82 Kat resto-mod aka Project Bucket Case

[posplayr]

With a .650 spacer the rear wheel is centered in the frame. This is how I have arrived at this conclusion.

have drill rod through my steering stem and swingarm pivot. I have measured both triangles which showed me that the neck is straight in relation to the pivot. Reason being the distances are exactly the same with each side of the triangles.
I then measured from the pivot rod to the center of the rear rim. With the numbers from each end of the drill rod through the pivot being equal to the mm, you have to use a .650" spacer on the sprocket side.

This aligns the front and rear wheels in my frame. It aligns the wheels with the center line of the bike and it requires the custom offset front sprocket to align the chain. All said and done, for the kat and bandit arm, everything is at least as straight as from the factory. I am most confident in these numbers.

Rob,
Interesting setup. That does confirm your overall frame alignment :dancing:. . I think it is valid for the following combination:

• 5.5"x17" 2nd Gen GSXR rear wheel
• GS sprocket carrier
• Bandit swingarm centered in the pivot bosses

I'm using a different wheel, carrier and swingarm offset so mine is different.


Just as a double check I would measure the wheel position inside of the swinger forks and see if you get the right offset.


Jim

 

[posplayr]

Maybe this will help and you can let me know if I am doing it wrong which is what this thread is about.

I started with a straight frame. I checked it out when I bought it and my welder check it out when I got the bracing done.

Next, I got a complete 93 gsxr750 front end including the spacer, speedo, a 93 gsxr front wheel and even the brakes ect. Now, I did use a 02 CBR 954 tree but the spacing is the same. My thinking with this combo means that front wheel will be centered to the frame.

With the front wheel mounted, I made sure the forks were not out of line and the wheel was correct with the 3 axis-again, I hope my terminology is right.

This means my front wheel is a known at least to my thinking and the rear is the unknown

Now, the rear rim is a 93 gsxr750 rim as well. This meant that stock B12 spacers are the same (part number 64741-17e00/left side and 64751-46e00 the right side). With these spacers, I could mount the rear and make sure the front rim straight ahead. From here, I figured out the rear wheel spacer.

So, basically I work from my known (the front) to the unknown (the rear) which should take care of offsets. However, if I would have another unknown rims (R1, even B12) then I would have center the rear first.

Also, as I was using the laser to check the alingment. I was able to measure the laser along the frame especially at the cross member and the the distance was pretty much the same as the wheel alignment. About 1mm difference.

Let me know if I did this okay. You both, Katman and posplayr, know more about this then myself

And thanks for your advice and questions.

Personally I would not try and reference off the front fork as there is no good way to tell when the front fork is straight in the frame.

What Rob and I were trying to figure out before and I think he had already arrived at the 0.650" before was how to confirm the rear wheel spacer that centered the rear wheel.

He had confirmed that by simply measuring how much offset the swing arm has ( 3/16" in the case of Bandit swingarms) and positioned the rear wheel (trial and error ) until the offset of the wheel between the rear swing arm forks is offset to match. He also used depth gauges which I tried also to duplicate but never felt too confident in all the translations.

I used some similar results to modify my rear spacer with even a few more twists.

Unless you can duplicate what Rob did, the simple measurement is get the wheel offset in the fork to compensate for teh swingarm offset. I used a T square to measure my offset.

 

[Guest]

I rigged up a laser see how it may turn out. The holder is machined with a lathe and a mill so it is acurate. My laser is also fine tuned and checked between my chuck and dead center on the lathe. The two hangers were machined as well on the lathe.

I aligned the laser on the pivot bolt with the point of the drill rod through the steering head and I tightened the set screw. I was then able to rotate the laser front to back. I followed the dot up the drill rod and across the frame main back bone that the tank sits on. As I ran it back to the rear wheel it again confirmed my last measurements.
As Jim said,

This is for a 5.5 straight spoke wheel
bandit swingarm
gs1100 sprocket carrier

My checks on the chain alignment shows a .465" offset front spocket. I get them made for 79.00 any tooth and pitch. This setup gives you .160" (4mm) more room for the chain to get past the frame.

 

[ukilme]

Personally I would not try and reference off the front fork as there is no good way to tell when the front fork is straight in the frame.

What Rob and I were trying to figure out before and I think he had already arrived at the 0.650" before was how to confirm the rear wheel spacer that centered the rear wheel.

