FZRSupport: the FZROnline Archive

Just an idea I've been throwing around in my head for my fzr 600. It would clamp to the outside of the larger part of the forks, where the seals reside. (above the fender) I'd like to hear your comments.

That's not a very large area on the forks and with those fork bottoms being cast, they aren't exactly perfectly round or flat and would vary between bikes. Those would be my concerns.

If you took it one step further and made it thicker and had it also screw into the existing fender brace holes, then it might help. However; I cannot say if that is even feasible since I don't have any forks to measure.

Yeah, I thought of all those problems you mentioned. I just want an elegant looking fork brace. The thickness was arbitrarily chosen at 1/2". It could be as thick as that area on the forks where the seals sit.

I'll post up another design I've been thinking about later on, that addresses the inconsistent casting problem.

Why not just buy a Tarozzi brace from Fastfromthepast.com?

IMO that brace isn't as effective as it could be due to the geometry of the bridge and the way it bolts on.

Thanks for posting the pic. A fork brace in that area doesn't look as stupid as I thought it would. Maybe I could make my design a little less elegant than i had originally planned.

edit: found this http://www.telefix-products.de/stabi/gabelstabi.htm

seems like a really good option, addresses most of my concerns with the tarozzi brace.

The bolts will compensate for the tolerance stackup between the casting diameter, paint, fork spacing, etc. If you were to mass produce a solid one I don't see how it could fit perfectly on all bikes. For a one off you can obviously measure your specific setup and make it perfect.

If you haven't seen the Tarozzi brace in person I think you'd be surprised at how solid it is.

higher res picture here:
http://1.bp.blogspot.com/-cLq3Zjh35iI/T ... Yellow.jpg

The design you have posted will give you minimum clamping force for the pinch bolt position. If you have the pinch bolt on the outside of the fork tubes you'd be better off. Also, if you change the slot configuration, you will get a more even distribution of the clamp around the fork tube. I did up a quick model to show you what I mean:

I have yet to see a tarozzi brace in person, but I don't think that will change my mind about it.

My theory is that there is no need to have so much material around the fork legs. you just need enough to maintain alignment. The tarozzi is over built in that area, in my opinion. Where it can be improved is at the bridge, and this is where a solid fork brace would stand out over the tarozzi.

I have a few more ideas. SquadraCorse, if you could take some basic measurements of the bridge on the brace (like how thick it is, how much overlap there is between the adapters and the bridge) It would help me to create model of it and test it against my brace.

My brace will be a one off deal, but I will make the drawings available online if anyone wants to reproduce it on their own.

Great idea with the double slots and outside clamp. I think I'm going to incorporate the tarozzi clamp design just to simplify installation (not having to take the tubes out of the trees), but i still want to maintain a solid center section.

olie05 wrote:Yeah, I thought of all those problems you mentioned. I just want an elegant looking fork brace. The thickness was arbitrarily chosen at 1/2". It could be as thick as that area on the forks where the seals sit.

I'll post up another design I've been thinking about later on, that addresses the inconsistent casting problem.

hi Ollie,
suggest you read the threads on the Forum regarding the use of fork braces and the non-problem they do not fix ..................

A previous thread concerning fork braces :: viewtopic.php?f=8&t=761&start=0&hilit=fork+brace#p6094

ragedigital wrote:A previous thread concerning fork braces :: viewtopic.php?f=8&t=761&start=0&hilit=fork+brace#p6094

Thanks Rage, i never seem to be able to find the darn topic when I need it (i really have to get the hang of our search engine <BG> )

yamaha_george wrote:

olie05 wrote:Yeah, I thought of all those problems you mentioned. I just want an elegant looking fork brace. The thickness was arbitrarily chosen at 1/2". It could be as thick as that area on the forks where the seals sit.

I'll post up another design I've been thinking about later on, that addresses the inconsistent casting problem.

hi Ollie,
suggest you read the threads on the Forum regarding the use of fork braces and the non-problem they do not fix ..................

