I have been searching the forums and the www and found some pictures/info on GS500s with different swingarms. It looks the the Suzuki RGV250 VJ22 arm and the GSXR 93-95 swingarms have been installed on the GS chassis. I was just wondering if anyone knows if these swingarms are about the same length as the GS. As I understand it, if the front is to be maintained at the same rake and the swingarm length changes the angle of it changes as well which may alter the anti-squat behavior of the rear suspension. Alternatively does anyone know the anti-squat ratio/percent or have measurements of the rear geometry?
Edit: Or could someone tell me the angle of the stock GS swingarm at rest?
You need to ask yourself why you want to change your swingarm. ie. what do you know that the Suzuki engineers who designed it didn't know?
With that logic, why change the airbox? The front forks? Seats, springs, tires, and exhaust?
Bing-bong.....Ken to the front desk, Ken to the front desk please
My motivation to change the swingarm (suspension) is for both aesthetics and performance.
I don't know more then a team of engineers. I can however assume that the engineers probably had to make many compromises in the design. Low cost was probably a large influence on the design and a reason for the material selection (i.e. steel instead of aluminum) of the swingarm.
Quote from: jacob_ns on March 28, 2011, 07:13:38 PM
With that logic, why change the airbox? The front forks? Seats, springs, tires, and exhaust?
Yes, why?
Because, if you've thought it through, and the economics of an improvement makes sense to you, go for it, I have no problem with that. But once in a while there are posts that suggest IMHO that the poster hasn't thought it through, so I question it.
My motivation is to avoid having people waste their time and money on mods that maybe will not give the improvements they are hoping for.
(OP posted above while I was writing this, but I've posted it anyway as a general comment.)
How about a VFR400 single sided swinger? That'd be neat just from and engineering standpoint. I've done swingarms swaps before. Not really a big deal as long as your willing to play with spacing (axles, bearings, etc..). Adjustments can always be made with dogbones to correct for things. What kind of riding will you be doing?
I'm in the process of doing a RGV250 swingarm on my bike. My advise would be, unless you're racing, don't do it. Stocker works well enough.
With that said, I spoke to my suspension guy about this. The main concern regarding squat characteristics is going to be the angle of the swingarm. Anything more than 13 degrees, and the rear wheel is going to tend to want to drive under the bike as you get on the gas.
Swingarm angle can be adjusted by installing different suspension links, or different shocks. The GS500 stock shock is about the shortest direct swap you're going to find, without getting an after-market shock built. The RGV shock will lift up the rear end about 3/4th of an inch, and the GSX-R shock will lift it up a whole bunch (~2".) Katana and R6 shocks are the same length as stock.
I'm not sure how the RGV linkage compares to the GS500 linkage - it may be that the RGV swingarm naturally sits a little lower than the GS swingarm. If so, I'll probably run an GSXR shock, or swap in the GS parts. We'll see.
http://www.tonyfoale.com/
Thanks for the info burning1. This is along the lines I was wondering.
Does the RGV arm need to be at a greater angle to maintain the same ride height and front fork rake, if so what is the effective increase on squat? Alternatively if the swing arm angle is adjusted (with damper or dogbone length) to a proper angle for anti-squat and the forks maintained at the same rake is the ride height reduced significantly? Which leads to a question if maybe the slingshot or early WC GSXR arm is better suited (length) for the GS chassis? I was hoping someone would have measured/calculated this.
Foale's book is a great read. I also highly recommend Cossalter's book.
I'll be able to answer a lot of your questions better in a few days when I've had a chance to install the new swingarm.
Eye-balling the RGV swing-arm next to my desk, it appears to be somewhat similar in length to the stock GS swingarm... But I'm going by memory, not a side by side comparison. I'll provide full details later when I have real numbers to go by.
BTW... If you're doing this for visual reasons... I think the VFR400 swingarm is cooler looking overall - so give it some thought. As you know, the RGV swing-arm is European only... So get used to ordering stuff from overseas, and spending a lot of time searching the net to find compatible parts.
I'll provide as much detail as I can about it.
