4wd Baja 5e based on stretched truggy chassis

[othello]

After having red this thread and this one i always had this idea spinning in my head as i really like the look of the baja 5. Converting a true Baja 5 was no option as it would remain 2wd and would require a new ESC + motor. Powering 20lbs+ with authority would consume a lot of energy and quickly recharging would become problematic. So i decided to go another route with parts i had laying around.

After studying the manual of a baja 5 i ordered the needed parts to reproduce its look: front bumper, main roll cage, center roll cage, roof and clear body. I took 2 1:8 truggy chassis (Robitronic Mantis), overlayed them to get the wheelbase of a Baja and testfitted the roll cage, body and front bumper. I mounted wheel extenders and used proline lpr half offset wheels to extend track width.

I then cut the two chassis plates and fitted basic mounts for the roll cage. I mounted the centerdiff including a Neu 1515/2Y (1100kv) motor. I cut the rear center CVD and used an aluminium tube to extend its length.

There is plenty of room for batteries behind the center diff. I did not want to reconfigure my battery packs (5s1p and 4s1p A123 for my truggy, buggy and truck) so i placed them on the chassis to get a 50/50 front/rear balance. I'm still using a Kontronik Jazz 55/10/32 (55A cont and 10s lipo max) with car mode (forward, brake, backward) to power this car as it has proven to be very reliable in all my 1:8 cars. For peace of mind 2 40x40mm fans were mounted over the motor. 2 single A123 cells were added and gearing was adjusted to 1:14,86 (46t kyosho plastic spur with a 13t pinion). With 11s1p A123 (around 33V under light load) the 1100kv motor should rev up to 36000rpm calculating to a speed of 40mph (65km/h).

This is a pic of how i run the baja. It wheighs 5.5Kg (12.12lbs) with 11s1p A123. The painted body will add around 3.53oz (100gr).




Here is a video of its third test run.

Body is not painted yet, so i run it without it. No shock adjustments were made. I run it with my truggy setup without anti-roll bar -> offroad setup. Acceleration was good (still quite some unloading to the front tires) and ESC braking was amazing. Turning circle was impressive for such a large car ... Crimefighter tires provided huge amount of grip resulting in 3-4 tip overs.

I run the car for 6 minutes. Motor, ESC and Batteries were warm but not hot (outside temperature was 62°F (17°C). I could keep my finger on the motor as long as i wanted. Batteries took 1470mAh back while recharging. With 2000mAh utilisable, runtime would have been around 8 minutes with this driving style. This translates to an average Amp draw of 15A. With 33V (11s x 3V) average power calculates to 500W. Motor temp will climb and runtime will fall depending on how hard i drive.

There is more then enough room for improvements. Especially shock and anti-roll bar setup. This car is meant for offroad and not for onroad. It was sort of a proof of concept run and to get an idea if my lengthened CVD is up to the job (it vibrates too much but remained in one piece: a steel tube would be more apropriate).

What do you guys think?

[othello]

upps ... there are few pics missing in my previous post which where shown in preview mode when i edited the entry.

[Unsullied_Spy]

Looks good, but those are some LONG center shafts.

Try to get some 24mm hexes and Baja wheels/tires for it to complete the look. Pro-Line Desperado wheels with some Hostile A/T tires would work nicely.

[lincpimp]

Looks great. It is a pity that proline does not have more choice in the 40 series line. You could run 40 series on the back and mt tires on the front for the staggered tire look.

[lutach]

It looks faster then a Baja. Very nice build othello.

[othello]

Thanks guys.

Truely, tire choice is a pity. Wider Rear tire: i think Muggy tires should fit the bill but i don't think having a heavier rotating mass on the rear is a good choice with 4wd as it would make the center diff unload even more to the front tires = less acceleration. I really don't want to add too much wheight (especially rotating mass) as it is "only" powered by a Neu 1515. The original Baja tires would look good but the front tires were never designed for 4wd and due to its beadlock design should be relative heavy compared to truggy lpr race tires. Wow, those hostile tires look mean (would be perfect for grass i guess, but not a good choice for a dry track). I think i will just stick with truggy tires as handling seems already to be where i want it to be. Good handling is an important objective. Of course riding height will never reach Baja level with this smaller tire choice. Maybe i change my mind in the future ;-) I look forward to your 1:5 conversion, Lincpimp.

