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Main Area => General GS500 Discussion => Topic started by: bargovic on June 10, 2006, 06:01:55 PM

Title: Inverted forks, why?
Post by: bargovic on June 10, 2006, 06:01:55 PM
So i was drooling over the truimph speed triple again, as i read about it in cycle world this weekend.  It has inverted forks, which i think look awesome.  But whats the benefit of having them over a regular fork ? more travel ? And has anyone put them on a GS?
Title: Re: Inverted forks, why?
Post by: Egaeus on June 10, 2006, 07:22:15 PM
Less unsprung mass.  There is less weight on the wheel side, so there's not as much inertia.  That allows the wheel to move faster, causing it to respond to the road surface better.  Or at least that's my understanding.

Edit: unsprung....  Don't want to confuse anyone over the argument.
Title: Re: Inverted forks, why?
Post by: brembo on June 10, 2006, 07:33:34 PM
Inverted forks are more rigid so are less prone to deflection compared to a same-sized conventional fork. The main drawbacks to the USD forks are their higher cost and greater weight.
Title: Re: Inverted forks, why?
Post by: makenzie71 on June 10, 2006, 07:40:20 PM
Quote from: Egaeus on June 10, 2006, 07:22:15 PM
Less sprung mass. There is less weight on the wheel side, so there's not as much inertia. That allows the wheel to move faster, causing it to respond to the road surface better. Or at least that's my understanding.

Umm...unsprung weight is the same no matter which way the skinny end points.

Quote from: brembo on June 10, 2006, 07:33:34 PM
Inverted forks are more rigid so are less prone to deflection compared to a same-sized conventional fork. The main drawbacks to the USD forks are their higher cost and greater weight.

Partially right...they are less prone to flex.  More of the shock is "thick" and the the assembly as a whole is beefier.  But my 41mm TL forks weight the same as my 41mm Bandit forks.
Title: Re: Inverted forks, why?
Post by: Phaedrus on June 10, 2006, 07:47:49 PM
Because "Upside down forks R kewl"  :icon_razz:
Title: Re: Inverted forks, why?
Post by: corndog67 on June 10, 2006, 09:22:08 PM
I'm buying a set of GSXR 750 forks from a road racer guy that I work with, with the 6-piston calipers, front wheel, master cylinder, brake hoses, everything, that I am going to put on the little GS500E.  I will probably have to make a steering stem, or swap the GS stem into the GSXR triple clamps, figure out a headlight bracket, and a way to mount the gauges.  I am also going to put some standard handle bars on it.  As it is now, my stock forks suck.  They bottom out on grains of sand.  I checked out the weight of the GS, and the GSXR, and they are pretty close.  The spring rate should be about right.  We're talking 2 finger stoppies.  I will let you know how it works out.  I am a machinist, so it isn't going to be a hack job. 
Title: Re: Inverted forks, why?
Post by: werase643 on June 10, 2006, 09:41:28 PM
better brake calipers
better brake pads
better rotors
3.5x17 rim...better tire selection

Title: Re: Inverted forks, why?
Post by: makenzie71 on June 10, 2006, 10:06:23 PM
Quote from: corndog67 on June 10, 2006, 09:22:08 PM
I'm buying a set of GSXR 750 forks from a road racer guy that I work with, with the 6-piston calipers, front wheel, master cylinder, brake hoses, everything, that I am going to put on the little GS500E. I will probably have to make a steering stem, or swap the GS stem into the GSXR triple clamps, figure out a headlight bracket, and a way to mount the gauges. I am also going to put some standard handle bars on it. As it is now, my stock forks suck. They bottom out on grains of sand. I checked out the weight of the GS, and the GSXR, and they are pretty close. The spring rate should be about right. We're talking 2 finger stoppies. I will let you know how it works out. I am a machinist, so it isn't going to be a hack job.

You need a bearing kit...it'll cost about $75 as a whole for good bearings if you have a later GS.  The earlier 500's have ball bearings iirc...the newer E's should use rollers.

Bikebandit and ronayers both carry headlight mounts that stick an SV style 7" light to the GSXR inverted forks.  Sign up on TLzone and PM DRZDoug about how he mounted the guages...not too sure.

