FJowners.com

General Category => Dirt Bike / Dual Sport Stuff => Topic started by: FJ1100mjk on June 25, 2017, 09:17:07 PM

Title: Disc Brake on Engine's Output Shaft
Post by: FJ1100mjk on June 25, 2017, 09:17:07 PM
An innovative way to reduce un-sprung weight, and centralize mass.

1992 ATK 604

(http://fjowners.com/gallery/10/1388_25_06_17_8_10_37.jpeg)
Title: Re: Disc Brake on Engine's Output Shaft
Post by: FJmonkey on June 25, 2017, 09:36:58 PM
Neat concept. The rear only provides about 20% of possible braking. A small disc and 2 pot set up just might work on a heavy FJ. How much of the weight do you think would be saved from the rear un-sprung weight?
Title: Re: Disc Brake on Engine's Output Shaft
Post by: red on June 25, 2017, 09:47:43 PM
Just a consideration here, but if you break the drive chain,
you would lose the rear disk brake, as well as the engine braking.
Hope the front brake can handle the results.
Title: Re: Disc Brake on Engine's Output Shaft
Post by: simi_ed on June 25, 2017, 10:08:12 PM
I can attest that the front brakes will stop an FJ w/o any rear brake.   Even 2 up, not a problem. I've been riding that way for about 25 years.


Ed
Title: Re: Disc Brake on Engine's Output Shaft
Post by: CutterBill on June 25, 2017, 10:42:57 PM
What?  You have NO rear brake?  Care to elaborate?
Bill
Title: Re: Disc Brake on Engine's Output Shaft
Post by: ribbert on June 25, 2017, 10:43:34 PM
Quote from: FJmonkey on June 25, 2017, 09:36:58 PM

....The rear only provides about 20% of possible braking.


...yes, and the harder you brake with the front, the more that figure drops until near enough to zero.

Noel
Title: Re: Disc Brake on Engine's Output Shaft
Post by: FJmonkey on June 25, 2017, 10:56:35 PM
Yep...

(http://farm5.static.flickr.com/4052/4415477809_6491bd29e8.jpg)
Title: Re: Disc Brake on Engine's Output Shaft
Post by: ribbert on June 25, 2017, 10:59:10 PM
I don't conciously think about braking but always use both (except for slow full lock turns) but I lost my back brake on a fast ride down a mountain a while back. Obviously the bike could still be slowed but it felt wildly unsettled braking heavily with just the front. So much so I backed off.

Noel
Title: Re: Disc Brake on Engine's Output Shaft
Post by: ribbert on June 25, 2017, 11:01:09 PM
Quote from: FJmonkey on June 25, 2017, 10:56:35 PM
Yep...

(http://farm5.static.flickr.com/4052/4415477809_6491bd29e8.jpg)

OK, until zero.  :biggrin:
Title: Re: Disc Brake on Engine's Output Shaft
Post by: FJmonkey on June 25, 2017, 11:12:20 PM
Near enough I think Noel. I rarely use my rear brake in the twisties. My logic for this is predictability when leaned over. When leaned over to turn Left I have easy use of the rear brake. When leaned over to the Right my boot is getting stuffed between the lever and land. I fear that if the suspension is doing what it should and causes my boot to apply more brake than intended then bad stuff might happen. I am not a racer and have no intention of being the fastest in any group for any reason. I also could just be over thinking it, I tend to get wrapped around the axial for this.
Title: Re: Disc Brake on Engine's Output Shaft
Post by: ribbert on June 26, 2017, 06:54:19 AM
Quote from: FJmonkey on June 25, 2017, 11:12:20 PM
I rarely use my rear brake in the twisties. My logic for this is predictability when leaned over. When leaned over to turn Left I have easy use of the rear brake. When leaned over to the Right my boot is getting stuffed between the lever and land. I fear that if the suspension is doing what it should and causes my boot to apply more brake than intended then bad stuff might happen. I am not a racer and have no intention of being the fastest in any group for any reason. I also could just be over thinking it, I tend to get wrapped around the axial for this.

Mark, tempted as I am to further comment on this subject of corners and braking, I have been down this road before (pun intended) and it didn't end well, I think I'll leave it here.

Noel
Title: Re: Disc Brake on Engine's Output Shaft
Post by: FJ1100mjk on June 26, 2017, 08:01:06 AM
Quote from: ribbert on June 26, 2017, 06:54:19 AM
Mark, tempted as I am to further comment on this subject of corners and braking, I have been down this road before (pun intended) and it didn't end well, I think I'll leave it here.

Noel

We'll, that would be fantastic considering that this post was initiated simply to comment on a unique brake system (and on a dirt bike too), and was hijacked and morphed into personal braking techniques on road bikes.

:Facepalm:
Title: Re: Disc Brake on Engine's Output Shaft
Post by: ribbert on June 26, 2017, 08:39:28 AM
Quote from: FJ1100mjk on June 26, 2017, 08:01:06 AM
Quote from: ribbert on June 26, 2017, 06:54:19 AM
Mark, tempted as I am to further comment on this subject of corners and braking, I have been down this road before (pun intended) and it didn't end well, I think I'll leave it here.

Noel

We'll, that would be fantastic considering that this post was initiated simply to comment on a unique brake system (and on a dirt bike too), and was hijacked and morphed into personal braking techniques on road bikes.

:Facepalm:

Yep, you're right, that's exactly how some of the best, most informative and interesting discussions here come about.

Noel
Title: Re: Disc Brake on Engine's Output Shaft
Post by: simi_ed on June 26, 2017, 09:22:29 AM
Quote from: simi_ed on June 25, 2017, 10:08:12 PM
I can attest that the front brakes will stop an FJ w/o any rear brake.   Even 2 up, not a problem. I've been riding that way for about 25 years.


Ed
Sorry Bill, that is not quite accurate. I have a rear brake. I just don't use it.


Ed
Title: Re: Disc Brake on Engine's Output Shaft
Post by: Firehawk068 on June 27, 2017, 01:58:15 PM
Although this seems like an interesting idea for possibly reducing a little unsprung weight, and possibly to tidy up the rear wheel area if you have a show-bike, I honestly don't think it would work very well for anyone that lubes their chain regularly. There would be no way to prevent chain-lube from eventually getting on the brake disc or caliper/pads, rendering them useless................unless of course you had a dry, belt-driven bike.