• Required reading for all forum users!!!

    Welcome!
    Register to access the full functionality of the GSResources forum. Until you register and activate your account you will not have full forum access, nor will you be able to post or reply to messages.

    A note to new registrants...
    All new forum registrations must be activated via email before you have full access to the forum.

    A Special Note about Email accounts!
    DO NOT SIGN UP USING hotmail, outlook, gmx, sbcglobal, att, bellsouth or email.com. They delete our forum signup emails.

    A note to old forum members...
    I receive numerous requests from people who can no longer log in because their accounts were deleted. As mentioned in the forum FAQ, user accounts are deleted if you haven't logged in for the past 6 months. If you can't log in, then create a new forum account. If you don't get an error message, then check your email account for an activation message. If you get a message stating that the email address is already in use, then your account still exists so follow the instructions in the forum FAQ for resetting your password.

    Have you forgotten your password or have a new email address? Then read the forum FAQ for details on how to reset it.

    Any email requests for "can't log in anymore" problems or "lost my password" problems will be deleted. Read the forum FAQ and follow the instructions there - that's what we have one for...

  • Returning Visitors

    If you are a returning visitor who never received your confirmation email, then odds are your email provider is blockinig emails from our server. The only thing that can be done to get around this is you will have to try creating another forum account using an email address from another domain.

    If you are a returning visitor to the forum and can't log in using your old forum name and password but used to be able to then chances are your account is deleted. Purges of the databases are done regularly. You will have to create a new forum account and you should be all set.

T8's 750 Cafe Racer Project

  • Thread starter Thread starter T8erbug
  • Start date Start date
IMG_1716.jpg


That's pretty sharpe looking!

cg
 
Well bad news. . Our hub spacers we machined beautifully got messed up in the final process of drilling and counterboring the holes with one of the machines at the shop. I'm a little bummed but since it's not costing me anything I'm really just bummed to have to wait till Jan 5 for Ben to get back from Idaho after Christmas break. Anyways now that the bike is full steam ahead I couldn't stand to just sit around all break looking at the bike waiting to finish the front end SO I have started the swingarm swap. As much as I have looked I have yet to see a detailed GS1100 to GS750 swingarm swap. I'm going to give you guys all the information I can so that you will be well informed if you decide to undertake the same task. Here are pictures from today with some measurement details

I measured each swingarm from pivot bolt center to axle center (with axle installed and pushed all the way forward) The GS1100 measured 20" and the GS750 measured 19" so you will gain some wheelbase distance by going to the GS1100 alloy swinger
E2FkK2f.jpg


Here are the pivot bolts. The one on top is the GS1100 and the other is the 750's. The length of the 1100 from the inside of the bolt to the end is 13-3/16 and for the 750 it is 12-3/16
TTJDicc.jpg



This picture shows the ends of the axles (Not pivot bolts). The difference in the two is really just where the threads start and end. This confused me at first because the the 1100 and 750 share the same spacers and wheel width. After measuring the 1100 swingarm is slightly wider between the axle carriers by 1/8". This kind of worries me because with all the same hardware this means the swingarm has to flex a bit more to snug up when tightened. Overall though the extra length, as you can see from looking at the pictures, is just taking up space that the 750 axle should have had to begin with anyways.
FhHIKis.jpg


Yukzcws.jpg


The width on the fronts of the swingarms are the same between models. Note that the 1100 swingarm is larger up front so it will make things a little tighter but it will all clear.
yJAGmC2.jpg
 
Last edited:
So as a quick recap for you fellas:

-GS1100-20" from pivot bolt center to axle center (when axle is slid all the way forward)
-GS750-19"

-GS1100-16mm pivot bolt diameter by 13-3/16" length
-GS750-14mm by 12-3/16"

-GS1100-Same axle diameter as 750 but different overall length at 10-1/4"
-GS750-length is 10-1/18"

Tire clearances are almost the same even though the 1100 is an inch longer. All of the spacing hardware (including brake bracket) is identical.

