Downsizing....2 discs to 1 with H-D's ABS

[threadkiller]

Did a search, but............there's a trend for dropping a front rotor on FL's and I was curious? Has anyone done this with H-D's ABS system? Does the system "know" that you've eliminated one side? Can the ABS pump be regulated if factory pressures are designed to feed 2 sides instead of 1? Thank you & TIA. TK.   

[akajjmon]

Why would anyone want LESS stopping power??

[moscooter]

 
My buddy has a '05 Ultra and he also has diabetes and major leg problems.  He cannot raise the front of his right foot to apply the brakes.  He had one side of his front brake (crippled) (that means "disconnected" for those of you in Rio Linda).

A brake hose was then run from the junction block on the front brake to a T connector by the rear master cylinder.   He now is able to apply both the front and back brakes via his right hand.   Works just fine for him.

[Ed Y]

I agree, why?? And I'd debate the statement about "there's a trend for dropping a front rotor on FL's". Seriously doubt that. Anyone who knows anything about the dynamics of motorcycle braking would never consider reducing your stopping power.

[HD99FXR3]

They do it so that you can see the $$$$$$$ rim the just put on. The rotor hides it pretty good.

[calif phil]

Did a search, but............there's a trend for dropping a front rotor on FL's and I was curious? Has anyone done this with H-D's ABS system? Does the system "know" that you've eliminated one side? Can the ABS pump be regulated if factory pressures are designed to feed 2 sides instead of 1? Thank you & TIA. TK.

Good question. I have a friend who just asked me that today.  I would like to hear if it can be done, not wether it will reduce braking power.

[IndyHarley]

well i hate to be the smart aleck here but............the answer is yes it can be done and you can even take both front brakes off if you are so inclined.

[Dennis The Menace]

I presume you could put a bolt in the T and block off the hydraulic line to the side you are removing.  I dont know what the extra pressure would do to the remaining brake rotor/piston.  I suspect it might make it more sensitive to input. 

Keep in mind, the hydraulics are different for a 1 versus 2 rotor setup.  If you really want to do it right, get the 1-rotor reservoir setup.  Only diff is the line hole is smaller on single rotor setup.  At least, that is what I have read here on HTT...I dont know that to be fact.

Oops....just realized ABS is involved.  No f-en way I would mess with that.  I am sure you are talking about replacing a lot of parts to get it to work.  Just bleeding the brakes requires specialized equipment (Digital Tech).

menace

[TweekmyTwin]

My buddy has a '05 Ultra and he also has diabetes and major leg problems.  He cannot raise the front of his right foot to apply the brakes.  He had one side of his front brake (crippled) (that means "disconnected" for those of you in Rio Linda).

A brake hose was then run from the junction block on the front brake to a T connector by the rear master cylinder.   He now is able to apply both the front and back brakes via his right hand.   Works just fine for him.

So he rides a Ultra with Neuropathy..... We did a ride to Banff this year with guy like that.. that was scary. Did his shifter lever break in Wash.?  I'm with the rest of the guys here.. why? Matching rotors ( Clocked to the wheels ) looks real sharp and still stop when you really need it.
Jim

[mc9395]

Yes It can be done and looks and functions well and regardless what your dealer says you do not need a digital tech to bleed them although a mity vac does make faster to bleed. And no the system does not know a caliper is missing. I used a HHI 6 piston caliper to compensate for the missing caliper. The chrome shaved legs are also available. After test riding the bike I could not feel the difference in stoping power although there has to be less just because extra pistons on one side can not make up for a missing rotor. Pics were to large but can supply upon request with futher info

[threadkiller]

Thank you very much 9395. Thats EXACTLY the information I was looking for. Glad you are extremely happy with the way your bike looks AND stops with one rotor. If you squeeze the lever or step on a pedal and the brakes/wheels are locked up, well I guess you can't "realistically" ask any more from a brake system  TK.

[Ultrashovel]

I never heard of removing one of the front disks. I don't think I'll do that. If there's some specialized need, as with a disability, then I guess it would be OK, though.

I have a general idea how ABS works but I don't think I'd want one if they are difficult to bleed.

[akajjmon]

Good question. I have a friend who just asked me that today.  I would like to hear if it can be done, not wether it will reduce braking power.

ANYTHING can be done...it just usually costs more to do the dumb stuff.

As to the post about combining front/rear braking, what do you use to delineate pressure from front to rear? about 80/20 on a bike if I remember correctly.

[moscooter]

Good question. I have a friend who just asked me that today.  I would like to hear if it can be done, not wether it will reduce braking power.

ANYTHING can be done...it just usually costs more to do the dumb stuff.

As to the post about combining front/rear braking, what do you use to delineate pressure from front to rear? about 80/20 on a bike if I remember correctly.

