4wd 1:5 onroad car based on stretched 1:8 truggy chassis

[othello]

I have almost completed my next project which i like to share with you. After having converted 1:8 buggys, truggys, sc-trucks and toying around with 1:10 and 1:8 onroad chassis i thought the next logical step is to step up to 1:5 onroad cars. Living in the city makes it difficult to find a spot for driving a nitro/gas chassis and the performance of a sports 1:5 onroad chassis without a tuning motor/pipe seemed not very appealing to me ... so it had to be brushless. Considering the necessary investment to convert a "true" 1:5 onroad chassis and having seen prices of spare parts led me to the only possible choice: Using proven and reliable 1:8 parts as basis of custom chassis.

I found a used 1:5 onroad body in good condition. I would have prefered a Porsche body but at this time there were no good offers. So i chose a Mercedes touring car body which is depicted here next to my 1:8 and 1:10 bodys.


1:8 buggy tires have almost the same diameter as 1:5 onroad tires but are not as wide. I had good success with GRP Endurance onroad tires on my 1:8 rally game chassis ... so they were my logical choice.

1:8 GRP Endurance tire compared to a GRP 1:5 onroad tire


1:8 Robitronic Mantis truggy axles were a good starting point as they almost instantly gave the right width when paired with my 1:8 tire choice.


With 1:5 GRP tires mounted i have to shorten the arms and cvds by 1.5-2cm to fit the tires under the body.

Next step led me to cut 2 Mantis truggy chassis and joining them to get the right wheelbase


After this step i chose the bruhless components and where to place them on the chassis. Which resulted in this first test layout.


ESC: Xerun 150A Pro
Motor: Castle 1520
Batteries: 2x Turnigy 6s 3600 used in parallel
Steering Servo: Hitec 5955TG

As i was never able to come up with a well balanced custom long CVD (on my previous projects) to join the center diff with the front axle i decided to join those with the aid of a second blocked center diff which required only a short custom CVD/bone. A rather unusual and not very efficient solution but as of yet it has proven to be reliable.

One of the last steps was to find a way to mount the body to the chassis. With some 1:8 parts in my spare bin i came up with this rather simple solution.



With mounted body


After a few test runs with the castle 1520 motor i stepped up to the Castle 1717 motor which was an easy fit when paired with a 22t pinion.


Depending on the batteries i choose the wheight ready to run lies between 6.2 and 6.4Kg (13.7 - 14.1lbs). I'am using lighter Zippy 6s 2800 paired in parallel (depicted on the image above ... the blue ones) or heavier Turnigy 6s 3600 also paired in parallel.

Gear ratio is 1:8.4 with a calculated top speed of 93km/h (58mph) without taking into account tire balloning. By changing the axle ratio from 42/10 (truggy ratio) to 42/12 (buggy ratio) i can augment speed to 110km/h (68mph).

If you wonder how does it perform, well here is a video while testing this setup on a rather small parking lot.

At this point there are still a few things to get done:
. In my opinion the chassis is too flexible and does need a top deck
. I have to come up with a typical 1:5 front bumper
. Damper setup has optimisation potential