AC201 FF, Front Wheel Drive Buggy
 

Here is my project/prototype car, a TRF201 based front wheel driven buggy:

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Specs/Features List:
- TRF201 Gearbox
- DB01 Front Uprights+Caster Blocks.
- TRF HL Aeration Dampers.
- Double Wishbone Front Suspension with Inboard Dampers.
- Trailing Arm Rear Suspension (2 Degrees Toe-In, -2 Degrees Camber each side).
- Developed for use with a Low Profile Steering Servo and 'Shorty' (=95mm long) LiPo Stick Pack.
- Compatible with modern Pin-Type Rear Wheels on the whole car.
- BRCA, EFRA and BNK Legal to run in 2WD Dlass.
- Approx. 284mm Wheelbase, 250mm Width.

Existing/Production parts in the design:
- TRF201 Gearbox.
- TRF HL (TRF201) Aeration Dampers.
- TRF201 Steering Arms+Servo Saver.
- DB01+TRF201 Suspension Blocks on the front suspension.
- DB01/DF03 Hybrid Universal Shafts (DF03 70mm dogbone, DB01 rear axle).
- TRF201 45mm Titanium Turnbuckles (for camber links).
- TRF Adjusters on the whole car.
- DB01/TRF Rear Wheel Axles (for the rear wheels).
- 4x Pin-Type Rear Wheels.


So you might ask, why front wheel drive!? Well, the thing is, I've built one before from a Tamiya FF01 touring car and DF01 buggy parts. It was a basic car and the weight balance wasn't optimal at all, but I liked the way it drove. From that point on I really wanted to build a serious FWD buggy.

Also, these cars seemed to have potential (at least from what I've heard) back in the late 80s/early 90s. However, I feel these cars didn't get a good chance to prove how good they are, and since development on these buggies has practically stood still for 20 years, perhaps it's time to redo this and see how well these cars could do on modern tracks with modern equipment, materials and geometry.

Lastly, I've been told these cars carry more cornering speed than RWDs... which could prove, especially as the video footage I've seen seems to confirm it. It will require a very different driving style, and a very consistent one probably, but it could prove to work very well!

I've been posting about the project in this topic. I want to thank the oOple members for their input and advice on the car so far, it really helped to make it the car it has become. Also, Jonathan supported me in making this with some great advice too, as well as the manufacturing of carbon and 3D printed parts! I think I wouldn't even be able to afford building the car without his support!

Very nice :thumbsup: looks even better built up.

Looks great! What's the 3D printed material, ABS? Also, loving the use of the wing nuts!!! :thumbsup:

Looks wicked but wont the motor be a bit prone to damage when you crash as its usually the front that takes the damage first.

And how did you get all the yellow bits made?

Thanks guys! :) The orange parts are 3D printed by Jonathan, I believe the material is PLA: it didn't smell like ABS when I shaved a little material off here and there during the build, it's smelled pretty good actually. No wonder, PLA is a bio-based (and biodegradable) plastic - so I better clean the car well after every race :lol:

All in all though, not too many mods were needed to the car to get it ready for it's first test drive. I've already driven it (on tarmac, I have no nearby track or good dirt/astro surface) - it seemed to be going really well, though I think more 'buildup' of negative camber on the uptravel of the suspension would be a first step to help increase acceleration through corners. If I have more grip on the outside though, I need to reduce roll (as much of the power is already going to the inside wheel on the corners).

LIKE !!!!!

Time for an update. I painted the body - it's not a stunner but it works for me :)

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It's a (very) chopped up Tamiya DB02/Leonis bodyshell :lol:

NEED

LOVE!:thumbsup:

That is just sex....:drool:

Even the shell is the right color ;)

yes yes yes
i have actually raced a fwd car
admittedtly it was a a maxxum
but i got the feel for it
release this kit and make everybody happy
and yourself a decent pension
awsome

Thats one superb car!

Great effort seeing the project through and well done to AC's work making it come to life.

Look forward to updates on this beast, good job dude! :thumbsup:

Awesome :o

Always loved FF cars.

