Best Swingarm?

Or, find a Suzuki Bandit 1200 swingarm, and if you like twin rear shocks, buy/fabricate a pair of rear shock mounts and have them welded on.

Got an almost new '97 Bandit 1200 swingarm for $60 on ebay, the cost of shipping was included in that price. Made a spacer for this Bandit 1200 swingarm so that I can use the stock KZ1000 swingarm pivot bolt.

wireman wrote:

those shock mounts are pretty cheesey looking!

They're adjustable.

Post edited by: guitargeek, at: 2006/12/10 22:39

wireman wrote:

if you are going roadracing id reccomend going no longer than the stock arm;)

Actually, a longer arm is in the cards.

Other than the normal decrease weight/increase chassis rigidity/improve suspension/etc., my goals with this project are:

1) Increase cornering clearance by lifting the bike up (The old Muzzy-built Kawasaki Superbikes of this era were about 1.5 inches higher at the lower frame rails)

2) Quicken steering by decreasing both rake and trail.

3) Move weight bias forward

4) Decrease the wheelbase if at all possible

#1 can be accomplished a variety of ways. 17" wheels compound the issue. Jacking up the back with longer shocks is easy, but then you run into issues with an improper swingarm angle -- a swingarm with the axle below a line drawn from the countershaft through the swingarm pivot will rise and stiffen during acceleration, which causes problems (ie: loss of traction, potential highsides) at corner exits. Jacking up the rear end past this line decreases the wheelbase, but moves the weight bias even more to the rear. Increasing the front clearance can be done by decreasing the rake and/or by raising the front with longer fork.

#2 (at least the decreasing rake part) can be accomplished by dropping the front or raising the rear. However, simply dropping the front just adds to ground clearance issues, and simply raising the rear causes the issues described in the previous paragraph. The stock '82 GPz 750 has a rake of 27 degrees and a trail of 107mm. The 2007 GSXR 1000 (pretty much the open-class racebike of choice) has a rake of 23.8 degrees and a trail of 98mm. I'd be shooting for 25 degrees and about 100mm. Changing the trail can be done with different offset triple clamps or adjustable triple clamps.

#3 can be accomplished by moving the engine forward within the wheelbase. This can be done by moving the front wheel back (by decreaseing rake)or by increasing the swingarm length.

#4 can be accomplished by decreasing the front rake, shortening the swingarm (with the problems noted above), or shortening the stock frame (difficult at best)or using a custom frame.

So, my planned course of action is to decrease the front rake through either modifying the steering head angle, using custom triple clamps, or both. The resulting loss in wheelbase will then be made up with a longer swingarm. The longer swingarm will also raise the rear of the bike without moving the wheel axle beyond the countershaft/swingarm pivot line.

Those changes will accomplish goals #1-#3, but not #4. The above plan of action will result in the wheelbase staying about the same. That is a good tradeoff to accomplish three first three goals. The only way to accomplish all four would be to use a custom frame, which isn't legal in AHRMA Vintage Superbike.

I'll keep folks posted with details and pics as the project unfolds.

wireman wrote:

if you are going roadracing id reccomend going no longer than the stock arm;)

Actually, a longer arm is in the cards.

Other than the normal decrease weight/increase chassis rigidity/improve suspension/etc., my goals with this project are:

1) Increase cornering clearance by lifting the bike up (The old Muzzy-built Kawasaki Superbikes of this era were about 1.5 inches higher at the lower frame rails)

2) Quicken steering by decreasing both rake and trail.

3) Move weight bias forward

4) Decrease the wheelbase if at all possible

#1 can be accomplished a variety of ways. 17" wheels compound the issue. Jacking up the back with longer shocks is easy, but then you run into issues with an improper swingarm angle -- a swingarm with the axle below a line drawn from the countershaft through the swingarm pivot will rise and stiffen during acceleration, which causes problems (ie: loss of traction, potential highsides) at corner exits. Jacking up the rear end past this line decreases the wheelbase, but moves the weight bias even more to the rear. Increasing the front clearance can be done by decreasing the rake and/or by raising the front with longer fork.

