micholix

Thanks, I much appreciate that!
I forgot about that, that it is the inner weel, because i just was testing at the bench...

fredswain

iTrader: (1)

I just checked it. With the chassis bottomed out the tires can only come off the ground about an 1/8". That's even with the long front tower and shocks but retaining the bump stops. This is also somewhat dependent on the lower arm mounting location. In my case it's the outer location all around.

micholix

Thank you very much!
1/8", that is around 3.2 mm, if i remember correctly!?

I'm still using the V1 shocks, the V2 tower and V1 front arms now, but as i do not use bladders, i could swap my bump stopper with an old shock O-Ring, this gives me still enough room, so the piston, or piston-screw does not hit the shock cap.

What would be the most benefit, if i would change to the flat V2 arms, exapt from ground clearence?

fredswain

iTrader: (1)

The shape of the arms actually has absolutely nothing to do with handling, as so many somehow believe. Gullwing arms don't give better cornering or vice versa. As you pointed out, ground clearance is one potentially affected aspect. The most important thing that shape does involved shock mounting locations. Draw an imaginary line from the inner hinge pin to the outer hinge pin. With a straight arm, the shock mounts somewhere on this line. With a gullwing arm, the shock mounts somewhere below it.

Durango didn't change the shock tower mounting points with the change in arms. Draw an imaginary line between the inner hinge pin and the shock mount location on the arm. Now draw an imaginary line through the center of the shock from mount point to mount point. You'll see that for the exact same location on the shock tower, the angle on the gullwing arm is greater. That's less leverage than on the straight arm. Associated figured this out with the B5. The straight arms use a tower that is slightly taller and narrower while the gullwing arms use a tower that is slightly wider and lower. They maintain the same shocks. The intent was never to mix and match as a tuning feature. It was all about fundamental geometry. The reason these different towers need to be used with different arms has to do with that angle between the imaginary lines from the inner hinge pin to shock mounting point vs the line through the shocks. With the proper arm and tower combination, two different cars with each setup will maintain the same equivalent shock angle and hence leverage. The only difference to handling coming from the fact that the gullwing arm equipped car has shocks that are mounted slightly lower but the upper part of the shocks are slightly farther out. By contrast, the straight arm car has the shocks mounted slightly higher but the tops are slightly closer in. That slight change in center of gravity of the shocks based on their location is the only thing that has any effect on handling. The rest is a placebo effect.

When Durango designed the 210, they copied the geometry of the B4. Even the prototype cars used the B4 suspension components. The shapes changed for production but the 210 has an Associated derived suspension geometry. A problem happened at the front end with the V1. The front arms became gullwing, following the lead of the then brand new 22 but taking the shape to more of an extreme. The shock tower shape was never changed to compensate as Associated did later on the B5. It should have been. When the V2 came out, the B4 geometry was restored but the shocks were just made shorter to account for the length difference between the mounting points. Durango and Associated shocks aren't quite the same length though so travel is slightly effected. The shock tower should have been lower and wider with the V1 than it was. The V2 tower should have been slightly taller and the original shocks maintained. My solution to the problem was to use the DESC front tower and longer shocks. This setup actually gives the perfect amount of travel and at the perfect angle to the arms.

theclutch

iTrader: (2)

I beg to differ. The shape has a LOT to do with handling as the shape helps dictate whether the arm is stiff or not, if it flexes in the corner or not, etc.

fredswain

iTrader: (1)

Placebo effect. Nice in theory but worthless in practice with the material used. Let's play devil's advocate and say that there is in fact a noticeable difference in performance. You have drawn the conclusion that the effect is the result of an arm being straight vs gullwing. I would offer the alternative that the arm is entirely different in area and cross section in every dimension rather than just being the same arm but straight. This would bring the possibility that any potential handling change is the result of this and not a flat vs gullwing profile. It's strange how no one makes that correlation. Keep in mind that any flex would not be over the length of the arm but rather from the shock mount location to the outer hinge pin. This is a shorter distance that further reduces any perceived change.

windstar

So! The issue is the rear Spoiler. It hits the Tire.
I will look if I cut it.

