XXX-CR Thread

[RaceAce701]

i never had a problem with my tranny i just bought a new one not my old xxx-t

[Laterilus]

Hope this revision actually works this time for Losi. Been a fan of their products for years, but like AxiomJacob said, Associated will never release another product until they start losing.... or at least break even with Losi in the A-main at any major event. I for one was hoping Losi would have started over from scratch and really come out with something innovative like X-Factory is doing with their X-6. My BK2 (if you wanna call it that anymore) will only be getting that new steering rack. Maybe then it will actually turn instead of going straight when I turn the wheel. I've already spent 175$+ on my BK2 for old XXX and XXCR parts to make it 'supposedly' turn, but nothing has worked so far. I'm done spending money on new 2WD buggy kits from Losi until I see someone on the club level actually get one of these 'new' XXX CR kits to turn. Maybe then I'll consider getting the new car.

[party_wagon]

I don't understand why they use the same arms and axle carriers for the adjustability part. They should just make two seperate ones. Thats nothing but unsprung weight which is why the ad2 actualy breaks more then the ad1 even though the ad2 is made of tougher materials. As far as handling is concerned it all comes down to driver preferance. The xxx and the b4 require two differant driving styles. The xxx is one that requires the buggy to be pushed a whole lot harder to be fast, but its more stable when its being pushed hard then the b4 would be. The b4 needs a more precise driving style. If you know the limits of the b4 so that you can push it hard you will be very fast. The typical driver is not going to drive a car enough to realy learn the limits of these cars. The reason losi hasn't released a totaly new kit is probly because most of these mods are mods that the drivers were making and not being designed by r&d. The losi r&d department has more then likley been pretty buisey with a new 1/8th scale and tc as of late.

[ApexSpeed]

Originally Posted by Laterilus

I for one was hoping Losi would have started over from scratch and really come out with something innovative like X-Factory is doing with their X-6.

I love the guys at X-Factory, but there is very little innovative about the X6. The ideas in that car are about 15 years old, and have already proven to be nothing spectacular (otherwise, all of the existing cars would look like that).

Nice idea, too bad Tekin and many others did it in the late 80s.



There will probably be few drastically innovative ideas in 2wd buggy, that haven't already been tried, but you never know. I give credit to anyone trying new ideas.



The XXXCR looks like fine tuning of a proven and performing platform. I think a complete redesign would be doing an injustince to the labor and track tuning that has been done to the BK2. The car is not utterly a mess—it doesn't need a ground-up redesign.

[Aaron Waldron]

Serzoni - Sometimes you gotta try stuff to learn. The weight difference of the graphite material does not make up for the fact that the extra flex provided by a plastic composite makes the car easier to drive. Weight has very little to do with how well an R/C car works with the current engineering technology that we have. Racers add weight to their cars all the time...Associated guys normally run weight in the front and rear of the cars, at least the last I heard.

dasdaman - There were more to those shocks than simply being top-filled. They were more of an engineering exercise than anything else.

raceace - Sometimes a lower CG isn't always the best thing..and mounting the tranny lower changes the roll center. Those were both things that were looked at when deciding to go back to the black XXX tranny.

Laterilus - Innovation doesn't always lead to greatness. The new 'CR' is just an evolution of the XXX platform...Losi will come up with something new when they're ready for it.

party_wagon - The added unsprung weight due to the VLA design is very negligible...besides, unsprung weight can make a car easier to drive. Having to use two different sets of the arms and hub carriers would be an added expense and something the racer doesn't need to pay for.

The AD2 breaks more often than the AD1? No way! I've had several of both trucks and I can beat on my AD2 way more than I could the original truck!

ApexSpeed has it all figured out :-)

[Aaron Waldron]

Originally Posted by AxiomJacob

Until the b4 starts to lose more big races I dont think there will be a replacement.

By that logic, the B4 was YEARS overdue. Basically from the Worlds in 1999, to Maifield's win with the B4 in 2003 at the B4's first race at the Cactus Classic, Losi and the original XXX platform dominated off-road racing.

