Topic: noob question about 180 tire and a swingarm that will fit 76 frame.

[caldurham]

ok so i just recently got a 76 cb750 ss that i am molesting into a streetfighter/cafe racer and i've been lurking here for a few weeks.  i am wanting to fit a 180 tire/wheel package on the back of my project bike. i've done a few searches for 180 tire fitments which i can find but i don't see alot of explanation into the swingarm used to do such. and before anyone asks it just simply is because #1 i WANT to do it and know i can and #2 i'm going streetfighterish here.

i know that to fit a 180 i'll need an offset sprocket, so i am good there. i also know that my stock swingarm isn't going to work and i need to be looking for a different swingarm, actually i've already ditched the stock swingy. and in fact i have an early 90's swingarm from a gsxr 750 that i am sure i could modify to work. but it's a braced swingarm and i'm not sure i like how it looks after mocking it up. but it was free along with the inverted forks, triples and brakes from the front of the same bike that i know i can get to work on the front of my 76 frame.

so my question boils down to this ...... does anyone know of a good boxed swingarm that will accommodate a 180 tire/wheel package that will fit my 76 frame fairly easily?

i know i may have to weld tabs for the shocks and work with pivot area some but honestly none of that is a big deal to me.

btw here is a shot of the gsxr braced swingarm mocked onto my frame. like i said after getting it there i am not sure at all if i like the look of it. i think a nice boxed swingarm would look alot better.

[Toxic]

You are right it doesn't look right with the twin shocks.
Why not just cut the brace off ?  It sounds like you have the skills to weld it up properly.

[caldurham]

check this out

tho i know it's a DOHC 1100... at least i think, i really like what he did with the shock mounts.

i am considering cutting off the brace. i definitely want to keep the dual shocks. just not THOSE lol. and i am going to have to cut the passenger peg brackets off and either weld them back on at a different angle to clear swingarm OR just weld on a completely fabbed passenger peg bracket as i'd like to be able to haul some bootay around on it when i am done.


correct me if i am wrong but shouldn't the 79-82 DOHC swingy's be able to fit a 180 tire if you gring off the pinch weld and reweld it flat?

my other problem is i REALLY want to use the wheel off the gsxr braced swingarm if i do not modify or use it to work with my frame. i'm starting to sound picky i think. 

[Harsh]

Have you thought about a Suzuki SV1000 swingarm?

[Geeto67]

first off - GSXR swing-arms are usually asymmetrical, so make sure yours isn't otherwise you'll be shifting the center line of the wheel off. The best advice I can give you when doing this sort of custom work is to mark out the center-line of the frame with some tape and mark the center-line of the arm and wheel with some chalk or tape. This way while you mock everything up it is an easy and quick visual reference to make sure stuff is aligning properly.

as for the 180 tire thing - usually when you do a 180 rear you want the 77-78 engines, not the 76. The output shaft is different and spaced out further.

have you considered a 160 tire instead? on a Sock-4 it will still look plenty huge and won't kill the handling nearly as much as a 180 gumball will. Streetfighters are really crashed sportbikes without plastics so there is supposed to be some semblance of performance there, adding a 180 just for looks is a very chopper thing to do - all show no go. Anyway, the favorite amoung the DOHC guys is the CBR600f2 swingarm and rear wheel.

there is another reason a 160 might be a better choice. The only places I have seen a 180 tire on a sock-4 are custom framed choppers. I think this may be because you are going to run into chain line interference with frame rails. I mean, you aren't breaking new ground here - people have been thinking about how to stuff a 180 on the back of anything since the 180 tire came out but you don't see it too often on SOHC4s, chain line interference may be why.

