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Origineelreclamebord 21-11-2011 08:57 AM

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.

Battle_axe 21-11-2011 10:10 AM

so do you think in low traction this will be a better choice than a mid or rear wheel drive buggy?

qatmix 21-11-2011 10:11 AM

Cant wait to see it take shape :thumbsup:

Conrad 21-11-2011 12:03 PM

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?

coleman758 21-11-2011 12:23 PM

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.

daz 21-11-2011 12:43 PM

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.

Welshy40 21-11-2011 06:30 PM

Quote:

Originally Posted by daz (Post 584773)
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.

I agree, it was crap and didnt do well anywhere hence why it didnt sell. From a design point of view itll be fun but will be pants if you race it.

Origineelreclamebord 21-11-2011 07:02 PM

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

terry.sc 21-11-2011 07:23 PM

Quote:

Originally Posted by Conrad (Post 584746)
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?

Because FF buggies don't work well with inboard motors.

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

Origineelreclamebord 21-11-2011 08:04 PM

+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 :)

Bugle 22-11-2011 04:04 PM

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.

jimmy 22-11-2011 04:14 PM

Awesome project - I've also thought about making such a buggy for a long time after seeing some Japanese projects. Very cool.

Origineelreclamebord 22-11-2011 05:28 PM

Quote:

Originally Posted by Bugle (Post 585445)
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.

Well, considering they are some 20 years of development the RWDs got and the FWDs didn't, I doubt the FWDs will be nearly as fast. Given they would get enough development they may become more competitive. However, it's indeed likely the FWDs won't be able to keep up with RWDs like they did back then. Even more reason to let FWDs compete in the 2WD class again :)

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:

Chalkie 25-11-2011 08:51 PM

Quote:

Originally Posted by Origineelreclamebord (Post 585488)
Well, considering they are some 20 years of development the RWDs got and the FWDs didn't, I doubt the FWDs will be nearly as fast. Given they would get enough development they may become more competitive. However, it's indeed likely the FWDs won't be able to keep up with RWDs like they did back then. Even more reason to let FWDs compete in the 2WD class again :)

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:

Some thoughts for you, a TLR 22 steering rack will be ideal, they're very durable and compact.
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?

Rebelrc 25-11-2011 09:34 PM

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

Origineelreclamebord 25-11-2011 11:13 PM

Quote:

Originally Posted by Rebelrc (Post 586909)
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

Thanks :) You're right about the front arms, they are altogether quite a crucial thing on the car. There are several problems using the stock TRF arms (TRF201 or TRF511):

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:

Originally Posted by Chalkie (Post 586892)
Some thoughts for you, a TLR 22 steering rack will be ideal, they're very durable and compact.
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?

Thanks for the info, I guess it's a TLR22 steering rack then that I'll order this weekend for it! The 210 gearbox and saddle pack would be nice, but money is the issue here: I can't start two spares bulks, one for my TRF201 and one for an FWD car that shares no parts with it at all ;) Same goes for the saddle pack: If I'd use a saddle pack in my TRF201, then so I could on this chassis. With the knowledge I hope to gather from driving this car (and perhaps letting experienced drivers try it too) the aim is to build an FWD buggy as radical as the DEX210 is amongst the RWD buggies.

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.

mrspeedy 26-11-2011 12:12 AM

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:

Origineelreclamebord 03-12-2011 08:38 AM

Quote:

Originally Posted by mrspeedy (Post 586982)
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:

Thanks for the advice. A big motor overhang will help for the balance but may also become a problem when landing with the nose too far down :lol: it's definetely something I'll have a look at though.

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.

Battle_axe 03-12-2011 07:18 PM

Quote:

Originally Posted by Origineelreclamebord (Post 590214)
Thanks for the advice. A big motor overhang will help for the balance but may also become a problem when landing with the nose too far down :lol: it's definetely something I'll have a look at though.

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.


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:

Origineelreclamebord 04-12-2011 08:19 AM

Quote:

Originally Posted by Battle_axe (Post 590392)
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:

Cool, thanks for the offer! :) I need loads of bits made actually, even though I try to use as many existing parts as possible! At school we have a CNC machine: The smallest bits are 3mm, which is not a problem but I must keep that in mind when designing. The problem currently is that I don't have a working piece of software to program the paths for the CNC machine (something like Mastercam) and have never worked with it either.

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


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