In the case of my friends '05 Ultra, I don't think any changes had to be made to the master cylinder size.  Since I own a streetrod,  I can tell ya that a (proportioning valve) that is adjustable is a readily obtained item to dial in the pressure you want between front and rear braking.

[09WGULTRA]

 

Why would anyone want LESS stopping power??

[redrokit8]

IMO you have gotta be out of your flippin mind to decrease braking power just to look cool with a single disc.  is this all about??

[02roadcling]

Not anti-lock but I did it with my 02 RK. Those softails only have 1 and when loaded up weigh more than mine does. Considering that, whats the big deal anyway? My rim is awesome and I got tired of hiding it. Bike stops just fine.

cling

[ViennaHog]

The ABS sensor of the missing disk will generate a error code that disables the ABS in the front circuit. There is no known way of tricking the sensor. I would consider this before tearing out the brake. You may have sufficient braking power for short stops, but you will notice a rapid overheating of the single brake under conditions of heavy loads in hilly areas.
I wouldn't even think about his option.

[Ultrashovel]

The ABS sensor of the missing disk will generate a error code that disables the ABS in the front circuit. There is no known way of tricking the sensor. I would consider this before tearing out the brake. You may have sufficient braking power for short stops, but you will notice a rapid overheating of the single brake under conditions of heavy loads in hilly areas.
I wouldn't even think about his option.

That's a very good explanation. Removing brake discs in the name of vanity is unsafe. How about just riding the motorcycle and enjoying the scenery?

[mc9395]

Only one front sensor and it's on the left

[ViennaHog]

That's correct, but I did not know which disk he wants to take out.

[threadkiller]

Not anti-lock but I did it with my 02 RK. Those softails only have 1 and when loaded up weigh more than mine does. Considering that, whats the big deal anyway? My rim is awesome and I got tired of hiding it. Bike stops just fine.

cling

Thanks Cling. You are absolutely correct about loaded softies and braking. A sensible answer to my question without adding to the "debate".

[02roadcling]

Thanks, I didn't answer your question really, just sticking up for us maniacs, lol.

cling

[boooby1744]

Some folks that go to single side brake  go with a 13" disc and 6 piston caliper........................

[crash1292]

after you rear end someone the lawyers will be all over your azz for modding the factory system and reducing the brakeing power

[Ridetard]

This has to be a joke.
Is it April 1st allready?

[threadkiller]

How MANY severely overloaded SINGLE DISC Softails (2 fatties AND ALL their "Potty mouth") have never been in accidents due to "reduced braking forces"? Got verifiable published statistics on single disc motorcycle accidents vs dual disc accidents? 

[crash1292]

the burden of proof that you did not degrade the braking will be yours to prove in court....just saying

[threadkiller]

Completely understood. As Brian and the other Mods have tried to stress, this is a technical forum. I originally asked for technical "information" and out of 20 posts only received 2 "legitimate" answers with the rest being opinions, jokes, and random speculations. Is someone asks for a torque specification, hopefully the members here will state some facts and not the proverbial "I never torque stuff" or "I'd never tighten it that much". TK.

[Ultrashovel]

Completely understood. As Brian and the other Mods have tried to stress, this is a technical forum. I originally asked for technical "information" and out of 20 posts only received 2 "legitimate" answers with the rest being opinions, jokes, and random speculations. Is someone asks for a torque specification, hopefully the members here will state some facts and not the proverbial "I never torque stuff" or "I'd never tighten it that much". TK.

I know that removing a brake disc can be done but it's not something that I'd ever do. Like many here, I was riding Harleys back when the brakes were simply terrible. I'm referring to the earlier drum brakes on Knuckleheads, Panheads and early Shovelheads. I always longed for a front brake on my former Shovelhead that would actually stop in a safe distance. It was an '82 FXS with two discs and braking was still marginal. Had I removed one disc, I might as well have taken the other one off.

What you have to remember is that is only the internet. It's not enough to ask a question and expect that the respondents are going to give only the technical andwer. For every "How", there's also a "Why".

Happy New Year!   

[ederdelyi]

And then there are those that just don't answer posts like this anymore .... cuz it's just not worth the trouble, IMO.

Back to lurk mode, Happy New Year, all.

[threadkiller]

Posts like what exactly, Ed? This topic "troubled" you enough to drop a response. At least this wasn't a "do you wave" or mandatory oil thread.

[ederdelyi]

>>Posts like what exactly, Ed? This topic "troubled" you enough to drop a response.<<

Even if the calcs for the braking power required were given, or the braking efficiency requirements were given for the vehicle to pass a braking efficiency test it would not change the minds of those who are concerned with form over function.