He had confirmed that by simply measuring how much offset the swing arm has ( 3/16" in the case of Bandit swingarms) and positioned the rear wheel (trial and error ) until the offset of the wheel between the rear swing arm forks is offset to match. He also used depth gauges which I tried also to duplicate but never felt too confident in all the translations.

I used some similar results to modify my rear spacer with even a few more twists.

Unless you can duplicate what Rob did, the simple measurement is get the wheel offset in the fork to compensate for teh swingarm offset. I used a T square to measure my offset.

What do you mean by straight? Are you talking, fork pinching, forks being parellel to the center line or offset to the center line?

I guess the method I used can lead to more errors then Rob and yours. But the good news is I can still double check it before I mount the motor.

Jim, didn't you get your top hat spacers offset? Or am I thinking of someone else? I just got the standard top hat spacers from Rob.

And Rob, I will most likely hit you up for the sprocket as a 18 or 19 tooth sprocket is not easy to come by. And I love the tools that you make that center line tool is really cool.

 

[posplayr]

What do you mean by straight? Are you talking, fork pinching, forks being parellel to the center line or offset to the center line?

I guess the method I used can lead to more errors then Rob and yours. But the good news is I can still double check it before I mount the motor.

Jim, didn't you get your top hat spacers offset? Or am I thinking of someone else? I just got the standard top hat spacers from Rob.

And Rob, I will most likely hit you up for the sprocket as a 18 or 19 tooth sprocket is not easy to come by. And I love the tools that you make that center line tool is really cool.

The forks are straight when the front wheel lies in a plane parallel to a vertical plane running through the centerline of the frame. Assuming the frame is straight, this occurs somewhere along the line as you turn the handlebars from left to right. The question is where and it is hard to measure unless you can somehow lock down the front fork.

 

[ukilme]

The forks are straight when the front wheel lies in a plane parallel to a vertical plane running through the centerline of the frame. Assuming the frame is straight, this occurs somewhere along the line as you turn the handlebars from left to right. The question is where and it is hard to measure unless you can somehow lock down the front fork.

Got it. That's what I tought you meant. Thanks.

 

[Guest]

That is where the drill rod and a couple cones come in handy

 

[posplayr]

What do you mean by straight? Are you talking, fork pinching, forks being parellel to the center line or offset to the center line?

I guess the method I used can lead to more errors then Rob and yours. But the good news is I can still double check it before I mount the motor.

Jim, didn't you get your top hat spacers offset? Or am I thinking of someone else? I just got the standard top hat spacers from Rob.

And Rob, I will most likely hit you up for the sprocket as a 18 or 19 tooth sprocket is not easy to come by. And I love the tools that you make that center line tool is really cool.

Rob and I went around and around chasing down what I think was just measurement error on the measurement in wheel spacers for a Bandit arm. In the end I used his original numbers although I did a variation to offset the swingarm to use the stock rear brake setup. I have a single 1.0" spacer sprocket side with all stock 88 GSXR 1100 wheel/sprocket carrier/brake arm.

I tried to confirm the rear wheel spacing by using a straight edge from the front wheel back to the rear wheel (with the frame upside down) and the distance is just too great to get an accurate read. My straight edge was good to about 1/2 mm in 8 ft, but that was not the issue.

That is why I recommend the following steps:

1.) center the Rear wheel with the proper spacers (1-2mm tolerance)
2.) string adjust rear wheel to align with front wheel (4 measurements FB of both left and right rotor) (1-2 mm)
3.) align the chain with counter sprocket/surfacing sprocket carrier (1 mm.

 

[ukilme]

I used a 8 foot metal level that was straight to make sure the front wheel was aligned and took my measurements from the rim.

I have today off, so, I'll double check the wheel and see if it is centered.

NOw, I have a question with regards to the swing arm. I realize you, guys, wouldn't have done it the same way, but would you use it or redo it?

As Rob mentioned, the mounts are pretty far forward and gives me about 25-26 degrees overall rake and stock Katana is around 28 degrees. I was going for a little more rake and not even thinking chain clearance with the swing arm.

So, the issue are chain clearance which can be fixed with custom sprocket (cross my figures) and the mounts themselves. While strong and similiar designs used by others, can be made stronger even if the shock are square.

 

[posplayr]

I used a 8 foot metal level that was straight to make sure the front wheel was aligned and took my measurements from the rim.

I have today off, so, I'll double check the wheel and see if it is centered.

NOw, I have a question with regards to the swing arm. I realize you, guys, wouldn't have done it the same way, but would you use it or redo it?

