2011 Ifmar Off Road Worlds on now!

[DerbyDan]

Its incredible to think that the B4 is still the car to beat... especially when you consider that the gearbox & shock absorber designs can be traced back to the original stealth RC10s!

Makes you wonder if the design development of the 2wd off road buggy reached its peak in the mid 90s..... especially for running on a clay/dirt surface? I honestly think a B3 or XX would have served any of the A finalists just as well on that particular track.

[Lonestar]

Makes you wonder if the design development of the 2wd off road buggy reached its peak in the mid 90s..... especially for running on a clay/dirt surface? I honestly think a B3 or XX would have served any of the A finalists just as well on that particular track.

at their level, no... every tenth counts...

but at the (decent to good, but not stellar) club level, a good buddy of mine pulled out his xxcr to battle it out with us recently, and he was only marginally slower than us (say half a second on a 20s lap) which is a lot at the worlds level, but not much at ours. He even made the A (there was A, B, C, 25 drivers or sthing).... as he was able to run the car a full qualifier without breaking it and mains were built on the best qualifier only But most of the runs, he broke it, sometimes for no reason. Plastics have aged really badly it seems.

All in all, newer cars ARE better and faster, but it isn't night and day, its more like 6am light vs. 6:10am light

Paul

[fredswain]

I just bought a mid motor car so I'm going to find out for myself how they handle. The one I got is an Atomic Carbon CR2. It is basically a mid motor XXX. I don't think mid motor is going away. I don't think it's fully caught on yet and is still misunderstood. Mid motor today is where rear motor was 20 years ago. The manufacturers pretty much did just about peak at the 2WD buggy designs. Look at them all. They are all very similar and aren't fundamentally all that different from what the original RC10 became in it's life. We are seeing little changes today such as big bore shocks and different shaped arms that get the shock mounting positions a bit lower (AE isn't doing this yet) but the designs are still all about the same when you get down to the technical side of things.

Modern cars have longer arms, longer wheelbases, and run lower roll centers. It's because they typically run at higher modern speeds, jump farther, and run on smoother tracks. It's an evolution around track design. Put these modern wonders on a track from the late 80's and the original RC10 is going to hold it's own very well if not win. We aren't seeing anything very new being tried with the new stuff. Look at the cars at worlds. They are basically the same as off the shelf cars but with some tweaks here and there. Gone are the days of the new car or the experimental suspension geometry. It's gotten boring.

Now let's look at mid motor. We've got people taking rear motor design and just flipping the rear end around and hoping it works well. Not so much. There are several things that need to be treated differently. We've seen many techniques used on the various mid motor cars that have come out but while each of them has great ideas, no one has of yet put all of those ideas together into one car. They still haven't quite figured out the design that finally works the way people hope it will.

First off X-Factory can pretty much take the credit for the 4 gear gearbox. They figured out that by having the motor rotate in the same direction as the wheels that the inertial of the motor would help push the rear end down increasing forward traction. Schumacher soon followed suit as has Losi, and every other mid motor car maker. It's now the mid motor gearbox standard. X-Factory also figured out that by changing the height of the gearbox that you could alter the rotational inertia location to give a bit more or less forward traction.

Schumacher with the Cougar SV has the 4 gear at the back but they have a variation of the gearbox height theme in that their gearbox not only has 3 different internal ratios to choose from which they call high, medium and low inertia settings, but they also have the ability to run the diff higher or lower within the gearbox changing the rotational inertia height within the gearbox which alters forward traction.

Losi with the 22 has a car that can be built in either rear or mid motor. They've integrated some neat things into the design of that car that are useful in mid motor but they've also ignored the work of others. One thing I like about their design is the adjustable front end rake. In my opinion all 2WD cars should have this regardless of motor location. The whole reason we have front end rake on a 2WD is because all of our weight is way at the back. With more front end rake we promote dive under braking which increases our front end grip and cornering power. However is we have too much rake, we end up having a car where the rear end swings around hard. Too little rake and we understeer into the corner because we can't get the front end grip. A mid motor car has it's weight in a very different location than a rear motor car. Sure it's still behind centerline. That's not the problem. It's that it is closer to the front of the car and when under hard braking it will be easier to transfer that weight forward. This means a mid motor car should need less front end rake. This is a concern I have about my CR2. I don't have the car yet btw. It's on it's way. That car has the same front end rake as the XXX and I fear it's too much. Losi gives you the ability to fine tune this front end rake on the 22 which is brilliant. However they have only given us the 4 gear in the back. There is no way to adjust height or intertia. Their solution is to add brass weights at the back. This is a valid technique to a point but it shouldn't be the only way to adjust rear end grip. They also require a shorter battery when in mid motor since their chassis is so narrow. More of their weight ends up forward of where other mid motor cars have theirs centered so it's not hard to see why no one runs that car in mid configuration.

