T8's 750 Cafe Racer Project

[T8erbug]

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!

[T8erbug]

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

[GSXR7ED]

Subscribed.




Ed

[Shwartz]

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.

[T8erbug]

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

[UncleMike]

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

[T8erbug]

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.

[mlymanz71]

That front end is shaping up nicely, love the look of the rotor on that spoked wheel.

[Sci85]

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.

[shwokee]

Just following along. So inspirational. Awesome job.

[T8erbug]

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




Clamping situation





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

[T8erbug]

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.

[T8erbug]

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.















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.

[DannyMotor]

Looking good so far!! It's going to have a long stance!

[storm 64]

Lookin' good T8 ! I also love them spokes!