Yamaha R1DT - Four Wheel Superbike For Dirt Tracks

I just found out this was a thing, but Yamaha has been trying to tell people about it since at least September. The basic recipe is half dirt modified/half modern superbike.

Yamaha says it is a prototype, but I think they already have production figured out. What I imagine they're waiting for is a place to race it. I know that Legends and Dwarfs already exist, but this is much more attractive to me.

I also wonder how much potential it has to turn both directions. It will theoretically cost a little over $20k. This would make it roughly half the price of a new SRF with something like twice the horsepower and rpm, not to mention native data acquisition and a sequential gearbox.

I love it when big companies build club level race cars (Honda's side by side, Dome's Cheetah, I feel like I'm forgetting some...) and I really hope Yamaha is successful with this one.

I like it! Thanks for the heads up. I could see this eventually supplanting Legends in popularity...And for good reason:

I built a dwarf car from scratch that was powered by an r1 engine. $20k for a new factory built car is a freakin steal!

Interesting, is the hump next to the cockpit open at the back to let radiator exhaust air out? Makes it look like you have a cool robot for a co-driver anyway

Does it have left turn bias built in?  Or can we get it to turn both ways?

Interesting, is the hump next to the cockpit open at the back to let radiator exhaust air out? Makes it look like you have a cool robot for a co-driver anyway 

I was thinking more of an intake since thats the engine compartment, but you need both. Hmm. 

This thing looks like scary fun.  

Appleseed said:

Does it have left turn bias built in?  Or can we get it to turn both ways?

If it does, generally that’s fixed by adding left side bits(upper control arms mostly) flipped to the right side on a circle track car.  Some are built with an offset in the chassis with shorter wheelbase on one side.  

Isn't this similar to a thunder roadster? or the baby grands or whatever they are called?

or maybe even a Palatov D4?

If you guys give me 20k I'll promise never to turn right again.

In reply to Jaynen :

It seems like kind of a cross between a Legends/Thunder Roadster/Baby Grand and a D4. Sounds like it's supposed to be less than 1/3 the price of a D4, but had a similar drivetrain layout. It also ditches the not-otherwise-sold-in-America and out-of-production air cooled engines used by the others, for one of the highest production water cooled spot bike engines sold in this country... From the looks of it in totally stock (or nearly stock) form from air box through header, rather than trying to modify it for use in a conventional front engine RWD configuration. It also has a simple and cheap to manufacture/maintain/repair non-differential chain driven single disc brake IRS, rather than having an out of production axle modified to fit or using an expensive custom Quick Change axle. 

Looks like it does the same thing as a Mod lite

They're fast and handle so well that they're boring to watch on a 1/4 - 3/8 mile track

I bet it's a lot safer than a Legends car. I've seen a lot of bad Legends crashes over the years.

I like where that is headed, but ultimately I'm still looking for a powersports company to bring a crosskart to market:

Appleseed said:

Does it have left turn bias built in?  Or can we get it to turn both ways?

Yes. Apparently the tires are staggered. However, the suspension is supposed to be symmetrical and the chain drive looks ideal for the purposes of adding a differential.

nderwater said:

I like where that is headed, but ultimately I'm still looking for a powersports company to bring a crosskart to market:

Why a crosskart vs a side by side which is readily available?

white_fly said:

...and the chain drive looks ideal for the purposes of adding a differential.

I kind of like the non-differential rear end at this level. A differential is not required for a racecar to be fast or fun, and not having one maximizes simplicity and affordability for the racers. 

And I saw it the other way. Diffs are typically very low maintenance but what do you think chain and sprocket life will be with that amount of power and that weight?

Suprf1y said:

And I saw it the other way. Diffs are typically very low maintenance but what do you think chain and sprocket life will be with that amount of power and that weight?

Sportbikes, obviously much lighter, with quality components and regular cleaning and lubing typically last 10k+ miles before needing replacement. 

