RC51 Brakes vs VTR, Upgrade pics and review
 

Hi all,

I thought id post some pics of my brake upgrade. I was able to score an RC51 caliper set and master cylinder for my baby hawk. The difference was astonishing, and well worth the investment.

I had to machine the calipers just like some of the other members on the forum. When I was researching it though, I found it hard to tell just how much to take off. Fortunately, I was able to bring my old bent VTR fork to the machine shop and continually test fit as I machined it away. There are some close up pics as well as a comparison between the caliper and MCs. Note the RC lever is bent--that is not normal and I fixed it since installing the MC.

http://combier.net/images/RCbrakes001.JPG.
http://combier.net/images/RCbrakes002.JPG
http://combier.net/images/RCbrakes003.JPG
http://combier.net/images/RCbrakes004.JPG
http://combier.net/images/brakecomparsion.JPG


I also sketched a subjective braking power "feel" diagram. The RC overall has much more powerful feedback. You really feel like you can endo the bike with one finger. Interestingly, the trail-braking is much more usable with the RC brakes as well. On the sketch there are the both the lever depress and lever release curves. I hope this plot makes some sense, keep in mind it is completely subjective. An engineer might say that they are equal (and I leave that open to debate).

Enjoy!

-Robert C.
Atlanta, GA

Nice. I love the professionally made scientific graph chart

If the actual feel were like the diagam those original brakes must have had some air inside or a very badly worn main sylinder.

To me it seems like brakes are almost like tires. People compare rotten apples and fresh oranges and the oranges always come out on top. Strange?
I'm sure the RC51 brakes are better. Larger pots and better main pump, non the less, without fresh, air free liquid, same hoses, same pads and rotors a comparison become tintet by those variables.

With my new EBC Rotors and pads I can't ask for more. Quite a difference from warped original rotor and worn, dirty pads. 2 fingers are never stressed to do a stoppie or a controlled front slide at with and no problem controlling them. And the lever position is more like your RC51 diagram: Just pressure deciding the power, little to no movement. Had a non warped rotor on for a few days with the dirty old pads and it was ok, just harder and less initial bite.

I did new EBC HH pads, Galfer Steel Braided Lines on the stock brake setup before swaping to the RC51 MC and Calipers (with a new set of EBC HH pads as well) and the same steel lines... and the RC stuff felt like a huge improvement...

So I'd say there is a noticable improvement between the two steups using the same playing field...

I haven't heard person who's made the swap say they brakes weren't vastly better... but that is all seat of the pants... so take it for what it's worth I guess.

J.

I highly doubt there was air. I replaced the fluid and bled the brakes not 2 months ago, and the feel hasn't changed since then. My bike has 40k, so yes, maybe my master cylinder was worn out.

Good point, although it doesn't invalidate my test. I used the same exact rotors, with the same exact (stock) VTR lines, both sets of pads were EBC and not new.

What I was trying to illustrate was that it takes MUCH less lever effort (pressure) and less lever displacement to stop the bike. So much so that I was bottoming the forks for the first 10 miles or so until I got used to them.

I'm not bashing the VTR brakes. I always thought they were plenty good. However, for the $100 that I spent in used parts, (not including the income from selling the old parts), the difference is amazing. To me, stopping is as important as going (and turning), and I've already done a 15/43 520 conversion and a set of Pilot Powers, so this was next. Next up is suspension ($$$)...

Well, I'm MORE sure. It is one thing for 'people' to talk about this is better than that, etc etc, but what I wanted to share was the information I was looking for--and didnt find--before attempting this upgrade.

Having made the switch as well to a RC set-up (and having run braided lines and HH pads prior to doing so), I can say that to try it is to adopt it. It is a definite improvement over the stock set-up (even with the lines and pads). I would be curious to try it back-to-back against the GSX-R (6 piston) modded set-up but I am more than happy with my present braking performance.

I've heard buys on the Speedilla board were not to happy with the GSXR 6 pots over the stock RC stuff (from a few posts I read)... according to them... HRC pads are all you need to make the RC brakes outstanding...

But what do they know... they drive full fairing V-Twins!!! Hahahaha

J.

It's all about leverage ratios, but in my experience both the F4i setup and the 954 (same as the 600RR and RC51) setup are better than the stock VTR items. I'm not saying, however, that a well setup stock VTR setup with good pads won't give excellent performance.

are the stock brake really that bad? i just try to turn faster! lol...

larger rotors, yes! radial pump, better pads, yes! steel lines, yes!
calipers,????

