GSXR Conversion/Swingarm Questions

[Sc0ttzi]

I just bought another 79 GS1000 and I was planning on doing something similar to what 80GS1000 did with his. Although, I would like to keep a dual sided shock swingarm on it to keep more of the old look, and because I would like to be able to mount dual Ohlins su143's. Does anyone know of a good swingarm that would fit any of the later GSXR wheels, be something of a straight bolt on to the frame, and would be a decent doner for having shock mounts welded on or has shock mounts already? I know I've seen someone with a Bandit swingarm on an 1100, I'm just not sure how well it would work for the older 1000, or how long it would be comparable to the original swingarms length. Also a question about the front end. If I were to purchase any complete 00-08 GSXR1000 front end, would it just bolt on without any modification (other than being resprung and having steering stops welded on the frame)?

 

[jwhelan65]

Conversion

Conversion

Check with Rob Wilton (katman) he is an excellent source. His email is rob@robwilton.com. Check out his website for some details under Tech at robwilton.com. He walked me through my rear conversion.

 

[TheRooster]

I got a GS1100 Aluminum Swingarm

 

[makenzie71]

Look for a TL1000S or TL1000R swingarm...preferably the R because the braced swingarm looks so much cooler.

Anyway...the tops of the TL swingarms are flat and about 1.25" wide, they accomidate a 6" wheel, and they're short. A lot of linked suspension swingarms are longer and the TL's had a rotary damper setup that didn't require that extra length...makes them ideal for this kind of thing.

I used an R swingarm on a CB900 project. I took some heavy guage box tubing and cut out mounts for the bottoms of my shock. I then just drilled the swingarma nd bolted the mounts through the spars. held great. Looked great with the 6" wheel, too.

 

[80GS1000]

If you want a 00+ GSXR front end, you have to monoshock the rear. This is because the newer front ends are so short that with a dual shock rear the ride height is unacceptable for anything except for a drag bike. With mine I was able to adjust the ride height and headstock rake angle to the correct and appropriate levels by the position of the monoshock frame mounts. It was quite the lowrider with just the 04 GSXR 1000 front end.

Others have had luck with using a Bandit 1200 swingarm with shock mounting lugs welded on combined with a GSXR 1100 front end. The B12 swinger lets you use your desired dualshock rear setup and the GSXR 1100 front end is almost the same length as the GS front end so you preserve ride height. The B12 rear wheels have that nice looking 3 spoke design too.

Here's some more info: http://www.robwilton.com/xtech.html

 

[makenzie71]

If you want to maintain stock height you can run with a dirtbike setup...I've done that as well, but finding adequate springs can be nightmarish. I used a CR250 front end on that same CB900 job but I had beefier springs...

 

[Mark M]

If you want to maintain stock height you can run with a dirtbike setup...I've done that as well, but finding adequate springs can be nightmarish. I used a CR250 front end on that same CB900 job but I had beefier springs...

What did you do for brakes? Or did you just run one disc?

Mark

 

[makenzie71]

At the time there were no brakes. I ran a CBR600 enkei wheel up front...had I had time to tweak before ditching the project I would have pulled one of the discs and cut a hanger to relocate the caliper to fit the other properly.

 

[Sc0ttzi]

I'm a little confused with what you mean by "low rider" with the front end being so short. Is it that the bike leans too far forward with a dual sided shock swingarm? If this is the case would it be possible to reposition the shock mounts, or to used shorter shocks?

 

[TheCafeKid]

I'm a little confused with what you mean by "low rider" with the front end being so short. Is it that the bike leans too far forward with a dual sided shock swingarm? If this is the case would it be possible to reposition the shock mounts, or to used shorter shocks?

You really start messing with the geometry of the bike at that point. Swapping over to "modern" front and rear on the GSs is pretty common, and the best ways to go about it seem to be what 80GS1000 suggested, as well as isleoman, Katman, and a few others. I am in the process of collecting the parts to do some conversions myself on my 1100ES, tho i will be using 88 GSXR1100 wheels, which look just like stock, except can accomodate a 150 or 160 rear, and a 110 or 120 front tire. I will also be able to modify the STOCK GS swinger to accept the set up, which will make it look even more stock. Incase you havent figured it out, MY goal is to improve handling a bit, while maintaining a damn near stock look.

If you mess with the geometry on these old frames alot, you are setting up for trouble, as they simply cant deal with the flex, and no bike feels good in the corners when the frame feels like it has a hinge in the middle.

 

[80GS1000]

I'm a little confused with what you mean by "low rider" with the front end being so short. Is it that the bike leans too far forward with a dual sided shock swingarm? If this is the case would it be possible to reposition the shock mounts, or to used shorter shocks?

The shorter front forks cause the bike to ride lower than stock. A couple of pics to illustrate, this is very early on in my project just after the GSXR 1000 front end was installed. There was only had 2" of ground clearance under the header.

In order to get the Gixxer front end to work I had to raise the rear end by monoshocking and making a custom 4-2-1 header so there's enough ground clearance under the exhaust (about 5"). To my knowledge there aren't rear dual shocks long enough to make a GSXR 1000 front end work, maybe you'll pioneer this.

To preserve stock ride height with a dual shock rear setup you probably want a GSXR 1100 front end.

