K8 GSXR wheel and 180 tire in factory swingarm!

[Colin Green]

Excellent progress. That is one seriously fat looking wheel

 

[posplayr]

Got axle shaft made and cush drive rubbers shaved to fit. Now all I need is to order my offset front sprocket and 520 chain.

Love the look of the fat tire!

Looks good. You have confirmed the wheel is centered in the swing arm right? I would do the following:

1. I would put your straight edge across the tire or rim(rim is better) and measure the distance to the inside of both fork legs. Once from one side and then the other. Stock GS swinger is on center and both sides should be equal. Not so with some others like Bandit arm. This insures wheel is centered in swingam.
2. Do a quick string alignment to get the rear wheel aligned with the front. You are adjusting your rear axle adjusters to do this.
3. Check the chain offset. It is pretty easy using a straight edge under the rear sprocket running against the wheel/tire and just next to the chain.

If that all checks out you are good to go. What are you going to do in the front? It would be best to run radial on the front as well. With a 180 the side wall is pretty stiff but.........?

 

[Darkstang]

After I made the axle shaft so I could properly bolt in the rear, I did both string and straight edge alignment to the front rim. Then I checked the sprocket alignment with a straight edge. With 5/8 behind the front sprocket, the outside edges of the front and rear sprockets are less pretty much dead on! With access to a machine shop, I can modify the offset sprocket if needed for final installation.

Before I machined anything, I measured the complete stock rear end to get reference dimensions for width of the entire setup and distance from the edge of the left spacer to the factory rear sprocket. I verified that the factory rear was centered in this arrangement.

Then i tried my best to duplicate those with the GSXR wheel. I had to play with several dimensions on the cush drive to get it in far enough, such as machining the face for the sprocket and several other things that did not effect the alignment of the wheel itself.


Frontend?? k7 GSXR frontend is setting in the shop waiting

I hope I do not have to go back and rearrange anything on the rear after the front is installed. With the rear being in the center of the swingarm I hope it will be good.

When I powder coat the rims, I will use the rim edges to check everything for better alignment.

Ken

 

[posplayr]

After I made the axle shaft so I could properly bolt in the rear, I did both string and straight edge alignment to the front rim. Then I checked the sprocket alignment with a straight edge. With 5/8 behind the front sprocket, the outside edges of the front and rear sprockets are less pretty much dead on! With access to a machine shop, I can modify the offset sprocket if needed for final installation.

Before I machined anything, I measured the complete stock rear end to get reference dimensions for width of the entire setup and distance from the edge of the left spacer to the factory rear sprocket. I verified that the factory rear was centered in this arrangement.

Then i tried my best to duplicate those with the GSXR wheel. I had to play with several dimensions on the cush drive to get it in far enough, such as machining the face for the sprocket and several other things that did not effect the alignment of the wheel itself.


Frontend?? k7 GSXR frontend is setting in the shop waiting

I hope I do not have to go back and rearrange anything on the rear after the front is installed. With the rear being in the center of the swingarm I hope it will be good.

When I powder coat the rims, I will use the rim edges to check everything for better alignment.

Ken

Sounds like you were very thorough. The trickyist part in all this is figuring out how to put the rear wheel into the centerline of the bike. For a GS arm that simply means being equally spaced on either side of the swing arm forks.

After putting in the new forks I would just rerun the string alignment but you should already be good to go.

So you ended up taking about 0.400 off of the sprocket side, how did your spacers end up? What brake arm are you using?

 

[Darkstang]

I took .400" off both sides to get it centered. Then I still had to play with the cush drive to get the chain/sprockets lined up.

To get the 400thou on the drive side, 200 came out of the outboard axle spacer and 200 out of the cush drive spacer (GSXR Factory spacers). This netted me the 400 thou to center up the wheel and also netted me 200 thousandths on the sprocket to wheel/tire placement. I needed more than 200 to get to the 5/8 offset front sprocket, so I machined the sprocket face of the cush drive AND flipped the sprocket over and that got me to where I am. 400 also came off the brake side outboard spacer.

I can get exact measurements if anyone wants them. As far as brake arm, I am using the GSXR arm but will modify it with an adjustable bracket that bolts on with the axle assembly. It is in my head right now, and will get it machined this weekend.

When I am done, NO mods will be made to the factory swingarm etc so I can go back to all original if desired.

Ken

 

[posplayr]

I took .400" off both sides to get it centered. Then I still had to play with the cush drive to get the chain/sprockets lined up.

I went back and read your original post and here is what is bothering me.

You have assumed that the GSXR 750 wheel is centered between the GSXR swing arm forks. And since the GS arm is symmetrical and centered you simply removed the same amount of spacer stack height from both sides of the wheel to remove the total of 0.800" from the total.

It is that assumption in red above that worries me. It is not clear that this is true and in general it is not. For example the center of the bandit swingarm forks is offset by about 3/16" to the sprocket side. This gives more room on the sprocket side to clear the wide tires. But the frame pivots are usually on center and so the wheel can't be centered in the swing arm.