Funkymojo where are you !

Looking great with the shell added, will be good to see it on the track once the
extra bits of carbon and new plastic parts get to you :thumbsup:

Will be interesting to see this run at a regional or national :woot:

Love to see a video of it running!

Post a conversion to Lee Martin, see what he could do with it! :woot:

Be interesting to see what a top national driver made of it and what lap times they could do with it.

Thanks for the replies! I'm really looking forward to testing the car thoroughly, this should yield enough data to come up with some useful updates on the car! That is pretty much what this car has been built for, to gather data about these cars in detail. And I hope the data can be put to use to give people eager to get a 'different' car one that (hopefully) doesn't leave huge room for improvement - a design that goes quick and is nice and easy to work on - as I have to admit, this car leaves room for improvement when it comes to the ease of maintainance :p

@janus: Hehe, I thought you'd like the colour :lol: I decided to ditch the plan of black sidepods for 'obvious' reasons (this includes my laziness and some advice I recently got on bright paintjobs)!

@johnygibbon: I restored a Maxxum FF a few years back. Being the collector I was back then I was too afraid to drive it/damage it after the restoration :thumbdown: So I liked the car, but sadly I can't comment on it's performance! How did it handle?

So are you thinking of going into production with this car??

I hope so be great seeing some of these ripping round a track

Any chance of talking us through your design concept?
And how and why the car ended up looking the way that it does?
Great job
Well done

A production car/conversion kit? I can only hope! I would love to, I think it's up to a few factors: Demand (with the curious faces and the responses so far I think there's a market for a conversion), Performance (That it will be a nice drive I'm pretty sure... whether it's a true RWD-eater or even competitive compared to these days' RWDs I've yet to find out) and what Jonathan's opinion is on making a conversion.

Eh, I haven't prepared my speech, but here it goes! :lol:

I started this project last year in november. I had a TRF201 as a runner, and I wanted an FF buggy next to it. To reduce the amount of spares I'd need, I wanted to use a TRF201 (and some 4WD Tamiya buggy bits) as a donor car/base for the car . I decided that I wanted to use as many existing parts as possible. This is where my initial choice of the double wishbone rear suspension came from, together with my lack of knowledge about setups for cars (so I thought using a suspension system I knew would keep things understandable for me).

To be honest, Initially I barely had knowledge on vehicle dynamics, so I was modeling what I thought would work well and look good based on existing cars. The main challenge was to make everything fit around the front suspension, so I wanted to tackle that first.

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This proved very difficult: I managed to make the dampers fit in an upright position, but tolerances were tight and there was no room to place the damper differently (and thus not enough room to change the setup). I was very unhappy with the way the front shocks mounted. I've always been a fan of different stuff, and both technically and aesthetically an inboard suspension system appealed to me. However, I had doubts on my knowledge to solve that puzzle.

However, that didn't hold me back: I was going to model an inboard system on the front end. The first thing I did was mock up how the dampers would need to be positioned to clear everything. It seemed possible (at least as possible as the shock tower system), so I decided to go with that.

I looked at an inboard system on the rear as well, but decided against it: It was going to make the suspension more complicated than it needed to be - even though a slightly forward weight balance and potentially lower CoG could help the car's performance.

By this time I had had my first two or three track events, which really helped a lot to get an understanding about how these vehicles actually 'work' (how different geometry and the properties of the car such as weight balance, rigidity, tires and suspension setup affect handling), even though I was still a novice at it.

When I pretty much had the Double Wishbone car finished Jonathan first replied in the topic I believe... He mentioned he'd really change to using trailing arms - and wide rear wheels to make it BRCA legal. This is where contact with Jonathan started.

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From there I had to rest the project a bit because school was busy... a month later I managed to pick it back up. In that time I thought about all the opinions, replies, advice etc... And I decided to ditch the whole rear end of the car and go for trailing arms.

