3LikesBMI Racing "Copperhead 12" discussion and support
10-18-2010, 11:31 AM
#1096
10-21-2010, 08:51 PM
#1101
Had a couple issues with my new front end, but Jason's handling it. 
Despite that, I got my front end put on and hopefully dialed in. Full on testing and tweaking will happen tomorrow, really looking forward to it. It was real sweet to build, typical BMI quality, top notch, and no shims!
Gotta thank you guys that mentioned the paper trick for setting droop. It got me in the ball park. When set properly for 1mm of front droop, the flex link [ride height] set screw never lifts from the chassis [with the kit 1.5mm links], which should limit any gouging of the chassis plate through use.
So far, adjustments are easy to make, everything seems well thought-out, and I can't wait to turn some laps.
Despite that, I got my front end put on and hopefully dialed in. Full on testing and tweaking will happen tomorrow, really looking forward to it. It was real sweet to build, typical BMI quality, top notch, and no shims!
Gotta thank you guys that mentioned the paper trick for setting droop. It got me in the ball park. When set properly for 1mm of front droop, the flex link [ride height] set screw never lifts from the chassis [with the kit 1.5mm links], which should limit any gouging of the chassis plate through use.
So far, adjustments are easy to make, everything seems well thought-out, and I can't wait to turn some laps.
10-22-2010, 11:19 AM
#1102
mailman just showed up with a box of bmi!!!!!
anything i need to know before i build my ch12 with the new front end or for the ch10 with the old front end???
i am super giddy about building these cars and i know the quality will be top shelf... look out x-ray you got a new benchmark!
thanks
anthony
anything i need to know before i build my ch12 with the new front end or for the ch10 with the old front end???
i am super giddy about building these cars and i know the quality will be top shelf... look out x-ray you got a new benchmark!
thanks
anthony
10-22-2010, 06:34 PM
#1104
Got some laps in with my Copperhead today, I'm very happy.
Traction on the track is severely lacking since it hasn't been raced on since last winter, but the car did well as a very narrow groove came in from just a couple of us turning laps. Should be a bit better tomorrow, our carpet season starts in 2 weeks, so there will be more guys helping to run-in the carpet in the coming days.
I did notice that the front flex links take a couple runs to "settle in", had to readjust my ride height and droop once, and it was good the rest of the day. 3mm ride height, 1.5mm pod droop, 1mm front droop.
I ran the 2mm standoffs, and the car had a lot of double-steer. Spent more time trying to just get the car around the track than actually pushing the limits, so I didn't try the kit standoffs. Are the taller standoffs better suited for high grip, or will the shorter standoffs create more front grip through roll?
With the current grip on the track, I tried CRC magenta fronts, and didn't ever find the need to try the purple fronts I had. Started off with pink rears, car was a bit too free, tried a blue spring, and it helped. Tried yellow rears and the car pushed real bad on-power, going back to a gold spring brought the balance back, but the yellow rears dropped grip a lot quicker as the tire prep dried out through the run than the pinks, and the edges started to tear pretty quick. None of my tires are glued on the sidewall.
I'm also running the 1.2mm cf rear flex links, and for the current low grip levels, I still need more overall grip, but I don't want to chase the grip through tires that won't be needed again once the carpet grooves up.
Any ideas? Everyone's struggling for grip right now, but Magenta/Pink is a popular combo when grip is up, with Purple fronts being the second choice.
Anything I can do suspension/setup wise to get a bit more grip out of the chassis? Or just wait it out and let the track come to me?
Another thing, when the car would snap loose from too much throttle and not enough grip, the car would snap away from the corner I was straightening out from. As in exiting a right hander, it would snap left, exiting a left turn, it would snap right. What causes that?
Right now I'm running 10k diff fluid on the front damper tube, 3k on the side tubes, if that makes any difference.
Traction on the track is severely lacking since it hasn't been raced on since last winter, but the car did well as a very narrow groove came in from just a couple of us turning laps. Should be a bit better tomorrow, our carpet season starts in 2 weeks, so there will be more guys helping to run-in the carpet in the coming days.
