Topic: 1975 CB400F -> Project "something fun to build and ride"

[FunJimmy]

Some times you've gotta do the real work to help pay for the UNREAL work.

Nice progress on the front wheel.
Feels good to get that finished eh!

FJ

[Syscrush]

Looks beautiful.

[gsnorcal]

$562 worth of OEM parts for the motor and chassis are on the way. OUCH!

Dave

[gsnorcal]

Need some frame mod advice...

I've been thinking of doing the typical rear hoop mod:


Photo: jessezm

So, to do the calcs, I removed the spring from a shock and measured it fully compressed, eye-to-eye. At full travel, the rear wheel passes through the plane where the plate in that photo is welded. It uses up a good bit of the space that the stock fender support arch provides.

This is a pretty common mod, so how do people handle it?

* Is bottoming just not a practical concern?

* Are folks modifying the travel of the shock, with longer bumpers.

Thanks in advance for any tips.

Dave

[gsnorcal]

BTW, thanks for the continued encouragement. I have a Canadian fan club!

[gsnorcal]

I took me forever to find a decent CAD program for the Mac. AutoCAD for the Mac has some problems. It crashes on launch. Too bad since it is free for students.

In the end, I found QCad which is only like 20 euro to buy. But it is shareware, so I can try it for a while.

Anyway, I got started drawing the triple design. Will write the G code by hand. This drawing lacks the detail for the pinch bolts, but it is a start. I'll probably bore the holes first, then contour the part. Dunno, still learning.



I ordered two slabs of 6061, 5" x 12", upper is 3/4" thick, lower 1.5" thick. Just under $60. The dimensions are based on the stock R6 parts, but with the 400's offset.

Dave

[Syscrush]

* Is bottoming just not a practical concern?

I haven't done this mod, but bottoming is definitely a practical concern on any vehicle.  You need to be sure that with the suspension fully compressed that tire is not going to contact anything or some very bad stuff could go down.

[FunJimmy]

Hey Dave

That triple tree drawing looks like a great start. I’ve never worked with CNC machines and the required software before so I’m very interested to see where this takes you. The R6 triple trees have spacing that is a fair bit wider than the CB400 triples, and you might not require that wide spacing unless you are planning on a wider rim and tire. Have you considered narrowing the spacing to be closer to the CB400 spacing?

I’m thinking as I type, so the narrow spacing might not work now that you’ve finished fitting the hub and caliper.

Keep it up.

Your Canadian Fan
Jimmy

[gsnorcal]

I’m thinking as I type, so the narrow spacing might not work now that you’ve finished fitting the hub and caliper.

You are partially correct. Luckily the spacers also add width to the critical spoke-caliper clearance. And even with them, I'll still shave the corner of the caliper off like you did.

Otherwise, I'd want to throw the spacers at you. :-). j/k

Plus, there is the axle that I'd need to modify/replace.

Dave

[gsnorcal]

* Is bottoming just not a practical concern?

I haven't done this mod, but bottoming is definitely a practical concern on any vehicle.  You need to be sure that with the suspension fully compressed that tire is not going to contact anything or some very bad stuff could go down.

Yea, my first reaction was the same. Limiting travel of the shock seems less-than-desireable too. I think I won't relocate the battery to the tail. I've got some other ideas that will work and still keep the frame open. And keep the mass more centralized.

Dave

[gsnorcal]

I started polishing some select engine bits today, too. Off to a good start, but it's a slippery slope--hard to stop once you see that it's not perfect.

Dave

[RickB]

I'd be very interested to know about the rear frame hoop travel issue too. As it's done so often, I just assumed it was all good. Has anybody got an explanation as to how it's done safely?

[gsnorcal]

Started laying out toolpaths for the milling today. Using a 13 year old computer with MasterCAM. Stone age, but it works and does the job nicely.

[gsnorcal]

I was waiting on the correct drill bit in order to do a "mock" lacing of my front wheel. The nipples I got are .281", so I reamed out the holes in the rim using a letter "L" drill, which is .290". That worked nicely. Turns out, lacing a wheel is pretty darn easy.

The procedure that I figured out is to insert the "inner" spokes on both sides of the hub before starting.



Then I inserted the outer for one side:



Followed by the outer on the other side:



Then I mounted it up:



It's quite gratifying to see that front end mocked up like that. I might not even have to mill any material off the caliper, but I won't know until I true the wheel. It's gonna look sweet with the rims powdercoated black.

This was the first wheel I've ever laced. Granted, I haven't trued it yet, but it was really quite easy.

Dave

[Syscrush]

Glad it's gone well so far, and it really does look great.

I have a feeling that the truing is where the effort is, though.  If the lacing went well, that should make the truing easier, but I suspect that with wheel building as with anything else - the devil is gonna be in the details.

[FunJimmy]

Anything new to share?

[gsnorcal]

Hi Jimmy,

Project is stalled. One of my crank bearing shells is on back-order and the CNC machine at the school broke as soon as I was done finishing the programming for the triple clamps. I did find a friend-of-a-friend who would mill them for free, but I kind of want the satisfaction of building them myself.

Plus, I was in Baja this weekend for the San Felipe 250 race. And going back to Baja this weekend for another off-road event.

Some stuff I can do is painting the cases--I have decided on POR-15 engine paint. And of course I can keep polishing the other engine parts. We'll see what I get done this week.

Thanks for staying tuned.

Dave

[gsnorcal]

the CNC machine at the school broke

Good news--the machine is fixed. With any luck, chips will fly next Tuesday, the next class day. I finished all the preparations today.

Dave

[FunJimmy]

I have decided on POR-15 engine paint.

Dave

Glad to hear that chips will soon be flying again and those triples will get to see the business end of your 400.

I’m verry interested in your POR-15 engine painting results. I have a spare engine her that I’m planning on freshening up for another bike and wanted to use POR-15 for that one too.

Later
FJ

[Syscrush]

I’m verry interested in your POR-15 engine painting results. I have a spare engine her that I’m planning on freshening up for another bike and wanted to use POR-15 for that one too.

Have you seen this?

[gsnorcal]

I’m verry interested in your POR-15 engine painting results. I have a spare engine her that I’m planning on freshening up for another bike and wanted to use POR-15 for that one too.

Have you seen this?

Ok, you had me scared for a minute. I clicked there and read to the end, waiting for the horror story. But it looks A-OK. Phew. Too many VHT horror stories scared me away.

Dave

[Syscrush]

Ok, you had me scared for a minute. I clicked there and read to the end, waiting for the horror story. But it looks A-OK. Phew. Too many VHT horror stories scared me away.

The POR-15 with freshly-plated exhaust flanges and SS exhaust looks amazing IMO.  I think I'm gonna go that way with my motor when the time comes.

[gsnorcal]

Chips flew tonight, but only the wooden, test variety. Made a few program tweaks tonight. I will definitely start milling the actual parts tomorrow evening.



Dave

[gsnorcal]

Progress... slow, but progress...



Dave

[gsnorcal]

With any luck, I'll get the lower triple clamp done this week.

I also finally got the last parts that I needed to start assembling the motor. Crankshaft main bearings were continually back-ordered from Service Honda, via American Honda, presumably via Honda Japan. Luckily, David Silver Spares had them in stock.

I prepped the engine cases for paint last week. Started with some soda blasting before following the POR-15 instructions to the letter. Maybe I'll paint them today.