One bit of good news for now though... The RGV brake calliper uses the same pads as the old gen (88-07) Ninja 250. :)
I just checked: The RGV swing-arm is about an inch longer than the GS500 swing-arm, depending on where you put the axle.
Also, while the RGV linkage appears to be similar for the most part, the bike uses a GSX-R style wishbone - your GS500 links won't work with it without building spacers and/or bearings of some sort.
The part of The Ken now will be played by "The buddha"
As surewin is asking his well thought out and very precise questions a hand expression is being made by "The ken" which is like making a fist and holding it to the side of the body and moving it up an down (sorta like a jerking off action).
After the question is complete and ~2 mins have passed ... brrrrrr (blowing raspberries).
Cool.
Buddha.
burning1, Many thanks. I would have thought just the opposite regarding the length. Good to know.
Who is "The Ken?"
I'm guessing you were referring to this thread http://gstwins.com/gsboard/index.php?topic=55220.0
you can change everything and you can change nothing
the GS does not have the best geometry
start looking at different numbers for different bikes
TZ250... the new moto GP bikes
and work your way towards them
if you understand that you are pissin up a rope before you start...GO FOR IT.
if you want bling....GO FOR IT!
the prob with old skool honda SSSA's no linkage and 800-1200# springs
the GSXR and bandit SA are wider at the swingarm pivot point and use bigger axle and you have to make ugly brackets to get the foot pegs to clear the SA
the RGV is narrower than the GS and bigger pivot axle so some spacer/reducers can be fabbed up fairly easily
I need to make a set for my last RGV braced arm
this is the book you need to answer almost all your questions
http://www.amazon.com/Racing-Motorcycle-Technical-Guide-Constructors/dp/0951292927
then you will determine that you make it as good as you can afford
did I mention something about pissin up a rope? good luck
you probably can skip the chapter on designing new internal gear ratios for individual tracks...but if the budget is there....it would be sweeeeeet
werase643, I have already read a few books regarding motorcycle suspension and physics. Thanks for the recommendation though. After you read the books though you have to apply the material, this means measuring and calculating before doing modification. I have modeled the anti-squat geometry as well as the wheel rate on other motorcycles I've owned/modified, it isn't that difficult. See following picture of CAD drawing and Fortran code.
I mainly modify for cosmetic reasons, but I do my best to maintain or improve performance. I wrench on motorcycles for fun just as a hobby, I'm not relying on this GS for daily transportation or worried about the economic analysis of spending a couple hundred bucks on some mods. Speaking about pissing up a rope, you should see the cafe racer I built. I spent a ton of time on it and it's performance is still worlds behind a modern sport bike.
Quote from: werase643 on March 30, 2011, 07:50:35 PM
the GS does not have the best geometry
Can we steer the discussion in this direction? I would love to talk about ways to improve the suspension geometry. This was my original intent as I was hoping someone already quantified the anti-squat when they swapped the SA.
BTW. I am not looking to invest tons of money into my GS500, or build a totally engineered race bike, but I'm sure I can swap the suspension for a nominal amount, perform basic geometry calculations, and still have fun doing it.
(http://img690.imageshack.us/img690/5334/geometryo.jpg)
(http://img94.imageshack.us/img94/7718/codeys.jpg)
Quote from: Surewin on March 30, 2011, 07:24:06 PM
burning1, Many thanks. I would have thought just the opposite regarding the length. Good to know.
Who is "The Ken?"
The trend on modern race bikes is to stack the transmission output shafts, attempting to make the engine as compact as possible so that you can install a long swingarm without extending the wheelbase of the bike.
One other thing I discovered about the RGV swingarm... The stock RGV sprocket is 4 teeth larger than the GS500 sprocket. So, there's a good chance you'll need a longer chain, but also a good chance that the gearing will work out nicely for street use, assuming you've stuck to the stock GS500 countershaft sprocket.
make it handle like a fat 1992 TZ250 and you will be happy
the number crunching is almost a waste of time
this is thomas edison light bulb design 101, fab a different SA onto a gs and see what it does
then yo can make the measurement points and plug it into your program to determine if it is ideal
then what determines what is ideal squat for a gs?