[party_wagon]

As soon as I went to captured ends in the rear and got rid of the slop that showed up all the time in my ad1 it virtualy never broke. If the ad2 composite was available for the ad1 it would more then likely be just as durable as a gt. The extra half ounce added to the 4 ounce arm and carrier does make a differance. Go shave off the excess and you will notice the differance on a rough track. If unsprung weight made the car easier to drive then I'm sure we'd be looking at setups that feature shocks run upside down to lower the cg. When there is more unsprung weight the shocks aren't as effective. Yes, the tires do absorb some of the load. However the less unsprung weight there is the more responsive the suspension will be to bumps. Remeber the goal of a race cars suspension is to keep the right tires planted at the right time, not to make sure your gas tank is happy and doesn't have a bumpy ride.

[Aaron Waldron]

More unsprung weight will make the car rotate slower and increase its inertia to continue driving in a straight line. That will make any car easier to drive. We don't run inverted shocks because it doesn't allow an emulsion shock to work properly.

The weight added to the front end of the AD2 versus the AD1 is not nearly a half an ounce..it's a little bit of plastic at the end of the arm and the inside of the caster block. Now the rear end does have aluminum hub carriers, but we ran the Trinity one degree aluminum hubs on the old truck anyway. There is more to making a truck work, especially on a bumpy track, then reducing unsprung weight. If that was the case, we'd be working on lighter tires and wheels.

[Juan Valdez]

Originally Posted by Aaron Waldron

raceace - Sometimes a lower CG isn't always the best thing..and mounting the tranny lower changes the roll center. Those were both things that were looked at when deciding to go back to the black XXX tranny.

Aaron, could you explain the how the tranny height affects roll center? I know changing diff height on a touring car affects handling. Todd Hodge explained that the diff height affects dogbone angles, affecting how much dogbone bind you get in the diff outdrives. This will make the car corner flatter/roll more, depending on which way you move it. I've been able to easily tell the difference between a low diff and a high diff on my JRX-S. Is this what you are refering to? I've never heard of driveline height affecting the rollcenter, but I don't know everything. Just asking and hoping to learn something new. Thanks!

[party_wagon]

So basicly adding unsprung weight will make the car less responsive?

[That0neguy]

Anyone wana buy a tricked BK2???lol....seriously.

[semper]

Originally Posted by Juan Valdez

Aaron, could you explain the how the tranny height affects roll center? I know changing diff height on a touring car affects handling. Todd Hodge explained that the diff height affects dogbone angles, affecting how much dogbone bind you get in the diff outdrives. This will make the car corner flatter/roll more, depending on which way you move it. I've been able to easily tell the difference between a low diff and a high diff on my JRX-S. Is this what you are refering to? I've never heard of driveline height affecting the rollcenter, but I don't know everything. Just asking and hoping to learn something new. Thanks!

I suspect u hit the nail on the head. The X6 apparently will come with shims to raise lower the g/box, which I guess would only affect diff/outdrive height... It's supposed to alter the balance btw fwd traction and side bite... Then there's the dogbone vs cvd thing, where the cvd give more fwd traction at the expense of side bite... So my guess is u're right in assuming it has nothing to do with roll centre but everything to do with 'diff height', binding etc..

[Scottmisfits]

When thinking of center of gravity, think of one of those piano timing things. With the weight at the bottom of the rod, it moves from side to side quicker. That would be the BKS tranny. With the weight at the top of the rod, the rod travels slower, the original tranny. The higher the weight is, the more it will roll and the slower it should react.

[Aaron Waldron]

Juan - Any time you change the position of the weight in relation to the car, you're changing its roll center provided you make no other changes. Yes, diff height has a big effect on dogbone angle, etc. also.

party_wagon - Yes.

[elvo]

Originally Posted by Juan Valdez

Aaron, could you explain the how the tranny height affects roll center? I know changing diff height on a touring car affects handling. Todd Hodge explained that the diff height affects dogbone angles, affecting how much dogbone bind you get in the diff outdrives. This will make the car corner flatter/roll more, depending on which way you move it. I've been able to easily tell the difference between a low diff and a high diff on my JRX-S. Is this what you are refering to? I've never heard of driveline height affecting the rollcenter, but I don't know everything. Just asking and hoping to learn something new. Thanks!

Changing the position of the motor doesn't change the position of the rear roll center, BUT.... it does change the way the car rolls, which is exactly the same effect as a change in roll center.
Keep in mind that an electric motor is - relative to the rest of the car - a big, heavy flywheel doing 40.000 RPM. It's got a huge effect on the car's handling.