FWD/FF Buggy
I'm really disappointed that we don't see them around: FF Buggies! When I first saw these buggies a few years back (the Ryuz FF for example), I fell in love with them. They are beautiful, quirky and a comeback into the 2WD scene would make things very interesting! It's not likely this will happen anytime soon as many organisations state in their rules that FF buggies are to be run amongst 4WD buggies.
Anyway, in 2009 I already set myself the task to make a basic FF buggy from a Tamiya FF01, using Tamiya DF01 suspension arms: http://i65.photobucket.com/albums/h2...e/DSC00355.jpg http://i65.photobucket.com/albums/h2...e/DSC00358.jpg http://www.tamiyaclub.com/forum/inde...howtopic=51668 http://www.tamiyaclub.com/showroom_model.asp?cid=90871 The goal was to make a conversion without making custom parts. It went rather well and it was absolutely a blast to drive, but of course with a chassis from the early to mid 90's, no slipper clutch and 70mm shocks I wasn't going to get anywhere on a track without the car falling apart. For a while I just put the idea of making an FF buggy aside. Recently I picked this project back up, but not with the car you see above. I plan to build a new chassis that is ready for testing on the track. The screenshot below shows what I built up this weekend in Solidworks: http://i65.photobucket.com/albums/h2...LowQuality.jpg The chassis will be based on a TRF201, as I already have one (so they can share the same bulk of spares). The gearbox and front suspension will be taken from a TRF201, the front uprights and caster blocks will come from the DB01/TRF511. The front suspension arms are to be considered as Tamiya's existing buggy arms would make for a front end that's 260mm wide instead of 250mm (plus, the TRF201 driveshafts are about 5-8mm too short on each side with the existing arms). There are a few things which I need to clear up, which are how I'll mount the top end of the shocks and what steering assembly I'm going to use. |
so do you think in low traction this will be a better choice than a mid or rear wheel drive buggy?
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Cant wait to see it take shape :thumbsup:
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What about mounting the motor behind the diff, inside the body. Obviously the steering system becomes a big issue then but the car would be alot more balanced than having the motor out front, no?
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Id like to see the motor inboard! (Behind the diff) You could mount the servo similar to how the pred X11 is done, With the servo in the middle of the car.
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Anyone remember the Kyosho Maxumm FF, I had one in the 80's and it was a horrible car. All it did was wheelspin, couldnt get it to turn when on power and it jumped awful. Im guessing now with all the power we have, it will just be 10 times worse. Not trying to shoot you down or anything, just sharing my experience with them.
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Hehe, nice amount of replies with mixed opinions :)
My choice for the motor at the front is for several reasons: 1. Space: It will be hard to get a construction with the motor over the steering assembly, yet retaining a low CoG and a tough steering set. 2. Weight distribution: FWDs have more problems getting traction than RWDs, and considering their weight balance from front to back I guess a motor in front of the diff will work best. Plus, if the weight balance does need to be further back, it's easy to add weight inside the chassis. However, mounting them in front of the chassis is way less effective and harder to fit. I also considered using the DEX210's parts as a base, but as I am using a TRF201 right now it's only logical to use that as a base for this - I'm on a budget after all. Plus, making the Mid motor and Rear motor options possible on an FWD chassis is a bit more complicated than an RWD chassis. I just want a chassis with some degree of thought put into it that I can use to develop a better chassis - at least, that's the plan :p |
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The Maxxum had the motor behind the steering linkage, it could never put the power down. The successful Japanese FF buggies all had the motor hanging out in front, and on loose dirt tracks they they were as fast as any rwd buggy. A few examples: Grahoos Poprod Old Ryuz style FFs and Bloodclods Ryuz style build and on Oople Bloodclods FF03B A few old FF buggies in this thread |
+1 on Grahoo's buggy, I love the design of it! :)
http://www.youtube.com/watch?v=Obs-m...ure=plpp_video Here's a video with Grahoo's original Poprod from 1988 driving in a competition (at 1:10 interview with the driver, start of race around the 2:30 mark). Notice that it's easily as quick as the RWD buggies driving around and drove around on the first place for a while before making a mistake. I know the Wild one, Falcon and Fox are not like the RC10 would've been as a competitor, but it shows their potential on video. The potential that the Poprod shows is reflected in today's buggy regulations. Many organisations state that FWD buggies are to be driven with 4WD buggies. I recall reading this happened when some drivers started using FWD buggies for slippery tracks and RWD buggies for tracks where the RWDs could put the power down more easily. The regulations meant the instant end for FWD buggies in competition. After all they were put into use for their performance, not for their quirky construction. Grahoo rebuilt his Poprod a few years ago (Link), but with a TA03 transmission and a few modern parts I believe. This and Bloodclod's FF buggy build were of great inspiration to try and build my own FF Buggy :) |
Cool project, always wanted to make a Ryuz replica but not being able to race it in 2WD class is a bummer :(
With the speeds cars go these days compared to when they got banned I can't see a FWD being faster than a RWD. |
Awesome project - I've also thought about making such a buggy for a long time after seeing some Japanese projects. Very cool.