As Rob mentioned, the mounts are pretty far forward and gives me about 25-26 degrees overall rake and stock Katana is around 28 degrees. I was going for a little more rake and not even thinking chain clearance with the swing arm.

So, the issue are chain clearance which can be fixed with custom sprocket (cross my figures) and the mounts themselves. While strong and similiar designs used by others, can be made stronger even if the shock are square.

I added about 1" to my shock length to increase the rear ride height. It is hard to do that without spending a lot of money on shocks. 1" is a pretty common increase. How high do you figure you have raised the rear with relocation of the shock mounts?


If you remember the law of sines (a little trig) we can compare your swingarm angle to mine. You would need to measure the following three distances:

L1-swing arm pivot to rear axle (center to center)
L2-top shock to swingarm pivot
L3-top shock mount to rear axle

The ride height difference between yours and mine will be approximately
del_height = Sin (theta 3_yours-theta3_mine) *L1

 

[Guest]

NOw, I have a question with regards to the swing arm. I realize you, guys, wouldn't have done it the same way, but would you use it or redo it?

As Rob mentioned, the mounts are pretty far forward and gives me about 25-26 degrees overall rake and stock Katana is around 28 degrees. I was going for a little more rake and not even thinking chain clearance with the swing arm.

So, the issue are chain clearance which can be fixed with custom sprocket (cross my figures) and the mounts themselves. While strong and similiar designs used by others, can be made stronger even if the shock are square.

The serious issue is the trail. Stock is 4.65"(118mm) current sport bikes are (3.6" (90-95mm). Changing your chassis angle by 1 degree will decrease your trail by 1". With the gsxr 750 frontend, bandit back end and pirelli tires my trail is 4.25". This is with the shock mounts placed to equal stock shock angle and ride height in the rear.
There are many parameters that effect the handling including triple offset and swingarm angle. I am told that 12 degrees is optimal for swingarm angle with no sag.
I mounted a frontend less wheel on my bike and fired a laser through the steering stem. Since the stem is hollow I machined a plug that the laser fit into. below is the results of that. The bike attitude as tires just touching the ground but no weight on them. YOu had mentioned that compression of the suspension will help but that is dangerous in my opionion. As you travel down the road and all seems dandy, you turn up the wick and head into a corner (or not). you go over an irregularity which extense the forks, (lets say a bump or rise in the road) you can be in serious trouble. The instability occurs at speed. ONe second your happily travelling along, the next split second your into a wicked tank slapper and skidding accross the road hopefully not into oncomming traffic. Jacking the back end up is not a good idea. If you want more air between the tire and frame, modify the subframe.

Anyways, this is my humble opinion. cut the mounts off and move them back, or, get some extensions for the front forks. If you can change the mounts on your shocks I will send you a set of cnc GS style swing arm mounts for free. IF not, I would like to see new mounts made anyways given the design of the ones you currently have. You know what? I will machine you another set if you want to fit your current set up.

The bolt centers of the shocks should be directly over or just in front of center of the rear weld on the swing arm. One other point. the left hand mount should be outboard of center on the swing arm fork to allow for shock spring/chain clearence.

I used degrees of engine cradle for a base as my garage floor is not level. The setup was with tires touching so engine cradle angle is a point of ref that can be used by all.

 

[posplayr]

The serious issue is the trail. Stock is 4.65"(118mm) current sport bikes are (3.6" (90-95mm). Changing your chassis angle by 1 degree will decrease your trail by 1". With the gsxr 750 frontend, bandit back end and pirelli tires my trail is 4.25". This is with the shock mounts placed to equal stock shock angle and ride height in the rear.
There are many parameters that effect the handling including triple offset and swingarm angle. I am told that 12 degrees is optimal for swingarm angle with no sag.
I mounted a frontend less wheel on my bike and fired a laser through the steering stem. Since the stem is hollow I machined a plug that the laser fit into. below is the results of that. The bike attitude as tires just touching the ground but no weight on them. YOu had mentioned that compression of the suspension will help but that is dangerous in my opionion. As you travel down the road and all seems dandy, you turn up the wick and head into a corner (or not). you go over an irregularity which extense the forks, (lets say a bump or rise in the road) you can be in serious trouble. The instability occurs at speed. ONe second your happily travelling along, the next split second your into a wicked tank slapper and skidding accross the road hopefully not into oncomming traffic. Jacking the back end up is not a good idea. If you want more air between the tire and frame, modify the subframe.