Quote from: Surewin on March 30, 2011, 08:43:55 PMCan we steer the discussion in this direction? I would love to talk about ways to improve the suspension geometry. This was my original intent as I was hoping someone already quantified the anti-squat when they swapped the SA.
I haven't measured the amount of trail from the GS500 front end, but my impression is that like most entry level bikes, it probably has a centimetre or two more trail than is necessary. On my race bike, I resolved this in part by raising the forks 9mm in the triple clamps. It will be interesting to see what the GSX-R triple I just installed does for the trail numbers, ofset, etc.
At the rear end, the basic suspension design is pretty decent. The stock geometry raises the rear end up noticably when I get on the gas, and provides plenty of additional cornering clearance. I found that a lot of times, getting on the throttle would solve the front end grip and cornering clearance issues I encountered while racing.
Rear end grip seems to be much better than front end grip on this bike. I slid the front end a number of times riding off the throttle. I've only slid the rear end once or twice, even running WOT at pretty extreme lean angles. This may have to do with the tires, suspension, or my riding style as much as anything.
The rear end suspension geometry seems to use a higher lower leverage ratio against the rear shock compared to some newer bikes. E.g. we need fairly stiff springs, despite the fact that our bike is quite lightweight.
Although the linkage on our bike is fairly modern, there is very little clearance around the rear swing-arm cross-member. Physical clearance issues may be what has forced us to run a high leverage ratio suspension design. The RGV swingarm seems to provide significantly more clearance. I'll also be interested in comparing the suspension linkage geometry, to see what can be done with leverage, and ride hight.
I haven't looked a the stock GS linkage or the RGV linkage to comment on how progressive/digressive it is.
Quote from: the mole on March 28, 2011, 07:09:53 PM
You need to ask yourself why you want to change your swingarm. ie. what do you know that the Suzuki engineers who designed it didn't know?
statements like this are ridiculous and willfully ignorant
Quote from: werase643 on March 31, 2011, 05:07:05 AM
make it handle like a fat 1992 TZ250 and you will be happy
the number crunching is almost a waste of time
this is thomas edison light bulb design 101, fab a different SA onto a gs and see what it does
then yo can make the measurement points and plug it into your program to determine if it is ideal
then what determines what is ideal squat for a gs?
I use a much different methodology then persistent trial and error, and the opposite of what you suggest. I find it saves a lot of time and money to first make ballpark calculations to see how to modify the suspension, nothing needs to be exact or ideal just yet. Then when you know the parts can provide satisfactory results you modify and install.
For example, instead of just buying a new front fork set-up and installing it only to find out it is much to short and has drastically increased the rake, first verify that it is going to be a reasonable length then purchase and install. Of coarse rake is a mfg. published number and the fork length is a simple measurement. It gets a little more difficult when you start to swap shocks with different spring rates or when you alter rear linkage or anti-squat behavior.
It's not that hard to determine good estimations for these suspension parameters. Then after your parts are installed, you still have to take it for a ride and see how it handles. Then when you want to make changes you resort back to the analysis to make rational choices. IMHO, this is a much better method then fab and test, repeat. Of coarse if cosmetics is the only motivation, you can skip the analysis. Sometimes you get lucky too, other times you can just copy someone's mods (the later assumes that they either did there homework or got satisfactory results).
