My LS1 Miata build
04-11-2010, 01:03 AM
#201
Technically, the CV did not break. It's almost impossible to break a CV joint until it leaves the housing & slams against the ground. What broke was the spindle input shaft on the spindle end of the CV joint. Would expect the stock Miata shaft to break since even stock Ford's break. Although, on the Ford's it's the halfshaft usually, not the spindle stub. ls1_miata knows what I'm talking about.
Hair splitting aside, I was simply curious if any other parts were damaged when said defective part decided to let go. From the pictures it doesn't APPEAR things flew apart and took out anything else but curiosity tells me I have to ask.
04-11-2010, 11:08 AM
#202
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Agreed its not technically the "CV" that broke but sure is easier to type! 
I have destroyed a BMW e30 CV itself (5k rpm drop clutch...housing expanded and bearings exploded out).
It appears the hub bearing also got damaged as there is now play in it so that will be getting replaced as well. Best part is that I know everything was tightened down and free of play as I checked it Friday (the day before it broke).
I have destroyed a BMW e30 CV itself (5k rpm drop clutch...housing expanded and bearings exploded out).It appears the hub bearing also got damaged as there is now play in it so that will be getting replaced as well. Best part is that I know everything was tightened down and free of play as I checked it Friday (the day before it broke).
04-11-2010, 12:13 PM
#203
What is similar? ls1_miata knows of my torqued off Ford Cobra 8.8 IRS half shaft, which is really why I was being more specific. Since replacing the stock Ford half shaft w/the latest M5 material, the weak point is now either the rear end gear, input gear, true-trac differential, pumpkin flex or drive shaft. It's pretty much bullet proof, but, nothing truely is. ls1_miata breaking the outer miata shaft doesn't indicate where my next weak point may be because mine is a Ford outer, which is why I ask you what is similar. My guess is that the only other failure that mine will have will be due to flex in the aluminum pumpkin housing.
04-11-2010, 05:15 PM
#204
What is similar? ls1_miata knows of my torqued off Ford Cobra 8.8 IRS half shaft, which is really why I was being more specific. Since replacing the stock Ford half shaft w/the latest M5 material, the weak point is now either the rear end gear, input gear, true-trac differential, pumpkin flex or drive shaft. It's pretty much bullet proof, but, nothing truely is. ls1_miata breaking the outer miata shaft doesn't indicate where my next weak point may be because mine is a Ford outer, which is why I ask you what is similar. My guess is that the only other failure that mine will have will be due to flex in the aluminum pumpkin housing.
My car is an auto so there is no rev to 5K and drop the clutch but I still drive it pretty hard and expect things to fail from time to time. I just live on the idea of strengthen what you know will fail and hope you got everything. If you missed something you will find it eventually.
I saw a guy that had made a girdle for the aluminum 8.8 IRS center. I don't know if it actually worked or not and the site it was on has been gone for ages.
04-11-2010, 08:23 PM
#205
My Thunderbird is IRS like a Cobra or the Miata. It uses half shafts and CV joints and I have heard of and seen pictures from people twisting them off like LS1-Miata did but I haven't experienced that. The difference is I was never able to interact with the people since the deed was done long before I happened across the pictures, text or story of the result.
I've got T-bird half shafts that were saved as spares before buying the M5 materail spec'd half shafts (my Cobra uses 28 splines). If it helps, the half shafts in your IRS will go before the spindle or diff housing stubs will, since they are T-bird & not Miata. Although, ls1_miata only had the Miata stub on the spindle end of the CV assemblies. Also, the T-bird 8.8 housing is steel, stronger & more resistant to flex than my Cobra aluminum housing, as you already know. IMO, if you wanted to upgrade, the half shafts are the place to do it, M5 material. After that, I'd say the differential if it is stock.
