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ThunderDragonCy

TRF211 / TRF201XM/XR/XMW 3 gear Layback Dirt setup

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Any love for a TRF211 / TRF201XM/R 3 gear layback dirt setup? One of the guys who has bought the 3 gear laydown conversion said it would be cool to have a more rearward option like the B6.1D. Dark winter nights and all that, so I had a play with some ideas. I had a look at something like the B6.1D layback setup, but it's just a short laydown with a little idler. Only moved the motor back 5mm. I had a play around with existing Tamiya bits and came up with this: It's the regular 3 gear internals from the TRF201 (27t idler) but with space for a TA06 gear diff, or the usual ball diff with some spacers just like the laydown conversion.
 
TRF211 3 Gear Standup V6 (FF03 Motor Plate) Front ISO
It uses a FF03R motor plate (and therefore the option for using the FF03 AA part spur and pinion cover). Still got the shocks front mounted, and it doesn't mount the motor quite as far back as the TRF201XM/TRF211XM drivetrain. It's 21mm more rearward than the 3 gear laydown,14mm forward of the Tamiya 4 gear position. This means that if my measurements are correct it may also give the option of running a shorty longitudinally depending on the size of your ESC and steering servo. It would be packed in pretty tight, but then you want a battery nicely held.
 
Unlike the Tamiya drivetrain it's 3 gear so lighter and opposite motor rotation, and it's much lower CG than the 4 gear drivetrain with it's twin idlers sitting right over the diff.
 
TRF211 3 Gear Standup V6 (FF03 Motor Plate) Left View
 
The motor packaging is a little tight around the idler case so spur gear range is a bit limited, but I figured with a 78t spur and 84t spur (which probably wouldn't fit in the FF03 spur cover) I can get FDR from 10 (22/84) down to 5.9 (34/78) which covers mod to 17.5.
 
I have partly been into this (apart from having fun designing stuff) because although my 3 gear laydown 211 is epic on the track with the right tyres and conditions, it's window of operation seems a little narrow and it's pretty spiky on lower grip. Away from track days I run a lot on grass just having fun, and I ran my TRF201X for the first time in ages at the weekend and it was so easy to handle compared to my 211 3GL. Just thought this might be a good compromise to make the 211 a little friendlier / all rounder. Given that I don't race it's not all about the last drop of performance, although that's always fun on occasion ;-)
 
Anyone think this might be worth popping on Shapeways? Be interested to hear feedback. 4 gear really does seem to have gone by the wayside in the last couple of years.
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Never really hurts to pop it on shapeways right? Someone, someday might need it.

At least thats my philosophy.

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Well this one has been quite the saga for me! A variation on the design above using all Tamiya TRF201 internals including 27t idler, but still with a yokomo motor plate, is now available on my CTE RC Shapeways store. Its been tested by Ken and Jason at Cobra Racing Products (who will also make you a custom chassis plate, motor plate and battery retainer for the transmission too) and they are super happy. They have found (as I did) that whilst the laydown is really fast on high grip, it's got quite a narrow sweet spot where it works and outside that, especially on lower grip, it's quite a handful. I haven't been finding it that fun to drive on grass over the winter. The Layback keeps the low CG but uses the smaller idler to pull the motor and battery 10mm back to weight the rear wheels more. 

https://www.shapeways.com/shops/cotic-rc

I have today finally got my own up and running. It's a bit different to production because it uses up parts I had already, and although there is a CTE RC spur cover now for the transmission in my store, it's not full coverage. I had an FF03R motor plate from when I thought I could do this idea using an FF03 transmission (you can't because there is nowhere to mount a shock tower on the ff03 transmission case), and the only spare idler I have is a 26t kyosho from the gear diff conversion I did on my TRF201. I managed to pick up an FF03 spur/pinion cover from Stella models, but these are not easy to come by, so although perfect for my largely razzing about on grass needs, it's another reason why mine isn't the production version. Still needed some trimming here and there but generally it went together well. I also filled the rear diff with 300k diff oil whilst it was out to give me better performance on low to medium grip surfaces. 

Here it is installed this morning

Tamiya TRF211 3 GEAR LAYBACK. Using FF03R motor plate and cover, CTE RC transmission cases

And here I s a good view of the cover

Tamiya TRF211 3 GEAR LAYBACK. Using FF03R motor plate and cover, CTE RC transmission cases

Its at an angle because the layshaft is about 10mm lower than in an FF03 (that is effectively a 3 gear stand up), so the motor slot isn't parallel to the floor (yet another reason this isn't for production). The idler sits under the layshaft so it a really low transmission. You can also just spot that the cross mounted battery is as far back in the chassis as it can go. I needed to ream and dremel a 10mm hole in the cover to allow the slipper shaft to poke through, but apart from that it's fully enclosed. I also managed to keep the shocks on the front although they would just as neatly mount on the rear. I just didn't want to cut my wing. 

And running! 

20190324_135240

For me, this is such a big improvement over the laydown. It has so much more traction and the progression to oversteer is much less snappy. It was much more like my beloved TRF201X rear motor buggy on the grass, but turn in and front end grip is still really good. Really looking forward to running this on the track in a few weeks. 

I think the big thing for me was that recently when I ran the laydown I was constantly messing with the setup to get it to be more friendly. This is just tried a couple of different front tyres, tweaked the rear roll centre and drove a whole pack. I think this could be the perfect all round mid motor setup. 

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Mark Lapper (he of the awesome TRF racing buggy builds) is over on oople building a TRF201 Layback with my gearbox and a custom Cobra Chassis

attachment.php?attachmentid=114211&d=155

attachment.php?attachmentid=114210&d=155

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41 minutes ago, ThunderDragonCy said:

Mark Lapper (he of the awesome TRF racing buggy builds) is over on oople building a TRF201 Layback with my gearbox and a custom Cobra Chassis 

attachment.php?attachmentid=114211&d=155

attachment.php?attachmentid=114210&d=155

Check attachments please ;)

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