I did notice that the front flex links take a couple runs to "settle in", had to readjust my ride height and droop once, and it was good the rest of the day. 3mm ride height, 1.5mm pod droop, 1mm front droop.
I ran the 2mm standoffs, and the car had a lot of double-steer. Spent more time trying to just get the car around the track than actually pushing the limits, so I didn't try the kit standoffs. Are the taller standoffs better suited for high grip, or will the shorter standoffs create more front grip through roll?
With the current grip on the track, I tried CRC magenta fronts, and didn't ever find the need to try the purple fronts I had. Started off with pink rears, car was a bit too free, tried a blue spring, and it helped. Tried yellow rears and the car pushed real bad on-power, going back to a gold spring brought the balance back, but the yellow rears dropped grip a lot quicker as the tire prep dried out through the run than the pinks, and the edges started to tear pretty quick. None of my tires are glued on the sidewall.
I'm also running the 1.2mm cf rear flex links, and for the current low grip levels, I still need more overall grip, but I don't want to chase the grip through tires that won't be needed again once the carpet grooves up.
Any ideas? Everyone's struggling for grip right now, but Magenta/Pink is a popular combo when grip is up, with Purple fronts being the second choice.
Anything I can do suspension/setup wise to get a bit more grip out of the chassis? Or just wait it out and let the track come to me?
Another thing, when the car would snap loose from too much throttle and not enough grip, the car would snap away from the corner I was straightening out from. As in exiting a right hander, it would snap left, exiting a left turn, it would snap right. What causes that?
Right now I'm running 10k diff fluid on the front damper tube, 3k on the side tubes, if that makes any difference.
10-22-2010, 09:20 PM
#1105
Tech Adept
Harry,
I'm not running the new FE yet, but have a question that may shed some light on your double-steer.
Did you have a typo or are you running 3000wt in the rear tubes? I think Jasons directions in the CH12 recommend 10,000. I started with that on a new layout (green) and had to move up to 15,000 when the groove got big and sticky. Left the stock flex plates mounted in the forward position. Car is on rails! 10K might tidy you up in a hurry?
I'm not running the new FE yet, but have a question that may shed some light on your double-steer.
Did you have a typo or are you running 3000wt in the rear tubes? I think Jasons directions in the CH12 recommend 10,000. I started with that on a new layout (green) and had to move up to 15,000 when the groove got big and sticky. Left the stock flex plates mounted in the forward position. Car is on rails! 10K might tidy you up in a hurry?
10-23-2010, 05:43 AM
#1106
Yeah, no typo.
If you think I'm way under damped on the sides, I'm probably under damped in the front as well.
Thanks, gives me some thing to try today.
If you think I'm way under damped on the sides, I'm probably under damped in the front as well.
Thanks, gives me some thing to try today.
10-23-2010, 07:25 AM
#1107
Tech Adept
Harry,
I think that would be a good step toward tuning your car in. I apologize as I should have answered your question at the bottom of your post, rather than just throwing out some numbers at you.
Great description by the way. What you described sounds exactly like double-steer caused by the rear-end settings. With a weaker tube fluid, the side-links have a lot of leverage to quickly throw the chassis from one side to the other. When your loaded up and carving a right hander - everything works great. As you start to unwind the wheel the sidelinks unload to quickly and throw the chassis past center. This make your car suddlenly turn left on exit. The stiffer tube fluid is going to help you mellow out the way the chassis rolls because it better controls the leverage and speed in which the side-links function.
Your probably right on with your rear shock. From what I've seen here, gold seems to be the most commonly used spring.
I think that would be a good step toward tuning your car in. I apologize as I should have answered your question at the bottom of your post, rather than just throwing out some numbers at you.
Great description by the way. What you described sounds exactly like double-steer caused by the rear-end settings. With a weaker tube fluid, the side-links have a lot of leverage to quickly throw the chassis from one side to the other. When your loaded up and carving a right hander - everything works great. As you start to unwind the wheel the sidelinks unload to quickly and throw the chassis past center. This make your car suddlenly turn left on exit. The stiffer tube fluid is going to help you mellow out the way the chassis rolls because it better controls the leverage and speed in which the side-links function.
