gs1100e swingarm conversion swap to my 78 gs400x

[Chuck78]

Heck, with the dust caps off in this picture, you can see that you could practically use the step cut from where the dust cap sits to use as a guide to hand file the sides in to that dimension! Then you would need to figure out an alternate way of sealing the bearings. Cutting it narrower with a specific size of washer in mind with a large I.D. & small o.d. & then placing an o-ring in there, & then a slightly thinner washer bored out on the inside to the side of the o-ring...??? Hmmmm.... Probably would require frequent lubrication to not bind & wear/year o-ring, unless o-ring fit wasn't very tight at all.

Hmmm... I wonder how this twin shock 1981 Suzuki DR500 swingarm measures up????

[Chuck78]

I remembered reading this swap a few years ago

Re: Gs1100 swing arm swap onto Yamaha XS650 (pics)

---

The swing arm is about a inch too wide at the pivot point. So I have decided to modify both the frame and swing arm. One reason is the the swing arm is machined on the inside of the pivot tube to receive the bearings but only so deep. Their is about a 1/4" you can press the bearings deeper. So I took about a 1/4" from each side. In the pics below you can see a before and after I ground. The machining on the outside of the tube is where the dust seal sits and will need to be redone .


Now I need to grind the frame are about a 1/2". What I'm not sure about is how to go about grinding the frame so it's square and swing arm remains centered in the frame....?
One idea I have is to completely grind the factory spacers off. Then use the lathe to make spacers to center the swing arm?? What you think?
Here is a pic of the bike it is going on

[theironlung1976]

I got a question in to junkboy66 about that very swingarm (recognize the pic on ebay) to see what the widths n lengths r. For the price id b better off goin w one of those aftermarket swingers u pointed out. I can buy em from that motorcycle salvage yard for 125 so if it measures up, thats where ill b pickin it up. Unless someone here has em cheaper.

[theironlung1976]

If the dude from the xs build is sayin he can seat the bearings another 1/4" on each side that gives me a 1/2" right there. All i would need is to pull 1/8" (in rough tape measured dimensions anyways) off each frame bushing n it would fit... and deal w the seals obviously w that shouldered end on each side of the pivot... and deal w a bigger pivot bolt. It might work! Just wish i could talk to that dude u were gonna buy that project from about it. The answer is there.

[Chuck78]

If you were able to find any monoshock aluminum swingarms that would have a better width at the frame pivot, you could always get a small chunk of billet aluminum and drill it for an interference fit to fit in a pair of spherical eye bearings of the same i.d. as the stock shock bolt's shoulder o.d., something that would look like this:

By interference fit, I mean drilling the holes in the blocks to be .001-.003" smaller than the room temperature o.d. of the eye bearings, and then immediately after welding aluminum in, or immediately after heating the aluminum with a torch to 180 degrees or more (using an infrared thermometer to test), then press in the eye bearings. When it cools, it will be a tight press fit. You could drill it as close as possible to the size and use permament locktite while pressing the eye bearings in, but that stuff also requires 250 degrees of heat to remove it.

[Chuck78]

After seeing that the GS1100E swingarm has been narrowed to fit a Yamaha XS650 frame, I searched Yamaha XS650 aluminum swingarm. Seems that the almost direct bolt in for that is using aftermarket swingarms made for the Yamaha SR500 SR400 XT500 and TT500. ProFab and MotoLanna make them. Not as long as the GS1100E, which was a big bonus, as you said stock you can get the front wheel easily off the ground in 1st AND 2nd gears... half the reason to upgrade when upgrading the engine substantially as well.

Here are some photos.
Pro Fab SR500 swingarm:



$675 Kawasaki H2 2 stroke aftermarket swingarms:

http://www.usa2strokers.com/forum/forum_posts.asp?TID=37644&title=kawasaki-h2-aluminum-swing-arms-for-sale-pics

MotoLanna makes very nice swingarms for the Yamaha DR500/400/tt500/XT500 that also reportedly fit the XS650:

SuperLite version:
http://www.motolanna.com/ourshop/prod_2637748-Swingarm-Aluminum-Alloy-SuperLite.html




SuperTuff version:

http://www.motolanna.com/ourshop/prod_448876-Swingarm-Aluminum-Alloy-SuperTuff.html

I'm not sure why the Yamaha SR500 units have the right side offset inward near the pivot, but I assume the rear end is centered on the pivot. You will have to research this yourself and find out what the actual width of the units are after as well as the length center of axle adjustment to center of swingarm pivot bolt. The axle is a 17mm for these but the slots can me modified most likely.

