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Old 05-15-2015, 02:32 AM   #441
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Wheel hop can be caused by ANYTHING that flexes in the drivetrain.

Everything flexes a little bit. Some things more than others. Everything is a spring, so anytime a part flexes, it's a spring storing energy. If you made a list of every part in the drivetrain that sees torque or load, you'd have a list of all the things that can flex and lead to wheel hop. All of them flex. Some are tiny/insignificant. Others are the big ones that can be improved.

Wheel hop is caused by something or some-things flexing too much. If you want to reduce it/eliminate it, you need to stop all the things from flexing. You can't 100% make everything stop flexing, but rather you have to find the weak links/things that are "springy" and make them "not springy". Do that, and wheel hop goes away.

Also, first order of business is to learn to launch the car. Step one, don't spin the tires, and it won't wheel hop in the first place. Car is also faster when you don't spin the tires. I can get 2.0 60' consistently on hard old street tires just launching at 7K, riding the clutch, barely chirping the tires at all. If I get it right, 1.90 60'. If I had some sticky tires, easily knock a couple tenths off those numbers.
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Old 05-15-2015, 02:37 AM   #442
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Quote:
Originally Posted by Mobius View Post
I can't think of anyone that has actually broken a diff from power. Especially power through a 5 speed.
You won't break them from power, it will be from wheel hop. Every time. Peak loading breaks stuff, and for a miata diff that happens when you have wheel hop.
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Old 05-15-2015, 08:23 AM   #443
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andrew that reminds me, I think my bearing sleeves for the upper outer sphericals broke free from their green locktite. That could also contribute. But the wheel hop is certainly driver error. I need to figure out how to cut sub 800 lights while slipping the clutch.
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Old 05-15-2015, 08:37 AM   #444
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FIFY

Quote:
Originally Posted by Leafy View Post
andrew that reminds me, I think my bearing sleeves for the upper outer sphericals broke free from their green locktite. That could also contribute. But the wheel hop is certainly driver error. I need to figure out how to cut sub 600 lights while keeping wheel speed constant.
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Old 05-15-2015, 10:29 AM   #445
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Originally Posted by TNTUBA View Post
Holy Wheel hop!!!! That's what's killing your drive-train parts.

My first Launch sequence starts at 3:10 in this video.



You've got to fix your wheel hop issues or your better carry spare diffs, transmissions, driveshafts and axles everywhere you go.
Would you consider sharing your launch control settings?
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Old 05-16-2015, 09:36 PM   #446
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Pat was right on the money. I shattered one inner torsen gear and broke a big chunk off another one. R&P are undamaged except for where they ground up the gear bits. I wont be reusing them, in a pinch I could probably grind the burrs off and make it serviceable but I dont want to be that janky.





oh and this stupid thing broke too. I've never seen one not break. I tried to weld it back up and then it broke again when I bolted it on.



If the R&P had been ok I probably would have gotten the mfactory helical. But since I need one too it make sense just to get the whole thing together and work on making the car not wheel hop.

Oh yeah, what the **** bolt is supposed to thread into the metal sleeve thats in the forward boltin the diff-ppf. The write up just says to thread the big bolt in and pull down. Lol I have zero bolts that thread into it. Thankfully that bit was broken and I could get the diff out without popping the sleeve down.

Last edited by Leafy; 05-16-2015 at 09:55 PM.
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Old 05-23-2015, 07:30 PM   #447
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New torsen is in with the FC RX7 delrin diff bushings in and the poly pieces that go on the bottom brackets. The FC pieces work fine, the diameter of the lip is a little smaller and the lip is thicker by less than 1/8th inch. I'd have rather had the garage star ones meant to go in there, but out of stock.

I also finally turned on my clutch in rev limit for launching. I thought for some reason it didnt work well with the AEM but I think I was just wrong. I have to figure out more settings for it, needs less hysteresis and more cut cycles, it easily blows past the fuel cut and into the spark cut. But does build 5psi.

Race tomorrow.
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Old 05-23-2015, 11:19 PM   #448
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I know it actually is a racecar, but I would recommend using a fuel cut and only go to spark cut if the fuel cut doesn't work well enough.
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Old 05-24-2015, 10:01 PM   #449
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Its fuel cut at 5k, and spark cut at 6k. It shouldnt make it to the spark cut.

I drove crappy this morning, and then on my first afternoon run the IC pipe blew off the turbo and it didnt really fix well for my co driver and blew off again. I replaced the tbolt clamp with a hose clamp and then this was my next run.

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Old 05-24-2015, 10:05 PM   #450
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wut
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Old 05-24-2015, 10:05 PM   #451
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the wheel flew off??????????
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Old 05-24-2015, 10:07 PM   #452
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Please tell me someone outside filmed that.
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Old 05-24-2015, 10:07 PM   #453
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The wheel broke. Only real damage besides the wheel is the caliper got gouged and I think slightly bent in by one of the bolts in the wheel. The car was pulling left once we threw another wheel on to drive it back to paddock.
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Old 05-25-2015, 08:14 AM   #454
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Dude. I'm really sorry. That sucks. Will you be able to get it fixed in time for next weekend?
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Old 05-25-2015, 10:59 AM   #455
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I'm not going to the first wilmington. But like I have to like put a new brake caliper on and pull the fender back out. My good tires are on the spinwerks. I have the devens tour and then toledo before I need to put less good tires onto a set of wheels for a local.
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Old 05-25-2015, 07:26 PM   #456
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Exhibit A, The oxidized section of cracked wheel. Where the fail started.





B, the fale starting on other wheels.



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Old 05-25-2015, 09:49 PM   #457
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Pretty sure this is just a case of those wheels doing what those wheels do.
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Old 05-25-2015, 11:42 PM   #458
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No its the barrels that fail on keizers.
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Old 05-25-2015, 11:43 PM   #459
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We ran those on our FSAE car back in college, and I remember people saying they break. The part that broke is cast magnesium, right?
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Old 05-25-2015, 11:44 PM   #460
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Yeah looks cast and then machined. It probably would have lived though the casting flaw at least a lot longer if it was setup for tuner lugnuts and not a 19mm socket.
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