Sorry for using the tire comparison, it was not really pointed to you. RC51 should should and must be an improvement. It's just that I'm so happy with my brakes and the lever movement didn't seem right to me. It's not at all the way my brakes work. At 1/4 - 1/3 movement the lever more or less totally stop moving. And I also got those unwanted quick dives in the begining.
But then again, old OEM rubber lines, a little contaminated pads and I see how you could get a feel looking like a diagram.

Some might suspect me of not knowing what really good brakes are, but Aprilia RS250 with braided lines, SBS carbon pads and brembo calipers stop almost by thought control :-) and that was what I was racing with. Thing is, I'm still very happy with the VTR brakes now. And mind you, it's with EBC rotors, that is a substantial difference.

And just like you my next upgrade will be suspension.

Having switched off with a couple Superhawks with stock brakes at the Rally I think I know the problem with the stock master cylinder. It seems like there is a lot of lever movement before you actually get pressure buildup. I have not taken a stock one apart but I think it's due to too much distance between the resting position of the master cylinder piston and the bleed hole to the reservoir. I rode L8RGYZ's bike and other than the free play in the lever the brakes were wonderful....and all stock (dunno about pads or lines actually). A slightly longer piston would do wonders with the stock system. You guys follow what I'm saying here?

I did the gixxer 6 pots and pro-lites rotor upgrade this winter. I have fully drained the system twice and still have a spongy lever. Even did the lever compression over night with a cable tie - no improvement. The bike is massively more stable in braking than it was and it's VERY progressive - stoppy progressive! I just don't like the feel of the lever so I think I'll start watching for a MC setup next. I just don't think the stock MC can push enough juice for the six pots or I'm flexing the metal. Either way - the setup is going to be changing!

M/C too small for those calipers! Doug, you never returned my phone call!

Oh, sorry! I saw I had a message but I have been ass-deep in this big mower again for most of the day. I thought the gear motor was a challenge now I discover another gearbox that was supposed to be checked every 50 hours and oil change every 500. The machine has almost 600 hours on it and I must admit that I didn't even know it was there. I don't think we've damaged anything but I'm really sure it's out of lubricant. Problem is I can't even touch it. It's very buried inside the compartment and looks like I will have to remove several components to get to it. Why the hell would anybody manufacture something this fugging hard to maintain.

Yeah, like I said - the stockers just do not move enough juice. Although I will credit them and the stock MC with saving my life. Credit as well to the missing slam-down-diving of the front suspension upon hard braking which was corrected by you - makes for a much-improved package and extended life for the rider :lol: - but not perfect. I think the MC is probably the final touch to make it right.

BRAKE M/C F4i,954,929,RC51.
 

Hi Killer52, can you tell me more about f4i m/c, will it bolt straight up or need some mod? I currently run stock VTR m/c with GSX-R 1000 (01) calipers feel a lot more confidence w/this set up but still not sactify. over last winter there are many of m/c available and cost much lower. (I saw 1 on ebay 954 m/c from salvage yard run now more than $100+ship when i can buy new for $155). So does it 2mm diff of m/c between f 4i and vtr will make braking improve better like 954rr, man that bike can stop w/1 finger squeeze.:?

All hydraulics aside, don't forget that the 954 has 330 mm rotors whereas the VTR's are 296 mm. There is quite a bit more leverage on the 954, something no caliper or MC will be able to overcome.

A point which was made clear to me when I swapped the brake system from my stock VTR forks to the 954 forks. Same pads, calipers and m/c, but braking was much improved just from the increased rotor diameter. Still, the setup worked well with the stock VTR rotors.

Trinity012--
Most master cylinders will bolt right up, and the F4 m/c is no exception. It uses the same lever as the VTR, which makes it an even easier swap. The RC, 954, 929 and 600RR master cylinders use a different lever.

Thanks killer52, I saw 1 set of f4i m/c and 600RR m/c 05 kind of confused which one i should go for.

Because of its smaller piston, the F4i m/c should give more brake system pressure for a given amount of effort at the lever at the expense of slightly more lever travel than the 600RR m/c. The stock Suzuki m/c is the same bore as the F4i m/c.