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I hope to drive it next season next to my TRF201 at a club, and hopefully I can even enter the FWD in a 2WD race or championship if it's not at a high level. By the way, small update: http://i65.photobucket.com/albums/h2...LowQuality.jpg I changed the front suspension a bit: I decided to use DB01 suspension blocks at the rear. The reason is that I don't want the toe-out that the suspension arms get by using the TRF201 suspension blocks. Plus, it might give me extra space to move the steering rack further forward. I also made blanks for a low profile (Savox 1251MG geometry) servo and a stick pack (Team Orion 2S 4600mAh 45C LiPo) to explore the potential layouts for the chassis. The current one I got pictured is what I have in mind. It won't deliver the greatest front weight balance, but it does allow me to move the battery backwards all the way to the rear suspension block if I need to. Plus, if it's necessary I can place under servo weights on the car :) I plan to use the steering rack fro a TLR 22 if they are durable enough (I got a thread about that in the Losi section) as they are so compact and simple. Another thing I did was completing the structure of the gearbox. I hope it's accurate enough as it was hard to get good measurements on the critical mounting holes with some calipers and a set square. But after all it's much cheaper than having it run through a 3D scanner at a company for 100+ euros :lol: |
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Second I would use saddle packs side by side behind the steering servo to get the weight foward, seeing as i think getting traction will be the biggest issue. Third, how about cutting the 'rear' suspension block in half and turning the halves 90deg to give trailing arm rear suspension, it's seems to be the most popular layout so why not copy it? Finally why not use the durango 210 gearbox so you can try both 3 and 4 gear layouts to see which gives the better traction? |
Have you thought about turning the front wishbones around so that the car has less front overhang and will move the motor closer to the axle centre? Then shorten the rear wheel base accordingly to keep the same wheelbase as you originally planed?
Nice project though Nice drawings |
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1. The width of the car becomes too great (+/- 260mm, 250mm is often the legal max?) 2. The driveshafts become too short (by about 5-7mm each side - what a coincidence :p) 3. There's not enough space for the steering to move on the arms (when not using TRF511 front arms) 4. There's not a lot of space for the dampers. I thought about this issue before and back then it resulted in me postponing the project: My conclusion was I needed too complicated a construction to make for myself: Things like inboard suspension (and using cantilevers, as the rods take in no space at all), lengthening the driveshafts or making custom shorter arms. Things have changed though, I have access to many cool tools and awesome machines at school, making things possible that I could only ever dream of before :thumbsup: I thought about it a bit and by far the easiest way to solve things right now would be making custom front arms. It has one major drawback, namely that there will be custom parts used in a place that are normally the parts you most likely carry as spares. The arms need to be tough, so two materials came to mind for me: Polycarbonate and Delrin. I hope I can make the arms in the laser cutter or can machine them, though if it needs be there are plenty of tools to make them by hand. Anyway, here is the revised design: http://i65.photobucket.com/albums/h2...LowQuality.jpg It's got the shorter front arms, which will get the dampers fitted at the front of the suspension arm - at least, that's the plan. There's little room to mount them diagonally, but I'll have to accept that for now with all the other existing parts I'm using. If it's too tight I might still switch to a system with cantilevers - I really like the idea and looks of it, but I want to get this beast built asap so I have a car to test - not to mention that if it's as conventional as possible existing setup knowledge can be applied to the car :lol: Quote:
I really love the look and 'radicalness' of the trailing arms on the FWD buggies, but the same problems occur here as I wrote down above. However, your mention on just splitting the suspension block is a really nice idea, it could solve that problem. I'll definetely have a look into it :) Last spring I did a study on the geometry of the Yokomo YR-F2's suspension system if it were to be made for a buggy: http://i65.photobucket.com/albums/h2...LowQuality.jpg I was surprised by it's capabilities to create a negative camber on the outside wheel with chassis roll. It's really cool to see how the roll of the car influences the camber whereas an equal compression on both corners does not change the camber at all. |
Depending on what surface you intend to run on, but I would have thought traction would be your biggest priority with a FWD chassis. Big motor over hang will help here, as will a motor that spins in the opposite direction to the wheels and a good rear ward driveshaft sweep to minimise weight transfer under acceleration ....