I made a run on my prefered bashing spot. Here is a small video showing its handling on a small wood track. I did not push the car as the electric components were still unprotected without body and i haven't made any improvements yet to stop the long center shaft from swinging. I never hit full speed and never braked, just rolled into the curves. I was amazed by its handling. I could swing the rear axle around in a very controlled way, making even the hairpin curve very easy to drive. The car simply drifted over all 4 wheels: i guess i will maintain this slightly front biased wheight distribution.

[killajb]

Othello,

Dude this is great work! For such a long chassis, the 4wd really seems to keep things tame. I can't imagine why companies don't dig through their existing parts bins and make one. A longer chasis made of durable plastic and perhaps a thick Thunder Tiger SB4-style center tunnel to house the diff and protect the drive shaft. Can't see where extra cost would even factor in, maybe for wheels and tires perhaps.

[rootar]

that looks sick in the video you gotta get your litte bugs worked out with the swiing shaft and get that body on and painted this looks like itd be WAY nicer to have over a regular converted baja....

[magman]

When I started one of the threads you looked at, this is what I had in mind. Nice job

Nice job, i bet the long chassis should make it more stable.

...yup thats pretty much what i am looking at too but slightly shioorter...looks good though Othello...great work...more pictures (and slightly different ideas) for us to R&D...Good job...

...sorry...watched the video after i posted...was just going on the still shots...HELL nice ride to it mate...smooth and flowing...I think the length of it hides the shock action as opposed to a 'bouncy' truck...Corners really well with just the right slide...nice...

...i just mentioned in on oe the other conversion threads about the baja rim adaptors coming from HPI for the Savage 5T soon...I reckon that a FULL set of baja fronts will do the truck justice for sure...The rears i reckon would be just too heavy, as you suggested...

[othello]

Third video while running on grass.

This was its first run on this type of surface. Still not pushing the car to its limit due to running it without body. You can actually hear the long centershaft rubbing against metal especially when i release throttle to neutral. The aluminium tube copes well with torque as it doesn't twist, but is to thin and starts to swing. i can actually bend it with my fingers. Using a thicker aluminum tube or even better a steel tube should cure this problem.

Since i made this video i have already performed 7 further test runs. Even with 9s1p A123 i had a lot of fun while running on grass: motor temperature remains absolutely uncritical even when pushing the car on higher grass. With 9s1p runtime dropped to 7 minute plus while pushing the car hardly on my wood track. 10s1p A123 seems to be more then enough power and top speed is perfect for a smaller track: Motor temperature is higher though as i did not adjust the pinion. With 11s1p A123 i have all the power i need to goof around. Motor temperature will reach higher levels as with 9s1p or 10s1p A123 as more power is generated with higher voltage (witout changing pinion).

@killajb
I think every company featuring a 1:8 truggy could easely acomplish something similar with a more factory build finish ;-)

@rootar
Hard to say. I really would like to drive a real Baja. 2wd is fun to drive at times. I'm glad that hpi has built a baja as it is superbly looking when compared to other big rc-cars.

@magman:
Your question was the initial spark to get this project rolling.

@D8Driver
It is definitively more stable than my 1:8 truggy, Buggy or truck. Very easy and predictable to drive. With a 1:8 Buggy you have a lot more to do behind your transmitter.

@BitHed
Chassis length does help. Still needs more shock travel on the rear axle as tires are smaller than the original Baja ones. I think you can see on the video that the chassis is sometimes bottoming out on the rear axle.

[Maciolus]

Great project! I am jealous ;)

Where have you found those CVD's?

Are there any 24mm hex adapters avalible?

...i havent seen the HPI ones for the Savage 5T yet but they should be out soon...just wondering what time lag HPI will put on them...Shouldnt be TOO long because I reckon they are aiming for the XL to 5T crowd...Keep y'all posted...

[othello]

Body is now painted and stickers are applied. I'm not 100% convinced with the result. I might change sticker positions.





@Maciolus
I lenghtened an original center CVD by cutting it in two halves. Added length with an aluminium tube which is glued onto the two cvd halves. A steel tube would have been a better choice since my aluminum tube is to thin and starts to swing under load.