Not so fun repair

Southwest Montana SCCA discussions for the 2006 season.
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DaveMk1
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Not so fun repair

Postby DaveMk1 » Sat Oct 28, 2006 8:20 am

So........a few weeks back I took the Birkin out for a spin and it was running great as usual. I slowed down and noticed (hard to not notice really) that there was a strong vibration running through the chassis. The whole thing felt like one of those beds in a cheap hotel that you put quarters in (know what I talking about Russ?). I stopped and gave everything the once over and could find nothing wrong. It ran just fine but the vibration was intense.

So I get it home and start looking for the problem and can finding nothing at all wrong. Except that it vibrated enough to make my body buzz even after I got out of the car.

After lots of letting the car idle in the driveway and wiggling things I found the source of the vibration. The alternator (lower left side of the engine) was firmly pressed against the chassis rail. In fact the alternator was holding the engine up. I ain't no pro mechanic but even I know that the alternator isn't designed to hold up the engine.

It turns out that one of the two bolts that hold the motor mount to the block broke off flush to the block.....allowing the mount to twist and the engine to sag down onto the alternator. If it weren't for the alt hitting the chassis the engine would be sitting on the ground out in Bridger Canyon.

So now onto the repair. I thought for sure that I'd need to pull the motor to get at the broken bolt. So I did what anyone would do. I propped the motor up onto some blocks of wood to take stress off the good motor mount and left it there for a few days.

When I went back to it it was still broken. So onto plan B. So I borrowed a small right angle drill, bought an easy-out tool set, and started removing stuff to get at the broken bolt. I had to remove the entire exhaust system from the head back. Getting all those snaking header pipes out through the tiny hole in the body work was especially fun. So exhaust off, steering shaft removed, alternator removed and there was just enough room to get the drill in. Not enough room to get the drill with the bit in the chuck in though. So I shortened the cobalt bit (fun with abrasives) and had just enough room. So onto drilling and to my relief it went very smoothly. Hole drilled, tool tapped into the hole and a bit of pressure and out it came. I literally jumped up and down alone in my garage. Yes I felt silly.

Turns out out the there were a few issues that made the bolt break. First the bolts were crap. Soft stuff. Next was that the bolt was too long and had been bottomed out in the hole. This allowed the mount to vibrate on the bolt...not good for the fatigue thing to have the engine bounce up and down on the bolt. Lastly the bolt's alignment as it passed through the motor mount was very poor. And I thought that the South Africans were such skilled fabricators. So with the bolt passing through the mount at an angle it put a huge bending load on the bolts when tightened. Not good.

So new class 10 bolts (that are the correct length) and alignment of the holes and it all went back together.

Man is it smooth now. Not exactly like a Crown Victoria but pretty smooth.

Hey, Thanks for reading.

Dave
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fastneons
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Postby fastneons » Sat Oct 28, 2006 9:57 am

I literally jumped up and down alone in my garage. Yes I felt silly.


I know the feeling. Usually this phenomenon accompanies broken bolts! :lol:
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RayAR
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Postby RayAR » Sat Oct 28, 2006 11:50 am

I know the feeling well and have done plenty of jumping with excitement in my garage(you should have seen the party I had going on the first time I fired the engine). Drills are just a luxery, I usually spin the bit by hand. :shock: I just need a few tools to work on my car. A BFH, an even bigger FH, A flat screwdriver that also works as a prybar, chisel or gasket scraper, a phillips screwdriver that does double duty as a punch and an adjustable wrench. If I can't fix my car with those tools then it just can't be fixed. :lol:
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WD40
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Postby WD40 » Mon Oct 30, 2006 7:52 am

Cool Story!

So I did what anyone would do.
I propped the motor up onto some blocks of wood to take stress off the good motor mount and left it there for a few days.

When I went back to it it was still broken. So onto plan B.
^^^LOL! BTDT!
"Damn, it didn't just fix itself."..."Shoot!"

Funny thread ya got started here Dave. :mrgreen:
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