I wish people would stop posting that Can-Am, it always puts bad thoughts in my head...

z31maniac said:

Suprf1y said:

And I saw it the other way. Diffs are typically very low maintenance but what do you think chain and sprocket life will be with that amount of power and that weight?

Sportbikes, obviously much lighter, with quality components and regular cleaning and lubing typically last 10k+ miles before needing replacement. 

Exactly

A diff should never need replacement and requires service very infrequently.

In reply to Suprf1y :

I could be wrong, but I wouldn't expect that chain or sprocket life would be dramatically affected either way. 

Maintenance requirements depend on the type of diff.  A helical would be rather low maintenance, but a clutch type not as much so.  There is also the additional requirement/cost/maintenance of a sealed housing to keep it bathed in oil.  Is any of this a 'big deal'?  No, and I wouldn't complain about a Torsen in there either.  But as opposed to a zero maintenance (and zero tuning) single piece part that is impossible to have develop a leak and is a fraction the cost to replace in the event that something does happen to it for any unexpected reason, why bother?

More importantly though, racers will inevitably start modifying them (like changing bias ratio) to work better for given conditions as a means of gaining any advantage over the competition possible...Potentially resulting in competitive cars 'needing' to either disassemble and reassemble it at the track one or more times during the day/weekend, or stockpiling differentials all with different bias ratios to be swapped out at different tracks in different conditions.  The result of this tuning really only serving to exaggerate the performance gap between the have's and have-not's on track.  For an affordable/accessible weekend warrior spec (or near spec) class like this appears to be intended to build, leaving the differential out is one less advantage for higher budget racers if left wide open and one less item to police and have cheated if regulated.

With a kart style (no differential) solid axle and a rubber puck (no springs/dampers) suspension, based on the last few years SCCA Runoff's results, Formula 500 cars turn road course lap times on par with to slightly faster than Formula F (Ford/Fit) cars while being a fraction of both the cost and the complexity.  Simplicity can be a beautiful thing.

My biggest issue with a lot of those is a) need two seats for instructor or passenger b) finding trackdays where you can run something like that open wheel

For dirt track, the environment this car was built for, the spool is the ticket. For autocross, road race or even asphalt circle tracks, I feel like a diff would make sense.

I have a hard time seeing diff maintenance being a major problem in the long run. There are plenty of nice sealed setups that should be almost maintenance free. The only trouble is getting compatible axles or stubs.

If you're running a solid rear axle, adding a diff would be a lot of extra weight (now have to have a lot more bearings or even an axle tube enclosure). If you're running IRS, adding a diff should be no big deal.

Solid rear axle on dirt. Simple stupid and tire slip won't tax parts. Some 1L MC engine mini sprint builders tried a rear IRS before Y2K w/ no significant gains. That thought was abandoned as far as I know although it sounds great on paper.

Another story in road racing or auto-x tho. Locked rear w/ tire slip vs diff w/ minimal slip (as long as the tire stays planted) , opinions are still debated. Modern tire compounds will tax a locked rear CV and hub components on asphalt more than an open or biasing diff as compared to tire compounds of 20 years ago. That's the problem I ran into w/ a solid spool drive tube and 50 plus extra horsepower. NX600 CV axle splines and hubs would wear like crazy w/ newer compounds.

I went from this solid drive tube w/ single 10.5" disc :

to a VW Golf open diff w/ 8.5" discs. The diff assembly added at least 15 pounds rotational mass over the aluminum drive tube, not counting the additional weight of bearing blocks, mounts and calipers etc. It was getting heavier but the axles, CV's and hubs lived. Mucho planning and machine work there.

I still have my prints dated 1/91 for Quaife Golf internals in machined aluminum housing w/ chain drive. 

E36 M3, I coulda been the first kid on the block w/ a chain driven Quaife.  

Michael Quaife had said there was much interest in Europe as well as the US and they would look into developing a chain driven unit. They didn't appear till a few years later but w/ smaller Fiat internals as I remember. Pretty much the standard now. 

The old VW Golf/ Rabbit CV's, hubs and axles should be capable of 200 hp. Moser cut and splined my diff output stubs.