Your probably right on with your rear shock. From what I've seen here, gold seems to be the most commonly used spring.
10-23-2010, 01:23 PM
#1108
VRacing,
Really appreciate the feed back.
I jumped up to 20k tube lube, and it helped, the car still double steered a touch on entry, but it didn't step away from the corner nearly as aggressively on exit. After that, I tried 30k, and it pretty well eliminated that tendency, until I got off-line and on the still-dirty parts of the track.
Next weekend is our last asphalt race of the year, so after that's done there should be a lot of focus on getting the carpet clean and run-in for our first carpet race of the season on the 6th.
I also tried as high as 30k in the front tube, but couldn't really tell a difference. Transitions might have been a touch slower, but not enough to know for sure with the current track conditions.
Unfortunately, I did have enough encounters with the wall to start delaminating a 1.2 CF flex link in the rear, so my final runs of the day were with the fiberglas links, as I was concerned the 1.5 CF links might have been too aggressive.
But still, the car is pleasantly responsive to even small changes and the changes I need to make are sensible once explained "why", so once traction comes up, it should be just a matter of continued testing to dial in.
I also noticed with the 1.5 front flex links, there's some "settling" that goes on with use that you have to look out for. It took my car about 9 runs, gradually loosing ride height [and increasing droop] before they seem to be settled out, and now they seem to be settled. In all, I'd say they settled about 3mm worth of ride height before stabilizing.
3 runs today with no front end adjustments needed. I'm thinking the 1.8 front links will probably not have this issue, which will be picked up in my next order.
Really appreciate the feed back.
I jumped up to 20k tube lube, and it helped, the car still double steered a touch on entry, but it didn't step away from the corner nearly as aggressively on exit. After that, I tried 30k, and it pretty well eliminated that tendency, until I got off-line and on the still-dirty parts of the track.
Next weekend is our last asphalt race of the year, so after that's done there should be a lot of focus on getting the carpet clean and run-in for our first carpet race of the season on the 6th.
I also tried as high as 30k in the front tube, but couldn't really tell a difference. Transitions might have been a touch slower, but not enough to know for sure with the current track conditions.
Unfortunately, I did have enough encounters with the wall to start delaminating a 1.2 CF flex link in the rear, so my final runs of the day were with the fiberglas links, as I was concerned the 1.5 CF links might have been too aggressive.
But still, the car is pleasantly responsive to even small changes and the changes I need to make are sensible once explained "why", so once traction comes up, it should be just a matter of continued testing to dial in.
I also noticed with the 1.5 front flex links, there's some "settling" that goes on with use that you have to look out for. It took my car about 9 runs, gradually loosing ride height [and increasing droop] before they seem to be settled out, and now they seem to be settled. In all, I'd say they settled about 3mm worth of ride height before stabilizing.
3 runs today with no front end adjustments needed. I'm thinking the 1.8 front links will probably not have this issue, which will be picked up in my next order.
10-23-2010, 06:21 PM
#1109
You should put some CA or thread lock on the set screws in the front plates and on the droop screws. This will keep the adjustments from changing. Also, i like to run #4 shurlube in the tubes front and rear. The stock front standoffs are going to work better in low bite but when the bite comes up, the taller ones are the way to go.
10-23-2010, 06:29 PM
#1110
I already have CA on the set screws. I was definitely seeing a loss of ride height exceeding what I was losing from tire wear. It seems to be balanced out now, but it was happening. I'm not complaining, just an observation.
I'm not sure where #4 shur-lube falls out on anybody else's wt/cs scale, but Ofna 30k seems to be pretty good right now, I'll be dropping to back to the short stand-offs to see what change that makes.
This has been a very fun car to experiment with, can't wait to start racing it.
I'm not sure where #4 shur-lube falls out on anybody else's wt/cs scale, but Ofna 30k seems to be pretty good right now, I'll be dropping to back to the short stand-offs to see what change that makes.
This has been a very fun car to experiment with, can't wait to start racing it.