Jundis Posted March 28 Posted March 28 Hey guys and gals, whenever I don't know what to build next or stuck with a current MOC (looking at you, pesky crane); I build a Tractor. This time I tried to improve on my Fortschritt ZT 320 and wanted to add AWD and a front hitch. As Deere Tractors have a longer nose, it was my choice. And as a new 8R came around, this will be the loose aim, especially the 8R 410: Currently I am waiting for a new Li-Ion battery for the buwizz as the last battery died on the shelf, forgot to load it for half a year... :-/ The functions, powered by a Buwizz 3 are: - Drive (PU-L-Motor) - Steering (PU L-Motor) - rear PTO (PF L-Motor) - rear hitch (PF L-Motor) - front hitch (PU L-Motor) The front axle gave me the most headache. Made it even harder as the aim was to give it a 0.5 stud offset to the chassis, as I wanted it to be more leveled with the selected tire combination. I settled with a solution that unfortunately has an illegal building technique, the front pnedular point is 2 studs below the rear one... but this is way sturdier than all the other solutions to build around and as the pendular motion is limited in travel, I don't feel that there is too much stress on the frame. For the rear drive, the reversed portal axles give a little more space above for the PTO and rear hitch Here is a view of the mechanics and real pics. Not quite happy about the front hitch... hopefully can cover it to get the nose shape etched out a bit more. Pneumatic solution with a autovalve would be even bulkier, though. As there are no curved panels in green color, I will go with a brick-built solution on the hood. But first, the function test with Buwizz next week :-) Quote
jorgeopesi Posted March 28 Posted March 28 Very good and compacted I like a lot specially the front axle solutions. Quote
1gor Posted March 28 Posted March 28 It seems that you use this kind of axle. How do you compensate speed rotation difference between front and rear tires Quote
2GodBDGlory Posted March 28 Posted March 28 Looks nice! I like the assymmetry in the front axle, and the use of that triangle part for the steering linkage is clever! Quote
1gor Posted March 28 Posted March 28 51 minutes ago, 1gor said: It seems that you use this kind of axle. How do you compensate speed rotation difference between front and rear tires? I forgot one more thing; how much you can bend PU cables (they stick out very much) in order to work properly; I had a lot of cable issues with PF motors, so I have to fix 5 PF servos, two large motors (4 XL are fixed, but plastic looks like T-rex took it apart). First stage of Alzheimer... Quote
Jundis Posted March 28 Author Posted March 28 Thanks, guys! 3 hours ago, 1gor said: It seems that you use this kind of axle. How do you compensate speed rotation difference between front and rear tires Yeah, it actually gives more space on the sides so the tires don't scratch the frame even when fully turned and maximum pendular movement. I just did a quick calculation before. Here it comes in handy, that the 1/2 stud offset of the front axle allows the 12/28 gear combination. The remaining difference is neglectable by friction itself. It's not that fast, but torque is more important for me, as it only has 1 L-motor for drive. 3 hours ago, 1gor said: I forgot one more thing; how much you can bend PU cables (they stick out very much) in order to work properly; I had a lot of cable issues with PF motors, so I have to fix 5 PF servos, two large motors (4 XL are fixed, but plastic looks like T-rex took it apart). Puh, good question. I didn't care much about cable management so far in this built. Just left enough space for it to go to the Buwizz. Quote
1gor Posted March 28 Posted March 28 15 minutes ago, Jundis said: Thanks, guys! Yeah, it actually gives more space on the sides so the tires don't scratch the frame even when fully turned and maximum pendular movement. I just did a quick calculation before. Here it comes in handy, that the 1/2 stud offset of the front axle allows the 12/28 gear combination. The remaining difference is neglectable by friction itself. It's not that fast, but torque is more important for me, as it only has 1 L-motor for drive. Puh, good question. I didn't care much about cable management so far in this built. Just left enough space for it to go to the Buwizz. Yesterday I got BuWizz 3.0, so I plan do finally work on Fastrac next week (my head will explode since last days when I went to work were up to 120km/h wond blowing speeds)... Usually when you use such tire combination, easiest way is to use central differential and (no matter 12-28, 14-22 or 20-28 combo at axles) 12 to 20 refuction at portals on rear...hope I could make it sompler for you... Quote
falconluan Posted March 29 Posted March 29 Very promising progress you made here Especially packed lots of motors/functions in such tight space. Lots of 8R have independent suspenstion which I failed to achieve in my version, I was hoping the new suspenstion parts can help, seems still very challenging, unless get rid of the horizontal placed diff, which will take extra space in the chassis and lost extra realism... Quote