Btw the MM3 Position of Motor and gearcase feels better. One Jump of our Track is better to handle now, the Buggy will not go down so early like before with the front.

https://www.dropbox.com/s/g4b5xx4ddb...oiler.jpg?dl=0

micholix

Fred, thank again for this detaild description! I have to read it more often, as english is not my native language, but i do understand what you meen.

I did an overlay in photoshop, with a front pictures from the V1 and the V2, just to see, what the changes are with the different front arms, and i saw, that the angle of the shocks didn't change at all, only the length and the lower mounting position.

kerby

iTrader: (25)

Fred I see many detailed posts and I'm so surprised the Du engineers missed so much. How are your results?

fredswain

iTrader: (1)

Again, you make the assumption that everyone designing rc cars have Phd's in mechanical engineering. With the exception of Juraj Hudy, I'm not sure how many others do. The reality is that an engineering degree is almost irrelevant. By no means am I saying that any of them are stupid or untalented. Not at all. I consider them lucky to be doing something so fun and getting paid for it. Being in any industry, it gets very easy to get into a box of thinking where you concern yourself more with what the competition is doing. You see lots of copying and trends go back and forth between companies all the time. It gets very easy to say that it's always been done that way so why change, or to say that we know this particular thing works so why redesign it? There is validity in that way of thinking. It's easy for me to point things out because I'm not in the industry. My opinion isn't affected by a timeline or budget from management or what is trying to be replaced. It's strange when you are so used to working on something and your opinion of it is high and then you learn that there are others out there that disagree with it. How can this be? There are inherent personal biases in all of us. I'm not going to say that Durango designers or any others potentially missed something that I've discovered. Only they know why they made the decisions that they did. The only thing that can be said with any certainty is that we disagree on some things and have come to different conclusions on certain things. If everyone always agreed with everyone else, there would be no variety. It would be a bland and boring world.

There are things I like and dislike about every vehicle. In 1/10 buggy, I like the suspension geometry of the 22 2.0 in regards to arm lengths with the caveat that it would be run with a 20° nose kick. No one does that but that's my personal opinion. I like the caster adjustment inserts that Durango came up with and is now being copied by others. I like their convertible gearbox that can go 3 gear or 4 and mid or rear motor. I like the battery orientation options of the B5M. I'm still personally a fan of carbon fiber chassis rather than aluminum. My perfect 2WD buggy with be a hybrid of all of these cars. As I pointed out earlier, why reinvent the wheel when there is something out there already that you like and know that works? Each team of designers has copied some features but they've also created others and we've gotten some neat variety out of it. I don't consider any of them perfect though and I will attempt to change any aspect that I personally disagree with on anything that I personally own. I don't cloud my opinion with other people's setups. I also don't require anyone to agree with me.

fredswain

iTrader: (1)

The shock angle doesn't change relative to the camera. Draw an imaginary line from the inner hinge pin to the lower shock mounting point in each picture and another line through the length of the shock. Compare the angles. They are different. That's what matters.

sgtlt

iTrader: (5)

Should I convert my 210 to front hexes for a cost of about 45 dollars, or keep buying Durango front wheels for about 5.25 dollars a pair. Already have the rear converted to 12mm hex. If I change the front then the 210 can use same wheels as my B5m .

thanks

fredswain

iTrader: (1)

That's really up to you. If you have no problem with the current wheels, why change? It would be a change for convenience reasons not performance.

sgtlt

iTrader: (5)

fredswain: Thanks good insight as always, just wanted to hear someone say it. I don't mind the Durango front wheels.

kerby

iTrader: (25)

Use the Desc/Dest front hub with a b5 front axle...nowhere near $45 and you'll get way more selection on wheels...