[caldurham]

first off - GSXR swing-arms are usually asymmetrical, so make sure yours isn't otherwise you'll be shifting the center line of the wheel off. The best advice I can give you when doing this sort of custom work is to mark out the center-line of the frame with some tape and mark the center-line of the arm and wheel with some chalk or tape. This way while you mock everything up it is an easy and quick visual reference to make sure stuff is aligning properly.

already on top of this. the gsxr swingy is asymmetrical, but it will work fine. the only problem i see, IF i decide to use the swingarm i have is the left shock will need to be spaced out a bit further off the frame shock mount. well that is depending on how i choose to fab a bracket for it. and i won't need to space it out much, some thick spacing washers or nylon spacers should solve the problem nicely. and i've still got plenty of thread and room left on the frame shock mount to secure it down nicely. regardless i know i can get the swingarm to work. just not sure i want to use it and not too sure i like how it looks. also i am not sure i want to cut it up either cause if i can find a swingy that will work with less fabbing i can sell it on ebay along with my stock 76 swingy and have more money to spend on my project.

so if anyone knows of a swingarm that may work with a 180 tire/wheel combo with less  fab work i'm interested to hear any advice. i KNOW i'll need to do some fabbing and i don't really have a problem doing the work.

as for the 180 tire thing - usually when you do a 180 rear you want the 77-78 engines, not the 76. The output shaft is different and spaced out further.

actually i have already taken this into consideration. like i said i know i'll need an offset sprocket and plan on getting one from cycle-x shortly just to clear a 180 tire for my engine. so i'm good there. more than enough info on the forums and elsewhere to set me straight in this area.

have you considered a 160 tire instead? on a Sock-4 it will still look plenty huge and won't kill the handling nearly as much as a 180 gumball will. Streetfighters are really crashed sportbikes without plastics so there is supposed to be some semblance of performance there, adding a 180 just for looks is a very chopper thing to do - all show no go. Anyway, the favorite amoung the DOHC guys is the CBR600f2 swingarm and rear wheel.

there is another reason a 160 might be a better choice. The only places I have seen a 180 tire on a sock-4 are custom framed choppers. I think this may be because you are going to run into chain line interference with frame rails. I mean, you aren't breaking new ground here - people have been thinking about how to stuff a 180 on the back of anything since the 180 tire came out but you don't see it too often on SOHC4s, chain line interference may be why.

i've considered it yes. but i'm sticking with the 180, i really like the look and i really like the tires available for that size. i know it can be done, i've seen the pics to prove it from those whom already have. i've been lurking here a few weeks and have seen several posts with 180 tire fitments on their sohc bikes. alas rarely is the swingarm being used mentioned. almost everything else i need to know i've found easily.

with that being said every time i use the forum search function it never works, which is highly annoying. i can only ever get the google search to work from the forums. anyone else having this problem as well? i'm using firefox so that may be the problem, i dunno.

[lone*X]

The gsxr swingarm pictured is pretty beefy.  Have you thought of just removing the triangulation?  The boxed bottom half looks a lot stronger that the stock 750 swing arm.  Remember you will not be putting near the HP to it that the zuke did.

[Retro Rocket]

If you go with the GSXR wheels then you WON"T need an offset sprocket, you will either have to machine a small amount off the GSXR sprocket carrier and have a front offset sprocket made, or use a cycleX offset front sprocket and machine the rear carrier to suit. A K8 counter shaft will also help as they are 10mm longer. I have an old 1988 GSXR1100 swingarm with the monoshock section removed and shortened to go into my K2, these arms can be shortened at either end {if you know what you are doing} and look good IMO.
Here's an old pic of the shortened arm, it may be what you are looking for....
The bottom pic is the stock arm with a 4.5 inch rear rim with a 160 on it and it clears, just....

[caldurham]

If you go with the GSXR wheels then you WON"T need an offset sprocket, you will either have to machine a small amount off the GSXR sprocket carrier and have a front offset sprocket made, or use a cycleX offset front sprocket and machine the rear carrier to suit. A K8 counter shaft will also help as they are 10mm longer. I have an old 1988 GSXR1100 swingarm with the monoshock section removed and shortened to go into my K2, these arms can be shortened at either end {if you know what you are doing} and look good IMO.
Here's an old pic of the shortened arm, it may be what you are looking for....
The bottom pic is the stock arm with a 4.5 inch rear rim with a 160 on it and it clears, just....

i need to be careful when i reply here lol.
i meant i know i'll need an offset FRONT sprocket. and i plan on getting one from cycle-x shortly.
so you'll have to forgive my numbskull tendencies.

also what size tire and wheel do you have on the pic with the gsxr1100 swing arm? and what did you do to the pivot area to make that swing arm fit? shortening the swingarm should be fairly easy i'd say. also i dunno if there is a difference in the pivot hole area between the k and the f model. but my frame is a 76 f model.