Jundis Posted March 29 Author Posted March 29 On 3/28/2026 at 4:47 PM, 1gor said: Yesterday I got BuWizz 3.0, so I plan do finally work on Fastrac next week (my head will explode since last days when I went to work were up to 120km/h wond blowing speeds)... Usually when you use such tire combination, easiest way is to use central differential and (no matter 12-28, 14-22 or 20-28 combo at axles) 12 to 20 refuction at portals on rear...hope I could make it sompler for you... Looking forward for your progress on the Fastrac! I know, but in this very configuration here, all the gears fit very nicely in the intended frame, there is no unuseful combination :-) 19 hours ago, falconluan said: Very promising progress you made here Especially packed lots of motors/functions in such tight space. Lots of 8R have independent suspenstion which I failed to achieve in my version, I was hoping the new suspenstion parts can help, seems still very challenging, unless get rid of the horizontal placed diff, which will take extra space in the chassis and lost extra realism... Thanks, man! From the scratch I had a pendular axle in mind. There is no way to implement indipendent suspension without making it all flimsy in bricks ... would just not fit for a heavy working machine. I think @Thirdwigg tinkered with a floating diff some time ago, if I remember correctly...? This evening some progress and testing in stud.io lead to this solution. At least the iconic front look is nice. But the headlight are nearly 2 studs too high due to motor placement. Maybe I'll go to the system forum and ask if this is structurally sound :-/ I really don't have that much knowledge about system parts. Quote
Thirdwigg Posted March 30 Posted March 30 Cool project, and I'm happy you are making good progress. I never used a floating diff in a tractor, just in two different cars. It works well, but with the introduction of the shorter CV axles it can be achieved in other ways. I hope this helps, but I'd keep the axle you have now. Quote
Jundis Posted March 30 Author Posted March 30 (edited) 17 hours ago, Thirdwigg said: Cool project, and I'm happy you are making good progress. I never used a floating diff in a tractor, just in two different cars. It works well, but with the introduction of the shorter CV axles it can be achieved in other ways. I hope this helps, but I'd keep the axle you have now. That's what I meant :-) Was just an example that popped in my head for really narrow solution of indipendent suspension. It just dawned at me that an M-Motor can be used instead of the L-Motor.. makes things much easier now and 1 stud gained. *Edit: @1gor Now I know your struggle with creating a perfect hood.... *sigh* Edited March 30 by Jundis Quote
1gor Posted March 30 Posted March 30 44 minutes ago, Jundis said: It just dawned at me that an M-Motor can be used instead of the L-Motor.. makes things much easier now and 1 stud gained. *Edit: @1gor Now I know your struggle with creating a perfect hood.... *sigh* Using 4 M- motors is my plan on Fastrac update. 6000 series are tempting me; they have some advantages but two major problems - hood line (as you suffer yourself) and narrow axle like your front, but with 107mm tires and fully suspended... it is really complicated to make moders tractors because lots of them have curved sloped hood and ftont part is significantlly wider than part just in front cab...perhaps I'll see in your hood ideas something that I neglected, but it was all the time in front of my nose...and there is one more thing; I try to make realistic ground clearance... Kind regards Quote
steph77 Posted March 31 Posted March 31 I understand the difficultiy of building the front hood. I struggle à lot with it too. Keep it as simple as possible and maybe swap the l motor for a mini one. Cada and buwizz offer that possibility. And they work very very well. Quote
Jundis Posted April 2 Author Posted April 2 On 3/31/2026 at 8:18 AM, steph77 said: Keep it as simple as possible Really hard to get the shaping right with few parts. My best take on right now is this. Still I struggle to get me to order the parts as I know myself that somethings change during a week :D Can you guys give me an honest opinion about the solution? Also had a breakthrough on the front axle solving it's problem with the 2 stud difference of the pendular points; thanks to the new part highlighted in orange. This also frees the room for a way better solution of the upper attachment point of the 3-point hitch. Quote
1gor Posted April 2 Posted April 2 It is not a Deere, but bonnet shape is very similar; just scale it a bit down; your is 1:19.5 - 1:20 based on tires, and Steyr is 1:17... Quote
falconluan Posted April 3 Posted April 3 14 hours ago, Jundis said: Can you guys give me an honest opinion about the solution? I think a lot of things are sacrificed for the front hitch, especially the room took by the two small LAs. The 8R has a very unique shape at the front, which currently is not shown on your version. Quote
Jundis Posted April 4 Author Posted April 4 Thanks for your honest opinion, guys! On 4/2/2026 at 10:12 PM, 1gor said: It is not a Deere, but bonnet shape is very similar; just scale it a bit down; your is 1:19.5 - 1:20 based on tires, and Steyr is 1:17... Model looks great actually! The panels on the side actually makes way more sense for the frontal part right behind the headlights. Will try this. On 4/3/2026 at 11:47 AM, falconluan said: I think a lot of things are sacrificed for the front hitch, especially the room took by the two small LAs. The 8R has a very unique shape at the front, which currently is not shown on your version. You are right. First thought was using the small pneumatic cylinders like in the real model. But they have no power at all to lift anything above ca. 100 grams. Can't really change anything there, so the area around the headlights has to be improved. But first of, I wait to finish all the mechanism first. The steering is to wonky right now, as the ange of the motor is only +/- 20°. Maybe have to redo this also. I'll keep tinkering. :-) Quote
