Topic: CB400F Swing Arm

[brandon]

I was doing a bit of looking online and came across this thread which TTR400 makes reference saying that the rear swing arm from a Honda NSR 250 MC (which is a very sexy bike btw) is a doable upgrade with some modifications: http://forums.sohc4.net/index.php?topic=27089.0

I am genuinely curious, aside from the box swing arm that Kevin makes, if there are other alternatives out there for the little 400F swing arm? My little 400 is in the beginning stage of a major overhaul and I'm trying to get all of my eggs in one basket before starting.

Also to note, I am very interested in running a rear mag wheel with a disc setup, and moving away from the spoke wheels that the 400F currently has. Upgrading the rear swing arm to more substantial unit will help in this process.

Hmm. Would anyone know the measurement of the pivot point part of the cb400f swing arm?

Any help or insight would be appreciated.

[ttr400]

The pivot point of the CB400F frame is around 205mm (inside measurement). the NSR250 MC18 arm is 197mm. this arm can be made to fit with new bushes or bearings and spacers etc, will also need the shock mounts fabbed up and welded on. You will find many swingarms from more modern bikes that will work. I have found as with the MC18 arm is that they are to long, this one is 50mm to long. I will be making it shorter and removing the mono shock mounts etc.

Hope this helps.

Kevin

[brandon]

Hi Kevin,

Thank you for the reply. While I would totally love to run that nice swingarm you make, I digress, I am on a college students budget, but do frequent your website to look at things. Also your help speaks about your character - you sell killer parts, but still chime in to help. Much appreciated!

I know there is homework to be done on this and that is fine with me, but would you mind giving me another clue as to what may work? Is there a certain marque that I should focus on?

[MaaseyRacer]

What about this one:

http://www.motolanna.com/ourshop/prod_448876-Swingarm-Aluminum-Alloy.html

It uses a 17mm axle. Here are the dimensions.  I plan on ordering one of these. 

[brandon]

Looks pretty nice. Priced respectfully too.

On my quest to find a rear swing arm swap for my 400F I have found that these are relatively close at the pivot point, in addition to Kevin's recommendation of the Honda MC18, the:

Honda MC21 NSR250
Yamaha FZR250R
Suzuki RGV 250K

are all 205mm at the pivot. I have yet to delve into greater detail, such as length. Also a swing arm slightly smaller would work too, like the MC18.

EDIT: Finding information is tough, but fun, and a good learning experience. I did though, take the liberty of doing general searches on eBay, to ask sellers for measurements.

[fasturd]

So you are going mono shock and aluminum for sure?

I have a vintage perf. swing arm and if I remember right it was based on the CB360? Thicker axel plates and bronze bushings. This one also has an A-trac mod. I was going to use it on my Project 13 but it is a little too out there for that project . I am saving it for the next one. I have a stock swing arm with a Brembo rear disc set up on my 400. Take a look at my project link if you would like to see what it looks like.

Good luck on the build.

[brandon]

I would like to go aluminum, but am still on the fence with running a mono shock or not. The swing arm you made reference to, I am not familiar with. Well, I'm learning and a full on noob, so I'm not familiar with much at all!

I have seen your rear disc setup and it's pretty rad. I am hoping to change the rear to a mag wheel with disc setup...so I'll continue the search for something that works!

[ttr400]

Depending on the availability of the bikes in the states, have a look at the swingarm for the CB400 super four, this is a twin shock bike from around 1993. another one is from the CB1 from around 1990, monoshock bike but can be modified. Also take a look at some of the early CBR600's. The NSR250 MC21 has a gull arm, so I would not use that one unless you are planning on going monoshock.

Kevin

[MaaseyRacer]

Depending on the availability of the bikes in the states, have a look at the swingarm for the CB400 super four, this is a twin shock bike from around 1993. another one is from the CB1 from around 1990, monoshock bike but can be modified. Also take a look at some of the early CBR600's. The NSR250 MC21 has a gull arm, so I would not use that one unless you are planning on going monoshock.

Kevin

I do not think the super four made it into the US. I have been searching for a super four swing arm for some time now.

[Stevevo8]

Does anyone know the length of the stock 400f swingarm?

[MaaseyRacer]

CB400F swing arm is ~490mm

[malcolmgb]

Here is a picture I took back in 2007, looked like a Yamaha LC if I remember right.

[Stevevo8]

What about this one:

http://www.motolanna.com/ourshop/prod_448876-Swingarm-Aluminum-Alloy.html

It uses a 17mm axle. Here are the dimensions.  I plan on ordering one of these. 

Did you ever buy one?