Oh yeah...and it's "inverted" forks.  There's nothing "upside down" about them.
Title: Re: Inverted forks, why?
Post by: The Buddha on June 10, 2006, 10:15:08 PM
If you are buying inverted forks though ... get the 90-95 I believe GSXR 750 ones ... the newer ones were made thinner and thinner and thinner ... as in ... you bump into somehting and they break ... Of course the oldies are heavy as a mofo ...
Cool.
Srinath.
Title: Re: Inverted forks, why?
Post by: fettcols on June 11, 2006, 02:25:50 AM
With the older ones you'll probably run into less problems with the speedo...
Title: Re: Inverted forks, why?
Post by: Kasumi on June 11, 2006, 02:32:17 AM
The inverted forks on my new bike seem to give me alot better handling than conventional ones - yes they are heavier but they're stiff and hard and give a better feeling and i don't feel any touch of flex on long open fast corners. Theyre wonderful. Plus they look the dogs gonads. Im only talking from a riding perspective i am unsure of the physics of inverted forks.
Title: Re: Inverted forks, why?
Post by: Wrecent_Wryder on June 11, 2006, 04:35:08 AM
[5
Title: Re: Inverted forks, why?
Post by: fettcols on June 11, 2006, 11:25:12 AM
Quote from: Kasumi on June 11, 2006, 02:32:17 AM
The inverted forks on my new bike seem to give me alot better handling than conventional ones - yes they are heavier but they're stiff and hard and give a better feeling and i don't feel any touch of flex on long open fast corners. Theyre wonderful. Plus they look the dogs gonads. Im only talking from a riding perspective i am unsure of the physics of inverted forks.

Exactly... heavier without the squish/nosedive factor.       One bad thing about them... It's a little more expensive on the labor to replace the seals.. And when they go bad you get fork oil on your brakes...
Title: Re: Inverted forks, why?
Post by: makenzie71 on June 11, 2006, 02:06:19 PM
Quote from: Wrecent_Wryder on June 11, 2006, 04:35:08 AM
That's an unusual opinion. The rest of the world pretty much thinks that having the "big end" bouncing up and down with the wheel, as opposed to the "skinny end", really does increase the unsprung weight.


I'll try wording it a bit differently:

The skinny end of my TL1000S forks weighs the same as the big end of my Bandit forks.  Does that help?
Title: Re: Inverted forks, why?
Post by: red_phil on June 11, 2006, 03:18:13 PM
yeah, still for overall mass of forks, the Inverted forks has less unsprung mass.
so you get more stiffness without the extra unsprung mass.
Title: Re: Inverted forks, why?
Post by: makenzie71 on June 11, 2006, 04:02:24 PM
Quote from: makenzie71 on June 10, 2006, 07:40:20 PM
But my 41mm TL forks weight the same as my 41mm Bandit forks.

Quote from: makenzie71 on June 11, 2006, 02:06:19 PM
The skinny end of my TL1000S forks weighs the same as the big end of my Bandit forks.  Does that help?

Then...

Quote from: red_phil on June 11, 2006, 03:18:13 PM
yeah, still for overall mass of forks, the Inverted forks has less unsprung mass.
so you get more stiffness without the extra unsprung mass.

Read a bit, mate.  In the few instances there may be a difference in weight...it's neglegible as a whole or at either end.  The heavy stuff is inside the fork and is "unsprung weight" and remains pretty constant regardless of fork design variety.  The only forks made that are lighter over all are springers and telelevers and that's because all the springy shaZam! is bolted to the bike.
Title: Re: Inverted forks, why?
Post by: dgyver on June 11, 2006, 06:13:06 PM
Quote from: corndog67 on June 10, 2006, 09:22:08 PM
I'm buying a set of GSXR 750 forks from a road racer guy that I work with, with the 6-piston calipers, front wheel, master cylinder, brake hoses, everything, that I am going to put on the little GS500E.  I will probably have to make a steering stem, or swap the GS stem into the GSXR triple clamps, figure out a headlight bracket, and a way to mount the gauges.  I am also going to put some standard handle bars on it.  As it is now, my stock forks suck.  They bottom out on grains of sand.  I checked out the weight of the GS, and the GSXR, and they are pretty close.  The spring rate should be about right.  We're talking 2 finger stoppies.  I will let you know how it works out.  I am a machinist, so it isn't going to be a hack job. 

