Triumphrat

dazco · 03-02-2006

I'll be removing my forks to install chrome shrouds when they arrive. So i figure while i'm there i may as well change the fork oil. While the progressive springs did eliviate fork dive, not as much as i'd have liked. So my questions are as follows.

1)-what weight will help further to eliminate dive?(and whats the stock weight)

2)-will it make the ride much harsher?

3)-what amount of oil in each fork in "ounces"?

4)-if i simply turn the fork upside down to dump the old oil will that remove it all or is there something that holds some of the oil thereby not allowing full removal? And if so, how to remove it all?

5)-what kind of fork oil? Any perticular brands/types i should know about? (something i can buy local preferably...honda, yamaha, etc)

Note that i'm at work right now so i can't look in my manual, hence the weight and volume questions. Any other thoughts on this are welcome too.......don't wanna miss anything. Thanks.

[ This message was edited by: dazco on 2006-03-02 14:37 ]

WANG · 03-02-2006

The height/volume of the fork oil will do more to influence dive than the viscosity will. It will be most apparent toward the end of available travel, so harshness over small bumps won't be increased too much if you increase the oil volume a bit.

The viscosity of the oil will have more influence with the rebound damping.

I'd use 15 wt Bel-Ray. 15 wt because it's ostensibly thicker than G10 and it should slow the forks down a bit and Bel-Ray because that is what's on the shelf at the shop around the corner. Most of the major oil players have their respective lines of gucci fork fluid, so whatever gets you going when it comes to brand preference.

Turning the forks upside down, pumping them, and letting them drain out should work great.

Fork oil amount is typically discussed in mm from the top of the fork tube with spring removed and fork collapsed, one liter would probably get you where you want to be but buy 2 bottles, the stuff doesn't go stale, and sometimes stuff happens, ya know :wink:

dazco · 03-02-2006

Thanks. I'll try the bel ray if i can find it. By the way, i wasn't asking whether different volumes would help.....i was just asking what viscosity would help fork dive and asking what volume the forks are supposed to have in ounces. but i have a converter software so i looked in the manual and saw 484cc and found it's 16.3 ounces.

ssjones · 03-02-2006

I used Spectro 10W. We put in a specific height from the top of the fork. Or rather overfilled, than used the Motion Pro fork oil tool to siphon off to the specific height in mm's.

WANG · 03-03-2006

Quote:

On 2006-03-02 18:52, dazco wrote:
Thanks. I'll try the bel ray if i can find it. By the way, i wasn't asking whether different volumes would help.....i was just asking what viscosity would help fork dive and asking what volume the forks are supposed to have in ounces. but i have a converter software so i looked in the manual and saw 484cc and found it's 16.3 ounces.

I think that I got what you were typing , but I was trying to convey that decreasing the air column in the forks will make them more progressive, as the air column is effectively a spring, changing the oil viscosity alone will not have this effect.

[ This message was edited by: WANG on 2006-03-03 08:28 ]

dazco · 03-03-2006

I see. Sorry i misunderstood, and looking back at your post i don't see how i did !! :brk:

So you think i should try adding a bit more? How much? And can i be assured it won't be detremental to the seals by causing more pressure on them?

Wyrm74 · 03-03-2006

Daz - I wouldn't add more than the manual says, you may risk blowing your seals out if your fork gets compressed very hard/quick. Also, I understand that the Progressive springs displace a bit more fluid than stock anyway. I used good ol' Bel Ray, and mixed 10w and 15w in a 50/50 ratio and am quite happy with the results. Good luck.

dazco · 03-03-2006

Quote:

the Progressive springs displace a bit more fluid than stock anyway

Whoa, good point and i'm glad i saw that before i do this ! I did know that but forgot about it. This of course makes it harder to know what amount to use. I really wanted to go by volume and not have to measure the distance from the fork tops. Oh well.

Redmaster · 03-03-2006

....Yeah.... Wyrm74 has a good point....

Some other things to consider IF you change from the recommended specifications:

(1) Triumph won't honor the warranty on parts and assemblies that are directly or indirectly associated to your modification. (This could be construed to cover ALL sorts of failures)

(2) Remember as the oil heats up and changes viscosity, the performance of the suspension will not behave as the original set-up which may call for smaller valve openings, and stiffer springs.... Anyway, you're in for a lot of tweaking if you change viscosity..

I recommend that you start with different sized spacers in the top of the fork tubes, if you want less 'dive'...

You really don't want to monkey with the 'dampening' if you can avoid it.... However, I believe the 'dive' associated with the Speedmaster front-end is more of a designed in safety feature... Allowing more weight transfer to the front-end under hard braking situations, which gives the front tire more traction....

--Clark

WANG · 03-03-2006

Don't worry, your fork seals are not going to frag out on the first pothole you encounter if you increase the oil level in your forks a couple three or five mm. :-D OTOH, I don't know where you have it set now, and there is certainly an upper limit. I have toyed with different fork oil levels and flavors a bit, and haven't had any lasting negative effects from it, there is no reason to be intimidated by it.

As far as fade goes, the viscosity index and anti-foam properties are the differences between good fork oil and salad oil, and if you work the ol' speedy hard enough to induce a noticable loss of damping you will be my new hero.

The amount of dive under braking (once the forks reach equilibrium, anyway) is predominantly governed by the spring rate. Since the springs are progressive, increasing preload MIGHT get you what you want, but bear in mind that spring preload is typically only adjusted to set the sag. The forks will perform best with the static sag set at somewhere near 1/3 of available travel.