 

[TheCafeKid]

The shorter front forks cause the bike to ride lower than stock. A couple of pics to illustrate, this is very early on in my project just after the GSXR 1000 front end was installed. There was only had 2" of ground clearance under the header.

In order to get the Gixxer front end to work I had to raise the rear end by monoshocking and making a custom 4-2-1 header so there's enough ground clearance under the exhaust (about 5"). To my knowledge there aren't rear dual shocks long enough to make a GSXR 1000 front end work, maybe you'll pioneer this.

To preserve stock ride height with a dual shock rear setup you probably want a GSXR 1100 front end.

Approximately how long would they have to be, the dual shocks? I have seen them in as long as 15inch lengths...thats 2 inches over stock of the GS shocks...still not enough?

 

[80GS1000]

If you mess with the geometry on these old frames alot, you are setting up for trouble, as they simply cant deal with the flex, and no bike feels good in the corners when the frame feels like it has a hinge in the middle.

+1. If you start going with more rigid, newer running gear (forks/swingarm) frame bracing becomes almost a necessity to get the maximum gain from the upgrades. Especially if you like cornering aggressively. Can't have stiff running gear and a spaghetti frame.

 

[tone]

For a gs i'd go for a gsxr1100k or bandit 12 front end as they are long enough to maintain ride height but you will need to mess with bearings etc (both normal forks btw) if i wanted usd forks the first choice has to be gsxr1100wp as they are also the right length & a direct fit

ive done all the above swaps a few times so am speaking from experiance, buying a complete front end is always preferable as theres no messing around making wheels brakes etc fit

you can get a 4.5" wheel & 160 tyre in the stock swingarn easilly enough & a 5.5" with a 180 is possible but not at all easy if keeping the stock arm, i've seen zrx1100 twin shock arms fitted too but cant comment on that as ive not done it, basically any mono gsxr arm will go easilly enough if you are willing to go the mono route

hope it helps

 

[Sc0ttzi]

80GS1000, my question now is would you have a guess as to how much the shock mounts on a dual shocked swingarm have to be jacked to reach the same height as your bike if you were to used stock, or stock length shocks?

 

[80GS1000]

80GS1000, my question now is would you have a guess as to how much the shock mounts on a dual shocked swingarm have to be jacked to reach the same height as your bike if you were to used stock, or stock length shocks?

Get everything mocked up with the suspension components and steering geometry you want to use and the numbers for your shock length/shock spacer blocks will fall into place on their own.

Reverse engineer and/or research the steering geometry numbers from a newer bike whose handling you like. The mechanical engineers at Suzuki have already figured out what works best so it's best to copy their steering geometry numbers. I like the way the GSXR 1000 handles so I set up the GS1000's new geometry like the GSXR 1000. Once the steering geometry was correct on all fronts, we welded in the new shock mounts.

Do this carefully and with precision and you'll get a sweet handling bike, do it wrong and you might wind up on your ear, be careful.

Things to consider when designing and building your frame/suspension geometry:

*Rake, trail
*Ground clearance
*Swingarm angle and chain to swingarm clearance
*Forward/rear weight distribution
*Chain offset to clear larger rear tire
*Front/rear wheel alignment

Here's a handy steering geometry calculator, was very useful when I set up my chassis: http://www.papkegroup.com/superbikeengco/superbikesupensionkinematics1.html

You'll want to use a swingarm that doesn't have bracing on top of it because that will get in the way of welding on shock mount lugs.

 

[jwhelan65]

I agree with Tone...get the complete front end, I tried piecing together a GSXR 1100 front end for my GS 1100 conversion. It was kind of a nightmare....you end up without things like missing caliper bolts, missing fender bolts, no fender frame, pitted leaky forks you can't really add new seals to, a front wheel that's bent, the wrong rotors and oh yes.. $400.00 poorer with a bunch a stuff you cant use.....I found a complete front end with only 6000 miles....solved all my issues!!!!

 

[Guest]

Something you have to watch. YOu can't just jack the backend up as high as you like. If you go to high your chain will make a right turn around the pivot of your swingarm and "CHAINSAW" through it.
some guys have put rubber or balistic nylon on there to keep the damage to a minimun but, with your chain dragging across the pivot area guess what happens when you crack the throttle and that chain wants to straighten out?

With a bandit arm you can only raise the back end about an inch and a half before the chain impacts the swingarm and that doesn't do much for increasng header height at the other end of the bike.

of course this may be different with different swingarms. But its something you have to be careful of.

92-98 gsxr 1100 forks are 30.5" long. very close to your bike now. you can use other clipons (not the 1100's) or you can use risers and drag bars to take advantage of the whole length of the forks.
I believe '88 gsxr 1100 forks are also 30+" and a set of 18" wheels will put you pretty much at stock height.

 

[makenzie71]

Just for the sake of noting...an acquaintance of mine has a k4 1K front end on his GS750 with dual shocks. He's using RM250 shocks. He's trying to sort out what year for me.

 

[Guest]

What is the stock length of gs750 forks? the k4's are only 28' aren't them?

With a katana the forks are 31.5" and 19" wheel. so you lose 4" which is unacceptable to anyone who likes to corner.

They sure do look good on the gs though. I am wanting to mount a radial front end on my kat but haven't got the height loss figured out yet. I can do it if I turbo the bike which is a good idea anyway.....Then I have no header to worry about.