Topic: NHK steering dampers?

[jakec]

I've been thinking about getting a steering damper for 400F. Yamiya sells this damper by NHK (but it is out of stock)

http://www.yamiya750.com/index.php?main_page=product_info&cPath=179_281&products_id=3704

NHK seems to be the go to for vintage UJM's. Yamiya doesn't tell the stroke or other dimensions of their damper, but I'm sure I could email them and find out.

There are many affordable used or NOS dampers on ebay that often have no mounting hardware, like this one:

https://www.ebay.com/itm/142727525284?ViewItem=&vxp=mtr&item=142727525284

I'm just wondering if anyone has had experience with this brand or with installation of a damper on their sohc in general. I would like to do the necessary research so it can bolt up nicely and not need crazy shimming. There is a post here on the forum but the OP didn't state the size of the damper used (it didn't fit anyways, so not sure it would have helped).

[gareyc]

I believe I have a NHK but I'm not 100% off the top of my head. I have a 77 cb750f and bolted one eye directly to the lower triple (there is a threaded hole built in) and then used a clamp with a rubber insert to mount the lower portion. Its mounted with the adjustment dial sticking out to the right, attached on the right side downtube.

I had trouble finding a clamp that would work and didn't feel like paying $20+ bucks so I got a fence post clamp (I think) and bent it in to a smaller radius, then bent the tabs outward to create more space for the nut to clear. Works just fine for me. Probably 2500ish miles.

[Deltarider]

I've been thinking about getting a steering damper for 400F.

Why? Both hands at the handlebars and you'll be fine.

[PeWe]

Important to use a good clamp that will ensure a rigid mount of the steering damper. I cheaped out in the 80's using an exhaust clamp wich did not give the stability as the clamp made for it does as the mould alu clamp Yamiya sells with the kit. Clamp need to be thick were the bolt is attached, not 1mm plate as the exhaust clamp.

It helped a lot when touring and the center of gravity was moved backwards due to the luggage and passenger. Also good to reduce a front wobble caused by bad tires and other things. This is a standard solution on newer bikes.

[gareyc]

Required? No. Helpful? Sure.

I agree about the clamp. I went through a couple before I found one I felt comfortable with. I'll probably have something welded in place this summer when I have time. There are other purpose built clamps that may be cheaper if you find the two items separately elsewhere. Just an idea.

I'd definitely recommend getting one if you are on the fence. My opinion is that it helps smooth out the feeling some, especially on the roads around me where there are many grooves from construction. Also piece of mind may be worth something.

[slikwilli420]

I run one on my racer, but I used a shindy. I like the shindy because it was rebuildable and not that much more expensive. I have mine mounted across my front forks attached at the seam of the steering head. That keeps it out of the way of things like my oil cooler. There is no downside to having one at all so if it makes you feel better, go for it.

[jakec]

Before this bike I had a 750 dohc. The bars wanted to dive in corners so I dropped the forks in the triple clamp about 1 1/4" and it got a lot better. This new bike, the 400F, Has a bit of the same feeling, where the bars are comfortable in the middle and tend to dive to either side.

I actually watched a vintage moto safety video and the used a 400F to demonstrate speed wobbles, and they stated that the bike was particularly prone (which I assume is due to the geometry/rake of the bike).

I brought this up here before and others were saying it was steering head bearings, its not that, it's smooth all the way across. I think it has something to do with the rake. When it is on the center stand the bike wants to sit with the wheel to either side, you have to balance it to get the wheel to sit straight ahead.

I would like to install a damper to add some resistance to turning.The tendency to want to dive in corners (paired with brand new tires) has me hesitant to put the bike over at all.

[PeWe]

A sudden front wobble is not fun to get in around 150-170 kph. Giving more throttle to solve it is not always possible. That's why my bike got it.
It is sometimes stable with damper in softest setting. As already mentioned it will not do anything bad. Worn flat rear tire will cause instability in corners. Probably better with stock sized tires on stock sized rims.
4.0"-18 rear seems to be better than 120/90-18 on CB750K6. Yamiya's kit is also an old nostalgic aftermarket add-on.

[slikwilli420]

The CB400F is known as a good handling bike, so if its misbehaving, there is an issue that needs to be addressed first. A steering dampener may be a layer of protection, but should not be a band-aid for a larger issue. They are definitely more necessary for racing or very hard street riding.

[jakec]

I can't tell if it's misbehaving or not - I don't think it is. There is something about the geometry of the bike, which is most easily demonstrated when its on the center stand,

If the bike is on the stand with the wheel turned all the way to the right, the bike is resting. As you turn the bars to make the wheel point forward, the front of the bike rises a bit (like fraction of an inch), and there is the resistance of gravity.

At the center, with the wheel forward, it's balanced. But it only takes a little bump on either side and it will easily turn all the way to that side.

Anyways, what I need to do is ride the bike more and get used to it before I start slapping band aids on it. It could just be the new bike feeling giving me the willies. However I do think that this is a mod that I will do eventually, so I appreciate any advice that you guys have.

Right now everything is stock, with appropriately sized road riders. I do think I need new fork springs, some time soon. I have not checked the rear pre load since I bought it. I should see about that.

If anyone is interested, here's the video. It's very informative.

https://www.youtube.com/watch?v=fvsDIq3WwVA&t=686s