Nice looking CAD pics btw ... looking forward to seeing this one progress :thumbsup: |
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I'm just wondering how the rearward sweeping driveshafts minimise weight transfer? :confused: I'm quite a novice on car physics and logic gets the rough picture quite well, just eager to get more knowledgeable here. Anyway, I have an 'update' on the project - one that's bad news and good news at the same time. I was planning to use a laser cutter to cut out most if not all custom parts. However, the laser cutter at school: A) Has had some reliability problems recently (needed two cycles to cut through material where it shouldn't, so it's lacking power) B) It hasn't got the power to cut through 8-10mm PC or POM, only PMMA. It's a big setback for the easy and quick building of this prototype. It means I have to divert to the option 'CNC machine' to make the parts! :woot: This requires me to learn to work in new software to program the paths for the CNC machine once I made the models, and I have to keep in mind the smallest bits they use are 3mm. However, it does allow me enormous freedom in the size, shape and thickness of the parts. I'm no longer thinking in 'plates', I can make blocks with odd shapes now. In theory I could now machine a tub for this car :lol: I'll keep things simple, though I am very appealed by the idea of making sidepods and mounting blocks. PS: Have a look at this :) Oh, and turn off the sound, the music is quite horrible imo. What a contraption, it seems to change the geometry/placement of the front dampers when turning, and it has 4WS! I'd love to see it in action!\ Edit: I had a look something today which will define it's final looks: The body. To emphasize the weight and drive on the front, a front cab seems fitting - or at least not a rear cab and rear sidepods. It's hard to find, especially as I don't like the bulky and square looking Proline and Jconcepts shells. Anyway, I have a few contenders/bodies in mind that may work for the looks and chassis layout I have in mind: - Team Azarashi Gomurph (Simple, seems easy to mod due to the simple shape, has an undertray available for it so my chassis doesn't need to seal off the underside) - Team Azarashi Xeneiga (DF03 chassis is nice and narrow, and this is a nice cab-forward-like shell) - Tamiya DF03 body (Simply because the shape of the shell fits well what I'm looking for with my chassis layout) - Jconcepts B44 Illuzion Scoopless body (I might be able to turn it 180 degrees to make it a forward cab shell and paint the windows differently) - Tamiya Dirt Thrasher (pictured in first post. I think it looks so good it's almost sexy :p However, you can easily see how it will not cover the chassis at all without mods) - Tamiya Avante (It is a nice body, but I would have to make my own undercowl: The standard one wouldn't be practical) - Tamiya Vanquish (If I can get a repro, also a very nice body. Same story again though with 'sealing off' the body) Any more suggestions are very welcome. I want to define my choice of body early on so the chassis and body fit each other as good as possible. PS No.2: I'd love to make my own body, but I recall the vacuum forming machine at my school is too small for an RC body. If someone knows someone who can help me out with that, it would give my project a completely new direction. |
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if i can help at all with this awesome looking project i will be glad to help i have good cad skills (but so do you) i also own a small cnc mill so if you need anybits making let me know :thumbsup: |
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Anyway, time for an update: http://i65.photobucket.com/albums/h2...creenshot5.jpg http://i65.photobucket.com/albums/h2...creenshot6.jpg http://i65.photobucket.com/albums/h2...creenshot7.jpg A couple of changes have been made, all at the front suspension really. I tried to fit the lot together, and what do you know? It fits! :thumbsup: But only just as you can see in the pictures above. I can't really use several holes in the suspension arm for adjustment because of the lack of room, and at the top I might be able to use two or three holes from side to side. For considerations of weight balance and room for the damper I decided to shape the suspension arm like I did before: Slightly swept back. The hinges of left and rihgt are still parallel though. I'd still love to have an inboard suspension system on it, so I might have a look at it later on. For now though I at least have a front suspension system that will work. There were some suggestions for a trailing arm kind of system. As cool as I think they are, I'm still going for double wishbone suspension. It's a system I'm more familiar with, so it will be easier for me to set up right. It will guarantee the strength of the rear suspension as well, as the rear suspension will still get the same loads and from the same directions as it was developed for. Another FF Buggy video for you :) It is Grahoo's Poprod that was mentioned earlier in this thread, in action! It doesn't have a massive motor in it and it isn't a demanding track on your average buggy it seems, but with a TA03 transmission at the front (lightweight, no slipper) and NiMh in the middle (heavy) this car seems to do well in terms of weight balance? http://www.youtube.com/watch?v=QRgBdysVdjI And this one (Nichimo FF) shows why I didn't choose for a mid motor :) http://www.youtube.com/watch?v=JLzkk...eature=related |
As a side note, ifmar rules for electric buggy world championships put fwd cars in the same class with 4wds, not 2wds. Even though fwds are 2wd...
