Anti dive ?

[NHTodd]

Alrighty you almighty GS gurus I have a question on the anti dive. I have an 85 550es and an 83 550es parts bike. I noticed the anti dive looks like it's tied into the front caliper with a brake line on the 83 while the 85 is a gold tube kinda thing by itself is one better than the other? Trying to figure this out. Any advice is appreciated.
Todd W

[Steve]

I have not seen the '85-style system, but I have heard that many will disable the '83-style system to firm up the feel on the brakes.

With that style, the first bit of fluid that you push with the brake lever will move the valves in the anti-dive mechanism. After they are done moving, THEN you finally get to build pressure to move the pistons in the calipers.

My personal preference would be to update the old springs to fresh new ones that have a proper strength to keep you from diving, then put in the lightest-practical fork oil that damps the motion, and you will be good to go. I prefer straight-rate springs, I got mine from Sonic. The owner happens to be a member here, Rich Desmond. I also tend to use 10w fork oil, which does a fantastic job for my and my style of riding.

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[NHTodd]

Alrighty that makes sense then. I'll stick with the newer style then and yeah still gonna want to do the springs and oil down the road. Thanks for the advice much appreciated

[Steve]

I have no idea how the 'new' style works, can't tell you if it's any better than the old style.

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[tkent02]

There's a reason they don't put that crap on motorcycles anymore.

[NHTodd]

Kinda figured something like that lol

[dorkburger]

Not sure of the exact operation, but the later style meters fork oil thru the PDF I unit. Ive seen bikes with the later style PDF units removed with and off plates in their place, but dont know what other modifications, if any are involved.

[Steve]

I am not doubting you, but please explain "PDF".

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[dorkburger]

Pretty sure it was Suzuki lingo for posi damp fork. Thats for the later ones not linked to the brakes.

[dorkburger]

In case anyone is interested.

[NHTodd]

Doesn't look to me like it would affect anything to just remove it and put a block off plate then just treat it as a normal fork.

[tkent02]

I think I remember you had to leave a passage open for the fork to work right. Maybe you had to block off another passage. More to it than just a flat plate. Never done it, but I think I remember reading something like that a few years ago.

[derwood]

If you take apart a PDF fork, you will see that the damper rod has no holes in it (above the bottoming cone), all the oil is forced to travel through the PDF valve. the valve is adjustable to 1 of 4 settings.
If you block off the valve some how, the fork will be hydraulically locked.
You could dremmel or machine a passage of a fixed size in the block off plates, allowing the fork to compress. (kinda works)
You could block the PDF completely and drill holes in the damper rod above the bottoming cone so you have a conventional damper rod fork.(works a little better)
How many holes? what size? dunno, check some damper rods in conventional damper rod forks
.....or buy some cartridge emulators. ( that is what i ended up with )
either way, the PDF valves are old and the plastic knobs will soon break, then they will start to leak fork oil at the valve stem...... ( if not already)