Ok. Here's my XB808 prototype (sorry for the missing esthetics
![Wink ;)](./images/smilies/icon_wink.gif)
). I got more than 2 hours of track time with this setup this week. We had our indoor wintercup race yesterday and the car was perfect on the carpet track. I managed to get best lap 17.16s while best nitro was I think 17.9s. The car was well balanced and good to drive. I'd like to thank Bren for good tyre advice for running on carpet track
![Wink :wink:](./images/smilies/icon_wink.gif)
RTR weight was 3400g. The track was small so I only used 2300mAh out of quite heavy 5Ah battery. So if I had smaller (3300-4000mAh) battery the RTR weight would have been under 2300g with no lighter Xray parts used!
This layout has PERFECT left-to-right balance. And I mean perfect! The front-to-back balance is good also. Haven't run it on big jumps cause its winter here, but on our track it works really nice.
1. Tekin RX8 sensored ESC. It is mounted straight on the chassis plate with 3 layers of double sided tape and secured with few rubber bands running over it (a prototype
![Wink ;)](./images/smilies/icon_wink.gif)
) Sensor wire is too long at the moment, but runs niceley through under the rear chassis brace. Motor wires can be very short. 5.5mm bullets are used to connect battery and ESC.
2. I'm using cheap 60$ 4S soft LiPos from HobbyKing. Rated 35-40C weighing 550-570g measuring 147x51x36mm. They are well balanced, have more than enough performance - no problems so far! Pictured battery box is from Speed Passion, but mounting is done myself. Battery sits ~8mm above the chassis plate. Almost touching the steering mechanism and 1-2mm away from spurgear. Battery is secured by glassfibre tape at the moment but nice wide velcro straps would be better.
3. Carbon center diff plate. I think this is A MUST. It makes the motor mount more rigid. Transponder is mounted on top of it because we have overhead timing loop.
4. This is the best place for the receiver. Currently we run indoors so the rx is attached by 3 layers (for absorbing hits) of doublesided tape. For summer and running outdoors I'm trying to find a (radio)box that can fit only the rx and be mounted there.
5. Motor mount is from HobbyPro. I really like it. It has a good design and it's thigh enough. Also mounts the motor at just the right height. Motor on the picture is Tekin T8 2050kV with 17T pinion 42T stock spur. This mount gives ~4mm clearance to chassis plate. You have to have at least 3mm there or the chassis will hit the motor under flex. with 4mm I have no marks on either, with 2-3mm clearence you can see them touch eachother. This might easily bend the motor mount. Sideguard is dremeled thinner, mounting nut removed.
6. Overkill capacitors for the ESC.
7. Aluminum rear chassis brace. A MUST to reduce the chassis flex. There is still too much of it - not so much a handling issue but a reliability. It is easy to bend the chassis plate, bend the rear CVD shaft and break the diff pinion & bearings because of it. Would like to have longer brace there or something like nitro engine mounts bolted to the chassis.
I like this motor mount. One of our locally made motor mounts have a nice feature also. Lower screw is in a fixed place, upper screw moves in arc shaped opening. This way the motor is secured better and almost totally eliminates the possibility that the motor moves because of impact.
What about using smaller spur gear for 808E? When smaller spur is used then you can:
- lower the center diff and/or loose the opening in the chassis plate for spur.
- move the motor closer to centerline
- move the battery closer to centerline
Electric 808 really needs more space on the battery side. Wider chassis is needed. This way the battery could sit right on the chassis plate
![Exclamation :!:](./images/smilies/icon_exclaim.gif)
When converting regular XB808 to electric you have the clearence issue with the side guar. Only very thin battery can fit there sitting (4000mAh 4S).
I've ran the car with ESC up front and battery behind it. I didn't like how the car was handling. This setup with battery up front is far better. Ideal would be if you could move the battery 10-20mm front-to-back to change the balance!
If we could get the 808E with layed down servo like XB808, small radio box just for the RX mounted on top of it and battery mounted closer to chassis plate I'd be very happy
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+ something to stiffen the rear.