Fork Brace

[tmkaos]

James,

Just curious to know what the radial thickness of the cap on your fork brace is.
Knowing the thickness, it would be easy to measure to clearance.
I don't have a fork brace, but my Triumph seal protectors did interfere with the fairing.
I don't think a brace would get up into the fairing, but I did have to relieve the opening as well as carefully position the seal protectors to keep it from hitting.

Arnie

Arnie, the outer radial thickness is 20mm, I wanted to keep a bit of meat there for strength.

James

[Arnie]

James,

I wonder, (and I'm not an engineer), if you could get the same strength with just a steel strap.  It would look much less pretty, but should be able to clamp and locate the brace just as well.

Arnie

[ribbert]

James,

I wonder, (and I'm not an engineer), if you could get the same strength with just a steel strap.  It would look much less pretty, but should be able to clamp and locate the brace just as well.

Arnie

Arnie, I made similar suggestion to James, not strap but thinner ally. There are plenty of braces ( google images) that have thin ends that don't appear to be more than around 5mm. The problem as I see it is how to estimate the forces involved here and make it just sufficient.

With the forces difficult to calculate the easiest route is to make it so big it HAS to work.

Noel

[ribbert]

Noel, what fork springs do you have?
[/quote




I have the original progressive springs set to "Marshmallow," the hardest setting, and I can get the forks past the bottom of the fairing just bouncing on the bars.

I only have the forks 17mm through the yoke.

It seems some here say their forks never go that high. If the fork travel is 150mm (as per the manual) and it's only 110mm between the forks and the fairing, why not?

Noel

Noel,

If your forks are sprung soft enough that you can get the stanchions to or above the fairing just by bouncing.... then you really need some additional spring.
To use your numbers, if the fork has 150mm travel and there's only 110mm (after static sag of 25-35mm) between the fork stanchions and the fairing, then it won't take much of a pothole for you to bottom your forks - HARD.  This might cause a lesser rider than yourself to lose control.  That's why not.

Arnie

Arnie, I think you misunderstood my question. I either worded it poorly or it's the way you bloody Lethbridgians talk down there.

The "why not" question was, why don't other peoples forks compress beyond the bottom of the fairing. I was not suggesting because theirs don't that I fit the brace to mine.

Noel

[Pat Conlon]

Noel, who says they don't?

On my '92 the stock .475kg/mm fork springs did exactly what you describe...the fork dive was terrible.
Your progressive springs are not much better.

There was a reason they stopped using them in the '80's.

Add to the mix modern radial rubber and R-1 brakes, it's a wonder you're still alive.

[ribbert]

Noel, who says they don't?

On my '92 the stock .475kg/mm fork springs did exactly what you describe...the fork dive was terrible.
Your progressive springs are not much better.

There was a reason they stopped using them in the '80's.

Add to the mix modern radial rubber and R-1 brakes, it's a wonder you're still alive.

Oddly enough Pat, my bike handles really well. I ride it hard and I do ride modern bikes, including regular use of a  BMW 1200 with electronic suspension control and others. I know what good suspension feels like. I think I have a good idea how my bike will be improved with the RPM goodies. Besides being uncomfortable at anything less than high speed or with luggage, it has no bad habits. I can corner hard at speed with potholes, dips and bumps, corrugations, ride it flat out with luggage and it behaves.

It used to ride like a rubber cow but the changes I made and that fabulous RA2 on the front made it predictable and safe, if uncomfortable.

Having said that, I am REALLY looking forward to the suspension upgrade. Because of how my shock is set, I think the biggest thing I will notice is comfort. My rides are rarely less than 500-700 km's.

Noel

[tmkaos]

Ok so Noel this might clear up the issue for you a little.. I was under my bike on the weekend fitting the oil cooler, so I was nice and close to the forks and fairing, and I've realised why the forkbrace I've designed doesn't work on your bike. My fairing has been neatly modified by a P/O. It wasn't until i was looking at the pic of your front end that I noticed the difference. I have a much wider clearance around my forks on full lock as the fairing has been cleared away almost to the radius where it returns to vertical. As I've never seen another stock FJ up close, i always just assume mine is stock too, but that's bitten me on the ass before, I really should stop doing it.
so anyway, that's the reason. I designed the brace to fit my bike, with possibly a higher front ride height due to my custom top triple clamp and Renthal bars, and my possibly stiffer spring and shock setup resulting in less travel under load. Add all that up and that's why it fouls on your bike and isn't an issue on mine.

Cheers,

James

[ribbert]

James, I have been meaning to enquire, how goes the build? I was expecting to hear some news of your first ride by now. You were very close when you last posted.

Yes, it would appear those differences between the bikes explains the clearance issues.

I feel bad about returning the caps for further machining. I had someone here offer to turn down the end caps but it is slowly becoming obvious his good intentions exceed his capacity to follow through.
I guess I will have to return them to you.

Lets know where you are up to with the beast.

Noel

[tmkaos]

Yes, it would appear those differences between the bikes explains the clearance issues.

I feel bad about returning the caps for further machining. I had someone here offer to turn down the end caps but it is slowly becoming obvious his good intentions exceed his capacity to follow through.
I guess I will have to return them to you.

Lets know where you are up to with the beast.

Noel

Noel, don't feel bad about returning the caps. I made them, they aren't right for you so I'll fix them.  :drinks:On Wed I start a new job, so I will unfortunately lose my ability to make CNC machines jump to my command. I will still have access to a couple of manual machines and my old workmates can sneak me back in on a CNC on the weekends, so I can definitely fix your caps, just not as easily.

I'll update my rebuild page.. Not a lot of progress I must admit for reasons which will be apparent. :-)

cheers,

James