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Discussion Starter · #1 ·
1978 Suzuki GS750 frame
1998 Suzuki Bandit 1200 swingarm

I asked around about tips on doing a monoshock conversion on this at a fab shop. Was told that the swingarm shock mount would have to be changed, etc. Is this true or?

His reasoning was that you would have to replicate the shocks angle etc from the bike it came from. Is this really needed? I will not be racing the bike or anything like that. Was first going to use the bandit shock or a 06/07 GSXR shock but now I am going to use a linkage-less shock, XB12 or something.

What do you guys think? Is it really needed to replicate the stock shock angle?
 

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If you are going with a monoshock using linkage then I agree that you should try to get as close as possible to the B12 geometry. Sure, you can mix-match different components but Suzuki didn't just slap parts together hoping it'll work OK and neither should you. Trust me when I say that a bike with slapped together rear suspension isn't un-rideable but could be much more enjoyable with the correct parts located correctly.

If you are using the Buell shock without linkage then the B12 mount will probably need modded and yet again try to replicate the shock geometry.

Later, Doug
 

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Discussion Starter · #3 ·
If you are going with a monoshock using linkage then I agree that you should try to get as close as possible to the B12 geometry. Sure, you can mix-match different components but Suzuki didn't just slap parts together hoping it'll work OK and neither should you. Trust me when I say that a bike with slapped together rear suspension isn't un-rideable but could be much more enjoyable with the correct parts located correctly.

If you are using the Buell shock without linkage then the B12 mount will probably need modded and yet again try to replicate the shock geometry.

Later, Doug
Does it have to be exact or just as close as possible? Getting it close would be a lot easier as I would not have to source an XB12 to get measurements from. Could put strong bracing on the arm and mount to that? Looks like that is how Buell did it.
 

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The closer the better but unless you have special frame jigs and fixtures and CMM equipment, I doubt it'll ever be exact. On the couple projects I've done rear suspension swaps on, I'm about 1/8" from the original position as far as I can tell.

Later, Doug
 
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lɐʇuǝɯᴉɹǝdx&#4
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Close seems likely to be good enough, especially if you have some adjustable elements. Linkage behavior isn't linear, but 'looks the same' generally gets you close to the same, especially if actually using many of the same parts in the same configuration with roughly the same angles etc.

An easy rule of thumb (which I totally made up myself after some reading, and have only a theoretical basis for) seems to be that if your rear end travel and weight loading match the bike the shock came off, and the shock gets compressed fully at (but not before) full travel, you are probably doing OK. That covers getting the right basic spring rate; do that and valving should be close anyhow. You might end up with a rate that is more progressive or regressive than you like, but you shouldn't be crazy far off unless you did something radically different in mounting it. Of course, this says nothing about the structural integrity of the system, just its rough dynamics.

I fucked around with a lot of math before I realized that, and the decide to just go on eBay, pick a few (in my case rather hefty) shocks that looked likely to work, and look up specs for the bikes they came from. I still ended up mounting the shock I bought totally differently than the stock bike did, but at least I knew I had something that COULD work on my bike, because it matched in those regards. We'll see how it pans out in reality, could be I built a bucking bronco with a glass leg... but from bouncing on it, seems OK.
 
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I've put bandit & gsxr arms in just about every old gs & gsx frame heres a quick rundown of whats needed ..........

Fit arm with spacers as needed, you need to fit a center bearing spacer in the middle of the arm for your smaller pivot spindle, depending on model you may be able to slip the stock gs swingarm bearing spacers inside the bandit ones, or machine new ones to fit bandit etc bearings & gs spindle

Distance between top shock mount & bottom is roughly 300mm using a b12 shock, weld linkage mounts to gs frame on the standard cross tube but dont be tempted to use the centre stand mounts (you may need to remove these)

Fit stock bandit linkage at the same angle as on a stock bike (a pic of stock link on a stock bike will help here) fit shock then hold or wire shock to get correct angle & height, distance between the 2 mounts should be the 300mm mentioned before & gives you the position for your top shock mount

Weld in 2 tubes to take the top mount the top one tight up to where the frame curves in to the middle of the bike the lower far enough below to take the bottom of whatever plate or mount you use

Jobs a good un :rock:

sounds hard bit its the simple way & works well the bonus is theres lots of things you can do later to upgrade & improve suzuki parts are cheap

Just take care when taking pics of bandits etc for referance that they are actually stock as theres plenty out there with different shocks & jackup kits
 

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Discussion Starter · #7 ·
I've put bandit & gsxr arms in just about every old gs & gsx frame heres a quick rundown of whats needed ..........

