pastimesteve

Why does THIS seem to work so well? (mods to Hornet rear suspension)

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The OP's rod that eliminates the rotational slap is definitely a better design. To me I wouldn't want the front end of the gearbox rotating whatsoever. And with the DT02 design, it seems Tamiya agrees.

Does the DT02 use any additional springs to control the roll movement of the gearbox (like the grasshopper & lunchbox)? The more I think about it, the more I feel it's unnecessary as the gearbox is always supported by 3 points (solid center pivot, & two coilovers). I think I'm gonna convince my buddy to get his Grasshopper out of the closet.

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I said this a long time ago don't know if it was on here ...if you hold down the front of the gear box and don't let it lift up at all only let the axle swivel it makes the suspension work better...here is why when you give it gass and it lift up high in the slots the rear shocks become harder to compress down than when in the down position... actually the grasshoppers rear works better it don't lock up as much as the hornet type ... but then you don't have the axle twist so that is not good...so this is why if you hold down the axle but let it still pivot it will work much better.... I had a idea to do this a long time ago because I found in the lower position the suspension moves much more easy... I was simply going to get a plastic screw and nut at the hard ware and drill a hole in the chassis so the end of the plastic screw sits just 1mm or so above the center of the gearbox where the metal rod slides through so it will be a simple way to hold it down and let it swivel and twist as the same time.

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The double shock mod on the rear axle is basically an upgrade for the silly Hornet springs...

I value to keep the technique (mostly) contemporary since it was my first car (memory lane).

Locking the center of the axle might be a good idea though.

But it's somewhat less of a Grasshopper if it doesn't bounce around at least a bit.

:D

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Thanks for the pics.

What I can deduce is that the hole in the A5 joint is probably tapered on both openings ie. >=< , to allow the mb17 shaft to rock sideways.

You're right, this is how that joint works.

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The OP's rod that eliminates the rotational slap is definitely a better design. To me I wouldn't want the front end of the gearbox rotating whatsoever. And with the DT02 design, it seems Tamiya agrees.

Does the DT02 use any additional springs to control the roll movement of the gearbox (like the grasshopper & lunchbox)? The more I think about it, the more I feel it's unnecessary as the gearbox is always supported by 3 points (solid center pivot, & two coilovers). I think I'm gonna convince my buddy to get his Grasshopper out of the closet.

I assume you're talking of the DT-01, aren't you? As the DT-02 has double wishbone independent suspension front and rear.

To answer your question: The DT-01 rear end is only supported by the central pivot/A5 joint and the rear shocks. There are no torsion springs in the slots.

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^Ah yes thanks. I'm not familiar with either so I got confused. Good to know you don't need to add any torsional stiffness when running such a tri-pod rear end. This seriously sounds like a great mod for any grasshopper/hornet/lunchwagon.

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For normal running, you will be fine with the shocks acting as stabilizers. With my 16T BL system installed, the DT-01 Mad Bull likes to lift one rear wheel in sharp turns. I think this is a situation where it would benefit from a proper rear sway bar.

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typically a sway bar reduces traction. It would be interesting to see this with back to back comparison.

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Next phase for the upgraded axle springs I was working on earlier...

Spacing out the axle to position the adjusters correctly :

Grotefoto-LJDA4CT7.jpg

A combination of Frog, Hornet and Grasshopper suspension parts :

Grotefoto-IXDFIEMP.jpg

Mk.I is quite promising... I even think this setup works better without a pivot in the middle :

The next brackets I'll fabricate (later) will have a slightly different design.

At full stroke, the 540 motor is touching the lower lid in this configuration...

But only if the axle remains at it's lowest position.

Something that is an unlikely practical circumstance...

A field test will be next. :)

Edit - already went ahead a made some Mk.II brackets from aluminium profile.

Works slightly better and they are now also small enough to give a 540 clearance in all circumstances :

Grotefoto-NECNYVW6.jpg

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My Japanese is a bit rusty too...

I am wondering how exactly those adjusters were fitted on the rear shocks :

HopperRearMod_zpse899f0ec.jpg

Anybody have an idea? :)

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He did cut the top damper connectors and flatten the damper caps.

Then he made a 3 mm hole in the centre of both caps and fixed the adjusters with two 3 mm tread screws.

Easy, clean and fast.

Max

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Thanks for the reply, I was thinking in the same direction but was wondering if that's stable enough.

I reckon a bind head screw (with a wide base) would be best (and he added a nut on top).

Broke the shock mount off my Hopper before I even ran it (blame myself for tightening it too much).

Came up with this for now - technically not perfect but certainly functional :

Grotefoto-RBC3SE6N.jpg

I may switch to something similar to the CVA setup later...

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I think I will have a go fitting the linkage to see if it improves it, my Hornet is the only car I ever really run and it would be cool if it was a even just a little more controllable.

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Simple easy and done with it!

a angled plastic section glued to the chassis or melted bonded as i did with clear plastic liquid solvent cement raised off the axle a MM or 2 so the rear twists side to side but not up..

IMG_1370_zps9c865da3.jpg

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I have just ordered a 5200kV kit for my Grasshopper bodied Hornet, so my rear suspension might need some attention. :ph34r:

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In my opinion, 2500 kV is still plenty enough of speed and torque, as I experienced with the Mad Bull. It is able to do wheelies on gravel, even with the heavy spikeless chevron tires.

I was able to do wheelies on grass and gravel with the Hornet even when using the plain silvercan motor, since the rear spike tires bite so well into the ground.

Anyway, there's no reason not to try out that motor you chose. Make sure you have assembled the gearbox correctly with ball bearings and some grease, as well as assembling the two gearbox halves carefully together. Put a 18T mod 0.6 steel pinion on the motor for top speed, or use a Lunchbox motor adaptor and 10T Lunchbox brass pinion for more torque if needed. Your gears will thank you. Don't forget securing the battery door with a screw or something similar, or else you'll be surprised by a Hornet loosing its guts on every second bump. And most importantly, post a video to show off. :) please.

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Silver can is enough with a lipo, but I had to order a new esc, then thought I may as get one with cut off, then thought I may as well go brushless, then the 5200kv was the same price as the 3000kv. Etc etc. I don't race it, it's just for fun when I go camping. Ive rebuilt the car already. I had a lunchbox with 4200kv on Nimhs and that was comical.

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