mikstr

Hi,

I recall some of you mentioning that replacing the stock VTR front brake MC with one from a RC51 helps the braking rather dramatically (already have braided lines and EBC HH pads). My question is what exactly would I need to make the switch ? Is the lever the same? Reservoir? Anything else I should be aware of?

Finally, should I choose to go this route, how would I feel the difference ?

cheers
Mikstr

someonehappy

I think nobody will sell a master cylinder without the lever, and the reservoir is universal, you can use the original one.

SlowHAWK

As stated the reservoir can be retained, but everything else is different. If you find one without the reservior, you can use yours, but you'll need to make up or buy the little mounting bracket for the reservior, and cut a new hose length.

The handles/levers are different as well....

mikstr

thanks

If I buy the whole assembly (reservoir, brackets, lever and all) am I to assume that all else will be compatible (ie. electrical connections, mounting hardware, brake line,...). I currently have a Galfer braided steel line and so I hope that the line hook-ups would be the same.

Sorry if these questions seem mundane but I want to be sure before making an offer on one.

cheers
Mikstr

SlowHAWK

Everything "bolts-up" just fine... no fuss with connectors or lines. I think the mount hardware is the same, but I can't remember.

If you want to check each piece between the VTR and RC, look up the microfische on the Ron Ayers site of the 2 bikes... I sat there and checked each part number against eachother, real easy way to be sure on compatibiltiy.


J.

superbling

If buying an entire system, I think everything will bolt and wire up with the possible exception of brake line legth since the RC clipons are below the triple and has shorter forks IIRC. I run a GSXR 6p brake system and even it's brake light sensor matched the Honda wires!

Also, you do know the RC calipers require grinding to fit the VTR mounts, right?

mikstr

thanks

not looking at changing the calipers, just the MC

cheers
mikstr

mikstr

Update: I just picked up a RC51 front brake MC assembly on eBay and so am now looking forward to some much improved braking. BTW, I did some reserach on Google and found that the RC51 has a 19mm cylinder diameter (same as CBR929).

Woohoo!!!



Mikstr

mikstr

One last thing, it should work well with the new RC45 quick action throttle-tube I also picked up recently. Looks like there will be much more sensitivity on the right side clip-on this summer

cheers
Mikstr

killer5280

I tried the larger master cylinder and didn't like it at all. The lever was definitely firmer, but the effort required to generate hard stops was too high for my liking. I preferred the stock mushy m/c. It's all about leverage ratios.
Currently, I have the m/c and calipers from an F4i and this setup works well. If I were going to go with the m/c from an RC51 or 954 I would also go with the calipers from that respective bike as well; all the calipers from the various Honda models (RC51,954, 929, F4i, etc.) while outwardly identical, have different piston sizes and thus require different m/c sizes for optimal performance.

mikstr

thanks for the input

I will try the RC master cyl with the stock calipers as I have seen many postings from people who have tried and liked this particular set-up. If I don't like it, then I can simply go back to my stock one and re-sell the RC unit.

On another topic, how are you making out with the Flo-Commander?

cheers
Mikstr

killer5280

I think brake pads have a bit to do with whether people like the larger pistoned m/c or not. I was using stock pads when I did the switch and they just didn't generate the power necessary for really, really hard braking, even using four fingers on the lever. The EBC pads may generate enough power to make the increased lever effort a non issue.
No changes with the Flo-Commander since the last dyno posting. I'm having a valve job and some minor porting work done to the extra set of heads I have, and I'm debating whether to go with high compression pistons and cams. Once I sort all that stuff out I'll have it dynoed again and post it to the FC thread.

jschmidt

Sounds like your mind is made up, but there is no benefit to mismatching brake systems.

mikstr

"there is no benefit to mismatching brake systems"

Hmmm.....perhaps I should go and mention this to all the folks on the vtr1000.org and Micapeak sites who have successfully done what I am looking at doing (and incidentally, where I got the idea to try this mod out). It seems they all (without exception may I add) reported better brake feel and much enhanced power. Guess I'll be finding out soon if they are all liars.

cheers
Mikstr

mikstr

Final note: if the RC51 MC experiment does not work out, I simply re-install the original one and re-sell the RC part. No harm done.

While I do acknowledge that there is much hype on the Net (my short-lived experiment with the "TPS mod" is a fine example), there are some viable ideas (adding a long intake runner to the front cylinder for increased low-end). Also, I have an affinity for tinkering and as a result of trying things and thinking outside the box I have managed to fix many problems that I found to be particularly relevant (case in point: adjusting the length of the front intake runner on my VTR with the result being better low and mid power and a much smoother engine). I did similar experimenting with my snowmobiles and got some fantastic results (and some not-so-fantastic ones too). You don't know until you try it.
Call it the old pioneering spirit.

cheers
Mikstr

jschmidt

Geez. I thought the goal was better braking. Lets run through it:
- You can fix clunk die by turning your vent tubes around.
- K&Ns make more power.
- You can fix clunk die by lubricating the slides.
- Two long velocity stacks make more power.
- Drill holes in the airbox.
- Dog your engine; the manufacturer break-in procedure is a hose.
- On and on...

Everybody everywhere likes a mod, especially one they've done, and expecially on the internet.

IMHO, you want better braking, go with better brakes. Don't confuse more sensitivity (from over matching on the push side) with better braking, though. The M/C on the Superhawk is matched to the flow needs of the calipers. The M/C on the RC is matched to its bigger calipers. Nissen makes this decision.

What is your reason for not also replacing the calipers also?

mikstr

Hi again Jim

I would suggest you go back and re-read my second follow-up post. I share your cynicism about many Net mods and do not embark on mods for the sole sake of modding or try things that I cannot undo. While some cynicism is good (I believe), there is also too much of a good thing too. If mankind stuck strictly to what is proven and had no interest in thinking outside the box or trying new things we would still be living in caves.