Just as a precaution before you get any deeper into this, measure the distance between each side of the wheel or tire and the inside of the GS swingarm forks to see if it is symmetrical (use a straight edge across the tire and steel rule from there to swing arm fork). As I go through my mind what you have described it will be off by something like the 3/16" .


I could be wrong but it is a simple check.

 

[makenzie71]

I went back and read your original post and here is what is bothering me.

You have assumed that the GSXR 750 wheel is centered between the GSXR swing arm forks. And since the GS arm is symmetrical and centered you simply removed the same amount of spacer stack height from both sides of the wheel to remove the total of 0.800" from the total.

It is that assumption in red above that worries me. It is not clear that this is true and in general it is not. For example the center of the bandit swingarm forks is offset by about 3/16" to the sprocket side. This gives more room on the sprocket side to clear the wide tires. But the frame pivots are usually on center and so the wheel can't be centered in the swing arm.

Just as a precaution before you get any deeper into this, measure the distance between each side of the wheel or tire and the inside of the GS swingarm forks to see if it is symmetrical (use a straight edge across the tire and steel rule from there to swing arm fork). As I go through my mind what you have described it will be off by something like the 3/16" .


I could be wrong but it is a simple check.

Some swingarms do not have the wheels centered. My TL1000S did not have a wheel centered in the spars. However, no matter how you look at it, the wheel is center of the bike. Only reason it's placement between the spars on teh stock bike would matter is if he wanted to use all the stock spacers and such. Measurements off the GSXR swingarm basically end up moot.

 

[posplayr]

Some swingarms do not have the wheels centered. My TL1000S did not have a wheel centered in the spars. However, no matter how you look at it, the wheel is center of the bike. Only reason it's placement between the spars on teh stock bike would matter is if he wanted to use all the stock spacers and such. Measurements off the GSXR swingarm basically end up moot.

I think that is kinda my point

I suspect any swingarm designed for a 180 wheel and above is offset.

 

[makenzie71]

I think that is kinda my point

Probably...I'm on a great "completely misinterpret the conversation at hand" kick....

 

[Darkstang]

I will go back and measure again. It is currently aligned with the stock frontend. Do not know about the GSZR swingarm as I do not have one. I simply measured with a straight edge on the out board spacers to the wheel on both sides of the GSXR setup. I wrote those numbers down somewhere. Whatever they were, they did not alarm me, but teh cush drive being way offset was the kicker.

I will go measure now..

Ken

 

[Guest]

I am running a 160 rear on my 80 1100e, I used the rear wheel off a 97 600 Bandit , caliper and cush drive off a 89 gs500e, and had to custom make my caliper mounting arm, set it up with a 530 chain conversion,15/47 pulls like a train, spacers on the rear wheel were a combination of the gs1100 and the bandits just shuffled around. I used the stock Gs11 aluminum swing arm. Now I am looking for a decent set of rear shocks

 

[Darkstang]

Ok, back from the shop. Posplayr is right, I am about 3/16 off. No major problem right now though. I can either machine some new spacers or possibly add 3/16 to the caliper side. This would move the sprocket more to the outboard side by 3/32 or about .090". I still could machine some off the face of the cush drive to compensate, but untill I get a chain and offset sprocket, I will hold where I am at.

I am going to get the frontend installed and in before I make any changes right now to the rear.

It is currently closer to the caliper/brake side. It is between 4-5 mm offset.

It will not be a track bike and that may not effect it that much, but while I have the chance I will get it as close as I can.

Ken

 

[posplayr]

Ok, back from the shop. Posplayr is right, I am about 3/16 off. No major problem right now though. I can either machine some new spacers or possibly add 3/16 to the caliper side. This would move the sprocket more to the outboard side by 3/32 or about .090". I still could machine some off the face of the cush drive to compensate, but untill I get a chain and offset sprocket, I will hold where I am at.

I am going to get the frontend installed and in before I make any changes right now to the rear.

It is currently closer to the caliper/brake side. It is between 4-5 mm offset.

It will not be a track bike and that may not effect it that much, but while I have the chance I will get it as close as I can.

Ken

If you go back to those steps,

I would do the following:

1. I would put your straight edge across the tire or rim(rim is better) and measure the distance to the inside of both fork legs. Once from one side and then the other. Stock GS swinger is on center and both sides should be equal. Not so with some others like Bandit arm. This insures wheel is centered in swingam.
2. Do a quick string alignment to get the rear wheel aligned with the front. You are adjusting your rear axle adjusters to do this.
3. Check the chain offset. It is pretty easy using a straight edge under the rear sprocket running against the wheel/tire and just next to the chain.

I went around in circles for a few laps with Katman trying to figure out spacer and offsets between Bandit and GS; I used scaled powerpoint and a spreadsheet.

Anyway your previous adjustments are now off so you should redo steps #2 and #3 after you get the wheel in the center of the swingarm. 1-2 mm is probably fine. Some Busa's are way off when they put huge wheels in the back. The bike will just be more neutral if it is close to center.
Glad you found it out now rather than later.