#2 (at least the decreasing rake part) can be accomplished by dropping the front or raising the rear. However, simply dropping the front just adds to ground clearance issues, and simply raising the rear causes the issues described in the previous paragraph. The stock '82 GPz 750 has a rake of 27 degrees and a trail of 107mm. The 2007 GSXR 1000 (pretty much the open-class racebike of choice) has a rake of 23.8 degrees and a trail of 98mm. I'd be shooting for 25 degrees and about 100mm. Changing the trail can be done with different offset triple clamps or adjustable triple clamps.

#3 can be accomplished by moving the engine forward within the wheelbase. This can be done by moving the front wheel back (by decreaseing rake)or by increasing the swingarm length.

#4 can be accomplished by decreasing the front rake, shortening the swingarm (with the problems noted above), or shortening the stock frame (difficult at best)or using a custom frame.

So, my planned course of action is to decrease the front rake through either modifying the steering head angle, using custom triple clamps, or both. The resulting loss in wheelbase will then be made up with a longer swingarm. The longer swingarm will also raise the rear of the bike without moving the wheel axle beyond the countershaft/swingarm pivot line.

Those changes will accomplish goals #1-#3, but not #4. The above plan of action will result in the wheelbase staying about the same. That is a good tradeoff to accomplish three first three goals. The only way to accomplish all four would be to use a custom frame, which isn't legal in AHRMA Vintage Superbike.

I'll keep folks posted with details and pics as the project unfolds.

Sorry, really not sure why I'm seeing double posts when I only hit the submit button once.

mark1122 wrote:

this arm is about 1 3/4" longer than kz.the axle pivet bolt is 20mm.(about 13/16")my kz was 5/8".I had a sleave made. the width is 9 1/4" at the front(can be trimmed) .Shock mounts are 14 1/2" back from the pivot center.The length axle to axle is 21 1/2". I.D. at back is 10 3/4".Shocks are 14 1/8" long ,center to center. If you need anymore info let me now.Glad to help.

Thanks!

If you get a chance to weigh the swingarm, that would be great info to have as well.

guitargeek wrote:

Best swingarm? Hard to argue with these:

Yep, the custom swingarms are nice and certainly an option. The downside is the horror stories everyone has heard about the delivery time on these puppies, the damage incurred during shipping, the poor fitting, etc. Not to mention the price. An OEM swingarm that can be easily and cheaply sourced and modified (and replaced if damaged in a crash)is always the preferred option in my book.

Thanks for the links, though.

kyradawg wrote:

Or go here cgi.ebay.com/ebaymotors/Suzuki-GSXR750-S...QQrdZ1QQcmdZViewItem like I did and for $50 + $50 in custom machining get one of these

How did you mount up twin shocks to that beast? Any pics?

Hey Mark ? Are you the Mark Hatten that raced Honda Singles awhile back ? Welcome aboard if you are ..

anyone order from this PMC place in japan?What are shipping costs like?Guitargeek,how did you calculate those prices?The 1st arm says 140 yen,isnt a yen very close to $1?
Post edited by: mark1122, at: 2006/12/11 11:32

Post edited by: mark1122, at: 2006/12/11 11:35

Post edited by: mark1122, at: 2006/12/11 11:37

mark1122 wrote:

Guitargeek,how did you calculate those prices?The 1st arm says 140 yen,isnt a yen very close to $1?

They used a decimal where they should have used a comma.
I use Yahoo's currency converter:
quote.yahoo.com/m5?a=140000&s=JPY&t=USD&c=0

I have no idea about shipping costs, probably steep tough. Look at their other bits, some pretty sexy stuff!

www.win-pmc.com/english/menu.htm

The adjustable billet sidestand is especially nice, as is the stainless steel battery box.

Oh, and I don't guess anybody noticed since nobody commented on it, but all three of their swingarms are also oil tanks, see the fittings?

Oh, and look, just look will you, at the exhaust systems! ::droooools::