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Is that different from being able to choose if your rwd car is mid or rear motored depending on the track?
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Plus, I read here on oOple (first page of this topic) that the IFMAR only runs on 'natural' surfaces - so I guess mid motor cars are not a popular choice for IFMAR races anyway - no astroturf, no carpet and no other high grip surfaces a mid motor chassis has the edge over a rear motor chassis. |
Time for another update :)
http://i65.photobucket.com/albums/h2...creenshot8.jpg http://i65.photobucket.com/albums/h2...creenshot9.jpg http://i65.photobucket.com/albums/h2...reenshot10.jpg First off, the body choice: DEX410 body and Bugle 410 undertray, but hopefully in the long term a custom (extra) front cab body based off the chassis dimensions/curvature of the DEX410. The second thing, the steering: The TLR22 steering has arrived, I really like how simple and beefy it is. I measured it and though I can't make the front assembly as compact as I hoped, it does seem to get me the right geometry. And some progress on the chassis plates: I made a start on the design of the chassis plates. There is an upper chassis plate, to which two braces mount that reinforce the shock tower. The steering also mounts to this chassis plate. Then lastly, at the rear ends of this upper chassis plate, there will be two posts. These two posts are to reinforce the structure and the battery plate will also mount to these points. The battery plate will run over the battery to a rear upper plate. By changing the battery plate's amount of material or the material itself I can hopefully adjust flex in the chassis if needed. As I think it's necessary to have an adjustable wheelbase on this car, I am considering to split the lower chassis plate in two pieces as well. Either that, or I need to make many mounting holes at the back for the bulkhead. And last but not least, a bit of re-designing: The feature is not yet visible on the pictures, but I've added it to a newer version: The rear suspension blocks of the front end will not be mounted straight to the lower suspension plate to prevent potential damage to some expensive custom parts (front suspension arms, lower chassis plate). The two blocks will be mounted to a small plate, which is then mounted to the lower chassis plate. By deliberately making it the weakest link in the construction I can prevent the expensive parts from breaking (as 'regularly' as they usually would). |
I'm currently working on the rear suspension and I got a question to ask you guys.
For the rear I'm using the front suspension arms and, hubs and uprights of the TRF201. I'll use the turnbuckles that normally are for the steering to set up the rear toe angle. I could use the front suspension as intended, but it puts the turnbuckles of the steering exposed to impacts on the rear of the car. I'd like to turn the uprights around to get the turnbuckles in front of the axles. However, this also puts the rear axle in front of it's steering/pivoting point. Normally this would cause bad handling, but I was wondering if this also applies when the rear wheels don't steer (apart from perhaps a tiny bit of bump steer)? :confused: http://i65.photobucket.com/albums/h2...reenshot11.jpg Here's a picture of what I mean... |
Any slop in the ball joints and that will cause some bad rear end wobbling and it's pretty much impossible to eliminate all slop. Much better to have the axles trailing.
Could grab a sheet of Kydex and make a decent rear bumper? |
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A bumper may indeed be a good idea. I can also go for the option of constructing the rear end in a way that the shock tower will absorb most of the forces when it's hit on the rear end: A bit like the front end of the B44 and the Yokomo YZ-10 (which by the way looks very good as well imo)... |
I don't know if it is available for the 201, but AE sells inline steering hubs that you could use to get the toe-in turnbuckles inboard.