Anyways, this is my humble opinion. cut the mounts off and move them back, or, get some extensions for the front forks. If you can change the mounts on your shocks I will send you a set of cnc GS style swing arm mounts for free. IF not, I would like to see new mounts made anyways given the design of the ones you currently have. You know what? I will machine you another set if you want to fit your current set up.

The bolt centers of the shocks should be directly over or just in front of center of the rear weld on the swing arm. One other point. the left hand mount should be outboard of center on the swing arm fork to allow for shock spring/chain clearence.

I used degrees of engine cradle for a base as my garage floor is not level. The setup was with tires touching so engine cradle angle is a point of ref that can be used by all.

Rob so bottom line how far is he lifting the rear end with the current mount locations with those piggyback shocks? 1"-1.25" is desireable for these old beasts

 

[Guest]

I don't know off had how much lift he is getting. An inch or so isn't critical in the rear but, if you drop the front end by 3" at the same time it gets more critical. Some guys are using gsxr triples so are realizing a 4" change effecting trail before any changes in the back end.
We only have about an inch of trail to work with before things get hairy. The gsxr and cbr triples have much less offset than the kats which works in favor of increased trail offsetting some of the loss by the shortened front end. There are many numbers to take into account for sure but considering the possible outcome of getting things wrong it is best to double and triple check your work.
There are companies around the States that can measure your suspension geometry. Race teams use them. They can be a couple hundred bucks but cheap compared to sliding down the road on your head or even taking out an innocent on the side of the road.
rember also that all the new bikes have steering stablizers. They have to have them in the 90-95mm trail range. If I remember correctly, the TLR1000's first came without one and after several crashes Suzuki added the stablizers.
Handling and stablizing the bike is not a question of one or two factors. My point is simply that modifications can lead to dangerous situations and there are limits that should not be pushed with these old bikes. Many guys out there may not have had any stability issues but these old bikes are all different with different combinations of parts and riding styles and abilities. Because one guy gets away with it doesn't mean you will, or he will for long. Error on safety, these are not race bikes and we are not riding them to their current stock abilities as it is.

If anything we should be dropping the back end not raising it, from a stability point of view.

 

[ukilme]

Okay, good news is the rear is centered witin a 1-2mm. It took longer to setup and check with the laser then I thought it would. With all the measurement using the center of the cross member and swing arm pivot. I was able to check the alignment again. So, my method worked but is not the best method and I got lucky.

Now with the swing arm, I had to redo the height measurements with the modified swing arm and the stock as I could not find my notes which means I proably forgot to to it. Anyways, there was a big difference between stock and my setup which does have me concerned- just over 3"

And with what you are saying are saying Rob, if I have 25 of rake which is 3 degrees less then stock. It would be about 75mm less then stock and would put me near 43mm for my trail . I did not realize this and I am glad you caught this. The stupid thing is if I had reversed the mounts it would have given 27 degrees or so. And would have put the hole right by the swing arm welds. I went for look on this.-Lesson learned again.

I had a speed wobble once in a 100km/hr corner at a track and just about **** my pants. I caused it by releasing my brakes to fast while trail braking. I also had a 170km crash at the track because of a bike issue at the corner entrance which threw my way off line.

So, this is a no brainer, I messed up and the shock mounts are coming off as there are too many concerns. Good lesson learned here.

A couple of questions:

1. Does aluminum re-act to heat cycles like metal and get weaker with repeated welding? If so, should I go for another swinger?

2. Also, what is the length of shock you guys using? Stock is 13 (340mm) inches and the zrx, I am using, are 14 (370 mm) which will jack it up.

Also Rob, the shock mounts are offset. The inside is 10mm think and the outside are 5mm thick. Any further over, the shock will to for over on the stud.

I will get back to you about your offer. I want to think some more about if I am going to go with the zrx shock or another "GS" type shock.

If I do go with celvis style, I will buy your mounts. No need to give them out. I wanted a honest anwser and I got it.

 

[Guest]

Okay, good news is the rear is centered witin a 1-2mm. It took longer to setup and check with the laser then I thought it would. With all the measurement using the center of the cross member and swing arm pivot. I was able to check the alignment again. So, my method worked but is not the best method and I got lucky.