If anyone has any questions just let me know. I'm leaving on a cruise this week but next week I will be back to finish the swap. I have elected to go the route of reaming out the mounting holes in the frame to accept the larger 1100 pivot bolt. As mentioned earlier the pivot on the 1100 is an inch longer so I will probably try to thread it an inch further down the shaft and cut off the excess. After that we'll see where I'm at as far as spacing goes and final fitment.
 
YEAH! Nice to see a swinger swap on a thread that I can see. Thank you, bought a GS1100 swinger for my 750 as well and have not had the time to dig into it yet.
 
Ok fellas here is a quick update. Ben is officially back! We started finishing the machine work left on the hub adapters (drilling and counterboring the holes). I guess when he tried before the break to do it on his own the milling bit kept clogging and screwed up the part but it is salvageable. It has three counterbores that are just a tad messed up so we put it back in the vise and started over. He rewrote the program so that the CNC machine would drill the holes first then counterbore. The problem was that there were two planes in the same drill hole so we had to machine the counterbore down to meet the second plane (you'll see what I'm talking about when you look at the drawings or see the finished part). Anyways the machine took a long time to finish part one so we will finish the other on Tuesday. Finally after hours and days of public deliberation I have decided once and for all to drill the frame to accept the 16mm GS1100 pivot bolt. Ben has a drill press in his shop big enough we can put the frame on it's side and do the work. I'll be sure to document it thoroughly to help those of you doing the same swap out if you should decide to go the same route as me.
Here are a couple quick vids of the machine work. I'll post final parts on Tues if we finish!

 
Rear Caliper Bracket Design (to accept Brembo caliper and convert to R1 rear disc)

Rear Caliper Bracket Design (to accept Brembo caliper and convert to R1 rear disc)

sZ6tGic.jpg


Started designing my parts in Solid Works today. Here's a pic of the caliper bracket I came up with. All I need now are the proper offset measurements and it will be ready to go. Also, here is a pic of the Brembo Caliper I bought for the fine price of $30. It's common on Ducatis and Triumph I believe. I am Designing a unit for the rear to accept this and a modern rear rotor. The only decision I have to make now is whether to design it to bolt up to the GS750 rear wheel or to find a supermoto rear wheel that already accepts a modern rotor and go from there. If I do the latter I'd only need to design a caliper bracket to fit.. I'm thinking that's the route I'll go as long as I can find a good deal on a SM wheel

d0aVUxm.jpg
 
Last edited:
CaliperBracket-Tate_zpsd7bb28fe.jpg


Started designing my parts in Solid Works today. Here's a pic of the caliper bracket I came up with. All I need now are the proper offset measurements and it will be ready to go. Also, here is a pic of the Brembo Caliper I bought for the fine price of $30. It's common on Ducatis and Triumph I believe. I am Designing a unit for the rear to accept this and a modern rear rotor. The only decision I have to make now is whether to design it to bolt up to the GS750 rear wheel or to find a supermoto rear wheel that already accepts a modern rotor and go from there. If I do the latter I'd only need to design a caliper bracket to fit.. I'm thinking that's the route I'll go as long as I can find a good deal on a SM wheel

BremboCaliper_zps14e4d8ae.jpg

I may be simplifying this too much but doesn't going with a larger, newer rim allow you to run radial tires? It would seem a shame to do all this customization to have a limited tire selection with the older 750 rim.

Or maybe I'm missing something.
 
I may be simplifying this too much but doesn't going with a larger, newer rim allow you to run radial tires? It would seem a shame to do all this customization to have a limited tire selection with the older 750 rim.

Or maybe I'm missing something.

