Hello, I'm new and I got a suspension problem.

[aol000xw]

Hello everyone

First my Lego background...

My First Lego Technic set was 8860 at 8 then nothing until I was a working adult and an omninous Dark age was waiting for those sets. I paid the occasional glance at stores and got a few sets sometimes few years apart, that were built once and put in a shelve or simply stored in boxes. Some sealed in their box for a few years.

Besides 8860 chassis I got 8865 test car 8880 Supercar, 8448,Street sensation, 8458 Silver Champion, 8466 4x4 offroader, 8455 Back hoe, 8421 Crane, 8043 Excavator, 8258 Truck and some mindstorms

And a few weeks ago 8110 Unimog.... I always loved Unimogs, so this time I built it. But this marvel made me want more, and opened those old sealed boxes, and got a couple small models, a Crawler too, and thanks to these forums In my Lego shopping spree I got a couple 41999 ;) and started toying around, modding some battery boxes... and obviously wanted to build a sports car .

So now the problem...

First off, I know that half my problems can be solved with the 42000 wheel hubs, but by now my Lego budget is between zero and some high negative number.

I wanted to do a sports car, wheels not attached by axle, 3 pins looked nice, and wanted the ¿wishbones? of the silver champion. So that let me with the portal hubs of the crawler and those long arms of the silver champion.. Yeah an absurd combination specially with portal hubs for a sports car... welll, my Lego, my rules

In the next picture two different aproaches showing maximun width I can use.

Just dirty builds to try things out...

The left one is stiffier so won´t lower the chassis much under the weight of the body but it is too wide with no room left for a differential,

The right one is a bit too tall. will get the right height with the weight and makes room for a differential.

Also ignore those on the righ,t one is a steering unit with the portal sideways and the other is just ... another test.

Those on the left (exchanged in relation to the previous picture) are my best trys by now... Notice the left one gets one stud under the arms so I can get the 3 studs wide needed for a diff. as I can only separate left and right arms 1 stud.

I don't know If you can see what I was trying with those pictures, but how can I make this more compact albeit the builky wheel hubs?

Do you think what I made will work at all? Should I try a pushrod suspension?

Has anyone tried that combination in a constrained width fashion? Hints? Suggestions?

[Tamas Juhasz]

Hello!

The problem is about the width/U-joint/Silver champion wishbones. If you bild without the long black wishbones, everything can be solved, and you can still use the 9398 hubs. Use simple liftarms as wishbones. The middle of the U-joints should be in line with the turning points of the wishbones. That's very important. Now the angle of the joints are too big, it's good until about 30°.

42000 hubs (with the homocinetic joint) are pretty weak and you don't need them to solve your problem, but with those the suspension would be simplier.

Edited August 13, 2013 by Mbmc

[aol000xw]

Hello, thanks for your answer

About the long wishbones... well it is a whim, not a matter of practicality, I just want to make that combination work.

However I take note about angle and alignment, there is a lot to learn...

The homocinetic joint is thiis? If so, what stronger alternative is there that accounts for variations in distance between hub and diff when the suspension works? I think 8880 has a nicer system integrated in the hub, but I save those for another MOC.

[Tamas Juhasz]

Yes, that's the homocinetic joint. If the wheel is steered, the light gray piece can came out from this: http://www.bricklink.../PL/92909.jpg?2

But it depends on the use, it can be enough if you drive the car in flat surface, so not in terrain.

Stronger portal hubs with wishbones are trial-like suspensions, like these:

http://www.brickshel...ry.cgi?f=427907

http://www.brickshel...ry.cgi?f=427909

Stronger shaft between the diff and the hub is the 3L U joint, or you can build a very big U-joint with technic parts, but that would be huge for this and unnecessary. Or you can use bevel gears instead of U and homocinetic joints. (something like this: http://www.brickshel...y.cgi?i=4533572 - not tatra, and not this, I just didn't found what I wanted to)

Edited August 13, 2013 by Mbmc

[Alasdair Ryan]

You could use the light grey piece above with the yellow steering hub.

[Tamas Juhasz]

Yes, this would be a simple way to solve the problem, but He wants to use the black wishbones (or not?).

[Alasdair Ryan]

Yes, this would be a simple way to solve the problem, but He wants to use the black wishbones (or not?).

Errr...what bout using some long steering links (with the ball joint ends)?

[aol000xw]

Yes, I want to use the black wishbones

The point is using the black wishbones with a three pin fixation for the wheels, These use ball joints so it would be even harder to attach them. than the crawler ones.

It will be used in a road chassis, so I don't need great travel or eficiency, just make it as compact as possible and good enougth for the car not to be torn apart by a pothole.

Ok this isn't the simplest route but is funny and it might work in the end

[aol000xw]

Well, after many tries, angle checks and failures finally got something working with that homocinetic joint and no friction at any point of the suspenssion travel.

Stiff enougth rear to support the batteries and soft enougth front to react to terrain, and finally "compact" enougth albeit the black wishbones.

the steering works quite well but I was unable to use the hubs in upright position, It could use a longer rack, but good enougth for now...

Also made the front a couple studs lower just for the looks... I'll need a chassis.

Any hint on gearboxes that can work with the car in movement and focused on speed? Everything I see is crawler type or not useful with the vehicle at speed.

I'm thinking on using a clutch with a linear gearbox controled with the servomotor, but before grinding gears with my own ideas would be nice to try something already tested...