Quote from: cd on March 31, 2011, 06:23:50 PM
statements like this are ridiculous and willfully ignorant
:cheers:
That it is a normal response to most out of the box ideas, non-bolt on mods, or any engine related power mods around here. You get used to it. :dunno_black:
Quote from: tb0lt on March 31, 2011, 07:57:39 PM
Quote from: cd on March 31, 2011, 06:23:50 PM
statements like this are ridiculous and willfully ignorant
:cheers:
That it is a normal response to most out of the box ideas, non-bolt on mods, or any engine related power mods around here. You get used to it. :dunno_black:
When you have been around here for a few years like some have and read all the "I am going to fit FI/a turbo/under-seat exhaust/in line 4 etc etc" threads that show up from time to time, then watch as the poster suddenly vanishes off the radar when the enormity of their idea, the lack of forethought and the practicalities involved in actually making it happen sinks in.......you too may become a tad cynical about such claims when you first read them :thumb:
Quote from: sledge on April 01, 2011, 01:08:03 AM
When you have been around here for a few years like some have and read all the "I am going to fit FI/a turbo/under-seat exhaust/in line 4 etc etc" threads that show up from time to time, then watch as the poster suddenly vanishes off the radar when the enormity of their idea, the lack of forethought and the practicalities involved in actually making it happen sinks in.......you too may become a tad cynical about such claims when you first read them :thumb:
I know it can get tiring when you see stuff like this for years and later realize you got all excited for nothing. Still... if you have nothing positive to add to the discussion or what you say is only going to stifle any creativity and energy in the thread.... you could just watch the thread and not post in it. Believe me, I understand how you feel and I also think the same of some posts... but i'd rather not post an utterly useless reply no one wants especially if it doesn't add anything useful or it is just negative and all I'm doing is adding to my post count (like that means crap). This would be especially true for a technical natured post like the OP. No offense. :cheers:
you can design to your hearts content, but, we are working with given entities. swing arms are x in length and y in width and the linkage points are set in....weld or cast. The light bulb methodology actually is skewed. If you have the ability to make a swing arm, make it to your ideal calculations.
If you gather data from many different sources, and do trend analysis of the top 10-20 sport bikes in the last 20 yrs. You will find a set of close majik numbers. there will be some variances due to some mfgs trying to think outside the box....think rotary shock on the TL-R(how did that work....).
The formula... bike 350#....600 or 1000 is in that range now therefore if you use the swing arm and stock linkage for a given platform and adapt everything including mount locations....it SHOULD? work just like it was on the other bike except that it is now on a gutless turd. I don't need cad/calculations to figure that out.
I have no problem with your approach, but all you are doing is recalculating known data. If you are modifying a given swing arm to a GS and adapting to GS links.... then your calculations are valid. The data will then have to be compared to known data from a ideal chassis. If this is still for bling, you are having fun playing with your expensive cad program, again, kewl.
I'm not bashing you(much)
there are only a hand full of nutter ID10TS that will take on the task of spending stupid $ on a turd entry level bike.
FYI....the mad German spent close to 20k building that orange monster.
so a couple of hundred...for a swing arm to try.....
you will get help if you ask realistic questions. If you come up with something outside of the box that works.... post it with results. I thought the triumph sssa bike never would get finished.... that guy did huge mods in a relatively short amount of time with beautiful results.
cheers mate
smoke me a kipper
Quote from: werase643 on April 01, 2011, 08:22:58 AM
If you are modifying a given swing arm to a GS and adapting to GS links.... then your calculations are valid.
Thanks, I'll take that as a complement.
Even if I did swap everything over from a modern sportbike, including relocating the rocker and shock mount as you point out, I would still have to relocate the engine so that the sprocket is in the same position. As chain angle is also a factor in anti-squat.
The CAD program was free, it's an older version of DraftSight (http://www.3ds.com/products/draftsight/free-cad-software/) which is free to download. The Fortran compiler was also a free download.
I never considered my self that extreme in the financial investment or custom fabrication of motorcycles. I've seen plenty of pictures of old CB cafe racers, XS dirt trackers, RD -TZ racers, and chopped Harleys with much greater money invested per performance ratios. I also know amateur level racers spend large amount of money to support their racing hobby. I don't think modifying "turd" motorcycles is really that expensive of a hobby compared to anything else. I think it is fun to make modify things and that it is fun to try to become involved in the design aspect.
My original question was what are the lengths of a RGV or GSXR swingarm compared to the GS. I included why I wanted this information, i.e. I wanted to calculated anti-squat. I though including this would show that I'm not new to this. I though this was a realistic question, buy I am new here so will have to adjust to attitude around here.
