BMI's DB12R
10-28-2007, 10:06 AM
#2506
The holes in the chassis are not going to be off. The countersink does come close to breaking through the chassis so the hole size may vary slightly but i assure you,it is impossible for them to be off. When the arms are mounted and the screws are not bent or anything like that,the arms are dead straight.
10-28-2007, 10:07 AM
#2507
The DB12R's looked good yesterday at "The Track" in Gaithersburg, MD. Casey Young had his working really good in 19T and Wes Lion had his working really good stock. Craig (Casey's NYC Buddy) finished putting electronics in his at the track. By the end of the night had his really looking good.
Great to hear buddy.Thanks
10-28-2007, 10:20 AM
#2508
I finally got to see the DB12R in person for the first time the other night. I have to say thats the best looking 12th scale I have ever seen by far! If 12th scale picks back up again in my area I might just have to get one! 
10-28-2007, 11:55 AM
#2511
I hit the track Friday night with the "weight forward" concept. I moved my servo forward, installed the ball studs facing back and moved the bats all the way to the front. Put 40wt in the center shock with 2mm under the nose. Screwed on a set of 2xpinks & yellows. .5mm chassis lift in the middle or -.25mm droop, the rear pod .5mm lower in the front vs the rear. Slathered on 2/3's Jack on the fronts, full rears. Pretty dang good. Keep in mind, this very same combo pushed off the track at 4 minutes in a previous test with weight back. It would seem that weight forward may solve the changing tire traction conditions through out the 8 minutes. This is the first bit of good news to help cure this issue since it showed up. In the good old days, we didn't have conditions change during the run. You either pushed or were loose.
When I got back to the shop, I set up the scale and did a little weight bias check. With the servo forward like I described, a 19t motor, the bats forward, the wieght bias is 41.6/58.4%. With the bats back, it's 40.5/59.5%. I would be curious to put the servo back were it was to measure it for comparison. This makes me wonder if there is a "magic number" to shoot for. I checked my MS2.3 and it was lighter on the nose; 38.9/61.1% and 40.1/59.9%.
Results at the track were: 3 other drivers really liked the weight shift and improved their times. I took a step sideways, no time improvement, but I liked the characteristics of the car better. I ran a 2xpink wrap with a yellow prism in practice and the 1st round that showed big potential. When I went to all prism, I actually went slower. I was quite surprised. My next test will be on all wraps in that combo. If that works out, I suspect that it will be quite fatal to the rest.
Is anyone in on this thread capable of making up an Excel style set up sheet that we can share between everyone? I don't know how and not affraid to admitt it. Something with scanned images?
When I got back to the shop, I set up the scale and did a little weight bias check. With the servo forward like I described, a 19t motor, the bats forward, the wieght bias is 41.6/58.4%. With the bats back, it's 40.5/59.5%. I would be curious to put the servo back were it was to measure it for comparison. This makes me wonder if there is a "magic number" to shoot for. I checked my MS2.3 and it was lighter on the nose; 38.9/61.1% and 40.1/59.9%.
Results at the track were: 3 other drivers really liked the weight shift and improved their times. I took a step sideways, no time improvement, but I liked the characteristics of the car better. I ran a 2xpink wrap with a yellow prism in practice and the 1st round that showed big potential. When I went to all prism, I actually went slower. I was quite surprised. My next test will be on all wraps in that combo. If that works out, I suspect that it will be quite fatal to the rest.
Is anyone in on this thread capable of making up an Excel style set up sheet that we can share between everyone? I don't know how and not affraid to admitt it. Something with scanned images?
10-28-2007, 12:26 PM
#2512
I hit the track Friday night with the "weight forward" concept. I moved my servo forward, installed the ball studs facing back and moved the bats all the way to the front. Put 40wt in the center shock with 2mm under the nose. Screwed on a set of 2xpinks & yellows. .5mm chassis lift in the middle or -.25mm droop, the rear pod .5mm lower in the front vs the rear. Slathered on 2/3's Jack on the fronts, full rears. Pretty dang good. Keep in mind, this very same combo pushed off the track at 4 minutes in a previous test with weight back. It would seem that weight forward may solve the changing tire traction conditions through out the 8 minutes. This is the first bit of good news to help cure this issue since it showed up. In the good old days, we didn't have conditions change during the run. You either pushed or were loose.
When I got back to the shop, I set up the scale and did a little weight bias check. With the servo forward like I described, a 19t motor, the bats forward, the wieght bias is 41.6/58.4%. With the bats back, it's 40.5/59.5%. I would be curious to put the servo back were it was to measure it for comparison. This makes me wonder if there is a "magic number" to shoot for. I checked my MS2.3 and it was lighter on the nose; 38.9/61.1% and 40.1/59.9%.
Results at the track were: 3 other drivers really liked the weight shift and improved their times. I took a step sideways, no time improvement, but I liked the characteristics of the car better. I ran a 2xpink wrap with a yellow prism in practice and the 1st round that showed big potential. When I went to all prism, I actually went slower. I was quite surprised. My next test will be on all wraps in that combo. If that works out, I suspect that it will be quite fatal to the rest.
Is anyone in on this thread capable of making up an Excel style set up sheet that we can share between everyone? I don't know how and not affraid to admitt it. Something with scanned images?
