Hpsd

[Jeremy Wilkey]

Honda's HPSD has gotten mixed reviews from the media and riders alike. I thought it would be fun to talk about what you guys think and why you feel the way you do. That being said lets do some survey action and then we can talk about the what and why.

Here are my observations. I like the HPSD. It’s a cool little gadget. I have found it’s not adjustable enough. And since the fluid volume is so low the performance seems to tail off rather precipitously as it wears out.

Jer

 

[fatcat216]

A friend of mine who is 50+/45+ "A" rider installed one of these about a month or so ago of his 450r. He said he likes it. He's having a great year.

How long a life do you estimate these have, Jeremy?

**(I'm assuming it's this baby- however, having read the gushing rave reviews on the net maybe I'm mistaken and he just replaced his old one? He gave a very understated grunt. "Yeah it helps" when I asked about it. Maybe he thought if he gushed, he'd be less manly? :p Or perhaps he felt I would not understand the integration with the triple clamp offset and resultant shortened wheelbase? sheesh, guys.)

Edit: My friend confirms I did not call his mx manlihood in question- Rather, it was not this little gizmo. He did, however, reduce the triple clamp offset, and took the damper off his kx. His success can't be attributed to this Gizmo, I'm afraid. ;)

PP: Vital MX has a video graphic that shows what you are describing:

http://www.vitalmx.com/features/First-Look-HPSD-Honda-Progressive-Steering-Damper,1903

 

[Pete Payne]

I like how the HPSD is loose in the middle (when the bars are straight ) and then tightens up as the bars are turned more . Unlike the usual steering damper that is only speed sensitive . The HPSD is position sensitive as well.

 

[Jeremy Wilkey]

The position sensitive component by use of geometry is very intelligent. I think the design was brilliant compared to your standard issue Ohlins, ElKA etc, designs.

So the consensuses so far 3 votes... Seems to follow that we all agree it’s cool. Which in-turn brings the question?

What in the design causes it to not live up to its potential?

How would we change it to perform better?

Some specifics:

The piston is a V4 style Showa. With about 70% of the area devoted to the out side (Traditional rebound but in this case the result of handllebar deflection.) and 30% of the area devoted to return. (Traditional compression.) As a note remember this thing works in reverse. Like the insanely hard to think about Buel shock.

For the sake of ease of thought lets define this as "in" and "out".

In stack is as follows:

17.15 x 3
16.15
10.15
9.2
16.15
16.2


Out:
17.2 x 2
17.15
16.2
15.2
14.2
13.2
12.2
11.4.2 x 2
.5mm bleed common to the piston.

So at this point we need more opinions.. What does it need to do better? I know what I think, but that’s not the point. What needs to happen, and then we can talk about how we might make it better.




Some techno for the day:

I've been playing around with assembly techniques and as you my guess, I can't seem to get a good bleed with a hand assembly techniques. The volume is so low that even the tiniest amount of air can cause histeresus (SP) in the short run plus the oil longevity is compromised. Due to the design the damper works ok with small amounts of air (It’s stiffest at greatest internal pressure.) but I don't like how fast it goes away as the oil wears out.
I decided to make an adaptor that allows me to assemble the unit using our shock vacuum system. This really seems to improve longevity.

That’s all for now.. See you next week.

Jer

 

[Pete Payne]

Xould we make an external oil tank to increase the oil volume so it would not fade as quick ? But this would ruin the nice and neat design .

 

[Jeremy Wilkey]

BTW.. It seems to head south around 25 hours.

 

[The Heckler]

It seems muted. The action is too soft at full hard, by my experience.

Vacuum system to bleed this thing? I'm sure everyone has one in stock on the work bench.

I'd say 86 the bleed on the piston.

The Heckler

 

[Jeremy Wilkey]

It seems muted. The action is too soft at full hard, by my experience.

Vacuum system to bleed this thing? I'm sure everyone has one in stock on the work bench.

I'd say 86 the bleed on the piston.

The Heckler

Heckler,

Sometimes it’s not what is practical but what is best. I'm contemplating offering a DIY bleed free piston kit for this bike. I'm not sure whether there is interest at this point, but if we move forward we would need to offer a bench bleed method. Because I suspect very few people have a vacum system there disposal.

Do people want better performance, at the price of more frequent service?

I know I would be able to offer performance and longevity, so when you lay out the dollars for a service, your getting something of value for the cost. ;)

Jer

 

[MRW]

This is one little damper that I think would be a perfect candidate for "submerged" bleeding. I think, I`ve never done one. :yikes:

Just keep a little Tupperware tub around with with some 5wt. and
change the fluid every 25 hours :) Not to messy and cheap :cool:

Kinda like the air filter tub idea. ;)

 

[Matt90GT]

old post, but you can retro fit that to about any bike:

http://www.mxbonz.com/NS2.htm

 

[biglou]

New HPSD owner here. I like mine so far (only 0.5 hrs on the bike). I had no twitchiness or "lock-to-lock" handlebar swapouts like I would get once in a while on the YZ450. On the stand, I can feel it work. Also, from what I've read, the 09 is a bit more responsive to tuning the clicker than the 08? And, in the manual, they give inspection and rebuild instructions, and time intervals, I'm sure, although I don't remember the specifics.

Overall, after years of ridng blue, I think this is a great little gadget that takes any twitch out of that wonderful Honda steering. So far... :)