I'm taking the swingarm to Gerry Piazza of GP Frame and Wheel today to have a few parts measured and spacers built. I'll see if I can get parts measurements for reproduction.
I had a chance to look at the linkages of both bikes today, and the first thing that was immediately obvious is that the RGV cushion lever is much shorter overall than the GS500 lever. This means that the shock is going to point somewhat more downward than it would with the GS500 lever. It remains to be seen what impact this will ultimately have on the suspension - at this point, my plan is to bolt it on, and work from there.
On the plus side, the bolts are all the same size, and while one of the bushings is shorter, it is a direct swap from the GS500 to the RGV part.
Ken is the daddy when it comes to this sort of thing but you need to be aware that this forum is populated in the main by humble spanner-wan**rs of varying ability and opinion. Not designers or specialists or even individuals familiar with the level of questions you are asking.
With this in mind can I suggest you post the question and ask for advice in here... http://www.eng-tips.com/threadminder.cfm?pid=668 instead.
They just love this sort of thing and you stand far more chance of finding the info and answers you need on your level you are looking for :thumb:
We dont need no shteenkin swingarm, ish jusssh for looks.
Cool.
Buddha.
Please keep me updated burning1, I am working on sourcing a RGV SA and will post my measurements when I can.
I will check out the eng-tips forums, thanks for the suggestion. Crossing my fingers that a few members are GS500 owners.
give or take 1-2 inches
nothing really huge in difference between them mostly how they attach to the frame.
Most of us work with what is in front of us. I used to run to the salvage yard with a tape and a caliper and measured many swing arms. Did I save that data... no. I wonder if anybody considered installing a buell swing arm.... it was a v-twin...so the arm should be narrow at the pivot....
ooooo, under-mount shock working in expansion......
nope, i don't need no more projects
so do you have data for the GS?
any other bikes?
GSXR?
R6?
ZX6?
what is your baseline data?
what is considered bad numbers?
how does the GS compare?
when I was modding
swing arm angle was important 9-13 degrees (i think, been a few yrs)
getting everything to mount was important
making sure the chain didn't saw into the swing arm was important
and an adjustable shock was important
whatever swing arm went on was off of a similar weight bike....therefore, close enough to be able to make adjustments and ride around any problems.
with your calc's, will you make new parts to solv problem or just use info to determine what will not work?
dog bones are easy to fab
rocker links are probably $$ due to the cad/cam required to fab one out of billet.
shock theory....buy a fox/ohlins/penske/elka/....and get it re-valved after you determine what problems are.
after that, you either fab a different swing arm with different mount points or start hacking the mount points off the frame and re-locating them.
good luck,
we will help if we can
but most us us are dum hicks
I am sorry, I do not have the info on the RG-V SA....I'll try to get it this weekend.
what year GSXR swing arm do you want info on
600/750/1000/1100
what year?1985-2011
many variables
old skool 1100's were 1-2 inch longer than same year 750
I have some 86-87 SA's but the linkage on them is weird.
if you get to the point where you have to move the engine.... don't waste your time/money using a gs lump. KTM DUKE/KL-R/DR650(DR800)/XR650L/Raptor 660
and build a frame to go around a worthy power-plant and go with the ultimate SOS bike(drool...) and build around the 225# goal.
RG-V 21.25-22.5 inch
87 GSXR11 22.25-23.5
87 GSXR7.5 21.75-23
chain adjusters will make a slight difference in the calcs
Well... I had the RGV spacers machined up this weekend, and mounted the RGV swingarm to the bike during lunch at my trackday. Best I can tell, is that the braced RGV swingarm isn't really a direct bolt on. I had very limited time to investigate, by initial impressions is that the RGV dog-bones may raise the rear end way too high. Never managed to bolt things up, since the swingarm would not clear the shock, no matter what link I used.
Major issue with the RGV double braced swingarm is that the linkage is not based around a couple of easily machined bones like the GS500. It uses a set of bones that are welded together at the swingarm end, similar to the linkage used on newer GSX-Rs.
http://www.cmsnl.com/suzuki-rgv250-1993-p_model14009/partslist/FIG54A.html
When I have more time, I'll mock up the swingarm to confirm. *If* this issue can be resolved using new linkage, and *if* I can find a set of cheap compatible links I'll try proceeding. But right now, I think the best approach may be to trade my braced swingarm with someone who has an older bananna swingarm that uses traditional links.
