What M/c For Vtr Brakes?

[wera803]

After reading some posts about changing over VTR forks on this board, I took a close look at my GF's VFR that she bought last year and noticed the previous owner did not change the master cylinder when he put VTR forks on the bike. So it still has a 1/2" M/C on there. I asked my GF about the braking ability and she said it wasn't really that great. This is her first street bike, so she really doesn't have the experience to say that something is wrong and I just haven't ridden the bike much to noticed. The only other bike she has really ridden is my '06 GSXR600 with SS brake lines and is a lot lighter than the VFR, so stops a ton better. She knows the VFR won't ever be that good, but would like something better.

I've read all the threads I can find about it, but still not sure which M/C to hunt down and put on her VFR. The VTR has a 14mm stock and she wants to keep the casket style M/C so both sides match.

Looks like the ST1100 has a casket style in a 14mm. I also found the F4i has a 5/8" casket style.

A lot of the VTR guys are going up to the 5/8" as an upgrade, so would that one be better on the VFR with VTR brakes too?

Anyone try either of these master cylinders?

[mello dude]

Since your GF is riding it, go with a stock Honda 14mm MC. That could be VTR or I think even 6th gen went to 14mm. With 5/8, that means she has to squeze the lever harder to get the same output as a 14mm. Its the classic P= F/A equation and I'm lazy right now to punch in the numbers.

[texasvfr]

Are the brakes up to snuff? MCN always list the VFR as one of the ten best brakes on the road. If I recall 107' from 60 mph.

[wera803]

Since your GF is riding it, go with a stock Honda 14mm MC. That could be VTR or I think even 6th gen went to 14mm. With 5/8, that means she has to squeze the lever harder to get the same output as a 14mm. Its the classic P= F/A equation and I'm lazy right now to punch in the numbers.

True, That was one thing I was concerned about. If I went to the 5/8", would she have the hand strength to squeeze the lever?

Are the brakes up to snuff? MCN always list the VFR as one of the ten best brakes on the road. If I recall 107' from 60 mph.

What do you mean by "up to snuff". The bike has VTR forks on it, so de-linked brakes. It also has a 1/2" M/C operating VTR calipers that originally had a 14mm M/C. The brakes are nowhere close to being stock VFR brakes.

[vfrjim2002]

Wera, have you ridden it? (edit: of course you have. sorry to be so dense.) A number of years ago I converted a KZ900 from the original single disc setup to one of the Lawson replica (street version) dual disc arrangements using stainless lines. I bought the MC along with the calipers and tried both it and the original. I ended up staying with the original even though the piston was substantially smaller than the dual disc version. Why? Power Brakes. It had a little more travel than the larger piston MC, but the stainless lines reduced that, and the power and feel were worth it.

Making the brakes hyper sensitive might not be the best thing for your GF, but I'd recommend trying it both ways and making the call based on your experience.

[wera803]

Wera, have you ridden it? (edit: of course you have. sorry to be so dense.) A number of years ago I converted a KZ900 from the original single disc setup to one of the Lawson replica (street version) dual disc arrangements using stainless lines. I bought the MC along with the calipers and tried both it and the original. I ended up staying with the original even though the piston was substantially smaller than the dual disc version. Why? Power Brakes. It had a little more travel than the larger piston MC, but the stainless lines reduced that, and the power and feel were worth it.

Making the brakes hyper sensitive might not be the best thing for your GF, but I'd recommend trying it both ways and making the call based on your experience.

I have ridden, but not much. I test rode it when she bought it, but it was cold and I was trying to feel and test so many other things (and not pushing braking limits), I never noticed a problem. I have also ridden it up and down the street, but nothing that would really give me good information. I guess I need to go out and really ride it one day to see.

She commented that she feels like she is pulling the lever, but it just isn't stopping. I think that means she pulls the lever a certain amount and thinks the bike should be stopping quicker than it is. A larger piston M/C wouldn't have to be pulled as much, which I think would give her the feeling she is looking for.

[2thdr]

Maybe by "up to snuff" he meant what condition the pads are in and when the system was last purged and replenished with new fluid?

[wera803]

Just scored some stainless steel brake lines on e-pay as well (for a VTR), so hopefully between those and a new M/C, the brakes will be better than she could have ever expected.

[YoshiHNS]

So the brake could need to be re-bled to get it nice and solid, or perhaps she just isn't using enough force on the levers. Tough to tell from just words.

I don't think I have an ST1100 MC, but I might have a 1300 you could borrow to try. Might be easier and not much more to just pick one off of ebay though.

[wera803]

So the brake could need to be re-bled to get it nice and solid, or perhaps she just isn't using enough force on the levers. Tough to tell from just words.

I don't think I have an ST1100 MC, but I might have a 1300 you could borrow to try. Might be easier and not much more to just pick one off of ebay though.

Thanks for the offer Yoshi, but the ST1300 M/C is 1/2" just like the VFR. I'm watching a couple of ST1100 M/C's on ebay right now in the $35-40 range, so they aren't too much.

[vfrjim2002]

Wera, have you ridden it? (edit: of course you have. sorry to be so dense.) A number of years ago I converted a KZ900 from the original single disc setup to one of the Lawson replica (street version) dual disc arrangements using stainless lines. I bought the MC along with the calipers and tried both it and the original. I ended up staying with the original even though the piston was substantially smaller than the dual disc version. Why? Power Brakes. It had a little more travel than the larger piston MC, but the stainless lines reduced that, and the power and feel were worth it.

Making the brakes hyper sensitive might not be the best thing for your GF, but I'd recommend trying it both ways and making the call based on your experience.

