What is wrong with my suspension?

[Wallace]

Hi there.

I recently emerged from my dark ages when I got the 8109 as a holiday present. Since bought 8043 and 8110 so now it is time to try my own creations.

Currently building a 4x4 vehicle (concentrating on getting things to work not looks) with2 M motors powering the thing. I just bumped into a problem: My shockabsorbers do not compress when lifting a wheel from the ground. Anyone got sugestions?

Possible problems I campe up with:

- shockabsorbers from the unimog ar just to hard.

- body is not stiff enough.

- shockabsorbers should be used more directly above the wheels (instead of the 45 degree to the back they are now)

http://www.brickshelf.com/gallery/JJvdW/4x4/dsc_2026.jpg

http://www.brickshelf.com/gallery/JJvdW/4x4/dsc_2028.jpg

Edited August 6, 2012 by LuxorV
Converted huge deeplinked pictures to links.

[Lipko]

Simple solution:

- shockabsorbers should be used more directly above the wheels (instead of the 45 degree to the back they are now)

This may not be enough. Just try to observe the motions of the suspension without the shock absorbers.

It should not be hard to find a point on the axle and a point on the chassis (on each side) whose distance is definitely and always changing if you actuate the suspension.

Edited August 5, 2012 by Lipko

[z3_2drive]

change the side your shocks are mounted by, this is similar to my crawler's shock placement, so look at my topic as an example hope it helps and good luck with your truck.

I agree with lipko, see how it moves without shocks to understand the movements.

Edited August 5, 2012 by z3_2drive

[efferman]

when you mount the upper end of the shock absorbers more together, it should work better

Edited August 5, 2012 by efferman

[Zerobricks]

Also if you must mount them so they are a stud offset, mount it so that the offset part is on diagonal sides, so it deosnt bend the spring.

[Wallace]

Thanks for the fast replies. Will mess about a bit to find a solution with your sugestions!

[Hopey]

As a guess, I'd say it's because the 6L links that stop it moving sideways are too high up to work properly, so when you lift one wheel up it's moving sideways instead up compressing the springs. They should be down at the same level as the torque tube, like in the 9398.

(I've got exactly the same 3 sets as you, by the way)

[DLuders]

@ Wallace: Welcome to Eurobricks! I know that you are using the 9.5-studs-long (9.5L) Lego Technic Shock Absorbers, but you should be aware of the different "spring rates" in case you use other shock absorbers in the future.

Below is a chart that shows the decreasing spring resistance (in grams) of standard shocks. I can't remember where I got it from on the internet. As you noted, yellow is the stiffest (at 1300 grams), Dark Grey is next at 600 grams, then Light Grey at 520 grams and and Dark Turquoise is the weakest at 430 grams. I wonder if placing a toothed 1/2 bushing on a Light Grey shock will make it more stiff than a Dark Grey shock or not....

For the RED 6.5L shock absorber, Bricklink lists Part 731c01 as "Technic, Shock Absorber 6.5L, Complete Assembly (Spring Undetermined)", so I don't know what spring strength it has. The Dark Turquoise 6.5L shock is 731c06, "Technic, Shock Absorber 6.5L, Complete Assembly (Soft Spring)", but apparently it is not as "soft" as the Light Grey shock. The 731c05 6.5L "Normal Spring" shock comes in the "Known Colors" of Dark Grey, Light Grey, and Red. See http://www.bricklink.com/catalogList.asp?q=technic+shock for all of the possibilities.

[dikkie klijn]

Try to set your shocks more vertical. Take the shocks of and figure out what the line of motion of of your suspension, then set your shocks in line with this line of motion.

[nicjasno]

What is wrong with my suspension?

Where should we start....

[Bricktrain]

Where should we start....

very helpfull...not.

I cant see if you have more links behind the wheels only the top links, maybe a pic without the wheels would be usefull. Is there any free play in the length of the steering shaft, that could be binding. Moving the shocks more vertical will effectively make them stiffer so probably wont be a good thing.

[LuxorV]

Could you please reduce the pics size to 800 pixels maximum, as per our Member Guidelines? Thank you.

If you need help with re-sizing images, you can find an useful tutorial by following the link in my signature.