The main reasons for this are several things... The successful FF buggy protos from the late 80s/early 90s had this system, and with the knowledge of those people back then and of many people that posted in the forum stating it needed more weight on the front, I had the feeling I should listen to that. It was going to be easier shifting weight to the back than to the front if it needed to be changed. Also, I shouldn't make a car that's limited to my knowledge in making setups etc - I should hone those skills to learn make good setups for that car instead! And by then it was apparent there was a lot of support on the forums and the 'local' racing community, so in the end I'd get a good setup. Lastly, I had some offers to help me on the production of the parts for the car and I had some success with 3D printed parts for mechanical use, so I was less worried about using many custom components on the car.

Throughout the project I started taking this project way more seriously. The goal was no longer just to create a nice FF buggy (like it was in the beginning), it became my goal to make a serious prototype as a base to test how much potential there is in an FF buggy (thanks to the advice on the forums and the discussions with Jonathan about the car).

I think my change in mentality is visible on the car: On the double wishbone version car I still really felt there wasn't going to be a later version of it - once the car was built I'd drive it and have fun with it, so the finished result had to look the bomb! Also, it had to be adjustable to the max without making changes to the design of the car.

However a month later when switching to a trailing arm rear end I knew this car would be open for development and improvement, opening potential for simplifying the design.

As the car will be updated and improved, it doesn't need adjustability everywhere: the 20mm adjustable wheelbase was ditched, as well as pretty much all other adjustability on the rear end (toe, camber etc) - The rear end is just there to keep the car stable really, the main focus has always been on the front of the car (makes sense as the power and steering is on that end of the car, right)? :lol:

As for some other choices on the car that haven't yet been mentioned... The low profile servo was chosen to keep a low CoG and more freedom for the layout on the chassis. It wouldn't make the chassis too wide if it was fitted beside the battery lying flat, standing up it would still be low and at the right height to fit to a steering rack (without turning it upside down), etc.

The choice for Shorty LiPos came with the trailing arms. If I was working on getting the weight balance as far to the front as possible, why not use a shorter battery? They easily have enough capacity.

The choice to remove the battery from the back was purely practical: Removing from the side was difficult without messing with side to side weight balance. Removing from the top or bottom would require extensive redesigning. It did somewhat determine where the rear arms were going to mount, but going by the short test run they don't seem to be in a wrong spot :lol:

The wing mount was a headache: I had pretty much the whole design done and I hadn't done that yet! I wanted a strong wing mount as it's so long, in the end I decided to combine the battery plate/retainer with the wing mount, this also removes the bulky frame and wing when you're trying to do work on the car.

The choice for the elaborate rear arms and mounts came from my thoughts about the loads these long arms have to carry. They are about twice as long as the front suspension arms and get a huge sideways load at all times. As machined or printed parts are pretty valuable I wanted carbon plates on the suspension arms as the pivoting points of the arm: It's strong, and if it breaks, it is 'just' a plate. The suspension blocks are reinforced with carbon plates on both sides of it to take the peak loads off the block and/or to spread them over the entire block. I just hope it works as good in practice as it would according to my theory.

I've got plenty of ideas now to try out on this car - looking back on it I probably would've used a different donor car, and I wouldn't have kept the rocker arm geometry for last (no big issues showed up - I was very lucky there), it could have spelled disaster if big mods were needed. All in all though I'm very proud of the result. This project is way more complicated and technically challenging than I've been prepared for in my study. I learned a lot on the front of vehicle dynamics, about how to handle this size of project and I feel the help I got from others was essential to keep the project heading in the right way.

That's all for tonight I guess... Are there questions about what I just wrote or what I didn't write? :)

Never mind that - when and how much! :thumbsup:

wont you have to get pw to change the rules? sure it was discussed you can not use rear tyres on the front?

awsome work though, very good to see it and not just cad pictures!

PW? What's that? Anyway, if you mean the racing organisations, there is no rule in the BRCA, EFRA or BNK (Belgian-Dutch Championship) that specifically states that rear tires on the front are against the rules. (Actually, the BRCA even mentions very clearly that both FWD and RWD cars are to be run in 2WD class, which makes me feel like the regulations have been made so as not to cripple the basic FF concept and demotivate people from using it). However, the BRCA does state it is mandatory to use rear tires on the rear, which is the only reason why the design has this - for grip it's not necessary, and if the rule didn't exist I'd use front tires on the rear :)

Wow, that is so cool and fresh!!! :thumbsup::woot::wub

*clap, clap, clap*

!WOW!

