bolts isn't too long and sticking through the back of the caliper and fouling the disc slightly... Don't ask!
____________________
“Rule one: Always stick around for one more drink. That's when things happen. That's when you find out everything you want to know.”
I did the 2010 Round Britain Rally on my 350 Bullet. 89 landmarks, 3 months, 9,500 miles.

[Zen Dog]

A load of good ideas, I'll definitely check them out.

[Bhud]

OK cool. A Firestorm MC will be exactly right. There shouldn't be any problem, so there's something wrong. Are the lines good, are the copper washers new, is the bleed nipple hole damaged bubbling, etc. Lots of stuff to rule out.

If you suspect air's in the system then you've got to rule it out somehow. At the same time, rule out leaks. I've got a rough and ready method using zip-tie trick to kill 2 birds with one stone. I bind the brake lever halfway back, pressurising the system. Clean everything using whatever solvent, and dry it to bone dry with a cloth. Come back the next day, get your hands clean and dry, and then, leaving the ziptie where it is, touch your little finger under every banjo, and under the caliper seals, master cylinder, etc. If it's leaking anywhere, it will show on the tip of your little finger.

At least it's something you can rule out, if it's not the culprit. Could be a mechanical issue or quality issue as well, as the others are saying.

[stinkwheel]

Are all the pistons moving?
____________________
“Rule one: Always stick around for one more drink. That's when things happen. That's when you find out everything you want to know.”
I did the 2010 Round Britain Rally on my 350 Bullet. 89 landmarks, 3 months, 9,500 miles.

[to v or not to v]

[Nobby the Bastard]

Warped disks?
____________________
trevor saxe-coburg-gotha:"Remember this simple rule - scooters are for men who like to feel the breeze on their huge, flapping cunt lips."
Triumph Sprint ST 1050

[jeffyjeff]

[MCN]

Zip Tying (correct term Cable Tying) the lever back does Hee-Haw apart from waste time.

Physics: Apply a constant pressure to a fluid that contains a gas and push the gas into solution (overnight, as the myth dictates).

If there is air in the system it must be pushed/forced OUT.


01. By pumping the lever in sync with opening closing the bleeder valves in sequence.
For a front brake on a bike this can take a life time.
Hence the lore about using cable ties et al.

02 Pressure bleeding using a pressurised feed of clean fluid to force a stream of pure fluid through to the bleeders.
. I think most commercial shops use this simple and very efficacious method.

03 Or the other way using physics.
Suck the fluid out the bleeders using a vacuum pump, a big Eff-Off hypodermic syringe. (Available at ebay)
The theory is that entrained air in the system can form small bubbles. Trapped in sections.
Removing atmospheric pressure using vacuum causes the little bubbles to grow into bigger bubbles. Then the bigger bubbles will be less prone to being trapped. (BMW recommends this in their Bibles)

***Tef head off.***

Firestorm Brakes were/are shite.
The mod was to use Fireblade forks on a Firestorm.
If my mammaries serves me right.

[stinkwheel]

[trevor saxe-coburg-gotha]

[sickpup]

What brand and rating pads did you fit to it?
You still mates with Bill? does he still have access to a brake tester?

[Zen Dog]

[sickpup]

Non-sintered pads in a big bike often give a spongy feeling with a lack of initial bite and then fail to stop the bike at high temps due to brake fade.

The pads not moving at the top of the caliper would make sense as well. If they aren't moving smoothly they will pivot at the top which would explain the lack of contact around the outer edge of the disk. You get the same if the pad pins are notched. Both of these can give an odd feeling at the lever.

[stinkwheel]

I've even had brembo pads that I had to lightly file the paint off the edges of the backing because they were binding in the caliper slightly.

Incidentally, Brembo SA pads are great.
____________________
“Rule one: Always stick around for one more drink. That's when things happen. That's when you find out everything you want to know.”
I did the 2010 Round Britain Rally on my 350 Bullet. 89 landmarks, 3 months, 9,500 miles.

[jeffyjeff]

[MCN]

[Zen Dog]

Well... the thick plottens.

Did some checking of things today. Firstly, and most importantly, it appears I didn't fit new pads. Not doing so was bloody stupid and I certainly intended to, but the general grottiness of them (when they've done 30 miles), and looking back over my order history in various places, I can see no record of buying a new set. I'm blaming my terrible memory, that I DID buy and fit new pads for the 800 and the Striple, that I must have put the old pads back in to prevent accidentally pushing the pistons out when they were in storage (and then forgot), and the fact that this process took months. Still, I'm pretty shocked at the state of the left hand pads, despite having plenty of meat on them, they've lost a load of chunks of pad material. The ones on the right hand side look ok. Sintered EBC pads on order.

Moving on, the pad pins look ok, straight as far as I can tell (checked against a fork tube), and a little corrosion but no ridges or anything. The pads were a bit reluctant to come out, but we'll see if that's still the case when I get the new ones. The pistons on both calipers are moving pretty much as I remembered (all moving, some slightly more reluctant). The most significant thing I found was that the right hand calliper was out of alignment, being too close to the outside of the wheel, so the inner pistons could barely move, and the outer ones had to go further than usual. The left hand caliper is bang on though, despite neither of them having any kind of shims/washers between themselves and the fork leg mounting points, and it being the left hand one that's lost chunks of the pad. Looking at the pics, I think the cause of the misalignment is differing thickness of the right hand pads.

Still, new pads and thoroughly clean and maybe wet and dry the disks to remove any contamination, then we'll see where they are.

TL;DR - I'm a numpty. Though whether it all sorts itself with new pads we'll see.

https://i.imgur.com/6uDhMmTl.jpg
https://i.imgur.com/UxrA9djl.jpg
https://i.imgur.com/tSO1BVhl.jpg

Full Quality Versions
https://i.imgur.com/6uDhMmT.jpg
https://i.imgur.com/UxrA9dj.jpg
https://i.imgur.com/tSO1BVh.jpg
____________________
Current - '94 VFR750FR (Dead), '00 VFR800FI, 2011 CBF125 Previous - '10 Street Triple R, '92 MZ ETZ301, '05 TTR250, NSR125R, KMX125, "Honda" Win (chinese copy of an old Honda design with a C90 engine)
My bike trip around S.E. Asia 2010/2011

[Robby]

If the pads pins look OK, you can spin them in a drill and wrap some sandpaper round the pin to clean it off properly. Very hard to see if it's smooth unless it's really clean.

Those pads are fucked, which won't help.

Reassemble with the appropriate new parts, and cleaned and lubed other parts, and start diagnosis from there.

Also worth mentioning - if you have new pads and new discs, it can take a surprising amount of time for the brakes to feel good. About 100 miles on my 250. Felt a bit shit and wooden until then.

[MCN]

[Zen Dog]

Thoroughly cleaned the disks and fitted the new pads. Brakes are now fantastic, and I'm an idiot.

But if, in the future, anyone should want to know the consequences of fitting old (and almost certainly contaminated) pads to different rotors, please feel free to refer them to this thread.
____________________
Current - '94 VFR750FR (Dead), '00 VFR800FI, 2011 CBF125 Previous - '10 Street Triple R, '92 MZ ETZ301, '05 TTR250, NSR125R, KMX125, "Honda" Win (chinese copy of an old Honda design with a C90 engine)
My bike trip around S.E. Asia 2010/2011

[dave001]