[Chuck78]

Someone else has done it years ago, and another person that posted this had considered it:

http://www.thegsresources.com/_forum/showthread.php?91893-Narrowing-swingarm&highlight=swingarm

I have used those bicycle head tube/bottom bracket facing tools that they refer to the cutting heads of. I don't know if the tool itself would insert through the swingarm or not, but some other fixture could be made on a lathe or with some threaded rod to use the cutting heads at least.

Here are details on a steel GS500 swingarm swap, only about 0.200" wider than a GS450, and you'd have to weld on shock mount tabs (easy, no biggie on this one)

The GS450 swinger is something like 8.25" wide at the pivot and 18" long to the center of the axle adjustment. The GS500 should be about 8.425" wide at the pivot and 21.5" to the axle. The extra length is all in the section between the pivot and the monoshock mount. Here's an idea of what it looks like on a GS450 S/E model (converted to monoshock and modern wheels):

Well, the GS500 is steel (not aluminum) so it would be pretty easy to add shock mounts. Just food for thought...

Just checked: over the dust caps, the pivot point on the GS500 swinger is 8.626" wide. Without the dust caps, it is 8.375" wide. On the plus side: there is enough material on the sides that you could cut some of it off to fit the GS450 frame.

[Chuck78]

Bandit 400 swingarm, eh????

Looking in to doing a modern setup on our AHRMA GS425 Superbike Lightweight for this race season. From what we've heard on our end is that the front end and swingarm from a bandit 400 should bolt up w/o too much trouble to a GS425. Has anyone done a modern swap on a GS400/425?
joe bridgeport

This is for the larger cc bikes, not the Bandit 400, but a Bandit 600 or 1200 swinger into a 4cyl GS frame:

You can buy everything complete from Katman http://www.parts.suzuki-katana.com/ however I like to do things myself. Also I hate badgering Katman/Rob for info since I'm not buying the components from him. I did get some parts from him for my ES Sprocket/spacers. I've asked around on the forum and have got some info from members and from past builds.

I had these cut by a local machinist after I came up with a drawing with measurements.




I estimated some, but Jwhelan65 was nice enough to give me some better measurements of the mounts.

Height 35mm
Length (base) 50mm
Width 20mm
ID for bushing 22mm
Bushing ID 10mm
Bushing length 22.5mm

I centered the bushing with 5-6mm of meat on the upper part of the mount.

Seems like alot of the bandit arms I've seen have the mount located directly over the weld before the axle:



However, on a stock 1100 arm the Shock mount center to center of the pivot bolt is right at 18.5" or ~470mm which would place the mount location on a bandit arm here in stock format:



About 3/4-13/16 of an inch further forward.

Additionally, it seems that longer shocks are used when the mounts are over the weld:

Posplayr mentioned

"Alot of guys are running 14.0+" long shocks to quicken the suspension.

The SU-145 are about 350-370mm vs. 330 for the SU-143's which are closer to the 13" OEM's."

So for stock length shocks...move the mounts forward from the mount a bit that is assuming guys are running longer than stock shocks.



On a stock arm the measured from the outside of the mounts on either side is right at 12". I'm using a 1000 arm for reference.




Measuring the width of the Bandit arm from the outside edge of each leg is 13" give or take a 16th.

Measure a half inch in and you should be 12" from the outside of each shock mount. Which would place the mount this far in from the edge of the arm:




Some of this is conjecture and my measurements might not be 100% correct (me using a ****ty tape measure...) but it at least is a start point, and if others would like to take some measurements and or add some input that would be great.


Nic

[Chuck78]

The Bandit 400 swingarm is 220mm wide with dustcaps installed, as is the RF900R swingarm. B4 is steel and possibly the same as a GS500 arm, where the RF900R is aluminum. Both monoshock.

