Anti dive question

[Adavidson56304]

Ow do the antidives work on a mk2? There must be a solenoid that opens/closes flow of oil, but what I'm wondering, is it normally closed to stop the flow and opens when the antidive activates, or the other way around?

Thanks

[Snaggletooth]

Other way around. They are open until the use of the brakes activate the solenoids and they close down to restrict the flow of fork oil to control the forks compression, reducing the dive action.

 

From my Droid wherever I may happen to be at any given moment.

[Adavidson56304]

So, when people install block off plates, they are actually turning on the antidive permanently?

[skydoc_17]

Hey Aaron,

You are correct, Installing the Block Off Plates restricts the flow of fork oil to the lower fork tubes all the time. Normally, when the Block Off Plates are installed, Upgraded Progressive Fork Springs are installed as well. The combination of the increased fork travel of the Progressive Fork Springs, and the "dampened" fluid transfer of the fork oil due to the Anti-Dives being removed gives you a firmer feel to the front end of your bike, improves handling in those "sweeper" curves, (my personal favorite) and keeps the front end from bottoming out during rapid deceleration. By adding or subtracting the amount of shim to the fork springs and changing the weight of the fork oil, you can "set your bike up" for the type of riding you do, much the same way a motocross rider would "customize" his machine for his weight and riding style. These adjustments DO require a bit of "tinkering" with the variables mentioned above, BUT once you have the front end set up properly, Your bike will be taken to a whole new level of performance as far as "carving the twisties" goes. Some riders take their bikes to the limit in regards to the amount of "lean" they can achieve, (I being one) other riders are just as happy blasting down the highway at 85MPH, strait up! In my opinion, "personalizing" your motorcycle to your size, weight, and riding habits, is one of the nicest things about owning a motorcycle. Modifying the handling characteristics of an automobile or truck is much harder, and much more expensive than a motorcycle.With a car, "It is what it is" so to speak, but with a bike, the adjustments are infinite. Here are a few links you might find helpful:

 

http://www.venturerider.org/classifieds/showproduct.php?product=3768&title=first-gen1983-1993-progressive-fork-springs-21&cat=22

 

http://www.venturerider.org/classifieds/showproduct.php?product=3776&title=first-genmkii-vr-s-santi-dive-block-off-plates-21&cat=22

 

This type of upgrade truly makes your bike "customized for you". If you are the type of rider that wants to feel like they are part of their machine, then this is an excellent upgrade! If you are the type of rider that merely "sits" on their bike, and putts around, then the money for this upgrade could be better spent on some "safety chrome".

Just my thoughts, for what they are worth.

Earl

[MiCarl]

You can test how much it'll affect the ride as currently set up by simply unplugging the anti-dive solenoids. The plugs are accessible through the head light opening, toward the right fairing.

[Adavidson56304]

I actually replaced the springs with progressives last fall. I disconnected the antidives at the same time. They ride nice. I started with 10wt, now am riding 15wt. I have 2 washers on the top of each spring. But, ever since, I have bottomed out on big bumps and fast stops. So I was wondering if block off plates will help with this. Sounds like it will.

Thanks

Aaron

[MiCarl]

I actually replaced the springs with progressives last fall. I disconnected the antidives at the same time. They ride nice. I started with 10wt, now am riding 15wt. I have 2 washers on the top of each spring. But, ever since, I have bottomed out on big bumps and fast stops. So I was wondering if block off plates will help with this. Sounds like it will.

Thanks

Aaron

 

Assuming the anti-dives were working properly disconnecting them would have the same effect as using the block off plate.

[Adavidson56304]

If they were stuck open, is it possible that could cause me to bottom out? Or could it be something else? I'm replacing fork seals and bushings this week, anything I should be looking at?

[MiCarl]

IIRC the progressive springs require a bit less oil. If the oil level is too high they effectively bottom early. According to Progressive the maximum oil level is 5.5".

 

Also, you did install the spacers that came with the springs?

[Adavidson56304]

The oil level was 5 3/4" from the top just to be sure I did not use too much. I did not use the PVC spacers but at one point did have 10 or 12 washers on each side for preload, but the ride felt too stiff to me, but it was still bottoming out when I slammed on the brakes.

[Adavidson56304]

The po did tell me the fork seals were recently replaced when I bought this bike. After the other problems I've had on this bike, it would not surprise me if something was put together wrong or missing in the forks.

[MiCarl]

I mis-stated something earlier. Disconnection the anti-dives isn't the same as the block off plates. Disconnecting leaves the passage open, where the block off plate keeps it closed. Terribly sorry for my hasty oversight.

 

Having cleared that up, I'm not convinced they actually do much. Dingy has dissected the internals and is of the conclusion that they should only have effect at the very bottom of travel.

 

Your diving is probably because you didn't use the PVC spacer. You need the preload on the spring.

 

When you say "stiff" I wonder if you don't mean harsh. If the fork oil is too heavy the ride will be harsh. Is the oil still what the PO had in? If so, he may have used heavy oil in a misguided attempt to compensate for poor springs.

 

What many people don't understand is the spring and oil have different functions:

 

The spring supports the weight of the motorcycle and absorbs shock from the bumps in the road. If the suspension is bottoming out it's because the spring is too soft or doesn't have enough preload.

 

In addition to lubrication, the fork oil is to damp oscillation of the fork. Without the oil you have a pogo stick and will go bouncing down the road. When the fork moves, the oil is forced through orifices to convert the energy in the spring into heat and stopping excessive bounce. If the oil is too light it'll be like riding a boat, too heavy and the fork won't move fast enough to absorb the big bumps - leading to a harsh ride.

 

If it were mine I'd put in the recommended quantity of 10w fork oil and the spacer supplied by Progressive. I'd also reconnect the anti-dives. See how it rides and work from there.

[Adavidson56304]

Has anyone thought about simply tapping the holes for the antidives and putting bolts and gaskets in?

[KIC]

Has anyone thought about simply tapping the holes for the antidives and putting bolts and gaskets in?

 

hmmm

[Adavidson56304]

So, I have found that the forks were put together incorrectly. The special washers are at the very bottom and the oil lock piece above that. I'm guessing this could cause some problems. They are stuck in the lower fork, probably beat in from bottoming out because it was put together wrong. Hopefully I can get those pieces out, get it together properly and then start testing how it handles best. Might be looking for some different lower forks if I can't get the piece and washers out.

[Snaggletooth]

Had that problem on a set of forks i bought off eBay.

PiTA!

 

Ended up using a heated parts washer / high heat/ for about a 15 minute cycle on the lowers to heat the whole assembly. Then dropped small chunks of dry ice into the bottom end onto the wedged spindle lock / oil lock. Then using a small pick i was able to work through the ports for the anti dives and start prying the spindle upwards and out. Took a bit of work but was able to save the lowers.

 

From my Droid wherever I may happen to be at any given moment.

[Adavidson56304]

I was able to pry them out with a screwdriver. I gave up on trying to save them and put some force into it and they popped out. One was a little beat up, but I filed it down and it should work fine.