1983 Honda 750 Nighthawk

26mm from the inside of the fork leg/outside of the caliper to the center line of the disk rotor.

+/- about 1mm.

You might get away with shaving a small amount off the lower inside face of the caliper, but I think I see a GSXR front wheel in your future.

What rear wheel are you using?
 
26mm from the inside of the fork leg/outside of the caliper to the center line of the disk rotor.

+/- about 1mm.

You might get away with shaving a small amount off the lower inside face of the caliper, but I think I see a GSXR front wheel in your future.

What rear wheel are you using?

I'm not going 17" front under no circumstances. This guy did it using radial brakes, which should be even tougher to pull off. I dont know how much he had to shave off the inside, but its clear hes using spacers to bring the caliper as far back as possible. I'm pretty sure it's the exact same comstar wheel.

My rear wheel is a 17" from a '92 nighthawk. Using the original '83 20mm axle instead of the 92's 17mm. The rear spacers are finished and I'm happy with the way it sits with a 150/70/17 tire.

Thanks for the numbers! It should help me figure out the caliper situation. I might PM you for the exact model of them if I decide to go with those 4 piston ones. I agree, the 6 piston ones are probably not my best option.
 

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I have not seen anyone use aluminum for a seat pan that they plan to bend to shape.

I mean, if you're going aluminum for ease of bending you'll just end up with a flimsy pan. If you go with something that will be sturdy, then it won't be any easier to bend

*shrug*
 
I think Titan suggested aluminum as it is less springy when bending it vs steel, it's also lighter and easier to cut/shape. when you bend aluminum, it just stays bent and you don't need to over bend past for the spring back. Now if you are welding it etc. then steel is much easier. Either way keep going, it's starting to shape up for you.
 
I think Titan suggested aluminum as it is less springy when bending it vs steel, it's also lighter and easier to cut/shape. when you bend aluminum, it just stays bent and you don't need to over bend past for the spring back. Now if you are welding it etc. then steel is much easier. Either way keep going, it's starting to shape up for you.

Ah, ok. I suppose that would help. I didn't think aluminum wouldn't bounce back.
Probably might just have to tack a couple of machine screws to the pan, and that's it
 
I used an alloy seat pan, didn't need the bends you have to make, but to add stiffness, and you may have to anyway even with steel, I ran a few bead patterns.

b1Hngln.jpg
 
Seat pans aren't that heavily stressed. They hold at most 2 peoples weight. So 400 lbs, and they are generally supported by the tubes under neath. The pan really just bridges the gap. IMO, rolled beads are mainly for stopping pans from drumming, though they do increase rigidity.
 
That would certainly be the way to go, but i just don't have the tools to do that and make it look good.
OEM seat pans are a different story. Those are stamped out and yes, have a ton of rigidity to them as a result.
However, unlike the OEM seat pan, this will sit along the frame and have more support all around than the OEM one does. We'll see. Plenty of others have done the same and it worked out fine for them.
 
Seat pans aren't that heavily stressed. They hold at most 2 peoples weight. So 400 lbs, and they are generally supported by the tubes under neath. The pan really just bridges the gap. IMO, rolled beads are mainly for stopping pans from drumming, though they do increase rigidity.

Yes, you could be right but that 400lbs is spread over usually 6 or so rubber mounts not over the entire pan surface. By drumming do you mean to keep it from noisily resonating, if so, That's interesting, I never thought about that before.
 
6 or so rubber mounts as opposed to the pan sitting on a significant section of the frame in this scenario. This requires far less rigidity from the pan.

Yes, resonance is a large issue with big panels, so they roll beads to help keep them from generating noise. Sometimes the stiffness is needed for other purposes as well.
 
6 or so rubber mounts as opposed to the pan sitting on a significant section of the frame in this scenario. This requires far less rigidity from the pan.

Yes, resonance is a large issue with big panels, so they roll beads to help keep them from generating noise. Sometimes the stiffness is needed for other purposes as well.

Do they muffle farts?
 
you need rigity in the pan to prevent the seat cover from turning it into a taco, whatever supports below are probably fine. The first time you park in the sun and the cover shrinks its game over.
 
Most early GoldWing pans had only the front tongue (with support from a frame-mounted hoop under), two rubber pads in the middle, and the two bolt ears near the back. Ten large holes, I guess to let air in & out. And one X near the front to reinforce. The sides rolled down over the frame significantly which added strength. I have never seen one that was bent in use. Now, those were the early ones - before Honda saw the loads that GoldWing seats would be asked to carry. Also required to be comfortable for older butts on longer rides than most of the seats I see on here. Notice tbe reinforcing buttresses on each side to prevent the tacoing doc_rot mentions.BTW, with the foam glued to tge pan, there should be no resonance problems. Easy to find dense (you need dense to keep butt bones from hitting the pan) foam is carpet padding called "rebond". I have found carpet dealers will either give away left-over scraps, or sell it in small quantities cheap. Glue with 3M 80 spray adhesive, cut with electric carving knife (NOT hers!) Final shape with a course grit grinder.
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ok. does anyone have any pics of the so called "tacoing" phenomenon?

While it makes sense in theory, i've come across MANY builds that use sheetmetal seat pans and i have yet to see a single one complain about this.
Grinding on the seat with your ass seems like it would put more stress on the fabric than just letting it sit out in the sun for a while.

Fiberglass would be more rigid, i agree, but i have zero fiberglass experience and don't really want to invest in all of the materials only to come out with mediocre results from me not knowing what i'm doing

I think i repaired a canoe once like 15 years ago, and it all came out lumpy like a pile of garbage. Just don't really have the desire to learn the process.
 
If your pan is largely going to sit on the frame tubes, aluminium will work just fine. It's easy to work and shape, and attaching some heavy rubber strips will help cushion it.
 
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