Bolts, classing, hardness, and strength...
#21
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Yeah, that ENTIRE engine would be in the scrap metal pile. I overrevved an engine by just a few thousand RPM's once (11,000) and thought a head rebuild would be enough (all 16 valves bent), and it did for about 6 months, until a crank bearing spun in the block at random one day. I'm sure it was attributed to the high revs. Later found out that there was other block damage that rendered it useless for a rebuild from some guy I sold it to.
I also doubt 15,000, had to have been a sensor issue. I doubt even a 5th to 1st shift would allow that high of a rev without just sliding the tires or breaking something else first.
n/m, actually read the thread now. Obviously it wasn't the claimed 15k.
I also doubt 15,000, had to have been a sensor issue. I doubt even a 5th to 1st shift would allow that high of a rev without just sliding the tires or breaking something else first.
n/m, actually read the thread now. Obviously it wasn't the claimed 15k.
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In my case, the mating surface for the bolts (apart from some common cut-washers) is the 36-1 timing wheel, which is made from mild steel about 3/16" thick. This wheel sits on top of the almost completely solid face of the aluminum center hub, which in turn sits on top of the crankshaft pulley, in the place where the large steel washer with five holes sat in the stock configuration.
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My socket cap bolts failed again. Two of them broke, mid shaft. Seriously.
The resulting noise made me think that something in the motor collided into something that it should not have. Luckily for me, that wasn't the case. I'm not saying that these bolts belong in Dante's 9th layer or anything, since they did last several thousand miles, but I wouldn't lose a minute of sleep if they found themselves condemned to the 7th or 8th layer.
I'm going to come up with something better.
The resulting noise made me think that something in the motor collided into something that it should not have. Luckily for me, that wasn't the case. I'm not saying that these bolts belong in Dante's 9th layer or anything, since they did last several thousand miles, but I wouldn't lose a minute of sleep if they found themselves condemned to the 7th or 8th layer.
I'm going to come up with something better.
#27
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Ben,
is any area of the wheel coming in contact with the thread of the cap head screw?Could they have vibrated loose prior to failure.You may want to try stripper bolt or shoulder bolts,or even aircraft hardware.
http://www.mcmaster.com/#shoulder-screws/=6oz54m
(G)
is any area of the wheel coming in contact with the thread of the cap head screw?Could they have vibrated loose prior to failure.You may want to try stripper bolt or shoulder bolts,or even aircraft hardware.
http://www.mcmaster.com/#shoulder-screws/=6oz54m
(G)
Last edited by Reverend Greg; 04-16-2010 at 11:29 PM. Reason: link&edit
#30
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That's kind of what I was thinking too. Greg doesn't know it yet, but he's going to machine a giant washer for me. ![Giggle](https://www.miataturbo.net/images/smilies/gay.gif)
The problem is that there's no room for hex head bolts due to the small ID of the trigger wheel overlay where it fits inside the pulley. So giant washer plus fancy socket cap shoulder bolts hopefully will be win.
Or I will get one of our 36-1 wheels off the shelf and run it similar to Joe Perez.
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The problem is that there's no room for hex head bolts due to the small ID of the trigger wheel overlay where it fits inside the pulley. So giant washer plus fancy socket cap shoulder bolts hopefully will be win.
Or I will get one of our 36-1 wheels off the shelf and run it similar to Joe Perez.
#35
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So, here's pics of Joe's nightmare. Only it's my nightmare.
Jay, the factory washer-ring must be an NA thing because it wasn't on my car.
Taking this as an assembly to a machine shop in the morning. I'm going to have them drill the assembly, tap the pulley boss for larger hardware, and mill the bolt areas of the trigger wheel "cup" for larger hardware. Figure I'll stud the boss, then use nylocks or other self locking hardware on the trigger wheel.
Don't mind too much the red color in the first pic. It's just a camera phone capture, and it's overly sensitive to the little bit of georgia red clay that's on the motor. Yeah, the dirt here is red.
Jay, the factory washer-ring must be an NA thing because it wasn't on my car.