I will typically try ideas (from others) if they are from what I sense to be a credible source or, if sourced from myself, if I can find some logical value in an idea. As hard as it is to believe, some of us actually do have some good ideas from time to time. Granted some are not so good too.

So, to answer your question, I am not changing the calipers as most of the posts I have read and persons I have discussed this with (including some reputable tuners) have stated that the MC ONLY needs to be changed (caliper change is considered optional and unnecessary). If this proves to be wrong (and sorry but I will have to trust my senses on this one) then I will look at my next step then and there.

By the way, in regards to one mod I came up with and tried (intermediate length intake runner mod), I can tell you that prior to trying it my hands would regularly fall asleep in about 50 kms or less of highway riding (a great source of discomfort and safety concern for my longer tours). Post-mod I have ridden over 700 km per day (on several occassions) with NO problems (and trust me my nerve endings are extremely objective). You see, some mods do work (and this particular one was the result of trial and error experimentation).

killer5280

Like I said, I tried it too, but you're not going to get more power by going from a small diameter m/c to a larger one. The stock VTR m/c (14mm diameter) will generate more pressure in the braking system for a given amount of effort at the lever at the expense of greater lever travel than the RC51 (19mm) m/c will. You will get a firmer lever and, like I said in a post above, perhaps the extra bite of the EBC pads will make the reduced braking pressure a non issue.

killer5280

As an aside and potential consolation to you Mikstr if you decide you don't like the RC m/c, I sold the 954 m/c and lever on eBay for almost twice what I paid for them. It's amazing what a bunch of high resolution pictures will do for interest in an item on eBay.
If I were you I would keep the m/c and look for RC or 954 calipers on eBay. Later you can match these components up to the 954 rotors attached to the 954 wheels attached to the 954 forks you decided you had to have.
Then you can balance everything out by installing high comp pistons and aftermarket cams. Of course, the piece de resistance will be the Flo-Commander!

(I have to mod bug, too.)

killer5280

Should have read, "I have the mod bug, too."

jschmidt

OK, lets try and move beyond whether the somebody knew what they were talking about or not.

When you apply a bigger master cylinder volume to a caliper, you move more volume of brake fluid with less lever travel. This doesn't increase braking ability but it does reduce range of travel to lockup and reduce the ability to modulate braking a commensurate amount.

Does anyone disagree with this statement?

killer5280

I would say that it's not quite an exact science. That's why OEMs juggle leverage ratios and pad compounds.

It is true that a larger m/c piston creates shorter lever travel for moving a given amount of fluid, but it also increases effort; the lever, in effect, is shorter, so it takes more effort but less travel to reach "lockup" or a certain pressure, which mitigates the reduced ability to modulate the brakes. When I changed to the larger m/c I couldn't have locked up the front even if I had gorilla hands, but the lever was firmer. I preferred the mushier, but more powerful, stock setup, even though it does leave something to be desired.

jschmidt

Good point, but the lever on the RC M/C is a good bit longer (like 1.5") than the one on the SH MC.

The MC itself is organized so that the lever end is in basically the same place, but the fulcrum is closer to the headstock.

When matched with RC calipers, its a terrific mod. Highly recommended.

killer5280

I'm sure the RC or 954 setup is a vast improvement. I have the setup from an F4i (I got the whole deal for about 40 bucks) and it's definitely better than stock, but probably not quite as good as either the RC or 954, especially with the giant 330 mm rotors on the 954.

mikstr

Good discussion gents You are helping to enlighten me in all things braking.

As I said, I will try simply changing the MC and if I am not happy with it I will either re-install the stock one or look for a set of calipers to match the RC one.

From what I know, the 929 and RC have the same diameter MC piston diameter (19 mm) so logically calipers for either model should do, correct?

cheers
Mikstr

killer5280

They would either work well, most likely. I don't remember the piston sizes for the RC, 929, or 954, but they are all fairly close. Riccardo, who posts here sometimes, compiled a list of the m/c and caliper piston sizes for the various Honda models and posted it to the old RLZ list, but I no longer have that information. If you really wanted to know you could probably find the caliper piston sizes from the service manuals for the RC and 929 (or 954). Somebody on one the CBR boards could probably help you with it.

jschmidt

They're the same. (929, 954, RC) You can even feel free to mix and match. And you have the option to go with braided hoses or use the stock hoses and bolts on the SH. Everything bolts up (after the caliper shave.)

mikstr

If the calipers on the three models (929, 954, RC) are indeed the same (and I have no reason to doubt you on that one Jim), then it confirms the fact that all of this is "not an exact science" as killer5280 stated since two of these bikes have 19 mm diameter MCs (929 and RC) and one (954) has a 17 mm diameter. Food for thought.

cheers
Mikstr

jschmidt

They all have the same part number. The center letters are the model application designation. It usually indicates the first model the part was used on but may also indicate a small change in finish or color.

M/C then Caliper:
RC
45510-MCF-006 45150-MCF-006
929
45510-MCJ-006 45150-MCJ-006
954
45510-MCJ-006 45150-MCJ-006

killer5280

The 954's m/c is 17mm and the 929's (and RC51) is 19mm. The calipers also have slightly different piston sizes; the trailing pistons on the 929 are 34mm and on the 954 caliper they are 32mm. The ad copy for the 954 boasted of a 10% increase in braking system pressure over the 929, which was achieved by the smaller diameter m/c. I don't think these differences are enough to keep the various pieces from working together mixed and matched, but there are subtle differences in the caliper piston sizes and a significant difference in m/c piston size, at least between the 929 and 954.