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Old 02-12-2011, 06:30 PM   #1576
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Here's my little 12th scale monster. I learned a lot about this past weekend at a big regional race. I spent hours and hours working on the it. . . more than most people spent on multiple cars, but it really paid off. I've got a better understanding of how to set up the front end at least.
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Old 02-12-2011, 07:01 PM   #1577
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Had a decent day with my car today, put the NFE back on it for the first time in 3 races after deciding what I was going to use for up travel limiting. Settled on using some stainless screws in the back with some new nylon diff nuts.

Worked really well, first time I've been able to race the car with the NFE on the car at our track and have the front ride height be nearly identical to what it was set to at the beginning of the run, minus tire wear. I'm very happy my spare front flex plates get to remain spares this week

I don't remember who first posted about their up travel limiting idea, but it's spot on, glad you mentioned it.

For anybody that runs really small front tires, this is a must-have mod for the BMI front-end to save your front flex plates.
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Old 02-12-2011, 07:45 PM   #1578
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What's wrong with upping the preload? I'm still on my original pair of flex plates, they've lasted several months and been through massive abuse. With coil springs they settle in and you have to up the preload, so as long as your flex plates haven't delaminated. . . ? ? ? ! ! !
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Old 02-12-2011, 08:18 PM   #1579
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The problem I was having was the flex plates settling so much that they would delaminate, even without hitting anything. And eventually getting to the point that I couldn't make ride height without going to a longer adjustment screw, AND bigger tires.

The front suspension has so much up travel, that if you run a front tire any smaller than brand new and uncut, one crash would also delaminate them.

I also found that once the flex plates started to "settle" the effective spring rate wouldn't be even left to right either. If you can see visible curve in the flex plates, I bet close inspection will show delamination starting to occur as well. I've got a pile of 'em that show serious fatigue.

But, some longer rear mount screws, a couple diff nuts, and my flex plates are still straight, consistent and ready for next week, even after some heavy crashes today trying to knock off 4 weeks worth of driver's rust.
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Old 02-13-2011, 01:52 PM   #1580
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Got any pics of that MOD HarryLeach?

Btw...finally finished up the CH12 Here ya go Jason
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BMI Racing "Copperhead 12" discussion and support-copperhead12-5.jpg   BMI Racing "Copperhead 12" discussion and support-copperhead12-4.jpg   BMI Racing "Copperhead 12" discussion and support-copperhead12.jpg   BMI Racing "Copperhead 12" discussion and support-copperhead12-7.jpg  
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Old 02-13-2011, 02:20 PM   #1581
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Quote:
Originally Posted by JayBee View Post
Got any pics of that MOD HarryLeach?
Certainly.


Top View

I used 8-32 x 3/4" Stainless screws and self-threading nylon diff nuts

At ride height, there's no touching of the lower arm on the screw or the nut. I've been setting up travel so my tapered ride height gauge will just fit under the chassis when compressing the front end, but not enough to read anything of interest, so less than .5mm. This setting didn't change the handling feel of the car at all, but did have the advantage of not changing the handling after a crash, since the flex plates aren't getting torqued so hard in an impact anymore.



It's not possible to get a nut driver on the adjustment nut with the wheels straight ahead, so it does take a few adjustments and checks to get the up travel adjusted correctly.

Again, I'm not the first one to do this, but now that I have, I'm still happy with the front end, and MUCH happier about my front flex plate's longevity.
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Old 02-13-2011, 02:38 PM   #1582
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Thanks brah. Fortunately I haven't ran into that particular issue. But I'll keep an eye on it. I break the edge of my flex plates really good, give them my special CA treatment and use a touch of Assoc. black grease on the set screw. Then run 'em thru nice & straight, and that seems to be working for me.
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Old 02-13-2011, 03:19 PM   #1583
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Quote:
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Thanks brah. Fortunately I haven't ran into that particular issue. But I'll keep an eye on it. I break the edge of my flex plates really good, give them my special CA treatment and use a touch of Assoc. black grease on the set screw. Then run 'em thru nice & straight, and that seems to be working for me.
Well, I wish you luck, but I haven't had a problem with delamination where the adjustment screw goes. I'm talking about delamination in the area the CF is supposed to flex, and once that happens, it goes softer and softer until it breaks completely.

I seem to have tossed out all the really bad sets I had, here's the set I took off last, hard to get good pictures, but I've circled the areas that are showing delamination. I don't think any amount of prep would prevent this, as it's pure over-deflection damage to the carbon.




I wish I'd at least taken pictures of the worst ones, they had nearly 45 degrees of twist in the plates, and some were broken over half the thickness through.

Got expensive to replace flex plates once or twice a race weekend, but thankfully it seems to be much better protected with 2 $0.35 screws and a couple $0.15 nuts.
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Old 02-13-2011, 03:28 PM   #1584
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I see now. Wow, weird. Yeah like I said I haven't had that issue but I will pay special attention to that area Thanks for the pics
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Old 02-13-2011, 03:44 PM   #1585
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No problem.

I love the car, and the new front end, but it can make for a frustrating day and ill handling car when a flex plate goes soft. I still keep the old front end ready to fill in if needed, but I hate putting it on when the new front end works so well and looks just as good. And after my promising "durability" testing yesterday, I shouldn't be putting the old front back on the car for quite a while
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Old 02-13-2011, 04:25 PM   #1586
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Your car looks killer JayBee, nice and clean . And thanks for the pics of your mod Harry, I have'nt had the car long enough to have that issue yet but will also take care to check it often.
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Old 02-13-2011, 06:00 PM   #1587
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No problem. Those of you that don't crash as often or as hard as I do probably won't see it happen, but I've also had a brand new set go dead on me without hitting anything, just from laying over on the nose from too much front end bite.

That said, I was downright giddy yesterday to find my front ride height just as I set it after each run, with the flex plates still in one piece and straight, and equal steering behavior left and right on the track each run. It gave me the time I needed to focus on adjusting my setup instead of replacing parts.
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Old 02-13-2011, 06:11 PM   #1588
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Quote:
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Your car looks killer JayBee, nice and clean . And thanks for the pics of your mod Harry, I have'nt had the car long enough to have that issue yet but will also take care to check it often.
Thanks bub
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Old 02-13-2011, 06:36 PM   #1589
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looks good guys,JB i tried my servo flat and cant get it had to leave it angled but that's how i have had it all along
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Old 02-13-2011, 07:28 PM   #1590
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looks good guys,JB i tried my servo flat and cant get it had to leave it angled but that's how i have had it all along
Thanks man. I was determined to lay it down, so I drilled and countersunk 2 new holes
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