gs1100e swingarm conversion swap to my 78 gs400x

[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/f...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.

 

[Guest]

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!

 

[Guest]

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.

 

[Chuck78]

Here is the wonderful write up that John did about the gusset added to the gs450 frames that was missing from the gs400/425 frames & is why they twist in the front in hard bumpy cornering:
http://www.thegsresources.com/_forum/showthread.php?231838-GS400-450-frame-reinforcement

My machinist friend looked at some photos I sent but said he'd really have to see one in person to tell me what it'd take to jig it up to run in a mill. The vintage Japanese mc junkyard only had 2 swingarms on bikes that aren't likely to get parted out. My buddy has one tucked away for his kz1000, but he's uncertain the extent of mods he'll do to it now, especially needing a new can chain tunnel o-ring and the top end torn down (head gasket/base gasket while he's in there).
He might sell that to me, but not certain if he is/isn't going to use it. There are a few for sale online & eBay, but summer opening prices get inflated to $200+ on evilbay. I'm sure a forum member may come up with a spare sooner or later. As I read elsewhere, "makes ya wonder what keeps happening to all these poor GS1100E's that the swing arms keep popping up for sale and swapped onto all kinds of other bikes!"

 

[Shaun6691]

Not to raise the dead but did anything become of this? I ask because I have an 82 gs450 that I'm wanting to do this to. I even have the gs1100e swingarm already.

 

[Chuck78]

Larry decided he was too tall for a GS400 & is sticking with his Harley Choppers after throwing a rod through his GS1100E crankcase. He sold his GS400 project.

I am pursuing this swap, however.
It may be a while as I have a gs550 (740cc GS650 top end)resto-mod rebuild ahead of it for the wifey, & 2 or 3 friends' bikes to mechanically/electrically refurbish.

You'll need to basically mill off the rounded ends of the swingarm and convert to Kawasaki Zephyr style swingarm dust seals and hardware, but using a GS type bearing and races. You'll need to have a machinist bush the gs1100e inner races. You can get the bearings brand new in the gs1100e o.d. and i.d. and in the stock width and narrower widths.

So you have the options to either bore the bearing register deeper into the swingarm and narrow the center spacer, or run narrower bearings than the 1100E and narrow the center spacer. Perhaps with the gs450 inner spacer, maybe you need not narrow that any and can run the gs1100e inner races

 

[Chuck78]

I just got done measuring all of this again, and the GS400 (GS425 in my case) is about 205mm inside width. I had read 200mm on the GS400 swingarm from hillsy. Sounds about right + the thrust washers and dust shields.


I measured the GS1100E swingarms, and they are:
221mm pivot tube end to end with no thrust washers or dust seal shields.
I just measured some GS1100E dust caps and thrust washers installed on a custom cromoly Dresden style swingarm here, and they added 4.75mm width beyond the width of the inner bearing races, which also were wider than the actual pivot tube on this custom built swinger by approximately 2mm total both sides combined. So you're looking at like 228-230mm width. I will have to measure this GS750 frame here before I scrap it, it is same frame inside width as GS1100E. So we're looking at 5-7+mm extra to run the dust seals and thrust washers if the bearing races protrude some. I'll check on this with the swinger that has good bearings in it still.

20-1/8" to 21-5/8" swingarm length c-to-c depending on chain adjustment/axle position.
Around 263mm inside width at the rear wheel, without chain adjusters, which would put it right around 257mm or 258mm with the GS chain adjusters. ( all three swingarms here measured a different inside width)

The pivot tube is D-shaped aluminum stock, and where the external dust seals wrap around the tube (where the actual double-lipped sealing point is), the tube is turned down in diameter to round, and smaller than the circular portion of the larger D profile of the pivote tube.



The 3 GS1100E arms I have on the shelf here all measure different depths of machining this round portion, I suppose only the diameter was critical, not the extent the depth of the cut was as long as it was long enough for the seal cap to fit. I was hoping I could use that flat as a guide to use more crude tools to take down the width until I was flush with the flat end from the seal area machining.
The narrowest (deepest most inboard) cut here measured at 206mm, one was over 207mm, one was about 206.5mm. Still wider than the GS4xx frame opening. So for this application, they'd have to be cut beyond the flat end of the facing machined onto them for the seal caps.

I'm thinking that some extensive work to clamp the swingarm in a big lathe cross slide vise after aligning it using dead centers on either end, and then chucking up a cutting but in the lathe jaws offset like a boring bar cuts, may be the way to tackle narrowing these accurately. I'm only beginning to become familiarized with using my lathe, but this seems to be the way, but seems like a TON of work to jig up some fixture in a cross slide vise on the toolpost deck to get the swingarm clamped perfectly in place.
I should save whatever fixture I make, as I'm sure lots of people on DTT & CafeRacer would want to capitalize on the existence of some setup like this to get their 1100E arms cut down narrower!