Zerobricks Posted April 4 Posted April 4 (edited) On 4/2/2026 at 9:33 PM, Jundis said: Can you guys give me an honest opinion about the solution? I think the front axle is designed too weak, it will bend a lot in real life. You need an upper connection at the sides, or at the top of the diff to reinfoce it. Also, there is an issue with your 12 tooth gear driving the 20 and then the diff. The axle supporting the 12 tooth gear is not properly supported, the whole thing can pop out under load. Also, why not use planetary hubs if the model will be motorized? Edited April 4 by Zerobricks Quote
Jundis Posted April 4 Author Posted April 4 1 hour ago, Zerobricks said: I think the front axle is deisgned too weak, it will bend a lot in real life. You need an upper connection at the sides, or at the top of the diff to reinfoce it. Also, there is an issue with your 12 tooth gear driving the 20 and then the diff. The axle supporting the 12 tooth gear is not properly supported, the whole thing can pop out under load. Also, why not use planetary hubs if the model will be motorized? Thanks for the advice, but maybe the pics I posted didn't show the whole story. The front axle is very sturdy and has a 7L liftarm underneath, there is no significant bending going on. Same with the rear axle. Not sure what you mean the drive axle with the 12t gear ain't supported... ? The LBG liftarm with socket holding a 3L liftarm in front. Also the 15100 pin is second attachment in the back...? The planetary hubs weren't necessary as I described in the post above with the gear rations. Quote
1gor Posted April 4 Posted April 4 Johannes, 5 x 7 frames are designed to hold differentials, so 20 toogh should be driven directly...if you need 12 to 28 tooth reduction, then use eed differentials Quote
Jundis Posted April 4 Author Posted April 4 1 hour ago, 1gor said: Johannes, 5 x 7 frames are designed to hold differentials, so 20 toogh should be driven directly...if you need 12 to 28 tooth reduction, then use eed differentials But why should I replace my working configuration? Quote
1gor Posted April 4 Posted April 4 (edited) 22 minutes ago, Jundis said: But why should I replace my working configuration? I'm not saying that you must replace it, you wanted honest opinion and from our experience, we replied...I will missuse your tread and point that I changed configuration of my Fastrac suspension to suspension like on 9398 set just because replicating original with so many 6L links didn't give me robustness that I needed for tractor...I'm affraid that if you try to pull some trailer that at the front there will ve skipping gears and clicks between 12 and 20 tooth gears It is just a friendly advice, nothing more... Edited April 4 by 1gor Quote
falconluan Posted April 5 Posted April 5 Agreed with @Zerobricks and @1gor, the 12T and 20T gear will skip at even moderate stress. I've tried similar setup during building my Axion TT not long ago. I used this setup at the rear axle, and my setup was more secured than yours in the pics. The 12T gear was fully enclosed all around, I also secured them vertically. However, they still skipped. The problem here is the 20T gear which drives diff is only half secured. When the rotate direction is pushing the gear apart, the 20T gear will bend away from the diff side and skip. Quote
1gor Posted April 5 Posted April 5 18 minutes ago, falconluan said: Agreed with @Zerobricks and @1gor, the 12T and 20T gear will skip at even moderate stress. I've tried similar setup during building my Axion TT not long ago. I used this setup at the rear axle, and my setup was more secured than yours in the pics. The 12T gear was fully enclosed all around, I also secured them vertically. However, they still skipped. The problem here is the 20T gear which drives diff is only half secured. When the rotate direction is pushing the gear apart, the 20T gear will bend away from the diff side and skip. That is why I recomend using daytona difs or old gray just with 20 toth double bevel...with red diffs I recomend using 28 tooth double bevel, the more gear tooth interract at the same time, less skipping is possible. That is why @Zerobricks recomended planetary hub reduction to have more pulling power (real tractors have planetary reduction hubs in real life) Quote
Jundis Posted April 5 Author Posted April 5 (edited) Hmm ok. I really appreciate all the input and will definitely use these advices in future models for tractors. But for this model, it would mean a complete overhaul of the design and starting from zero again, as I can't use the main frame and all motor setups. As all models should be, I will learn from the design mistakes and improve on them. Initially, I didn't even consider the Daytona diffs, but yes they make way more sense here, same goes with the planetary reductions. If I can't make the hull fit for an 8R 410, I'll go with just a generic JD tractor. Edit: Something like this: Edited April 5 by Jundis Quote
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