T8's 750 Cafe Racer Project

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.

F*cking hell. You could serve a pizza on that thing.

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

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

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.

[GSXR7ED]

Subscribed.




Ed

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



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

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!

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.

Nice build and pretty cool ideas and fabrications

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.

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


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



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.




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.

[Charlie G]

That's pretty sharpe looking!

cg

This looks very cool!! The disc is almost as large as the rim

As promised here are some photos from today. The lathe work is done and both parts are made. We did not, however, get the holes counterbored and drilled. I'm SO bummed. Monday folks Monday and she'll be put together. Unfortunately when Ben took the emery cloth to the parts he went to hard on the bearing area and now they are no longer press fit.. Kinda ****es me off but I just told him we'll throw it all together and see how things work. Anyways here are a couple pics from today.

[psyguy]

i like where you're going with this so i'll tag along