When I got back to the shop, I set up the scale and did a little weight bias check. With the servo forward like I described, a 19t motor, the bats forward, the wieght bias is 41.6/58.4%. With the bats back, it's 40.5/59.5%. I would be curious to put the servo back were it was to measure it for comparison. This makes me wonder if there is a "magic number" to shoot for. I checked my MS2.3 and it was lighter on the nose; 38.9/61.1% and 40.1/59.9%.
Results at the track were: 3 other drivers really liked the weight shift and improved their times. I took a step sideways, no time improvement, but I liked the characteristics of the car better. I ran a 2xpink wrap with a yellow prism in practice and the 1st round that showed big potential. When I went to all prism, I actually went slower. I was quite surprised. My next test will be on all wraps in that combo. If that works out, I suspect that it will be quite fatal to the rest.
Is anyone in on this thread capable of making up an Excel style set up sheet that we can share between everyone? I don't know how and not affraid to admitt it. Something with scanned images?
The further back you get your weight the more turn in you will have. Its a weight transfer issue. If it transfers you get steering....if its all up front already you get less transfer, less turn in and a lazier car.
If you look we really tried to get the batteries as far back as possible in the DB12R for this reason. It is in the same spot as on a t-car car. Most link cars most rearward position have the batts several milimeters forward of the DB12R and T-Bar cars.
This is one of the key reasons the DB12R works on asphalt.
10-28-2007, 12:34 PM
#2513
Tech Adept
The holes in the chassis are not going to be off. The countersink does come close to breaking through the chassis so the hole size may vary slightly but i assure you,it is impossible for them to be off. When the arms are mounted and the screws are not bent or anything like that,the arms are dead straight.
Jason is the hole spacing the same as an L4? I might try the carbon brace.
JasonB
10-28-2007, 12:41 PM
#2514
10-28-2007, 12:43 PM
#2516
I think the key words is Jack & CRC Fast Trac II. It seems that this combination has been difficult for a lot of drivers in the past year. This track is also bumpy for a carpet track. I don't have access to an asphalt track this time of year, but I am sure the DB12R is awesome on it. Jack tracks seem to build up front tire gum more then any other. It would seem if you push, even just a little, you get some tire scrub that eventually will change up the characteristic of the front tire. It would seem, that putting the weight forward reduces the tire scrub and improves the consistency of the tire.
10-28-2007, 12:52 PM
#2517
Tech Adept
Has anybody else found the latest screws much softer then the old blue AE ones?
JasonB
10-28-2007, 01:07 PM
#2518
Tech Fanatic
The screws do bend, I've done a couple on another car. But, that's not the main issue IMHO...
I found that the stack of washers under the arm slip when you have even a slight hit, and that moves the arm upsetting the angles and steering toe. I glued the washers together, and then to the underside of the arm, and this helps a little. However, it isn't as good as the AE arms, which are solid right down to whatever spacer you are using.
Because the washers are clearance over the thread, the ability of the arm to stay put in a shunt is solely down to how tight you do up the screws. Increasing the friction between the washers and the spacers and the chassis helps, but that means you have to do the screws up real tight, and eventually you strip out the threads in the arm - hence why I glued mine up into a stack to stop as much movement as possible.
On balance, the IRS arms are so accurate, and so resilient, it is a no-brainer to keep them on. They make the AE arms seem a bit agricultural by comparison! However, if the washers were tight enough to be threaded by the screw, and then you glued them together in a stack...
I found that the stack of washers under the arm slip when you have even a slight hit, and that moves the arm upsetting the angles and steering toe. I glued the washers together, and then to the underside of the arm, and this helps a little. However, it isn't as good as the AE arms, which are solid right down to whatever spacer you are using.
Because the washers are clearance over the thread, the ability of the arm to stay put in a shunt is solely down to how tight you do up the screws. Increasing the friction between the washers and the spacers and the chassis helps, but that means you have to do the screws up real tight, and eventually you strip out the threads in the arm - hence why I glued mine up into a stack to stop as much movement as possible.
On balance, the IRS arms are so accurate, and so resilient, it is a no-brainer to keep them on. They make the AE arms seem a bit agricultural by comparison! However, if the washers were tight enough to be threaded by the screw, and then you glued them together in a stack...
10-28-2007, 01:08 PM
#2519
If your car has an arm angle issue look elsewhere than the chassis.
10-28-2007, 07:33 PM
#2520
Jay...
I showed up for the FSEARA race "Sunday Only" and the car was awesome. Daytona has an odd surface that is highly abrasive and low traction... We had a really poor turnout for 12th but I ended up TQ'ing. My car was the only car that worked reasonably enough to run consistant laptimes...
I ended up for the year 2 points behind Mike Bruce.... Ohh well...
used .18 front springs, with a blue rear spring. With mudder tires to get some sidewall action going...
I showed up for the FSEARA race "Sunday Only" and the car was awesome. Daytona has an odd surface that is highly abrasive and low traction... We had a really poor turnout for 12th but I ended up TQ'ing. My car was the only car that worked reasonably enough to run consistant laptimes...
I ended up for the year 2 points behind Mike Bruce.... Ohh well...
used .18 front springs, with a blue rear spring. With mudder tires to get some sidewall action going...