Enemy's new ass... AKA moving the Jeffco

[fabr]

Now now,you're disputing the word of a very well known company. You KNOW they wouldn't build something unless it works don't you? I've heard it many times said that the King cars NEVER have any chain issues and all of their chains last for many years of hard driving. Uh huh,SURE they do. There's no magic chain made that will hold up/last behind a large bike motor for any time at all that short.  BUT ,as said, if you drive like a sissy school girl than yeah it might last long enough to climb to a dune top,stop and admire your accomplishment and then 20 minutes later do it again. Then stop again. There's one well known "builder" that snoops around here but doesn't post anymore due to the fact that we WILL argue with HIS WORD about how well his chains last. Every single time I ever saw him at the dunes or had reports of him at the dunes that's whaat his "testing" consists of.Going into the dunes,hunting for the groupies ,finding a bowl to make a couple of laps in and stopping. THAT'S TESTING? LOL!!!!! No,that's letting the design flaw cool down.
 I guess that my opinion of what's acceptable is a bit more along the lines of not having to do ANY babysitting of the car or it's components for at least a full season.Having to tension a chain damn near every time into the dunes is just BS IMO. We all KNOW that heat is the issue and we all KNOW that the short chain length gives inadequate chain cooling time before it gets another shot of friction/heat and it continues to escalate the chain temperature till it fails. That is indisputable. SOoooo,the ONLY way a short chain will survive is with pussy driving style OR running the hell out of the car for 2-3 minutes at a time and then allowing cooling time while sitting around watching others have all the fun.

[dsrace]

Anti dive on the front is IMO a good design element. Just my opinion. As for the rear-BS.

I don't doubt that anti dive is a nice design element in the front but is it really needed for sand dunes or dirt trails? can you post a link to some real info on the principal?  I am guessing that caster and tire dia effects this principal as well, don't knot tho. I know there is a thread on here somewhere.

[dsrace]

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?

[BDKW1]

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........

[dsrace]

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 sai ( 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* sai ( 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.

[Engineer]

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=833.0

But 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.

[fabr]

And there ya go in a nutshell. Why is it not normally used in a long travel? Well engineer hit that squarely also. Too much trouble mostly. My question is why would one NOT want it. I do agree tho that at long travel numbers it may not be practical. I LIKE BDKW's idea with the bypasses thing tho.

[dsrace]

I found the old anti-dive thread so we can limit the hijack of Enemy's work. 

http://dtsfab.com/index/index.php?topic=833.0

But 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.

ok so if the lower arm was mounted parallel to the frame which was mounted 5* then you took the upper arm and twisted the tabs so it was swinging on a 3* point, or the distance between the upper and lower arms in the front of lets say 9"s and in the rear sets say 8.5", is this what you are talking about? if so then your arm are traveling in two different directions at different times! you would have to try to set bump for a 34" stoke and only use 24"s of the middle to minimize bump and still wouldn't get the the desired full effect of all on a long travel 24" stroke ifs as far as I can see. this is why I am asking and enemy doesn't mind this discussion on his thread I called and asked him an hour ago.

[Nutz4sand]

I didn't feel like typing a 1000 words so..

[dsrace]

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!

[BDKW1]

Pigeon toed....... Viewed from the side, both arms are parallel.
 
Viewed from the top side the upper arm mounts are closer together in the front than the rear.
 
This will make the end of the upper arm swing an arc when viewed from the side. Set-up right this will give caster gain in bump and droop.
 
A set-up like the picture above will give you a linear gain throughout the travel. The downside of this is that when the suspension is fully drooped you may not have any caster at all. This is the method stock vehicles use, OK for limited travel but problematic on long travel.
 
Now if you mix both methods you can get some really good results in the caster gain curve.

[Enemy]

I didn't feel like typing a 1000 words so..

Cool! I may have built that in without having any knowledge of it! ...As bad as I am at reading a tape measure and an angle finder..

[Monster_44]

Sorry I didn't make it last night, the wife and I had to test the new work bench(bed)!   Where's the new pics! Get em up!

[fabr]

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!

The theory of antidive is for just that. Keeping the front end from "diving" during HARD braking and works fantastic on street cars and limited travel.  There's not any modern front suspensions without it that I know of. However,that said I see the difficulties of trying to get usable antidive on anything with long travel. Does that mean that it cannot be designed to function in a limited range of "normal" travel such as the middle section of travel we mostly see?? Hell I don't know but if it can be ,IMO,it would be foolish to intentionally delete it from the design. I HATE a diving front suspension. Sorry DS but this Rorty design has no antidive in it. You'll damn sure get a ride if I get the thing done in time for LS. The tranny stuff is really coming together now.

[fabr]

Engineers analogy of a 4 link was spot on as all antidive does is genarate an instant center that can be manipulated for more or less antidive in the exact same way as traction can be increased/decreased with adjusting a 4 link.