FWIW, my overall feeling on this project is "don't bother." I'm pretty deep into the hole on this one, and I'm going to be very surprised if the performance advantage is worth the cost and effort.
03 gsxr 1k arm that i just scrapped....22 - 23
I made some progress on my swingarm swap and analysis. I'll keep this short as I'm sure most people don't care about engineering principles or modifying turd motorcycles.
The RGV VJ22 swingarm fits will little trouble. The RGV swingarm pivot bolt is 20mm, the GS is 14mm. The RGV SA pivot length is smaller so you need to add ~ 5mm spacer on both sides. The GS rocker will work fine with the RGV dogbone is you trim the metal sleeve for the dogbone bearings, about 1.25mm per side. The dogbones are really close to the the rocker, but it is fine. The RGV dogbones are too short, as already noted. For my setup they needed to be about 6mm longer.
As for the analysis, I did measured the GS frame and rocker, along with my other suspension parts. I'm not using GS wheels, GS forks, GS rear damper or the same gearing, or even drive sprocket location so little can apply to the stock GS. However it does show some trends. It also provides direction to further modification.
I am showing two plots below. The first shows the wheel force as it varies with suspension displacement. You can see the suspension maintains a progressive nature (i.e. slope deviates from 45 degrees). The second plot shows the anti-squat behavior. Where squat ratio is the ratio between the tangent of the load transfer angle and the tangent of the squat angle. Both look like they need a little adjusting.
(http://img853.imageshack.us/img853/8599/gswheelrate.jpg)
(http://img197.imageshack.us/img197/4414/gssquat.jpg)
I welcome any discussion.
I'm still a little unclear as to what kind of suspension progression is ideal. What I'm seeing now is that 0-15 percent is a pretty typical range, but... Not entirely sure. I really should pick up Tony Foyle's book. I have a copy of Motorcycle Dynamics by Vittore Cossalter, but it didn't seem to have a really in depth discussion on suspension design.
I'm not sure what is best either. From what I have read it seems race bikes favor a more linear nature, whereas street bike tend to use progressive wheel rates. I would enjoy learning more about what typical race and street bike use.
I did a little more work on this project, with some mixed results.
1. It looks like the dogbone from the 06-10 GSX-R 600 & 750 is mostly compatible with the RGV linkage, and it's just about the perfect length to preserve the stock ride height using the RGV swingarm. I prefer this approach to re-welding the upper shock mount, as it will keep the linkage at it's stock orientation, preserving the damping rate curve. The linkage looks like it will bolt on by swapping the RGV inner spacer into the GSX-R linkage (same OD, and ID, different length.) The lower end of the dogbone may need to be machined down to fit the GS500/RGV rocker arm.
2. It looks like there are all kinds of clearance issues with the RGV swingarm, especially with a R6 shock installed. One of the chain guards hits the R6 reservoir, and it appears that the upper brace of the swingarm will hit the piggyback reservoir under compression. These first issue is easy to resolve - remove the chain guard. Second issue is harder - and may only be resolvable with a shock swap. I have an 06/07 R6 shock installed. An 08/09 shock is slightly different, and may offer the clearance we need.
3. As mentioned earlier, the GS500 rearsets need to be offset to clear the swingarm.
4. With the spacers that Gerry fabbed up, the RGV swingarm barely clears the exhaust.
5. It looks as if the passenger peg brackets interfere with the RGV swingarm. Right side should clear on my bike, but left will not. Left peg is going to need to be cut off, which I am not pleased about.
My general feeling on this project right now is: It's probably not worth the cost.
Nice find on the GSX-R dogbone. Looks like a nice cast aluminum piece.
So is the GSXR dogbone part might be too narrow to fit the GS or RGV rocker? Both the GS and RGV (VJ22) rockers are about 85mm where the dogbones attach.