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BMI Racing "Copperhead 12" discussion and support

Old 09-21-2011, 07:20 PM
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Tanks also i have the 12r5 front end will the bmi linear springs work on the front of it?
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Old 09-21-2011, 07:32 PM
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Originally Posted by LonnyJ1950
I understand why you might put a hole in the shock cap, but what is the actual effect on the handling?
to be honest i didnt really notice anything different in how it drove. but the shock does feel better when you build it.
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Old 09-23-2011, 11:34 AM
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Just finished building my CH for the IIC. It was the first time building the NFE and at first I was kinda thinking of just putting on the old front end that I know inside and out, but after I was done I like the new front end better. Won't get to run it till I put it on the carpet thou.

Last edited by AOD; 09-23-2011 at 05:03 PM. Reason: oldtimers
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Old 09-23-2011, 12:04 PM
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At my track we run 13.5 blinky and that is around the rollout we use so that seems kind of high for boosted. im sure someone around here will have an idea.
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Old 09-23-2011, 02:56 PM
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I was wondering does thicker damper fluid give u more or less rear grip. Also does it effect anything else handling wise? Try understand the the car so ill be able to tune it at the track.
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Old 09-23-2011, 04:35 PM
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Old 09-23-2011, 04:43 PM
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In general...anytime you stiffen or thicken suspension you reduce grip to that end of the car. So if you did it in the back the car would get more loose, at the front the car will push more. Technically it is a lot more complex than that and there may be cases where the opposite is true...but in general it is pretty correct.
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Old 09-23-2011, 06:50 PM
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Thanks so much. Also how do people like the gray-low tires (80%yellow 20%gray edge) Right now i have magenta fronts and them on the rear.
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Old 09-23-2011, 07:02 PM
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Grey-lows work well on the rear for 17.5, I find them too loose with 13.5 Boosted.

For 17.5 I've run Grey-lows or yellows in the rear, sometimes pink, but not often. In the front, it's usually blacks, sometimes play with double pinks.

For 13.5 Magenta front and rear work pretty well, sometimes use pink in the rear, and sometimes play with lilac on the front.
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Old 09-23-2011, 07:15 PM
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Originally Posted by HarryLeach
Grey-lows work well on the rear for 17.5, I find them too loose with 13.5 Boosted.

For 17.5 I've run Grey-lows or yellows in the rear, sometimes pink, but not often. In the front, it's usually blacks, sometimes play with double pinks.

For 13.5 Magenta front and rear work pretty well, sometimes use pink in the rear, and sometimes play with lilac on the front.
Is it typical for 17.5 1/12s to run a larger split in tire durometer, front to rear?
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Old 09-23-2011, 07:30 PM
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Thanks so much I thought magentas where harder then yellows so wouldnt that give you less grip and actualy be looser then running a yellow? just trying figure out the deifferent tires.
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Old 09-23-2011, 07:37 PM
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From my experience, yes.

Reason being, IME, is because the softer tires have good side bite with a little less forward bite, so you don't overpower the front tires, and allow a harder tire to turn the car without "digging in" and scrubbing so much speed in the corners. In the slower classes, you're down on power pretty well, corner speed is critical, and you can't rely on extra power to get the car rotated center-off the corner. In fact, if you can get a 17.5 to push, you're doing something very interesting.

The same compound tires on a 13.5 make for a push monster.


Lots of guys have differing opinions on tire compounds, what classes they're good for, and when you'd want to change to XXX compound, so don't take my response as gospel, I take all the tire advice I can get also!
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Old 09-23-2011, 07:39 PM
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Originally Posted by markiemark
Thanks so much I thought magentas where harder then yellows so wouldnt that give you less grip and actualy be looser then running a yellow? just trying figure out the deifferent tires.
Not exactly, there's differences in natural rubber compounds, synthetic rubber compounds, etc that change side and forward bite characteristics compared to other similar shore tires.

There's a reason so much pan car tuning is done with tires.
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Old 09-23-2011, 07:39 PM
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Originally Posted by HarryLeach
Grey-lows work well on the rear for 17.5, I find them too loose with 13.5 Boosted.

For 17.5 I've run Grey-lows or yellows in the rear, sometimes pink, but not often. In the front, it's usually blacks, sometimes play with double pinks.

For 13.5 Magenta front and rear work pretty well, sometimes use pink in the rear, and sometimes play with lilac on the front.
Are you saying you get more grip with magenta rears than yellow or graylow? We run yellows and graylows, magentas have virtually no grip.
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Old 09-23-2011, 07:50 PM
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Ok Thanks so the harder front tires allow you to turn with out loosing speed in the turns and the softer rears keep the rear planted.

And for 13.5 the softer fronts and little bit harder rears makes the car turn at higher speeds and then the harder rears help grip instead of the 13.5 just spining wheels outa the turn.

Am i some what correct in my thoughts im trying figure if im order jacos or bsr/crc tires then going pick 2 front and 2 rear sets and try it.

The track im going run at is putting down new crc carpet on a new plywood sub-floor. Right now i have
17.5 Blinky is the suggested class but might change to 13.5 blinky
Front
Magentas
.020 AE springs
5 caster
Both shims in front of arm
#3 shur lube on kingpin

Rear
Grey-lows
Olive center spring ( going to order bmi blue gold red springs)
40wt oil
#4 shur lube in tubes
1.2 flex plates
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