T8's 750 Cafe Racer Project

[Chuck78]

Awesome man! Really glad to hear that you are finally nearing the moment when you can get that thing on the road!

[T8erbug]

Seat Plug

I have been dreading this moment for a while now.. But with the last warm streak we had here I couldn't help but think about how this bike was already supposed to be "ready to ride". Anyways, the challenge with the plug is making it symmetrical. Since it's all been built from scratch there are minor imperfections everywhere.. as you shape it and reshape it some things get close while others seem to drift out of shape. Looks fine but I want it to look great and don't want nitpicky people to have anything catch their eyes. It's a tough deal but anyways hopefully I can get this done in the next week or so and finally experiment with laying some fiberglass.

[GregT]

What caliper are you using ? Number of pistons ?
Bore of the M/c you have now - usually cast into the underside.

tell me that and i'll give you a close figure for what size M/c to look for.

[Triam]

I have been dreading this moment for a while now.. But with the last warm streak we had here I couldn't help but think about how this bike was already supposed to be "ready to ride". Anyways, the challenge with the plug is making it symmetrical. Since it's all been built from scratch there are minor imperfections everywhere.. as you shape it and reshape it some things get close while others seem to drift out of shape. Looks fine but I want it to look great and don't want nitpicky people to have anything catch their eyes. It's a tough deal but anyways hopefully I can get this done in the next week or so and finally experiment with laying some fiberglass.

Maybe you could design what you want the seat to look like in solidworks, and then have your friend stick it in the mill and surface mill it until it looks like you want it. It'd be symmetrical if you did that.

[T8erbug]

What caliper are you using ? Number of pistons ?
Bore of the M/c you have now - usually cast into the underside.

tell me that and i'll give you a close figure for what size M/c to look for.

Awesome, thanks! I looked under the MC and didn't see a casting but I know it's not the stock unit for the donor forks/brakes (2001 GSXR600). It's a nissin unit, however the caliper is stock for the model and runs on four pistons.

Maybe you could design what you want the seat to look like in solidworks, and then have your friend stick it in the mill and surface mill it until it looks like you want it. It'd be symmetrical if you did that.

We do have a new mill that will do this kind of stuff in high density foam but at this point it's almost more work to stop where I'm at, design the part in solidworks, figure out a clamping situation, and try to mill it all straight in one try with my current plug.. If we'd have had the ability to do it this way from the start I would have done it no doubt because you're right about it being totally symetrical. I will be taking full advantage of the new mill when doing the underbelly pan plug. It should make things much easier.

[T8erbug]

Here is the rear brake situation now. All installed and ready to go!

[steve murdoch]

Any mechanical advantages to your brake stay?
I love the cool factor.

[GregT]

Awesome, thanks! I looked under the MC and didn't see a casting but I know it's not the stock unit for the donor forks/brakes (2001 GSXR600). It's a nissin unit, however the caliper is stock for the model and runs on four pistons.

Late 4 piston Nissin caliper - you'll find a surprisingly small M/c will work very well - 12mm or 1/2inch bore will give you a good feel and plenty of power. Look at dirt bike M/c for a start.

Your rear brake setup looks good. On my wire wheels I got discs with them very like yours but can't use either front or rear...wave discs are banned in the class I'm building the bike for...
How does your chain line work out ? I'm having to move mine inboard on the hub which isn't easy. Pics will come on my build thread soon.

[boontonmike]

T8,

Every time I see an update on your bike I get a little more jealous. I haven't touched mine in months and every update you post there is some new cool machined bit. Keep it up.

[Morrison]

Mad props! Subscribed!

[Chuck78]

Your brake stay's short reach and abrupt angle leave me wonderimg if an excessive amount of force at awkward side loaded angles would be generated, since the caluper will wat to push horizontally. It makes we wonder if the slightest amount of wear or slop would allow radial slippage movement if rge caliper/habger, sbd then more side loading if the stay's spherical heim jointsabd threaded connections.
Have other production bike used a similar setup?

[GregT]

Your brake stay's short reach and abrupt angle leave me wonderimg if an excessive amount of force at awkward side loaded angles would be generated, since the caluper will wat to push horizontally. It makes we wonder if the slightest amount of wear or slop would allow radial slippage movement if rge caliper/habger, sbd then more side loading if the stay's spherical heim jointsabd threaded connections.
Have other production bike used a similar setup?

Have another look - the caliper thrust is actually tangential to the disc and the arm angle follows this quite well. The arm itself is IMO well up to the loads involved. Can't see the point where it picks up on the swingarm but everything else is well enough done to give me confidence it's good too.
You may be surprised at some factory setups...look at some Ducati ones to see what you can get away with.

[Guest]

Question. What foam are you using for the old seat base? Is it compatible with the polyester resin? Normal fiberglass resin? Where to get foam that is compatible. I.E., won't melt once you apply the resin?
No epoxy, please.
Tnx
G

[T8erbug]

Late 4 piston Nissin caliper - you'll find a surprisingly small M/c will work very well - 12mm or 1/2inch bore will give you a good feel and plenty of power. Look at dirt bike M/c for a start.

Your rear brake setup looks good. On my wire wheels I got discs with them very like yours but can't use either front or rear...wave discs are banned in the class I'm building the bike for...
How does your chain line work out ? I'm having to move mine inboard on the hub which isn't easy. Pics will come on my build thread soon.

Hey Greg! Yeah, that goes right in line with what I was thinking as well as what I was told by one of the guys at Warp9. I'm going to use a dirt bike MC as soon as I can find the one I want for a good price!
As far as chain alignment, everything looks fine and has passed a visual inspection (as well as using a chain alignment tool, which is basically just a better way of eyeballing it). We'll see how it all works out when I get it rolling. I'll start by getting the wheels aligned and then go from there with the chain. Luckily it's relatively adjustable through the front sprocket as of now and I have some clearance to work with. The more I think about it the more daunting it seems but I'll just take it one bite at a time like I have throughout the rest of the build. Thanks for the info!

[T8erbug]

Any mechanical advantages to your brake stay?
I love the cool factor.

The biggest mechanical advantage to it is that I can adjust the alignment on the bike aka move the rear wheel side to side by adjusting wheel spacers without having to machine, weld, and/or tweak the stationary mating parts of the standard rear disc setup as well. The rod ends can each pivot so that is what makes the side to side movement possible where the standard modern set-up is totally stationary. The adjustability is a huge asset to me right now as I am still in the process of chain and wheel alignment. As for strength I can't say just yet. Set-ups like this have been used on custom springer front ends pretty regularly so it should hold up on the rear end without too many issues. I'll be sure to let everyone know if I do have any though!

PS It's also WAY easier to machine and install on a custom job