About the Anti-Dive

CYYJ · May 15, 2021

Pete68 said:
No service history to say fork oils etc changed..

In that case, you'll probably have to drill the old fork oil out

On a more serious note, it's a fairly easy task to tear the whole front fork system down and rebuild it from scratch. It's complex, in the sense that there are a lot of parts and a lot of steps to the process, but it's not difficult. Having said that, I think it is the kind of project best left for the wintertime when the bike is laid up, because that way you can complete the work over 3 or 4 days, and if you have to wait for parts to arrive, it won't cut into riding time.

I did a write-up explaining the whole fork rebuild process for a ST 1300, it is here: ST1300 Front Fork Overhaul: An Illustrated Bibliography The process for the ST 1100 is similar, although the ST 1100 has the anti-dive valve that the ST 1300 does not have.

Michael

ST1100Y · May 16, 2021

CYYJ said:
I think it's kind of impossible for an average ST 1100 owner to make an objective evaluation of how well the anti-dive system is working, or whether it is working at all.

I get frequent reminders that "it's there and operational"...
Like when diving into a hairpin a little ambitioned, hitting a bulge in the tarmac with applied brakes will cause a brief squeak caused by fork oil being driven through the smaller orifices...
I also think that a non operational anti-dive will cause a real spongy, deep diving front end during heavy braking...

mr.m · Mar 3, 2022

Just opened my Anti Dive and found some damaged rubbers. Dose the Piston part# 10 come with the fore most rubber face attached? I would think so as it is not numbered.
And is the hole in the Nylon bush # 3 elongated or did mine wear to an oval?
Time to source more parts.

Cheers

John OoSTerhuis · Mar 3, 2022

mr.m said:
ust opened my Anti Dive and found some damaged rubbers. Dose the Piston part# 10 come with the fore most rubber face attached? I would think so as it is not numbered.
And is the hole in the Nylon bush # 3 elongated or did mine wear to an oval?

Yes and yes. When I pulled mine years and miles ago I found a chip of the seal bonded to the face of the piston in the bottom of the fork slider. And yes, the bushing is oval, oriented long axis parallel to the direction of piston movement. I have poSTed this on the forums many times over the years (see #4 and #15 above).

John

mr.m · Mar 4, 2022

John OoSTerhuis said:
Yes and yes. When I pulled mine years and miles ago I found a chip of the seal bonded to the face of the piston in the bottom of the fork slider. And yes, the bushing is oval, oriented long axis parallel to the direction of piston movement. I have poSTed this on the forums many times over the years (see #4 and #15 above).

John

Thank's John
The nylon bush on my bike had the long axis rotated perpendicular to the piston. Maybe the former owner twisted it thinking it would correct an elongated wear pattern.

Rick Fisher · Mar 4, 2022

I had my anti dive disabled, and forks rebuilt with gold valves and a more aggressive spring. what a difference! it still dives a little, but the rebound feels much better. The bike is a lot more stable now.

Garry_Coates · Aug 12, 2022

[/QUOTE]

John OoSTerhuis said:
When I did mine I replaced all but the big plate and its bolts (#5 and #6).

John

Hi John, is it too late to ask what you found that was badly worn? I am interested in what you found that wears, as I am about to check mine after 27 years. My Haynes manual says to replace seals/orings as mandatory by nothing about the piston itself. The piston looks to have a bushing near the top. Have you found the piston to be badly worn? Anything else?

Regards
Garry Coates

ChriSTian_64 · Aug 13, 2022

Riding my ST1100 since only two years, and this beeing my first road bike, I guess I'm getting maybe too confident with it.
It is the third time in two months that I lock my rear wheel (for a few seconds) while braking (apparently too hard) at speed (60 mph).

I use to say that with a motorcycle, we only have two wheels to break, but when this happens, I have the feeling I only have one : the front one, since I feel the front bike is plunging due to the weight transfer, and that's probably why the rear locks.

I certainly have to learn to ease the throttle a bit more in advance, and braking more progressively (what I normally do), but in the same time, I'm wondering if it is not related to my Anti-Dive not preventing enough the plunge of the fork. :think1:

It is certainly possible. My ST has 22 years, low mileage, been sitting in a garage for years, so, I'm sure it is still the original fork oil and the anti-dive was never replaced or maintained.

Beeflips · Aug 13, 2022

ChriSTian_64 said:
Riding my ST1100 since only two years, and this beeing my first road bike, I guess I'm getting maybe too confident with it.
It is the third time in two months that I lock my rear wheel (for a few seconds) while braking (apparently too hard) at speed (60 mph).

I use to say that with a motorcycle, we only have two wheels to break, but when this happens, I have the feeling I only have one : the front one, since I feel the front bike is plunging due to the weight transfer, and that's probably why the rear locks.

I certainly have to learn to ease the throttle a bit more in advance, and braking more progressively (what I normally do), but in the same time, I'm wondering if it is not related to my Anti-Dive not preventing enough the plunge of the fork.

It is certainly possible. My ST has 22 years, low mileage, been sitting in a garage for years, so, I'm sure it is still the original fork oil and the anti-dive was never replaced or maintained.

I think you have a good point about the anti-dive Christian, I have the same bike you have, and I'm assuming you don't have ABS like myself either. I was having some wheel lock up in the back too, but I realized that it may have been a tire issue. Although like you, I'm curious if my anti-dive is working, I have a leaky fork seal on that same side as the anti-dive unit (BTW, I haven't spent even a minute researching to see if the leaky seal would affect the anti-dive) I just wanted to say that once I put new tires on, the skidding rear tire has pretty much gone away. Also could be a combination of the two.

John OoSTerhuis · Aug 13, 2022

Garry_Coates said:
Hi John, is it too late to ask what you found that was badly worn?

Nothing was badly worn, Garry. I explained my issue in post 24 above. The next time you take the fork off to properly replace the suspension fluid, just pull the anti-dive apart and inspect it. After I replaced my piston the proper functioning of the unit was quite apparent during quick/firm-and-hold application of the front brake - the forks started to compress and then stopped. I’d gotten used to ‘spongy’ front braking. FWIW, I suspect my failure was a very rare occurrence, but checking yours is easy and dead simple.

John

Garry_Coates · Aug 15, 2022

Thanks John,

John OoSTerhuis said:
Nothing was badly worn, Garry. I explained my issue in post 24 above. The next time you take the fork off to properly replace the suspension fluid, just pull the anti-dive apart and inspect it. After I replaced my piston the proper functioning of the unit was quite apparent during quick/firm-and-hold application of the front brake - the forks started to compress and then stopped. I’d gotten used to ‘spongy’ front braking. FWIW, I suspect my failure was a very rare occurrence, but checking yours is easy and dead simple.

John

Thanks John, I have ordered similar parts to you
Regards
Garry

About the Anti-Dive

CYYJ

Michael

ST1100Y

mr.m

John OoSTerhuis

Life Is Good!

mr.m

Rick Fisher

Garry_Coates

ChriSTian_64

Beeflips

(it's me...Greg) Returning some videotapes

John OoSTerhuis

Life Is Good!

Garry_Coates