Really cool project BTW, makes me want to build one :thumbsup::drool: |
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Awesome looking project so far! I'm really interested to see how it turns out.
Will you be running this on astro or dirt? I've found that on dirt wheelspin / forward traction is the main challenge to overcome. I can't wait to see how your design runs - we certainly could use more FF buggies running to test and refine designs. I modded a FF-03 into a buggy and it had a battery layout similar to yours but on the dirt where I run the car really struggled for forward traction. I just haven't gotten round to it but I've gotten all the parts needed to install a gear diff in my original FF (dubbed YKP locally)... plan is to put really hard oil in there to reduce the loss of any power especially on rutted areas of a dirt track. Good luck, I'll be following this thread with interest! |
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As for the terrain and weight distribution... I don't have a track that I usually go to (yet), though my preference goes to a natural surface (dirt, clay). Like I mentioned before, I want a narrow chassis and unfortunately I don't have saddle packs, so I'll need to play with under servo etc. weights if the the front traction is bad. It's good to know about it though, perhaps I can design the car to accept shorty LiPos and/or saddle packs as well in the future without the need for new parts :) |
Your going to need more work at the front or rear of original, no kick up no caster and toe out on arms
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Edit 30-12-2011: http://i65.photobucket.com/albums/h2...reenshot12.jpg This is a new plan for the chassis layout. That, or with the servo next to the battery. The plan is to build a (partially) custom steering set which allows me to run the steering rack over the battery. Reason for this is the advice I got several times to put the weight further forward, and the TLR22 steering rack may not give me the desired steering geometry (so I need a different system anyway). The chassis plate as you may noticed is also split between a main plate and rear plate. I want to make the wheelbase adjustable, and with the system I can hopefully also adjust the chassis flex (by using further forward or rearward mounting points between the two plates, or using a diff/slipper spring in the mounting points of the rear plates). |
unless your redoing the arm mounts the kick up inboard toe in will now be toe out, your also going to need to run the motor in reverse, not the best way to get good performance from a sensored system.
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As for the motor, I was completely unaware that sensored systems have different performance in the opposite direction! I guess I should take a sensorless system then, it also saves some money that I can put to good use on the chassis! |
Mark, what do you mean by 'master'? I'm not familiar with that concept and curious.
o.r.b., maybe you can copy the design of many 4WD's: battery on one side and the electronics on the other. Just keep the battery a little closer to the centerline since you don't have the moter on the electronics side to help balancing the weight. |
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As for the inboard toe out, from earlier in the thread: Quote:
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Update on the steering:
http://i65.photobucket.com/albums/h2...reenshot13.jpg http://i65.photobucket.com/albums/h2...reenshot14.jpg http://i65.photobucket.com/albums/h2...reenshot15.jpg I have replicated the TRF201 steering arms and tried to come up with a compact steering system at the front. I'm still not sure whether it will be the servo or the battery to be fitted between the steering arms, but either way the idea should work well. I hope the maximum deflection/steering lock of the DB01 uprights is enough for a tight cornering car. The geometry is ok in terms of the Ackermann angle: At the steering lock the angle is slightly bigger than needed for the 'ideal' angle of Mr.Ackermann's theory (in which the two lines coming from the front axles cross at the axis resembling the rear wheels). I read a bigger Ackermann angle would lead to predictable, unagressive steering behaviour: Something that should suit the consistency and smooth driving style needed for driving an FF quickly. However, I also need to keep in mind that a bigger Ackermann angle may reduce the amount of steering I have. There's a couple of issues I still need to solve: 1. Decrease the massive amount of bump steer when the outside of the suspension arm pivots below the horizontal point. (Above that point the bump steer is minimal) 2. How to build the front end around the steering geometry I developed :lol: |
interesting project but.. I'm not sure about traction on slippery surface... imho FWD is good for low-power motors (as in video you've posted, 1/10th buggy with 400-size silver can).. But with stronger motor it will have lot of wheel spin and no acceleration because of weight transfer towards to rear-end of car.. That's why I'm trying opposite project in RC rallying (there're lot of FWDs - based on Tamiyas FF-s or M-s - and no RWDs because there is no base onroad RWD with IRS), because FWDs has poor acceleration and have problems with jumps and hill climbing.. but RWD handling is much better, closer to 4WDs.. I think that buggy wil be very similar = good for high traction - low power, but not for low traction or high power conditions.
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