Fit arm with spacers as needed, you need to fit a center bearing spacer in the middle of the arm for your smaller pivot spindle, depending on model you may be able to slip the stock gs swingarm bearing spacers inside the bandit ones, or machine new ones to fit bandit etc bearings & gs spindle

Distance between top shock mount & bottom is roughly 300mm using a b12 shock, weld linkage mounts to gs frame on the standard cross tube but dont be tempted to use the centre stand mounts (you may need to remove these)

Fit stock bandit linkage at the same angle as on a stock bike (a pic of stock link on a stock bike will help here) fit shock then hold or wire shock to get correct angle & height, distance between the 2 mounts should be the 300mm mentioned before & gives you the position for your top shock mount

Weld in 2 tubes to take the top mount the top one tight up to where the frame curves in to the middle of the bike the lower far enough below to take the bottom of whatever plate or mount you use

Jobs a good un :rock:

sounds hard bit its the simple way & works well the bonus is theres lots of things you can do later to upgrade & improve suzuki parts are cheap

Just take care when taking pics of bandits etc for referance that they are actually stock as theres plenty out there with different shocks & jackup kits
That sounds like it might be a good option, pm'd you for pics.
 

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This is off topic but I just found out how hard it is to do a proper rearend swap and have the bike handle correctly. It now makes me wonder how many people have done rearend swaps and their bikes ride like shit because they didn't do it correctly. I thought rearend swaps were as easy as a front end swap boy was i wrong.
 

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Discussion Starter · #9 ·
This is off topic but I just found out how hard it is to do a proper rearend swap and have the bike handle correctly. It now makes me wonder how many people have done rearend swaps and their bikes ride like shit because they didn't do it correctly. I thought rearend swaps were as easy as a front end swap boy was i wrong.
Yeah sounds about right for the amount of trouble I am running into. Looks like if I at least get shock angle and length between mounts really close I should be ok. I am running into issues with the subframe too, do not want to keep the stock one at all, trying to fit an 06/07 GSXR tail to it.
 
G

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ive done quite a few back end swaps on all sorts of different bikes & never had a problem yet, careful measurements & marking out is the key, i aim for swingarms to be exactly central but 2mm either way will have no affect on the bike at all, similar numbers are acceptable for shock alignment but a little more off compared to stock vertically wont hurt anything

wheel alignment i always aim for less that 2mm out which i far better than a lot of stock untouched bikes & can usually get that easily

just as a point of interest your GS frame wont be dead straight at the rear as none were from the factory
 

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Discussion Starter · #11 ·
ive done quite a few back end swaps on all sorts of different bikes & never had a problem yet, careful measurements & marking out is the key, i aim for swingarms to be exactly central but 2mm either way will have no affect on the bike at all, similar numbers are acceptable for shock alignment but a little more off compared to stock vertically wont hurt anything

wheel alignment i always aim for less that 2mm out which i far better than a lot of stock untouched bikes & can usually get that easily

just as a point of interest your GS frame wont be dead straight at the rear as none were from the factory
For the swingarm it is all ready to go in, have the spacers ready to fit it in. Just need to ream the mount points out to 16mm from the stock 14mm. Just an issue of the shock now.

How bad would it look if I did up a custom subframe to accept the 06/07 gsxr 600/750 tail, that was properly braced to run twin shock? Or am I better off going mono? I would like to fit the GSXR tail either way.
 

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If you are going with a monoshock using linkage then I agree that you should try to get as close as possible to the B12 geometry. Sure, you can mix-match different components but Suzuki didn't just slap parts together hoping it'll work OK and neither should you. Trust me when I say that a bike with slapped together rear suspension isn't un-rideable but could be much more enjoyable with the correct parts located correctly.

If you are using the Buell shock without linkage then the B12 mount will probably need modded and yet again try to replicate the shock geometry.

Later, Doug

Youre right, bugt Im hoping to god I can prove you wrong or at least get lucky mis matching parts to get this Busa rear end to work on my slingshot frame.
 

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Discussion Starter · #13 ·
Anyone have pics and any measurements of a bandit 1200 shock all mounted up in a bandit 1200 frame please? Thanks!

I need to get my shock angle as close as possible.
 
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Hi just caught this again.
IMHO you are better to sleeve the bearings etc down to the gs spindle size, the reason for this is its really difficult to get the alignment right if trying to drill them out & you could be getting close to hitting the weld once you are out to 20mm , not good on strength either
 

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Hi just caught this again.
IMHO you are better to sleeve the bearings etc down to the gs spindle size, the reason for this is its really difficult to get the alignment right if trying to drill them out & you could be getting close to hitting the weld once you are out to 20mm , not good on strength either
REPT!
 
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Good luck with that mate, i think you are going to find it a little more difficult than you think getting them straight & true
 
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