Fork Swap Needed - GS to GS

[yoshisakan]

Hey all, I have a 1980 gs1100L 16v. It has the L-shaped forks. I need to swap in a non-L fork so that I can use a brake conversion kit. I don't know anything about motorcycle suspension, rake, geometry, etc; So I was hoping someone here could provide some advice. I don't intend on running rear sets, but don't mind an aggressive stance either. I don't want to lose turning stability.

Also, will I need to swap the triple trees too?

Thanks in advance.

 

[Steve]

If you simply swap fork tube, you WILL upset the steering geometry of the bike.

To restore proper geometry, you WILL need to change the triple trees, too.

Which ones will you need? Sorry, I don't have a clue about that, but I have heard of some rather simple swaps, just can't tell you what was used.

.

 

[yoshisakan]

Does anyone know the stock rake trail and offset for the different GS models? Maybe that would be a good starting point to determine what would fit me best. Id rather have the bike quick in the turns, which means a lower rake shorter fork would be in order. This is the style of most GS bikes. The L forks seem to be longer and have a higher rake.

 

[silverbullet132]

www.allballsracing.com/index.php/forkconversion

Early 90s gsxr750 or 1100 seem to be a good option, with cbr 929 triples. wont lose much length, and you will get USD forks +better suspension and brakes.

 

[yoshisakan]

Thanks for the link, but i'm not looking to upgrade to modern forks. I like the stance of my bike as is. Is there anywhere that has triple tree rake angles for the various models? I haven't been able to find them anywhere.

Basically, I need to swap in either 1980 GS1000G or 1980 GS850G forks. Those forks are identical, the triples are different. I have no way of knowing the differences between the triples other than looking at pictures of both bikes and comparing their rake, which seems to be the same. Its likely going to differ when installing on my bike, unless all the frames are identical.

Does anyone know if this is the case?

 

[portdave]

Where are you at? I have a whole set including the triples.

 

[2BRacing]

Is there anywhere that has triple tree rake angles for the various models? I haven't been able to find them anywhere.

I think the angles are listed in the chassis Specifications section of each bike's workshop manual.

Look on BassCliff's site for manuals.

 

[yoshisakan]

After more consideration, i'm keeping my L fork. It has a nice rake and if I swap to an 850, its going to have a shorter stance like a sport bike. I'm just going to fabricate my own brake brackets.

Thanks for the help all.

 

[tkent02]

It has a nice rake and if I swap to an 850, its going to have a shorter stance like a sport bike.

This is not true. Did you look at the specs?

 

[yoshisakan]

I didnt, but from the looks, its a shorter fork. There is definitely more rake with my fork and trips than most other GS. I think the 1980 gs1100lt trips are unique. Could be ny imagination tho, because I could find rake angle specs on trips in the book.

 

[yoshisakan]

Could also be frame steering tube angle, also have no way to verify.

 

[Guest]

Maybe refresh your Trig? You can measure and calculate.
The '80-'81 1100E had much the same front end except for the adjustable rebound. Suzuki, at the time, liked to keep thing much the same.
So maybe, You want a 1000 Katana front end and wheels? I am selling my setup.
Even the frame geometry was much the same between all the GS's. Just a little different things between them all. Raking the front out makes it handle poorly and more like a chopper.
Laters
Greg

 

[yoshisakan]

Maybe refresh your Trig? You can measure and calculate.
The '80-'81 1100E had much the same front end except for the adjustable rebound. Suzuki, at the time, liked to keep thing much the same.
So maybe, You want a 1000 Katana front end and wheels? I am selling my setup.
Even the frame geometry was much the same between all the GS's. Just a little different things between them all. Raking the front out makes it handle poorly and more like a chopper.
Laters
Greg

What year is your 1000? I am looking for a specific fork lower because they work with a brake setup that I want to install.

Also, after looking at the manual, I see that the 1100LT and 850G have the exact same rake (Caster). The trail of the 850 is 113mm, 1100 is 103mm.

 

[salty_monk]

If you put E/G model forks in L triples you increase rake and trail and end up with slower steering bike.
People have done it both ways and reported back that handling wasn't dangerous but I have no personal experience

 

[Guest]

The frontend is a center axle. Pretty much uses the same caliper as the rest of the same generation Suzuki's.
http://www.thegsresources.com/_forum/showthread.php?t=216296
Look and see if it is what you want.
http://www.thegsresources.com/_forum/showthread.php?t=216547

You should not mix leading axle and center axle parts. You could wind up with too much trail or not enough and have a serious wobbler.
I think the difference in trail is just from tire diameter. And how much air was in the tire.
You can also shorten the travel of the fork so it does not extend so much to lower the front as well. You do not need 6 1/2" of travel on a street bike. 4.5" is perfect as it is not a dirtbike.
Keep it in mind.
Laters
G

 

[yoshisakan]

Thanks for the reply gman. I'm looking for a set of forks without the antidive though, specifically from a 1980 or 81.

I didnt realize fork travel was adjustable though. How do you change that?

 

[Guest]

Inner spacers on the damper rod. And most do not know how to make the anti-dives work, either. They do work better on the Katana as the 1100E's had the adjustable rebound damping which bled the fluid past the anti units rendering them useless. Just need a shim under the actuator and between the valve and it works.
Sorry I cannot help.
Laters
Greg