Not sure if the RF900R could be narrowed much. I'll have to try and get a more exact measurement on the inside frame width on a GS400/425/450. If you chop off the monoshock mount, you might just have your donor material to make two twin shock mounts for a lower clevis mount!

Also with this setup, modern sport bikes run an underslung rear disc caliper, so you could retrofit that or also use the brake stay for your drum with minimal or no modification.

[theironlung1976]

Ive read that thread "lightweight swingarm". I think thats what got me on this path. As big rich pointed out, its steel and i really wanted lighter. I was going to just lighten the original swingarm by lightening holes in the gusset. That article got me lookin into the 1100e. If i could land one cheaper id just git one n try makin it work. Every aspect of it BESIDES the pivot width fits the build perfect. Monday im gonna run up to the salvage yard n do some measuring of some of the swingarms that might work... n take my 400 swingarm w me for comparison.

[Chuck78]

Hey Larry I'm chatting with my machinist bud about how to narrow the swingarm. I'll let you know what he thinks & if he has time to do 1 or 2.

The dust cap step is going to be difficult - that piece was turned in a lathe before it was welded on. I'm thinking it'd be much easier to drill/ream & dremel sanding drum out the bearing recess a little deeper, and find a seal to fit the o.d & i.d. requirements with maybe a spacer the same o.d. & i.d. as the inner race.

[John Park]

Considering that it's an early style GS400frame you may want to consider this thread:

file://localhost/Users/johnpark/Desktop/GS400:450%20frame%20reinforcement.webloc

Pretty easy fix; nothing that the factory didn't get around to later, and you don't have to worry about how tidy you are considering where it is.

If the link doesn't work, the thread is in page 2 of the modifications forum.

[Chuck78]

Great write up! I was well aware of the common frame bracing for the 4 cylinders that was shown in the two diagram photos posted by hillsy (referred to here as "OSS bracing" as it's origin to reach us was the now defunct OldSchoolSuzuki.info board/website (Skool with a "k"?)

I was not aware of the lack of triangulation by the coils, thank you very much on this tip!

[John Park]

Great write up! I was well aware of the common frame bracing for the 4 cylinders that was shown in the two diagram photos posted by hillsy (referred to here as "OSS bracing" as it's origin to reach us was the now defunct OldSchoolSuzuki.info board/website (Skool with a "k"?)

I was not aware of the lack of triangulation by the coils, thank you very much on this tip!

I've had both frames and the new one is way more secure when leaned over in bumpy corners, and just feels more stable overall. I'm also suspicious about the triple trees on the old one; I feel like the new ones have a bit more trail, as if they used the 19" trees with an 18" tire on the original. I've ridden the early frame with a 19" front wheel and it felt better. I don't have both here to measure.

The early tanks don't fit the later frames; in some ways you're better off starting with an early frame and doing what's needed as you get a longer rear for example.

I don't think you need to get too involved in gusseting the front end as per hillsys diagrams; that's more for the heavy big fours, and once your frame doesn't flex, adding more stiffness is irrelevant. Just getting it to 1982 level is stiff enough for me, and I live in the land of bumpy mountain roads.

Great thread by the way; you've acted upon my wicked thoughts. Inspiring.

[theironlung1976]

Thanks for the info john. My peg mount on the right is busted so ill b puttin 220 to it. Looks like itll b a little more than weldin a peg mount. Definitly doin that!

I went w the 850g trees n 500 legs. Ill b on a 19" too.

Must b the tunnels shallower on the older tanks. I put an 80 tank on my 78 n it fit fine. The cushion just ahead of the rear mount doesnt touch. Must b why the reverse, as u said, wont work.

Chuck... Lemme kno bout yer machinist. Got ahold of my local bearing n drive shop. I found those same bearings in a BUNCH of different widths. If i cant sink em far enuff i can pull em out n replace em w narrower bearings. I guess narrowing n the pain in the ass seal shoulder is all its gonna take... Probably narrow the collar inside the bearings to match the narrower bearing if theyre needed. After my 500 legs show up its on to cuttin up a perfectly good 1100e swinger.