i'd really LOVE to use the wheel from the swingarm i have if i don't use the swingarm itself and from memory i think it has a 180/55-17 tire on it. i am SURE about the tire being a 180.

also another reason i am asking about a swingarm that will both fit the 180 tire i want AND require minimal fabbing is because anything that can save me time is a huge plus. the braced gsxr swingy i have can be made to work but it's also gonna require alot of time in the pivot area and even more if i decide to cut the bracing. and the more i look at the bracing the less i like it.
also trying not to spend unless i need to. but the only thing i don't have much of, unfortunately, is time to work on it. we won't get into my time restraints   

right now i have 3 swingarms i could sell. one being the gsxr swingy i have mocked onto the bike. of course the stock 76 swingarm and i have another boxed swingarm that i have no clue what it fits, i'll have to figure it out. but i know it will not work as i have already tried to see if it would.

i'll try to be clearer in any future posts. and man i appreciate the help!

[Retro Rocket]

If you go with the GSXR wheels then you WON"T need an offset sprocket, you will either have to machine a small amount off the GSXR sprocket carrier and have a front offset sprocket made, or use a cycleX offset front sprocket and machine the rear carrier to suit. A K8 counter shaft will also help as they are 10mm longer. I have an old 1988 GSXR1100 swingarm with the monoshock section removed and shortened to go into my K2, these arms can be shortened at either end {if you know what you are doing} and look good IMO.
Here's an old pic of the shortened arm, it may be what you are looking for....
The bottom pic is the stock arm with a 4.5 inch rear rim with a 160 on it and it clears, just....

i need to be careful when i reply here lol.
i meant i know i'll need an offset FRONT sprocket. and i plan on getting one from cycle-x shortly.
so you'll have to forgive my numbskull tendencies.

also what size tire and wheel do you have on the pic with the gsxr1100 swing arm? and what did you do to the pivot area to make that swing arm fit? shortening the swingarm should be fairly easy i'd say. also i dunno if there is a difference in the pivot hole area between the k and the f model. but my frame is a 76 f model.

i'd really LOVE to use the wheel from the swingarm i have if i don't use the swingarm itself and from memory i think it has a 180/55-17 tire on it. i am SURE about the tire being a 180.

also another reason i am asking about a swingarm that will both fit the 180 tire i want AND require minimal fabbing is because anything that can save me time is a huge plus. the braced gsxr swingy i have can be made to work but it's also gonna require alot of time in the pivot area and even more if i decide to cut the bracing. and the more i look at the bracing the less i like it.
also trying not to spend unless i need to. but the only thing i don't have much of, unfortunately, is time to work on it. we won't get into my time restraints   

right now i have 3 swingarms i could sell. one being the gsxr swingy i have mocked onto the bike. of course the stock 76 swingarm and i have another boxed swingarm that i have no clue what it fits, i'll have to figure it out. but i know it will not work as i have already tried to see if it would.

i'll try to be clearer in any future posts. and man i appreciate the help!

The wheel in the pics is off a 1988 GSXR750J model, it is a 4.5X17 inch rim.
The GSXR swingarms off the early GSXR's {slab sided models} bolt straight in {that was a bonus}.
The early GSXR750 arms {F,G,H} also bolt strainght in but are slightly smaller in the box section, i am going to use a modified one on another build i have. The 1100 swingarm in those pics was shortened at the rear only, if i was to do it all over again i would take the swingarm pivot tube off the swingarm and shorten it there as well, it leaves more scope for wider wheels as it keeps the bend in the arm further toward the pivot {does that make sense?}.

[caldurham]

The wheel in the pics is off a 1988 GSXR750J model, it is a 4.5X17 inch rim.
The GSXR swingarms off the early GSXR's {slab sided models} bolt straight in {that was a bonus}.
The early GSXR750 arms {F,G,H} also bolt strainght in but are slightly smaller in the box section, i am going to use a modified one on another build i have.

on the gsxr750 swingarms by smaller box section do you mean the swingarm is not as wide as the 1100 or the actual boxing that makes up the arms is not as beefy as the 1100 swingarm?

