MOD: 8466 Off-Roader new springs.
Posted 30 April 2012 - 06:27 PM
With these springs:
The set originally contains 4 x "Technic, Shock Absorber 9.5L, Complete Assembly (Hard Spring)" (part no 2909c02), but I wanted to change it to four of these from the Unimog:
"Technic, Shock Absorber 9.5L, Complete Assembly (Extra Hard Spring)"
I've just ordered them yesterday, and will let you know as soon as they arrive with pics of the car.
Here is some pics of the model per today:
The main issue:
Normal state of display:
Front springs compressed, without any pressure applied:
Front spring position (neutral)
After a small bump:
Rear spring position:
After some pressure added, they return to this state:
The chassis is lowered approximately three studs, and doesn't come back up. I'm hoping the new springs will fix this issue.
Posted 01 May 2012 - 12:09 AM
To better the recoil of the front suspension, without having to change the springs (or the whole shock absorbers), I exchanged the two 1x7 liftarms where under the engine with two 1x9 liftarms, attaching the shock absorbers at the tips.
Doing so, the suspension works much better, increasing efficiency by slightly reducing the tire excursion.
Tomorrow I'll take some pictures of it.
Edited by Rikus, 01 May 2012 - 12:11 AM.
Posted 01 May 2012 - 10:23 AM
Posted 01 May 2012 - 12:57 PM
By the way, I think the core of the problem is the design fault in the springs, namely that the connection point is not in line with the spring, but offset by a stud. This produces frictional forces. You could solve this by using the longitudinal axle hole instead of the one the set uses.
8880 simply suffers from way too much suspension stiffness by the way. 8448 did this way better.
Posted 01 May 2012 - 02:39 PM
Ricco @ Technicbricks wrote:
There is a geometrical reason for this, the front axle is stabilized by a Panhard rod, the panhard rod is there to prevent the entire front axle from moving from side to side. The shock absorbers would simply be too flexible to support the front axle on their own.
When the suspension is fully compressed, the front axle needs to be centered right underneath the vehicle in order to prevent the wheels from hitting the chassis and wheels arches, when turning.
That means when the suspension is fully extended the panhard rod will make a “circular” moment that pushes the front axle slightly to the right of the vehicle.
In the real world, these geometries are balanced out by fine tuning the length the panhard rod.
So if your front axle is offset by half a module, you have built your new LEGO Technic U400 Unimog the right way.
Edited by Lost_In_Noise, 01 May 2012 - 02:40 PM.
Posted 01 May 2012 - 02:51 PM
Here is a link to some good photos
Posted 01 May 2012 - 09:10 PM
Rear Before compression:
Rear After compression:
Front before compression:
Front after compression:
The red beams are placeholders for L3 axles, to better indicate their position.
Side view, thin liftarms keeps the axles in place.
The rear suspension has a different setup, due to my parts availible.
Edited by Lost_In_Noise, 01 May 2012 - 09:40 PM.
Posted 09 May 2012 - 04:20 PM
Whole car without wheels:
The front is actually in line with the rear after the new springs have been applied. See comparison in pre-mod shots.
Front before/after compression:
Rear before/after compression:
Everything works like expected, and I can recommend anyone who has the spring problem with the originals to try this out.
Posted 05 June 2012 - 05:34 PM
Have you noticed any issues with the tracking when the off roader is being pushed forward?
None whatsoever. It works as you would expect.
Posted 09 June 2012 - 09:46 AM
control boxes in the rear tray, and piped each shock to one. Worked awesome! Pump it up hard and you can
hardly push the truck down, or drop them right down for city driving, like a Range rover. The benefit of
this as well is having control over the four corners, so you can prop it up on a rock, and squash two, and
extend two, articulation looks great on the model.
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