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Anti dive on the front is IMO a good design element. Just my opinion. As for the rear-BS.
ok let me ask this like some builders and I even saw one of yoshi's rails with this design, they mount the upper a-arm forward of the lower while still maintaining cast of course, with out cradle rake and the brake mounted in the rear would this dive or anti dive? I was reading the thread you started in the ap section under caliper position.now with upper arm mounted the same way with 10 degrees of rake what would that do to the equation?
The caliper location has zero effect on anti-dive. The top arm at the same 10* angle as the lower would not produce any anti-dive unless the top mounts were angled " pigeon toed". As to wither or not it's useful/needed in the sand, negligible as there is that much traction with ribbed sand tires. Trails with knobbies, Yes. The more rake you have in the front the more anti-dive you can use. Getting carried away with anti-dive will get you a car that is harsh under braking and will actually cut down on tire grip. I've been toying with the idea for a while of taking a set of bypass's and putting an electronically controlled valve in the long tube to be activated by the brakes. The increased damping would do a better job of controlling chassis roll that mechanical resistance. Suzuki used a similar set-up on there forks in the mid 80's but used hydraulic pressure to activate them. On the bikes I owned with the system they seemed to work very well.......... Of course since I hate bypass shocks this might be a while in the making LOL........
I am not sure what you mean by pigeon toed? if I had a pic I would post it. what I am referring to is the sus cradle at a 10 degree rake and the upper and lower arm in different positions. the upper being forward of the lower in the mounting points on the frame.also will asi ( kpi ) as well as rotor dia have any effect?lets take enemy's rail for example since that is the topic of discussion here. I designed his front end with 5 degrees of sus cradle rake and the upper a-arm is mounted 5 degrees behind the lower ( from a 90* stance ), his spindle has 10* asi ( kpi ) and 10* of caster with only a 2* progressive camber arc. if he were to add front brakes at a 2:30 position to keep the bleeders straight up with lets say a 10 - 12 " dia rotor would this create anti dive like I believe or am I looking at this backwards? would 60 front and 40 rear create more or less as well? I have never run front brakes, just never needed them until now with my heavy v-6 rail in the trails at higher speeds and enemys rail with the boost get to higher speeds faster and tighter turning areas this has become necessary for the both of us but in the sand I don't feel I need them for my rail.
I found the old anti-dive thread so we can limit the hijack of Enemy's work. http://dtsfab.com/index/index.php?topic=833.0But real quick, what they mean by pigeon toed is that basically the top and bottom arms are not parallel. Your referencing rake which is the angle that the arms are mounted on different than the frame of 5 deg. Anti dive results when you mount the two arms with different rakes the correct way. The bottom arm has say 5 deg and the top arm only has 3 deg.I can't argue its benefits or downfalls as I have no experience. However I have been working on designs and their trade offs for some time and many suspension principles get screwed up when you try to apply them to 20" of travel.When the A-arms are set up for anti dive with the arm mounts not parallel then you have a changing caster as the suspension strokes. How much are you willing for caster to change? If only 2-3 degrees over 20 inches of travel then your anti dive won't have much power.Because the caster changes as the suspension strokes, when the brakes are applied they try to make the spindle rotate. This rotation in turn tries to make the suspension move up or down based on the attempted caster change.Exact same principle as a four link in a drag car. Because the pinion rotates as the suspension moves up and down, forcing the pinion to rotate causes the suspension to move up and down.
I didn't feel like typing a 1000 words so..
thank you the diagram it is better than a thousand words to me!this is what I was saying though, the mounting points are closer together in the rear versus the front from top to bottom.normally I can understand things pretty quickly but I am having real trouble wrapping my brain around this one. I just can't see the benefits of a slight amount of anti dive with all the additional problems it produces in a 24" or 26" stroke long travel front end (which is what enemy's front end is 26" stroke ) for non racing applications. but this is just just my opinion. I'm sure it's needed for some. I will have to wait for a ride in fabbers rail to see and/or feel the benifits, if he'll take me for a ride that is!