AC201 FF, Front Wheel Drive Buggy

[jimmy]

Never mind that - when and how much!

[mark christopher]

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!

[Origineelreclamebord]

Originally Posted by mark christopher

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

[SHY]

Wow, that is so cool and fresh!!!

*clap, clap, clap*

[Body Paint]

!WOW!

[Chrislong]

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.

[VikNor]

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

[terry.sc]

Originally Posted by mark christopher

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

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.

[Phil Channon]

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.

[jaysllim]

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

[Origineelreclamebord]

Originally Posted by jaysllim

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!

[Chrislong]

Originally Posted by Origineelreclamebord

@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 keep up the great work.

[janus_77]

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

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

[Origineelreclamebord]

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!

[lcpvcce]

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

[OldTimer]

Originally Posted by janus_77

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

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

I am surprised you were not trying to dremel the tyres

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.

[ruf]

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

[GRIFF55]

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?

[johnnygibbon]

@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 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

[Origineelreclamebord]

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) 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!