I have done a lot of reading on fork braces on this site, and on other sites as well. My main goal in implementing one on my bike is to achieve similar effects to having a larger diameter front axle without having to go through the effort of making one fit, or swapping a front end.

The way i see it the bottom fork legs form a parallelogram, with the top of the parallelogram being just the fender and measly little bracket. Since I can't use triangulation to keep the fork legs in unison, then i can just use a nice big fork brace.

YG, what is your experience with fork braces?

The real question about fork braces is : "Are they really doing anything to improve the stability?" I see a lot of flex still occurring with fork braces. They are piece of flat metal clamped on to the fork tubes.

Here is the real test - take the fork tubes off the bike, put the fork brace on and see how well they prevent movement. My guess is that they don't. BUT, they most likely improve over the stock one AND that is what you're going for.

Manufacturers of newer bikes use a much larger axle. For example, my 05 GSXR600 has a huge axle on the front.

ragedigital wrote:They are piece of flat metal clamped on to the fork tubes.

That's exactly what I want to avoid in my design, and my main problem with the tarozzi brace.

olie05 wrote:YG, what is your experience with fork braces?

O,
from the mass of posts on this subject:-
QUOTE:-
Fork braces by armani are just fork braces the answer to a non -question.

Fork braces do NOT cure the source of crap front ends PERIOD.

I was as sceptical as you all when I read Eric's paper. ( Eric Buell ( of before Buell Motors ) back in the 80's )
BUT being an engineer I decided to try it out on my street drag racer (I am sure you are all familiar with illegal friday / saturday night drag races for money )

I checked the wheels and they could take the same size outer diam bearings BUT with 25mm inside instead of 15 mm (?) memory is iffy on that figure but it was way thin. I made the axle from a 1" construction bolt 14" long and turned & ground to suit the new bearings. I bored the stantions to take the new diam fitted it up on the saturday morning. Told my riding buddy I was gonna take it out for a trial.


Pictures at:- http://www.saltmine.org.uk/kgb/gallery.html

The trial was simple we had a piece of hiway with 6 sweepers over about 2 miles that connect 2 hiways at each end there were roundabouts.
The max on the bike was 80 ish mph thro those sweepers and you had better be good to do that.
over the next 3 hours I got that top speed upto 120 + and ran out of bottle (traffic was getting exciting at that speed ) without a wobble , twitch or any other oddity.
I lined the bar end up with the white line & RODE.

when I got back my buddy was glad to see me in one piece he thought I had got into a wreck I was gone so long. I told him ride the bike , that alone signified that something was definitely odd, you could probably ask my wife for sex and get a better odds than asking to ride any of my bikes. He went out and I swear he had trouble getting his helmet off afterwards due to that stupid grin.

He decide then and there that his bike had better have one and bought the bearings then at the store and by Sunday we both had fat axles. Neither of us have ever had skinny axles since.

The FZR I have not done YET due to the fact that I want the suspension done first because no amount of axle will stop those dead springs from diving,and wriggling under braking.
UNQUOTE

Since I wrote that piece I have changed my old dead springs , see:-

http://www.saltmine.org.uk/fzr/fork.html


I have used the bike solo & fully loaded with pillion since and never had cause for concern, which is why I have not bothered with a new bigger axle (I do have notes in the WIKI re:- axle / bearing swaps )

If I still had access to a full machine shop with a friendly boss I may have done it just because, but since I refuse to pay stupid money (80 pounds an hour ) for some one else to do what I for the most part am better experienced/ qualified to do, I have not bothered.


References for further reading :-
Eric Buell in Cycle world 1983 summer (memory is hazy) some of his early stuff on the Barton Engine is on the web and that will include his axle stuff.

Tony Foale 's seminal work on Frame design,
John Bradley's book Vol1 & 2 on building a race bike,
the Italian prof who is the guy who teaches the only Moto GP engineer course in the world ( his book is in the Reference book section on the Technology page of the WIKI

Enjoy