In need of help with drive/steering portals.

[BlindBuilder]

Hi. I've recently dived back into Lego Technic after decades away from it. I have bought a stack of lots off of eBay including many drive/steering portal hubs (part number92908c01). The plan was to cobble together my own 4 wheel drive, 4 wheel steering creation. Whilst it's easy to set up these portals for drive, I cannot figure out how to attach them to steering racks. My lego collection is mostly from the 80s/90s but even my most recent kit (42005) uses the steering rack design with which I am familiar and it does not appear possible to attach these portals to vintage/conventional racks. So my question is, how do I steer these portals? What parts do I need for a basic working steering system including these portals? BTW, I am a blind builder so please explain using words as I am unable to see images. Thanks.

[Jeroen Ottens]

That is a tough question you're asking.

Is there a way that you can get someone to guide you through the buildinginstructions of the 9398 crawler? That model uses these portal hubs, so I guess that is the easiest way to explain this.

The instructions can be downloaded from the lego website.

Part 92907 is the special part that you will need for this. You have to use two of them to create a vertical axis of rotation on a portal hub.

[BlindBuilder]

Thanks for the advice. I've read the 9398 online inventory and now have a shopping list to search on ebay. I've already got the perpendicular connecters to attach the portals to the pinion/chassis but still not sure how to attach the rack (that's the rear moving part, as opposed to the front fixed pivot right?). While I'm here, do Lego make spacers for those 3-pin wheel hubs so I can attach different wheels to the rather expensive 9398s? Thanks again.

[DrJB]

To steer the portal axles, check out the building instructions of the unimog 8110, available on the lego site.

http://service.lego....inginstructions - type/search for 8110. Link below is for first (of 5) manual

http://cache.lego.co...ons/4646565.pdf

Edited November 29, 2014 by DrJB

[Zerobricks]

I think Unimog's steering is not that good... Better use 9398's steering with a stud or two shorter steering arms so you get a higher steering angle.

[mihai_9600]

Hi, BlindBuilder, I will try to explain you with words how to assemble the hubs for the 9398 crawler. I don’t own this set but the building instructions are pretty clear for me. I hope I will be helpful to you.

First you need to select the needed parts and put them apart. You will need:

1 x 92908c01 (I assume you already inserted the hub in the portal)

2x 92907 (Axle and Pin Connector Perpendicular Split)

1 of the following pairs of gears, depending on your desired ratio: 8t and 24t; 12t and 20t; 2x 16t

1x axle 4 with stop

1x axle 3

2x axle 2 notched

2x frictionless pin

Building steps:

1. I will call the position of the hub of the 92908c01 as bottom left. Insert the larger gear in the frame, bottom position. Push the axle 4 through the hole at bottom right. Now the hub should rotate together with the larger gear.
   
2. Insert the smaller gear in the upper position of the frame and the push the axle 3 through the whole at top right. If you rotate the small gear, the hub should also rotate.
   
3. Now the 92907 connector: I will call the position of its only round hole as bottom right, if you pass an imaginary axle vertical through it. On the left side you will have 2 pairs of axle holes, one top and one bottom. Next, embrace the top right corner of the portal hub with the left side of the 92907 connector. Its round whole must be still in bottom right position. Then insert an axle 2 through the bottom left hole of the 92907 connector. The portal and the connector should stay together now. Finally, insert the frictionless pin in the round hole of the connector, coming from top.
   
4. The whole assembly will rotate when steered around the axle of the pin you inserted. Just below the 92907 connector is the hole through which you pushed the axle 3. This hole is a bit wider and can accommodate 1 stud of the 3L u-joint. This means that the joint of the u-joint is on the same axle as the frictionless pin.
   
5. Connect the second 92907 connector in the bottom right position of the portal hub, but with the round hole up, not down as the first connector. Insert the second axle 2 through the bottom hole of the connector. Insert a frictionless pin in the round hole of the connector, coming from bottom.
   
6. Build the hub for the opposite site and connect the top pair and the bottom pair of frictionless pins with beams. These beams will be connected to the chassis between the hubs. The free end of the u-join will connect to the drive shaft.
   
7. Steering: insert an axle through the top right hole of both portal hubs. This should also pass through the empty hole of the 92907 connector. At the ends of these axles attach a 6536 connector by the axle hole, of course. Insert frictionless pins in the round holes of the above connectors and then connect a gear rack (64781) to those pins. You will now have a parallelogram formed by the beam between the hubs, the 2 axles and the gear rack. This parallelogram can be deformed by rotating a 12t double bevel gear (which is static related to the chassis) over the gear rack.
   

Regarding other wheels to attach to these hubs, you can try the cheaper 56908 which accept 80.4 tires.

[BlindBuilder]

Thanks ever so much Mihai_9600. That was perfect. I think I had convinced myself it was a lot more complicated than that. Thank you.