When I did a 96-99 GSXR750 f/e, I had the gix stem turned to fit the GS. The GS stem is 0.5mm smaller in diameter than the gix and would not press into the gix lower triple. You can weld the GS stem and turn it to fit. The gix stem is very easy to turn to fit but you will need a lathe that can cut metric threads. One thread is 25x1.0 and dies are not made. Luckily I have access to a tooling shop. Also, I have a drawing of the stem if you need it.
Title: Re: Inverted forks, why?
Post by: corndog67 on June 11, 2006, 07:20:01 PM
Thanks dgyver, but I am a machinist in what I consider the baddest ass machine shop in the state.  We've got the machinery to do almost anything.  Metric threads included.  I will let you guys know when I am done.  It's going to be a  little while, we are way behind at work, so it's overtime for a while, then I will be able to do it. 
Title: Re: Inverted forks, why?
Post by: makenzie71 on June 11, 2006, 07:23:21 PM
The stem really needs to be turned down?  I thought it fit through the stock steering head...?  I know two people who've got GSXR forks (late 90's 750 on one, K4 1000 on the other) and I could have sworn they said they only have to get a different bearing set.
Title: Re: Inverted forks, why?
Post by: corndog67 on June 11, 2006, 07:30:16 PM
I will let you know what it needs when I get in there and start measuring.
Title: Re: Inverted forks, why?
Post by: werase643 on June 11, 2006, 07:42:18 PM
Quote from: makenzie71 on June 10, 2006, 10:06:23 PM

You need a bearing kit...it'll cost about $75 as a whole for good bearings if you have a later GS.  The earlier 500's have ball bearings iirc...the newer E's should use rollers.

Bikebandit and ronayers both carry headlight mounts that stick an SV style 7" light to the GSXR inverted forks.  Sign up on TLzone and PM DRZDoug about how he mounted the guages...not too sure.

Oh yeah...and it's "inverted" forks.  There's nothing "upside down" about them.

mak, all GS500's came with tapered roller bearings in the steering stem


http://houseofmotorcycles.bikebandit.com/partsbandit/oem_schematic_view~schem_dept_id~723994~section_dept_id~1~section_dept_name~OEM+%28Stock%29+Parts~dept_type_id~2~model_dept_year~1989~model_dept_mfr~Suzuki~model_dept_id~703240~model_dept_name~GS500EK.asp

as shown in the 89 parts schematic

and they are fine for reuse in a GS
also bike bandit lists them for about 45 bucks

Title: Re: Inverted forks, why?
Post by: makenzie71 on June 11, 2006, 07:43:35 PM
yeah they're fine to be reused...but not if you fit an unmodified stem from a different bike through them.  That's what I was sayings...Oh and I got my 500's mixed up...the early EX500's had ball bearings.
Title: Re: Inverted forks, why?
Post by: dgyver on June 12, 2006, 04:56:30 AM
Quote from: makenzie71 on June 11, 2006, 07:23:21 PM
The stem really needs to be turned down?  I thought it fit through the stock steering head...?  I know two people who've got GSXR forks (late 90's 750 on one, K4 1000 on the other) and I could have sworn they said they only have to get a different bearing set.

It does fit through the head but if you want to use the GS bearings, the stem needs to be turned. Plus it is too long. I shortened it by about 20mm (just a rough dimension).
Title: Re: Inverted forks, why?
Post by: werase643 on June 12, 2006, 05:23:10 AM
And the kewlest part was ....
Dgyver did 2 gsxr stems at one time
therefore my bike is looking good with the srad front on it.

missed ya yesterday for lunch,  D.

we just drove on thru and got home about 5
Title: Re: Inverted forks, why?
Post by: makenzie71 on June 12, 2006, 07:49:42 AM
Quote from: dgyver on June 12, 2006, 04:56:30 AM
It does fit through the head but if you want to use the GS bearings, the stem needs to be turned. Plus it is too long. I shortened it by about 20mm (just a rough dimension).

Yup...just got off the phone with one of my buds a bit ago and he said the same...he said it was cheaper for him to just get bearings to fit it.  He's gonna get the part numbers for the bearings fior me later.
Title: Re: Inverted forks, why?
Post by: Jake D on June 12, 2006, 08:21:02 AM
There really is no difference between saying upside down and inverted.  They mean the same thing.  As a matter of fact, invert means to reverse the position or turn upside down.    But whatever. 