Now remember that one key to mid motor forward traction is using rear end rotational intertia. The irony here is that some old tech may work best. An older brushed motor with it's heavier armature, lower torque, and higher rpm range may end up contributing much more to forward traction than a modern brushless. However X-Factory may have thought of that. They offer a brass flywheel which effectively does the same thing. Different tricks for different designs. Since rotation in the gearbox is important logically anything rotating the opposite direction would only hurt performance and anything rotating in the same direction as the wheels helps it. Go back to the old belt or even heavier chain drives. You'll need to flip the motor around and run a dual belt/chain system internally but the point is now everything rotates in the same direction as the wheels. A chain is heavier than a belt so it should have more of an effect. Combine this with the other tricks and I'll bet you'd have a mid motor car that has more than enough forward traction. I'd also run a saddle pack battery in side by side configuration as well as use adjustable front end rake. The problem with rear motor isn't having most of our weight behind center line. It's how far behind that is the problem. Behind the rear wheels is certainly not a good location. Yes we get good forward traction but it causes problems elsewhere. Remember how the older trailing arm cars could get better forward traction when grip was low? That sure sounds like a good design to try with mid motor.

We haven't seen the last of mid motor. It's just starting to get exciting. Someone needs to take all of the good ideas out there and put them all into one car. X-Factory actually seems to have the most good ideas of any company so far but their car isn't perfect either.

[DerbyDan]

fredswain - good luck with your CR2, this is the car that I am running now

I made a bit of a return to off-road racing last year with an RC10 & I decided to try something more modern for this year - the CR2s was bringing in some good results & owners seemed to be happy with the way they drove, as I already had a load of Losi wheels & spares left over from the orginal spec XXX that I had last raced some ten years previously.

However I was suprised that this car didn't seem to be an immediate improvement over the RC10 - especially on the grass circuit where I race most regularly - apart from maybe being more consistant over the ramps. One thing that I found weird with the mid-motor layout was how it suffered from lift-off oversteer.... this is something i've managed to dial out a bit & generally get more used to (anyone who's driven a Mk1 Toyota MR2 would probably find it familar). The other thing, is that despite the 4 gear-gearbox configuration, rear end traction on-power is distinctly less - its fine in high grip conditions but its a handfull when the track is wet or dusty. Having said that.... the car was a complete revelation when I took it to a fully Astro-turfed (high grip but bumpy) track - suddenly I felt like I could really push the car.. the lift-off oversteer could be used to my advantage, hooking it into corners etc - my RC10 on this same track - just felt so nervous.

I suppose the conclution is that I feel that on a dirt or clay track where the surface is 'loose' then a Mid-motor car is compromised - however on the high grip tracks that are common over here in Europe the mid-motor layout can work well. I understand that in the IFMAR rules - the Worlds track should always be built on dirt or clay.... i've been racing for over 20 years & have never seen a proper clay track - let alone raced on one.... in the UK, a clay track, unless it could be built indoors just would be washed away Given this fact, rear motored cars are likely be of preference at World Championship events.

Talking of track surfaces - that track a Vassa looked amazingly smooth, it seemed to promote some super fast driving... but certainly not a track that is typical of Europe. I can understand the critism that it was virtually a tarmac on-road track with a few ramps thrown in - but I think that the host club did well in building a track that stayed consistant throughout the 2wd event. I would certainly love to have a go at driving on it!

On such a smooth surface, i dissagree with Lonestar - I really do think that Brian's worlds winning XXCR (with the right tyres & modern electrics) in the hands of a Mr Cavalieri would be bang on the pace. Indeed, going back to my CR2 - I have fitted the 'TripleX' rear end conversion - which brings the inner hinge pins in-line with those on the front & makes the car more 'chuckable' ..... this conversion actually uses double X CR parts! Unfortunately manufacturers demand that their team drivers must run the latest chassis so my theory that the old buggies can be literally just as quick as the new cars will never be proven at the very top level.

[CAT3K]

It would be interesting to see where the top mid-motored buggy came at the worlds.

I can't seem to find a list of drivers and what buggy they were using for the event anywhere except for the A finalists

From looking at the B final it looks like the Cougar SV of Tom Cockerill might be the best of the mids, but i'm not sure.

Paul.

[fredswain]

None of the 22's were run in mid motor and to be quite blunt that car is practically garbage when built in mid motor. Can it be corrected? Of course it can. However, if you just build it to the factory mid motor configuration and run it you'll get little forward traction. The problem (one of them) is that their gearbox places the motor too far forward in relation to the rear wheels. On top of that due to the narrow chassis width you have to run a special short stick battery in front of it which means it's average weight is farther forward. In the end they've got too little weight on the rear end. Their solution is to add a weight at the back. That's fine but you still have the problem that the main object of inertia, the motor, which helps with forward traction, is still too far forwards and now you've got more weight slightly behind the rear axles again which is the whole point of going mid motor. I have no doubt that over time people are going to develop different things for this car and it will get better but I see no reason to build it mid motor unless you address many things that need help and this may or may not be easy.

X Factory didn't send any team drivers to finals this year since they'd rather spend their budget money on developing the next car. Only 1 person ran an X-6 at finals and they finished somewhere in the H main. Pretty far back.