I've learned not to confuse 'em with facts when their minds are made up or someone's uninformed SOP experience will be the advice that will be taken only because it answers the question in the way the poster wanted to hear in the first place.

Guess I'm too old or burnt out to go chasing after windmills any more.

[harleyjt]

The ABS sensor of the missing disk will generate a error code that disables the ABS in the front circuit. There is no known way of tricking the sensor. I would consider this before tearing out the brake. You may have sufficient braking power for short stops, but you will notice a rapid overheating of the single brake under conditions of heavy loads in hilly areas.
I wouldn't even think about his option.

There is only one front sensor in the Harley system - it's on the left side, and totally independent of the brake rotor.  The sensor is the wheel spacer, and the tone ring is in the left side bearing.  (BTW, whenever you are servicing those parts, don't ever put them in a magnetic parts tray).  I see no way for the missing rotor to generate an error.

The other thing that I remember here is that the bikes with a single front disc use a different diameter master cylinder.  I don't remember the exact sizes, but they do vary from single to dual disc systems.  If you make the modification, you may also want to consider that fact.
Personally, I'd never consider making that kind of modification.
jt

[cyrus]

I would think that the braking power would be the ratio of master cylinder piston area to total caliper piston surface area. You could increase or decrease this ratio, and could make a single disc system even more powerful than a twin disc system. The distance the caliper is mounted away from the center (axle) will also affect its effective leverage, but someone has mentioned that a twin disk system can disapate the heat better on long hard stops when heavily loaded. Short answer- you could make a single disc more powerfull but not better.

[Ridetard]

Posts like what exactly, Ed? This topic "troubled" you enough to drop a response. At least this wasn't a "do you wave" or mandatory oil thread.

Have to chime in here.   There is a huge difference between a dual brake front end as opposed to the single single brake.  I am not an engineer but own a  softtail and an bagger.  There is a huge difference in stopping power.  Anyone that would compromise brake performance in lue of appearance is really looking for trouble.  Why do you suppose the second brake is caliper is there anyway?  To beef up the price tag?
If you do elect to go through with this, please warn your buddies that you ride with and please, stay out of the mountains. At least consider a 3 piston caliper for the front end.
Foolish

[threadkiller]

Have we all gotten THAT old? I'm closing in on 50 with the last 20 wrenching on American V-Twins as a profession. I'm not looking to get myself or any of my clients killed, but have we gotten overly cautious? Are we that far from "hold my beer, and watch this"? No one does burnouts, wholeshots, or wheelies anymore? Not one of us has ever raced his buddies on the street? I can do the math, but sometimes its easier to work with the "bigger" numbers (GVW's of overloaded ST's vs 1 up FL's) I'm not big on what "Donnie" has to say nor the "table of knowledge" around the coffeepot at H-D dealerships. That's why I'm HERE. Not to "wait" for the answer I want  but to hopefully gets some "facts" along with the B.S. so I can make the best "informed" decision(s). If Paul Yaffe, does it, that might not make it "correct", esthetically pleasing to everyone's eye, or an indication that everyone should be doing "it", but dam it? can it done so a rider within his "skill" range at rational speeds won't kill themselves? TK

[02roadcling]

TK,
I would just make it the way you want it. If the abs doesn't work so be it, it wouldn't bother me, it would still have brakes as good as a regular Softail (or my RK). We didn't even have that crap up until a couple yrs ago anyway. When an older cars abs quits nobody I know fixes it due to expense either.

cling

[CraigArizona85248]

Have to chime in here.   There is a huge difference between a dual brake front end as opposed to the single single brake.  I am not an engineer but own a  softtail and an bagger.  There is a huge difference in stopping power.  Anyone that would compromise brake performance in lue of appearance is really looking for trouble.  Why do you suppose the second brake is caliper is there anyway?  To beef up the price tag?
If you do elect to go through with this, please warn your buddies that you ride with and please, stay out of the mountains. At least consider a 3 piston caliper for the front end.
Foolish

If this is really "Foolish" as you say, then shouldn't you be adding a rotor to you Softail to make it stop better?  Wouldn't it be foolish not to add one?  Do you warn your riding buddies when you ride your softail and stay out of the mountains?  Not, trying to pick on you Ridetard, just making a point.  Everything is relative.  If we are really concerned about having the best brakes out there, none of us would be riding a Harley period.

TK, I'd be willing to bet that with the right combination of rotor and caliper (maybe something from a sport bike) you can get better braking performance with a single rotor then with the stock dual rotor setup.  It will just take some experimenting with different setups to come up with the best combination.

-Craig

[Guitarplayer]

I think you have to replace your master cylinder from an 11/16" bore to a 5/8" bore when removing one of your brakes.

[02roadcling]