Taking this as an assembly to a machine shop in the morning. I'm going to have them drill the assembly, tap the pulley boss for larger hardware, and mill the bolt areas of the trigger wheel "cup" for larger hardware. Figure I'll stud the boss, then use nylocks or other self locking hardware on the trigger wheel.
Don't mind too much the red color in the first pic. It's just a camera phone capture, and it's overly sensitive to the little bit of georgia red clay that's on the motor. Yeah, the dirt here is red.
#36
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So, here's pics of Joe's nightmare. Only it's my nightmare.
Jay, the factory washer-ring must be an NA thing because it wasn't on my car.
Taking this as an assembly to a machine shop in the morning. I'm going to have them drill the assembly, tap the pulley boss for larger hardware, and mill the bolt areas of the trigger wheel "cup" for larger hardware. Figure I'll stud the boss, then use nylocks or other self locking hardware on the trigger wheel.
Don't mind too much the red color in the first pic. It's just a camera phone capture, and it's overly sensitive to the little bit of georgia red clay that's on the motor. Yeah, the dirt here is red.
Jay, the factory washer-ring must be an NA thing because it wasn't on my car.
Taking this as an assembly to a machine shop in the morning. I'm going to have them drill the assembly, tap the pulley boss for larger hardware, and mill the bolt areas of the trigger wheel "cup" for larger hardware. Figure I'll stud the boss, then use nylocks or other self locking hardware on the trigger wheel.
Don't mind too much the red color in the first pic. It's just a camera phone capture, and it's overly sensitive to the little bit of georgia red clay that's on the motor. Yeah, the dirt here is red.
I have the exact same set up with an Electromotive, and I hated the allen head bolts. I got rid of them and used some bolts from a Yamaha dirt bike motorcycle. The head is an 8mm instead of the stock 10 mm. It has a washer boss on the bolt, and it installs easily with a socket. They are a very high quality bolt as well. I use them over and over, and the threads stay clean and straight.
Get a new crank timing belt pulley, and try those Yamaha bolts. I have had that damn pulley on and off a 100 times and have not had any problems. It is also much easier to install than the allen heads. I am willing to bet that you are not torquing them correctly. It is hard to do with those alan heads. I will get you a picture of the bolt for you today when I get back to the house.
Last edited by miata2fast; 04-26-2010 at 07:52 PM.
#37
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From your pics, this is pretty much what happened to all Vishnu adapters -- the bolt heads abrade the soft aluminum, which takes the preload out of the four little bolts. They then loosen and eventually snap.
Larger bolt underhead area (replace tiny allenhead bolts with integral washer hex head) and a steel backing (NA washer ring, in my case) fixed it for me. No need to mess with larger dia bolts and such, in my case...
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m2f--I bet you I did torque them down correctly, with a allen head socket on a midget ratchet. Also loctited them.
If you can find me a part number or application for those bolts, that would be great. There's 3 Yamaha dealers within a short drive. Extracting broken bolts out of the pulley boss is easy enough.
Down the road I'll probably switch over to a DIYAutoTune.com 36-1 mild steel wheel, which will never have this problem. Only hold up is I'd need to fab a sensor bracket, which takes time that I don't have this week. I'd like to make the car self locomote by the weekend because there's an event at Road Atlanta Thurs-Sun. I also want to powder coat the mild steel which would take a few days.
If you can find me a part number or application for those bolts, that would be great. There's 3 Yamaha dealers within a short drive. Extracting broken bolts out of the pulley boss is easy enough.
Down the road I'll probably switch over to a DIYAutoTune.com 36-1 mild steel wheel, which will never have this problem. Only hold up is I'd need to fab a sensor bracket, which takes time that I don't have this week. I'd like to make the car self locomote by the weekend because there's an event at Road Atlanta Thurs-Sun. I also want to powder coat the mild steel which would take a few days.
#40
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Well stuffs is at the machine shop. Saying good bye to 6mm hardware and hello to 8mm hardware with a much larger shoulder. That should help. With a steel backing, we should be in the win category again very soon.