If a Cougar SV was in the B Main then I'd say that was pretty good. 5 different cars were in the A-main separated by a mere .7 seconds in qualifying so clearly a mid motor was close behind. They are still revising that car and trying new things as well. How much of the gap was car and how much was driver and their ability to set the car up? The two Ryan's are just quite simply amazing and I'm convinced that if they were driving for Losi, we'd have had a Losi win or if they drove for Kyosho that we'd have had a Kyosho win. Even the great Brian Kinwald didn't make the A main this year.

With the new CR2 the first thing I'm going to do is set it up as good as possible as it comes. I want to see how it drives and what it does well and what it doesn't do well. Then I want to take what I know of the other good ideas on mid motor cars and start trying to integrate changes on the car to see what effect they have. There is still much to learn in mid motor which is why I want to play with it. I never bought a modern buggy as I'm convinced I don't need one. My trusty old RC10 and JRX2 are still awesome cars when setup well. It's more fun to be the only different guy at the track anyways.

[fredswain]

Dan, the lift off oversteer that you describe is my biggest concern with the CR2 because I fear the front end rake is too steep. I would like to see less front end rake which would transfer less weight to the front and hence leave more weight and traction on the rear wheels when braking. I've even got this problem on my RC10 but I could just rebend the nose plate down a few degrees to fix it.

[Lonestar]

From looking at the B final it looks like the Cougar SV of Tom Cockerill might be the best of the mids, but i'm not sure.

you are correct

[MOmo]

I really like the looks of the X6`2. It does seem to be more popular at European style circuits run on turf as opposed to the nice blue-groove clay that our local track has. I also wonder peoples thoughts on that type of surface? obviously the Euro members on here are used to that, so i wonder how many have run on US tracks and how they would compare it?


I was having this discussion about AE cars the other day at a LHS with a guy. AE definitely takes their time when building and releasing new cars. They make subtle changes and don't try to re-invent the wheel so to speak. When Losi sold out to horizon, I almost wrote them off all together. Being a huge distributor and seeing what Traxxas had done, I saw them make strides n the niche market and figured the racing was done, however the TLR 22 does show promise. I think they feared the strong comeback by Kyosho and the continuing strides by AE. The obvious cost factor also plays a huge roll, but I love forum discussions (RC Tech) about AE releasing a new car and not just tweaks. I question how much those people really know about car setup and all that is involved. I STILL have my original B4 when it was first released and the "Factory team" chassis was the carbon upgrade kit. I haven't made too many changes since, except with the Lipo setups, I did add a new hole to the inside on my rear tower. Otherwise its practically stock trim.

I'm sure everyone on here can identify their track as favoring one company or another. Here in Portland, the Kyosho team manager's in-laws opened an indoor clay track, and thus, many of the folks run K cars, followed by AE and TLR. Contrast to WA, Scott Brown, AE team driver, has mostly AE cars. Other tracks I know favor the TLR cars. I think much of it comes down to who can provide setup help and support.


I like X-factory, and really want to get one of their cars. The other ones like Durrango are just too pricey for me and thus out of my budget. I have driven their 4wd buggy belonging to a fellow racer and the machining and fitment were incredible. But you pay for what you get. I'll settle for my AE meat and potatoes.



MOmo

[fredswain]

Associated spent 10 years slowly refining the original RC10 but it was still fundamentally the same car. They did such a great job with the original design that it was the template for all cars after it. Losi showed up to the game with the JRX2 a few years after the RC10. Within just 4 years they refined the JRX with the H arm conversion, the proformance upgrade kit, the proformanance upgrade kit, JRX-Pro, the JRX-Pro SE and Junior 2 (although it really doesn't count) and then a complete replacement with the XX. Meanwhile the RC10 was still the RC10. In it's life the front arms got longer, the wheels got larger, the gearbox changed, and the body changed. Of course I've left out a bunch of other details but the point is they didn't keep redesigning the entire car over and over again which is basically what happened to the JRX over it's life. The AE world finals cars were different but they were still learning. Everyone had a different car design for finals back then. Interestingly enough after 91 the finals car was using the tub again. If it works it works and even the B2 still had a tub.

AE has had far fewer big changes to their vehicle designs over the past 25 years than anyone else has and they keep winning with them. Losi is very creative. They do some very neat things. Some good and some bad. It just hasn't always worked out for them. As neat as the 22 is and as many neat ideas were built into the design, they made some pretty big mistakes on the car that will require some pretty big changes to the car. I suspect we'll start seeing them offer various upgrades for the car soon. AE is a great company and they definitely know what they are doing.

I personally think we'll see a B5 before the next finals. I think it'll look different and offer some neat features but I'm willing to bet if you were to measure the arm lengths, camber link locations, and just the general geometry it will be probably be the same design. It'll work exactly the same but will look entirely different. The 22 boosted 2WD buggy sales and racing again and AE could keep the momentum going. You know Kyosho will probably do it soon too considering they didn't want pictures of their finals cars with the bodies off.

One thing that's got me really excited that Reedy is back in the performance motor game again. I'd love to see the next championship be a Reedy powered RC10B5. That's heritage.

[Jirka]

You know Kyosho will probably do it soon too considering they didn't want pictures of their finals cars with the bodies off.

You mean pictures like this:

[adam lancia]

Cav took 4wd as well, double WC for him and Associated!