Title: Re: Inverted forks, why?
Post by: CirclesCenter on June 14, 2006, 12:30:12 AM
If it bouces woth e wheel it is unsprung, if it bounces with the bike it is sprung mass.

No tolerance left to exaplain, just know I am right ok?!?!?
Title: Re: Inverted forks, why?
Post by: werase643 on June 14, 2006, 05:44:19 AM
Quote from: makenzie71 on June 12, 2006, 07:49:42 AM
Quote from: dgyver on June 12, 2006, 04:56:30 AM
It does fit through the head but if you want to use the GS bearings, the stem needs to be turned. Plus it is too long. I shortened it by about 20mm (just a rough dimension).

Yup...just got off the phone with one of my buds a bit ago and he said the same...he said it was cheaper for him to just get bearings to fit it.  He's gonna get the part numbers for the bearings fior me later.

MAK, DO NOT START TALKIN EX CONVERSIONS HERE!!!!!!!!!!
parts from kaw/honda swap easily
same for yam/suz
when we are talkin front ends
the kaw lower has a 28mm ID and the yam/suz has a 30mm
you will start confusing the masses
Title: Re: Inverted forks, why?
Post by: octane on June 14, 2006, 05:56:04 AM
There's a great stem/bearing conversion chart here: http://www.ohiocaferacers.com/  Just click on the tech tips link.
Title: Re: Inverted forks, why?
Post by: werase643 on June 14, 2006, 06:21:18 AM
Quote from: octane on June 14, 2006, 05:56:04 AM
There's a great stem/bearing conversion chart here: http://www.ohiocaferacers.com/  Just click on the tech tips link.

dan that is a good site....
Buff  MOTORED ME down the front straight at VIR on that ratty CB350 of his!!!!
he can ride the wheels off that bike

but there are some new sizes that are at brg distributors....that have hon ID and SUZ OD
came out about 3-4 yrs ago....or somebody actually searched and figured a standard bearing for some tractor works on a bike conversion
Title: Re: Inverted forks, why?
Post by: Stephen072774 on June 14, 2006, 06:51:30 AM
Quote from: bargovic on June 10, 2006, 06:01:55 PM
It has inverted forks, which i think look awesome.  But whats the benefit of having them over a regular fork ? more travel ? And has anyone put them on a GS?

I'm not sure about other bikes, but the USD forks on my drz are 4-way adjustable.  Its nice to be able to dial in your suspention, but having so much adjustment can be a little overwhelming...  I might be playing with different settings for years :laugh:
Title: Re: Inverted forks, why?
Post by: werase643 on June 14, 2006, 07:01:27 AM
most modern street USD
are fully adjustable for preload/compression/rebound

i do not think the hyosung is adjustable.....but it isn't really a modern street bike
Title: Re: Inverted forks, why?
Post by: octane on June 14, 2006, 07:48:45 AM
Quote from: werase643 on June 14, 2006, 06:21:18 AM
Quote from: octane on June 14, 2006, 05:56:04 AM
There's a great stem/bearing conversion chart here: http://www.ohiocaferacers.com/  Just click on the tech tips link.

dan that is a good site....
Buff  MOTORED ME down the front straight at VIR on that ratty CB350 of his!!!!
he can ride the wheels off that bike

but there are some new sizes that are at brg distributors....that have hon ID and SUZ OD
came out about 3-4 yrs ago....or somebody actually searched and figured a standard bearing for some tractor works on a bike conversion

I searched high and low for a bearing that would have allowed me to swap the 'busa front end onto my XS11 without having a stem made - NOTHING! The bottom bearing is the same, the top was different, but the OD/ID was an odd combination and I couldn't find any tapered bearings with the right measurements. I could have had some manufactured in China though! Not sure what I'd do with the 4,999 bearings I'd have left over though...damn minimum orders! I ended up having a stem made. It's damn pretty too...and kinda pricey...too bad I can't even look at it now that it's installed!
Title: Re: Inverted forks, why?
Post by: makenzie71 on June 14, 2006, 06:43:57 PM
Quotewerase643
MAK, DO NOT START TALKIN EX CONVERSIONS HERE!!!!!!!!!!
parts from kaw/honda swap easily
same for yam/suz
when we are talkin front ends
the kaw lower has a 28mm ID and the yam/suz has a 30mm
you will start confusing the masses

Only one here confused is you, man...:dunno_white:  Only reference made to the EX's was when I got confused on early model bearing styles.