No you're absolutely right and that's why I'll likely be going to the supermoto cush wheel which is 17". The only benefit of doing this to fit the 750 wheel would be to retain the stock 18" wheel. At the beginning of my build I thought that's what I wanted but as it progresses my ideas have shifted some. Retaining the stock wheel would almost be an oxymoron.. Uprgrading a new part that relies on an old part.. Just doesn't make sense. So yeah you're right on the money. Some guys say these bikes handle best ('how they're supposed to') with stock wheel dimensions, BUT as I research many people who raced with these in and out of their era put a 17" rear wheel on.. The people who race the machines are always one step ahead of us regular folk so this project is sort of becoming a follow of their lead with some innovation here and there
 
Alright. Side one-DONE. Three of the counterbores were slighty off center but not to worry. I fixed them with the Dremel to get the bolt heads to slide through. The bolt holes are all perfect and centered. The next one should be perfect but anyone who has done any kind of work knows that the first time never goes as smooth or as fast as the second time. I couldn't help but test fit the new part on the wheel as well as a quick mock up on the bike even though we have not tapped the rotor bolt holes yet. The fit looks like it's gonna be perfect. To say I'm anxious to get this done would be a massive understatement. O and as a sidenote I got the bearings to press fit by scarring the inner housing a bit. The fitment was so close it didn't take much to get it to work like a charm.

zLzaVfw.jpg


H7fsath.jpg


Eue6WfR.jpg


c9DSK7k.jpg


RF5NnsD.jpg
 
Last edited:
That front end is shaping up nicely, love the look of the rotor on that spoked wheel.
 
Man, wish I had access to your setup. So awesome. And wow, that rotor looks HUGE on that spoked wheel. It's gonna be one sweet bike when you get her done.
 
Thanks for the love fellas. Welp, I finally got the 1100 swinger on! The way I did it was not super scientific or anything but I think the end result is close enough to perfect for the bike to perform correctly. I'll just take you through a step by step of what I did.

1) take the motor out
2) purchase a nice drill bit from Fastenal (I used a 5/8 bit which is slightly under 16mm)
3) set the frame in the drillpress and lightly clamp it down
4) put the stock pivot bolt in to help eyeball (I don't recommend eyeballing so if you have a wall laser or something of that sort use it to aid you in drilling a straight hole) alignment with the drill bit
5) once the drill bit and pivot bolt look to be perfectly parallel clamp the frame down snug
6) take out the stock pivot, line up the hole, and start drilling.
7) take your time and use drilling fluid to keep the bit cool
8) drill bits do NOT cut perfect sidewalls so when you are finished ream it to 16mm if possible if not just do what I did and whip out your dremel
9) turn your dremel speed down and be sure to grind a circular motion so you take off material evenly. You barely need to take anything off if using a 5/8 bit so don't overdo it. Finesse is the key here.
10) throw your new swingarm on and you're done

This is for those of you who choose to go the same route as me but should you go another route search for my bushing conversion thread. There are a lot of guys who have stated some excellent alternatives to do the swap without drilling.

Here is what I mean by using the pivot bolt to eyeball getting it parallel to the drill bit
kSjY35K.jpg


zFKeM42.jpg


Clamping situation
M84po4i.jpg


d6wmUas.jpg



Only drill a little at first to make sure you are centered
W1PeCS3.jpg


5ttSlwG.jpg


ICiTf8H.jpg
 
Last edited:
Using this attachment you will get the job done. Use a finer grit. This attachment actually ends up being almost 16mm so it does a great job.

sztP5bG.jpg
 
Last edited:
And here she is in her current state. Just mocking up where I anticipated the swingarm to be. I will need a 15" rear shock setup and I may also relocate the upper shock mounts a half inch lower. It should give me the right swinger angle without taking too much rake away.

eLnWzfg.jpg


KVffvJA.jpg


wokOwsW.jpg


DJPDH3B.jpg


K4Cjri2.jpg


lLS7bOJ.jpg


oJYBF5q.jpg


The next thing I need to do is get the 16mm die so I can cut the threads on the 1100 pivot bolt about an inch further down the shaft. I'd then need to cut off the excess and she'll be good to go. Once that's done I'm going to start working on the fab it will take to mount up the R1 rearsets I purchased. Anyone know where I can get a supermoto rear wheel with a cush drive for cheap?? Please let me know if you have any buddies that work at a powersports dealer or anyone with a hot lead to a good deal on one because that's next on my purchase list.
 
Last edited:
Back
Top