Now with the swing arm, I had to redo the height measurements with the modified swing arm and the stock as I could not find my notes which means I proably forgot to to it. Anyways, there was a big difference between stock and my setup which does have me concerned- just over 3"

And with what you are saying are saying Rob, if I have 25 of rake which is 3 degrees less then stock. It would be about 75mm less then stock and would put me near 43mm for my trail . I did not realize this and I am glad you caught this. The stupid thing is if I had reversed the mounts it would have given 27 degrees or so. And would have put the hole right by the swing arm welds. I went for look on this.-Lesson learned again.

I had a speed wobble once in a 100km/hr corner at a track and just about **** my pants. I caused it by releasing my brakes to fast while trail braking. I also had a 170km crash at the track because of a bike issue at the corner entrance which threw my way off line.

So, this is a no brainer, I messed up and the shock mounts are coming off as there are too many concerns. Good lesson learned here.

A couple of questions:

1. Does aluminum re-act to heat cycles like metal and get weaker with repeated welding? If so, should I go for another swinger?

2. Also, what is the length of shock you guys using? Stock is 13 (340mm) inches and the zrx, I am using, are 14 (370 mm) which will jack it up.

Also Rob, the shock mounts are offset. The inside is 10mm think and the outside are 5mm thick. Any further over, the shock will to for over on the stud.

I will get back to you about your offer. I want to think some more about if I am going to go with the zrx shock or another "GS" type shock.

If I do go with celvis style, I will buy your mounts. No need to give them out. I wanted a honest anwser and I got it.

Welding weakens alum yes. If you move the shock mounts back to the weld area you will be fine. I don't think a new swinger is needed. You are at the outside limit of thickness IMHO for mounts. 5mm is minimun thickness. I would not go less than that.
I would check your trail numbers. They can't be 43mm??? If so you can't ride it. I offered the mounts to you because I didn't want your decision to be a monitary one. YOur safety is more important than my cost on some mounts. ONce you move the mounts back you can go to a 17/48 sprocket set which is a smaller diameter set than the stop ones.
YOu are using a GS sprocket hub yes? not the gsxr and, you are using the GS inner bushing for that hub and not the GSXR yes? If not you could explode the wheel bearing.

Feel free to email or call if I can be of more help. parts@suzuki-katana.com

 

[ukilme]

Welding weakens alum yes. If you move the shock mounts back to the weld area you will be fine. I don't think a new swinger is needed. You are at the outside limit of thickness IMHO for mounts. 5mm is minimun thickness. I would not go less than that.
I would check your trail numbers. They can't be 43mm??? If so you can't ride it. I offered the mounts to you because I didn't want your decision to be a monitary one. YOur safety is more important than my cost on some mounts. ONce you move the mounts back you can go to a 17/48 sprocket set which is a smaller diameter set than the stop ones.
YOu are using a GS sprocket hub yes? not the gsxr and, you are using the GS inner bushing for that hub and not the GSXR yes? If not you could explode the wheel bearing.

Feel free to email or call if I can be of more help. parts@suzuki-katana.com

Ya, 43 is a little small, I was just taking the 1 inch for every 1 degree. In short, it really does not matter. I'd rather be safe then sorry.

GS hub with GS hub spacer is yes.

Here is a close up of the mount welded to the arm. The back is right on the factory weld. Is the swinger still usable?

I hate wasting money but I really not that much into the arm. Well, I'll keep telling my self that...lol

 

[Guest]

Ya, 43 is a little small, I was just taking the 1 inch for every 1 degree. In short, it really does not matter. I'd rather be safe then sorry.

GS hub with GS hub spacer is yes.

Here is a close up of the mount welded to the arm. The back is right on the factory weld. Is the swinger still usable?

I hate wasting money but I really not that much into the arm. Well, I'll keep telling my self that...lol

Email sent.

 

[ukilme]

Well, after some emails with Rob and a phone conversation today with him.

I have decided to get his mounts for the swinger and get rid of the zrx shocks. We did talk about mounts for my application but we thought it best to go the traditional way.

I guess this is like 2 steps back but that's life.

I have to say thanks to Rob and Jim for hashing this out with me.

 

[posplayr]

Well, after some emails with Rob and a phone conversation today with him.

I have decided to get his mounts for the swinger and get rid of the zrx shocks. We did talk about mounts for my application but we thought it best to go the traditional way.

I guess this is like 2 steps back but that's life.

I have to say thanks to Rob and Jim for hashing this out with me.

Rob is the real expert. I just know my bike and the set-up ; well I do know a little math

 

[ukilme]

Rob is the real expert. I just know my bike and the set-up ; well I do know a little math

Ya, I heard you new math. Rob and I spoke about your project for some time.