The 1100 swingarm in those pics was shortened at the rear only, if i was to do it all over again i would take the swingarm pivot tube off the swingarm and shorten it there as well, it leaves more scope for wider wheels as it keeps the bend in the arm further toward the pivot {does that make sense?}.

and if i understand you correctly yes that makes sense. cutting off the arms next to the pivot tube and shortening the arms on the pivot tube side then weld them back to the pivot tube?

so do you know offhand if these gsxr swingarms will accommodate a 5 or 5.5 inch wheel fairly reasonably?
it seems this would be the way to go if they simply bolt right in to the pivot area on the frame. and from past experience on ebay they are relatively cheap!

[Stev-o]

Only a 180?  Why not go really large and put a 330 on like this guy?!! (classic thread)


http://forums.sohc4.net/index.php?topic=64243.0

[caldurham]

Only a 180?  Why go really large and put a 330 on ot this guy?!! (classic thread)


http://forums.sohc4.net/index.php?topic=64243.0

LMAO!!! yeah i'll stick with the lowly 180.

[lucky]

I think the most important question is this:

If you put a 180mm wheel in the swing arm,will the wheel be able to be centered in the frame and at the same time will you be able to get sprockets for the front and rear that will line up?

Your best bet would be to use a H-D wheel since those are made to have different width spacers that you can use to space the rear sprocket out to where it will line up with the front sprocket.

I agree the swing arm in the photo is so massive and complicated it just does not look right. Maybe if it was painted black?

[lucky]

Only a 180?  Why go really large and put a 330 on ot this guy?!! (classic thread)


http://forums.sohc4.net/index.php?topic=64243.0

LMAO!!! yeah i'll stick with the lowly 180.

LOL....lol/lol, Of course that is not going to work. The part of the chain that has the most force being applied has to go over that little sprocket. I give it one week.

Also those choppers with big fat rear wheels are bad news if you go to pull off of a road. The front and rear tire do not match and it feels VERY weird and uncontrollable when on a slope. From personal experience.

[caldurham]

I think the most important question is this:

If you put a 180mm wheel in the swing arm,will the wheel be able to be centered in the frame and at the same time will you be able to get sprockets for the front and rear that will line up?

The swingarm i posted in the pic can be centered fairly easily with the right bushings and spacers, but it's the size of the pivot tube itself that will make it a job. at worse to get the wheel sprocket to line up i'll have to machine the carrier some but shouldn't be a big deal.

Your best bet would be to use a H-D wheel since those are made to have different width spacers that you can use to space the rear sprocket out to where it will line up with the front sprocket.

I agree the swing arm in the photo is so massive and complicated it just does not look right. Maybe if it was painted black?

this is the crux of my problem i think. i really love that wheel and want to use it plus it was free along with the swingarm and brake and matching front inverted forks, triples and front brakes. and i think i'll have no problem getting it spaced and or the carrier machined to get the sprockets to line up. but the work involved in getting that swingarm to work (i know it can be done) just seems like a waste of my valuable time. and i really really am starting to not like the bracing at all. the wheel is golden tho!

i'm starting to sound like a girl on a shoe shopping spree!

[Retro Rocket]

The wheel in the pics is off a 1988 GSXR750J model, it is a 4.5X17 inch rim.
The GSXR swingarms off the early GSXR's {slab sided models} bolt straight in {that was a bonus}.
The early GSXR750 arms {F,G,H} also bolt strainght in but are slightly smaller in the box section, i am going to use a modified one on another build i have.

on the gsxr750 swingarms by smaller box section do you mean the swingarm is not as wide as the 1100 or the actual boxing that makes up the arms is not as beefy as the 1100 swingarm?

The 1100 swingarm in those pics was shortened at the rear only, if i was to do it all over again i would take the swingarm pivot tube off the swingarm and shorten it there as well, it leaves more scope for wider wheels as it keeps the bend in the arm further toward the pivot {does that make sense?}.

and if i understand you correctly yes that makes sense. cutting off the arms next to the pivot tube and shortening the arms on the pivot tube side then weld them back to the pivot tube?

so do you know offhand if these gsxr swingarms will accommodate a 5 or 5.5 inch wheel fairly reasonably?
it seems this would be the way to go if they simply bolt right in to the pivot area on the frame. and from past experience on ebay they are relatively cheap!