That looks awesome. Would love to see a vid of it in action.

Can I suggest something which might help - the rear shocks are tilted slightly upside down, this would mean the piston will be in the air within the shock whilst at rest/normal ride height... so if you mount them the other way around the air should be away from piston at rest.

Edit, I said rear - I meant front... sorry.

Cant wait to see some action footage:). Would been nice with a FF in my collection ;)

The discussion during development was whether the spec rear tyre for BRCA meetings had to used on the rear, or just had to be used. There is nothing in the rules regarding front tyres at all.

Also the BRCA rules state that you must use the specified tyres on the rear, but while cutting and shutting them to narrow them isn't allowed, there is nothing preventing you from cutting off all the spikes for the rear of a fwd car. :thumbsup:

This years entry form states:

The permitted rear tyres at all venues in the 2012 BRCA Off-Road National Championship are :- Schumacher Mini-Spike (Original & Mk.2) and Ballistic Buggy Mini-Spike.

This to me means that you could run front Schumacher / Ballistic mini spikes on the rear axle, as no part number is specified, only a type. :thumbsup:

not 100% but thought it was on the drive axle? not front/rear? could be totally wrong

The BRCA states 'rear,' the EFRA (and BNK) state 'driven axle' (with the EFRA it's about standardized tires, with the BRCA it is about mandatory rear tires ont he rear end) - either way this car is legal :)

@ChrisLong: I have the dampers fitted like this because the majority of the damper is now not part of the unsprung weight - at least, that's how it would be on a regular system, I'm not sure if it works the dame with a rocker arm ssytem, but I guess it does add to it? Anyway, there's only one way to find out what works best, so turning around the long shocks will definetely be worth a shot!

:) I bet you'll be testing soooo sooo much anyway, you're right about the unsprung weight but on a rocker the amount of unsprung weight may not be as significant... only testing will tell so may aswell try this too? Hope it goes as well as it looks :thumbsup: keep up the great work.

Ok, it was on track for the 1st time today on a slippery, bumpy, dusty clay track.

The starting setup was just a wild guess, so it was hard to judge.

But general 1st impression. I was impressed that it still came of the line with some decent traction, not quite on par with a B4. But still pretty decent. :)

Driving "feel" is best discribed as a 4wd with a slight push and a slipper that is loose. But like I said, this was just without a decent setup. So still to test what it's able to do with a bit of work :woot:

Sadly the 3d printed parts are to fraigile for real testing, so even without jumping the car parts would not take any real abuse. Maybe that last "hop" was a bit to much for the front arm :blush:

Thanks for the feedback janus :) Here is a video of me behind the wheel:

http://www.youtube.com/watch?v=y5C378lYU6s

I've also posted the video in the development topic (with some details on setup, conditions etc):

http://www.oople.com/forums/showthre...523#post683523

The 3D printed parts don't seem to hold up: Even a bumpy track without doing the jumps became too much for the right front suspension arm after some 20-25 laps, and I also had a 'temporary' part break earlier that day (it was a part that will be replaced with a carbon one). However, it didn't hold back testing the car and I'm impressed with it and felt good about how the car drove, even with it's shabby (damping) setup! :p

Very nice video and I posted to HK rc-forum Link here :http://rc-evo.com/xbbs/forum.php?mod...=265391&extra= .............hahahaa:thumbsup:

I am surprised you were not trying to dremel the tyres :p

Hopefully there will shortly be another batch of stronger 3d printed parts and more carbon fibre parts to replace some of the plastic parts which were used to check the fit was ok.

Its interesting to watch the video and see that the back end does not step out like a normal 2wd would on dirt.

Fantastic! Looks like we've moved to an "official" thread!