I have ridden, but not much. I test rode it when she bought it, but it was cold and I was trying to feel and test so many other things (and not pushing braking limits), I never noticed a problem. I have also ridden it up and down the street, but nothing that would really give me good information. I guess I need to go out and really ride it one day to see.

She commented that she feels like she is pulling the lever, but it just isn't stopping. I think that means she pulls the lever a certain amount and thinks the bike should be stopping quicker than it is. A larger piston M/C wouldn't have to be pulled as much, which I think would give her the feeling she is looking for.

A good flush/bleed, combined with the SS lines may make a world of difference. Good luck with it.

[JZH]

She commented that she feels like she is pulling the lever, but it just isn't stopping. I think that means she pulls the lever a certain amount and thinks the bike should be stopping quicker than it is. A larger piston M/C wouldn't have to be pulled as much, which I think would give her the feeling she is looking for.

Applying the brakes and the bike not stopping is not good! Makes me wonder what else the bike's PO might have screwed up...

NISSIN 14mm integral m/cs are not very common, but I agree that fitting a 14mm m/c would give her very good, OEM-quality brakes.

Ciao,

[KevCarver]

Thanks for the offer Yoshi, but the ST1300 M/C is 1/2" just like the VFR. I'm watching a couple of ST1100 M/C's on ebay right now in the $35-40 range, so they aren't too much.

Yep, we got the same system between the two. I think it's the same as the 6th Gen, actually. Rear pads on the 1300 are extra thick, but that seems to be the only difference.

I'd say go with a 14mm. Keep it stock VTR.

[wera803]

Scored a nice ST1100 M/C with lever last night for $25 shipped. Now I just get to hurry up an wait for that and the SS lines to get here.

[CornerCarver]

Too little too late but I just checked and confirmed in the 5-8 different sets of calipers and m/c that we don't have a known VTR m/c. THe VTR forks with RC51 clipers and m/c are like a dream compared to stock VFR 5th gen.

I have a set of VTR calipers that will go on the 3rd gen when I get around to installing his rear shock and going through the forks.

[spacetiger]

I have a M/C like yours on my PC800 and used these covers that include ram ball mounts (choice of 1 or 2 balls):

http://www.motorcyclelarry.com/index.php?main_page=product_info&cPath=11&products_id=8

Jerry

[keny]

The diffrense betwen the oem ½ (~13mm) MC and a VTR14mm is not that big, and in teory she has to pull the level whit less force but more movement whit a ½ MC compare to a 14mm MC. The biggest thing that effects brake power is the calippers. How freely are the pistons moving and so on. I had a -87 VFR750F before my current 00 800Fi, and rebuilding the calippers as MC did a wounder to the braking power. Calippers in bad condission drag brake pads that glase the surface of the pads and give less braking power. Also fresh brake lines if they old give a better feel.

[spacetiger]

A few observations from my limited experience:

I am running VTR calipers on my NH-s. They are a 4 piston caliper design with 2 x 30mm and 2 x 27mm pistons (ignoring the small fractional round off) giving a total surface area of 2,560 mm² . So, for 2 calipers, that is 5,120 mm².

The diameter of the M/C piston matters as it sets the ratio of caliper piston area to M/C piston area

1/2" = 12.70mm = 126.7 mm²; 40 to 1 ratio

14mm = 14.00mm = 154.0 mm²; 33 to 1 ratio

5.8" = 15.88 mm = 198.0 mm²; 26 to 1 ratio

Then you have to factor in M/C leverage ratio...

For me, I would be worried about running 1/2" M/C because the ratio is so high. If you have a M/C with good leverage and/or good travel distance (and big hands), these might feel very light for effort.

A 14mm M/C is better because the ratio is 33 to 1. Again, leverage and travel distance are important, but in the end, might still feel a bit soft for the street.

I am using a 5/8" M/C which has a 26 to 1 ratio. It has good leverage but only so-so travel distance (its not a radial M/C design, but a Honda OEM design from the 80's). I find this to be a good compromise for the street because it has a good feel.

If you go with a larger M/C piston, the ratio will fall below the 26 to 1 and you start to loose brake feel; the British motorcycle magazines referred to this feel as a wooden spoon.

Much of this is rider feel/preference, but you can calculate ratios, etc to make things more objective. Here is a link for more info that I found useful:

http://roadstarclinic.com/content/view/89/95/

http://www.lemickracing.com/tech-faqs/14-brakes/46-brake-master-cylinder-piston-diameters-and-leverage-offsets

I think the Honda VTR and CBR fixed calipers have the potential for best brake feel because you are only moving the pistons. Floating (2 piston) caliper designs require some movement of the calipers to pinch the disc. If they are dirty, they will require more effort to move the calipers (that small distance) and can sometimes bind if they are dirty enough. I have seen many comments that the CBR fixed calipers are superior to the VTR fixed calipers. Maybe they are, but for my riding skill, I don't think I can tell a difference (I have the CBR 600 F4 calipers on my PC800). But I do feel a difference between the fixed calipers and floating calipers...

Only my 2 cents

Jerry

[V4 Rosso]

Looks like the ST1100 has a casket style in a 14mm. I also found the F4i has a 5/8" casket style.

Just a FYI: the 96-97 Fireblade also has a 14mm master cilinder.

[JZH]

By "casket" style I think he means integrated reservoir, to keep the OEM look and functionality--there aren't a lot of those out there that are not 12.7mm (1/2"). I had a 14mm 'Blade master on my FP initially, but got tired of the remote reservoir blocking my view of the fuel gauge or snagging on my tank bag and converted to the ST1100 master.

Ciao,