The 750 arm will fit up too 5.5 inch, and has smaller box section. they {1100, 750} will both accept the 5.5 inch rear wheels, i just recommended one of the 1100 swingers to a member in the hypo section of the forum and he is now using it on his drag bike..
They are far too long in their stock configuration for a road bike. Mine was shortened only at the rear now i will probably have to stick with 17 inch rims on that one because where the arm bends back in to the pivot area is now closer to the tire, with the monoshock in there there is no problems, with the mono section removed and rebraced, i only had material removed from the adjuster end of the arm so the tire is very close to where the arm comes back in near the pivot {i removed as much length as possible because i want this bike to stay close to the original wheelbase for handling reasons}, in hindsight i would have removed an inch from the pivot end as well, i wish to retain 18 inch rims {18x4.5 and 18 x 2.75}, with the 17's it isn't as close.  There is enough room on the GSXR rear sprocket carrier to remove some material to get the sprocket closer to the tire, this is necessary to get the chain lined up, with a 5.5 you may have to have custom offset sprockets made, there are places that make them to order... If i can find a link i'll post it here....

[Retro Rocket]

I agree the swing arm in the photo is so massive and complicated it just does not look right

Actually Lucky, if you see the whole bike in perspective it looks very good, i'm fussy as hell, if it looked like sh1t, it wouldn't be there....
Its on a F model frame, with the squarer lines of the F it looks cool....

[lucky]

I like the wheels and the aluminum swing arm, without the bracing.

[caldurham]

The wheel in the pics is off a 1988 GSXR750J model, it is a 4.5X17 inch rim.
The GSXR swingarms off the early GSXR's {slab sided models} bolt straight in {that was a bonus}.
The early GSXR750 arms {F,G,H} also bolt strainght in but are slightly smaller in the box section, i am going to use a modified one on another build i have.

on the gsxr750 swingarms by smaller box section do you mean the swingarm is not as wide as the 1100 or the actual boxing that makes up the arms is not as beefy as the 1100 swingarm?

The 1100 swingarm in those pics was shortened at the rear only, if i was to do it all over again i would take the swingarm pivot tube off the swingarm and shorten it there as well, it leaves more scope for wider wheels as it keeps the bend in the arm further toward the pivot {does that make sense?}.

and if i understand you correctly yes that makes sense. cutting off the arms next to the pivot tube and shortening the arms on the pivot tube side then weld them back to the pivot tube?

so do you know offhand if these gsxr swingarms will accommodate a 5 or 5.5 inch wheel fairly reasonably?
it seems this would be the way to go if they simply bolt right in to the pivot area on the frame. and from past experience on ebay they are relatively cheap!

The 750 arm will fit up too 5.5 inch, and has smaller box section. they {1100, 750} will both accept the 5.5 inch rear wheels, i just recommended one of the 1100 swingers to a member in the hypo section of the forum and he is now using it on his drag bike..
They are far too long in their stock configuration for a road bike. Mine was shortened only at the rear now i will probably have to stick with 17 inch rims on that one because where the arm bends back in to the pivot area is now closer to the tire, with the monoshock in there there is no problems, with the mono section removed and rebraced, i only had material removed from the adjuster end of the arm so the tire is very close to where the arm comes back in near the pivot {i removed as much length as possible because i want this bike to stay close to the original wheelbase for handling reasons}, in hindsight i would have removed an inch from the pivot end as well, i wish to retain 18 inch rims {18x4.5 and 18 x 2.75}, with the 17's it isn't as close.  There is enough room on the GSXR rear sprocket carrier to remove some material to get the sprocket closer to the tire, this is necessary to get the chain lined up, with a 5.5 you may have to have custom offset sprockets made, there are places that make them to order... If i can find a link i'll post it here....

DUDE all i can say is THANK YOU!!!!!!!! this is very valuable information. definitely gonna keep the 17 inch wheel i have and make it work. now just gotta score the right swingarm off ebay. once again man THANK YOU!!!!! this will definitely help me to achieve the look i am going for which is a combo cafe racer/streetfighter look. when that's squared away i'll start working on an engine build. wish i had more time to devout to it but so does everyone i guess.

I like the wheels and the aluminum swing arm, without the bracing.

i agree the bracing is almost too much. i think it looks good on the DOHC cb1100 streetfighter i posted but i think it will look weird if i were to do it to my 76 SOHC bike.

[Retro Rocket]

DUDE all i can say is THANK YOU!!!!!!!! this is very valuable information. definitely gonna keep the 17 inch wheel i have and make it work. now just gotta score the right swingarm off ebay. once again man THANK YOU!!!!! this will definitely help me to achieve the look i am going for which is a combo cafe racer/streetfighter look. when that's squared away i'll start working on an engine build. wish i had more time to devout to it but so does everyone i guess.

The only thing i haven't looked into is centering the rear wheel, i am not sure if the Suzuki wheel occupies the same spot as a honda wheel in the swingarm, but at worst you will have to fab up a couple of spacers, relatively easy to do..

I am also using a gsxr1100K {1989} front fork set up, Right side up 43mm cartridge forks, this can be used by having the Honda steering stem pressed out and pressed straight into the Suzuki clamps, yes, it is exactly the same OD as the Honda stem, cool eh.., the Suzuki clamps have a smaller offset {35mm compared to 60mm for the K} so it slows the steering down by increasing trail, i am having a member here make me some 50mm offset clamps to put the steering just where i want it..... I want my K2 to look like a modern version that maybe Honda would build now if it was to build a modern version of the old K model bikes....  Isn't it fun playing round with these old bikes....

Here's an old pic of the Suzuki front end with the Suzuki clamps and Honda stem...


Mick

[caldurham]

The only thing i haven't looked into is centering the rear wheel, i am not sure if the Suzuki wheel occupies the same spot as a honda wheel in the swingarm, but at worst you will have to fab up a couple of spacers, relatively easy to do..

I am also using a gsxr1100K {1989} front fork set up, Right side up 43mm cartridge forks, this can be used by having the Honda steering stem pressed out and pressed straight into the Suzuki clamps, yes, it is exactly the same OD as the Honda stem, cool eh.., the Suzuki clamps have a smaller offset {35mm compared to 60mm for the K} so it slows the steering down by increasing trail, i am having a member here make me some 50mm offset clamps to put the steering just where i want it..... I want my K2 to look like a modern version that maybe Honda would build now if it was to build a modern version of the old K model bikes....  Isn't it fun playing round with these old bikes....

Here's an old pic of the Suzuki front end with the Suzuki clamps and Honda stem...

Mick

yeah i am figuring i'll need some spacers. no biggy. just kind of hard to find the info i need. i still don't know why i can't use the forum search function. it just will not work for me.

i've wanted a cb750 for YEARS and finally got this one for $500. it had sat out in a shed for a while and has some rust but nothing too bad. it was a complete bike except for the side covers and it was running before i tore it down. after i get the frame and suspension done i want to do an 836 engine build.

i like your front forks. do you have any pics of the complete bike? i'd like to see 'em.

here are the front forks i plan on using on my 76. if you look you'll notice that i'll need to get rotors and a new wheel! lol. everything else is there tho. can't wait to get started on fitting this but i wanted to get the swingarm problem solved first.


btw here is a pic of the bike i ride currently.


it was an 883 hugger. been converted to a 1200, head work, carb work, reverse shift pattern, clip-ons and rearsets, 1200 sportster sport shocks. basically been set up to take the twisties. most of the HD faithful consider it blasphemy. it was my late brothers bike so i am very hesitant to do any cutting on the frame or tins. but when my brother had it it was a stock 883 hugger that he had planned on turning into a drag bike. unfortunately he never got the chance to mod it at all.

[Stev-o]

Mick - what's with the letteringon the Suzi? Used for work?!

[Retro Rocket]

Mick - what's with the letteringon the Suzi? Used for work?!

Hey Steve, thats actually my F frame with those bits on for a mock up, that is a K tank from an old drag bike complete with period advertising  , not off the drag bike i bought, another one...

[Retro Rocket]

The forum search is playing up due to a change of server, the mods are onto it..

i like your front forks. do you have any pics of the complete bike? i'd like to see 'em.

No more pics, i am going to go down as one of the slowest builders on here {maybe Jerry will beat me} I have been collecting parts for nearly 10 years, started out with one old 750 drag bike and now i have 3 but all are in parts, one 1000cc one 970ccc and a 900cc, one is an F0-1 a K2 and a K4 k2 hybrid, 2 of them are very expensive to build so its slow going, i have just moved into a house with a huge garage {shed} so things may speed up a bit now....