Looking good!!
Suprising what rear end grip it seems to have.
How does it act in the air/during flight to change angle? Does braking still drop the front or does it act differently?

vintage fwd
 

@johnygibbon: I restored a Maxxum FF a few years back. Being the collector I was back then I was too afraid to drive it/damage it after the restoration :thumbdown: So I liked the car, but sadly I can't comment on it's performance! How did it handle?[/QUOTE]

the maxxum i got was in the box i had to build it to race it
people said i was mad. they say that a lot any way. but when i finally finished with it i sold it on ebay for more than i paid for it . happy days
sorry to offend you collectors but i really wanted to race a fwd buggy and this was the cheapest way of doing it ,and vintage kyosho still have loads of spares for em so it was still raceable if i broke it
as i built it i relised how far buggys have come on in technology
the plastics were not the best and generally it seemed flimsy and very flexy
i fitted it with a 13 turn brushless system as i heard the gearbox and diff wouldnt take more but this made it a bit slow and hard to gear but i reckon a 8 maybe a 10 with turbo timing would have been better
and it would still wheelspin a bit if you were to puchy with the throttle
however this lower power made the car very smooth to drive and there was a lot of full throttle corners , i remeber packing the diff with thick grease, this helped and i reckon you will have to run the diff tight to gain traction
i raced it in 2wd regionals 2 years ago and it did not like big jumps
it would fly straight but was a bit cumbersome in the air and it was hard to blast a jump unless you had a good smooth run up
after watching your vid i would say your buggy looks and handles a lot more like a modern one , but watching it move reminds a lot of the maxxum , the back end seems loose but never spins out you just turn and it goes . i remember having to do a lot more concentration on steering but less on throttle . once you had traction that was it , just steer and smile.
does yours handle like this at all
i also found that battery placement and type massivley afftected handling
stick packs were best all round but saddles arranged differantly helped traction but made ir harder to jump and it grip rolled more (on astro)

i really enjoyed fwd racing it was not as punchy and raw as rwd but was very smooth and enjoyable to drive especially on corners , it just bfelt so smooth and flowing and a lot less twitchy than rwd or 4wd
in the end i sold it because there were certain parts that would break (steering system and wishbones) and although i had spares i would have had to spend to much money and time on custom parts and generally modify the buggy that much to race it properly it was not viable and i dont really think it would ever have been competative with new buggys

yours looks to have addressed a lot of these issues and the design looks a million times better than the maxxum. once you get some stronger plastics and some spares get it airborne , i bet she flys well .i hope some of my ramblings have helped you in some way, please keep us updated with pics info and vids and put me down on the preorder list -near the top please:woot:

Very cool story Johny! The gearbox in general indeed wasn't too good, though there are (nowadays very rare) machined gear sets for the Maxxum.

On the dusty clay the FF felt like a relaxing drive, whereas my TRF201 was all over the place: I just couldn't get the car balanced (it was very hard keeping it from suddenly spinning out - I guess the gear diff, too thin diff oil and rear suspension setup contributed to this, but I think you get the overall idea).

What you said about the focus on steering rather than throttle... I think it applies to this car as well. However, that's for unlocking the majority of it's speed. I think when I get to squeezing the last few tenths a lap from this car the throttle will get pretty important again... Once you have found the line which gives the least wheelspin you can put your car on the throttle earlier/longer, but you do need to feel with the throttle where that line exactly is.

Jumping... This is a big question mark for me. I'm not very good at clean/neat jumping (I kind of just clear the obstacle in one piece with my TRF201 to head to the next part of the track) :lol: I do think it will be challenging, but I don't think it will do kamikaze style diving unless you completely let go off the throttle.

The things you have mentioned are indeed useful: Diff (finding the right compromise between forward traction and cornering speed), weight balance, getting a good approach to jumps (which is now a high priority personal goal) :)

I hope I can improve the car and show that I can drive this car to similar or better results than I did with my TRF201... And not just me, it's the goal to have some experienced drivers try it out. If the jumping goes ok I think it could be very close! :thumbsup: