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Discussion Starter #1
I was feeling my oats a few days ago and ran it up the shifts on my 1986 spider to 6500 rpm in first and second. While shifting into 3rd at 6500 there was a sudden bang followed by a horrible loud rattling. At first I thought that I had a catastrophic engine failure. I pulled off the road and checked out the engine. It was running, but making a strange noise. Fortunately I was only a couple of miles from home and was able to limp home.

The car ran but had a scary loud knocking/Rattling sound that occurs at rpm over 3000 or at any rpm when I back off the throttle. The noise was so loud that I initially could not tell where it was coming from.

Once home, I checked the engine thoroughly. Good compression across all cylinders; no coolant in oil or oil in coolant; good oil pressure. Visual inspection showed nothing out of norm. I did find that the cam drive chain was a little loose, so I reset the tension. I was hoping that the loose chain was the problem.

After I buttoned up the engine, I jacked up the car and started it up - same noise. From under the car, it was clear that the noise was not the engine, but coming from inside the bell housing. I also was able to determine that pressing the clutch pedal did eliminate the thunderous rattle but not completely. I fear that the fix will likely be a major repair.

Any help with further diagnosis without pulling the trans/engine?

Further info on the car:
My 1986 spider has a complete rebuild of the engine and trans from last winter. Probably about 2000 mi on the new set up. Engine got new pistons, heads ported and polished, all new valves, comp valve springs. Lightened and balanced flywheel, new clutch, pressure plate and TO bearing. The trans had new synchro's in 2nd and 3rd and the first gear synchro fix.
 

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I would suspect the pressure plate
 

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But Mad North-Northwest
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The monopod tachs tend to read quite low over time. If yours hasn't been calibrated recently it's quite possible you were at much higher revs than the indicated 6500.
 

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Discussion Starter #4
I would suspect the pressure plate
Thanks - I am thinking possible pressure plate spring failure, Throwout bearing fork broken, pivot ball failure, trans input shaft broken. I will have to pull the trans to see for sure.

Strange, the drivetrain does not noticeably vibrate driving, but the sound from the bell housing is scary loud clanking

Anybody have a similar experience?
 

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Richard Jemison
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Clutch Lining Failure

It`s a common problem......Releasing the clutch at high RPM leaves the lining material dependant on it`s structural integrity to keep from exploding. The rivet holes are a weak point. They are not Bonded and Riveted so there it goes....

The clutch disk`s lining material has separated in chunks from the plate. The riveted lining separated.

The next phase will get a piece of the lining between the rest of the disk and pressure plate and then you won`t be able to release the clutch as it will be locked up.
 

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Discussion Starter #6
I finally got around to pulling the trans. Clutch, pressure plate, and TO bearing all fine. It turns out that the flywheel bolts loosened. What's up with that? This happened to a fresh engine rebuild from last winter with less than 2k miles on it. I am meticulous and sure that I cleaned the bolts and torqued to spec, and used locktite red sealant on the flywheel bolts.
Now I am concerned that if I just repeat the same assembly procedure that it will only fail again. Any suggestions on how to prodded from here?
 

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Discussion Starter #8
I installed the flywheel onto the crank shaft, then inserted the bolts each with a drop of red locktite through the spacer/washer and carefully torqued the flywheel bolts to 85 ft lbs using a cross pattern and gradual increase in torque. The engine ran great right up to the point in time when under a high rpm load, the bolts must have loosened enough to develop a wobble. This was evidenced on disassembly where the flywheel could be slip rotated a degree or two by hand and the bolts all came out without having to brake them loose.
I am now curious if there is a better way to install the bolts so that I can avoid a repeat of this failure? Thinking about new bolts, different locktite, lock washers. I got to believe that our race community has a preferred method of avoiding this type of problem.
 

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Richard Jemison
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Flywheel bolts

Use a different set of bolts with a liberal amount of red Loctite.
But first be sure the centering is good and the holes in the flywheel are not elongated.

Inadequate torque is the issue. Toss the torque wrench and use a 1/2 inch impact at full setting. Don`t keep hammering at each bolt Just until the socket stops turning.

Never had one come loose.

Uou could always drill a 3/8 hole in the flywheel & crank hub and instal a hardened pin to resolve any looseness.
 

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I installed the flywheel onto the crank shaft, then inserted the bolts each with a drop of red locktite through the spacer/washer and carefully torqued the flywheel bolts to 85 ft lbs using a cross pattern and gradual increase in torque. The engine ran great right up to the point in time when under a high rpm load, the bolts must have loosened enough to develop a wobble. This was evidenced on disassembly where the flywheel could be slip rotated a degree or two by hand and the bolts all came out without having to brake them loose.
I am now curious if there is a better way to install the bolts so that I can avoid a repeat of this failure? Thinking about new bolts, different locktite, lock washers. I got to believe that our race community has a preferred method of avoiding this type of problem.
i'm sure richard is correct on his advice but i would both ask a couple of questions and i would caution you on a couple things...

first... i don't remember is these flywheels used bolts with shoulders or not. normally you have one of two types of installations... an assy that locates the flywheel with a dowel pin and then uses un shouldered bolts or no dowel pin and shoulderd bolts and in these circunstances the bolts are usually special in that the shoulders are a very close tolerance fit to the holes.

what you do not ever want is unshouldered bolts in non dowel flywheels. the mistake that i see made very often is people thinkng that any shouldered bolts are the same as any other but flywheel bolts , as i said are generally quite different in the shoulder dimension. so... you need a set of real live , honest to god flywheel bolts... not just generic replacement hardware.

beyond that, the other thing that happens is that when the flywheel falls off or gets loose, the holes get elongated... in my opinion this scraps the flywheel. you can not rely on the frictional clamp load to hold the flywheel to the crank. that load is shearing force that goes thru the bolts. the friction contributes but to a minimal degree. if those bolts have any clearence at all in their holes ( assuming no dowel regester ) then its not going to matter how tight you make it because you will be doing it again soon anyway. thats why the shoulders are so important... they both eliminate that clearence and they usually extend into the crank a little but so the shear plane does not occur across a thread. as i said... i don't remember this installation specifically whether its doweled or not but my advice about the hardware needs to be heeded.
 

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Toss the torque wrench and use a 1/2 inch impact at full setting. Don`t keep hammering at each bolt Just until the socket stops turning.

Never had one come loose.
A method that has never failed me.
 

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Toss the torque wrench and use a 1/2 inch impact at full setting.
Absolutely wrong.


Start with new clean flange bolts. Also clean the mating threads with brake cleaner (brake cleaner does not leave a residue like carb cleaner). Make sure that all surfaces are clean and dry.
then inserted the bolts each with a drop of red locktite through the spacer/washer
Add a moderate amount of red locktite to the threads, not the spacer and washer. If there is anything between the spacers/washers you will not achieve the proper torque value. Then torque evenly.
 

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The monopod tachs tend to read quite low over time. If yours hasn't been calibrated recently it's quite possible you were at much higher revs than the indicated 6500.
Rut ro. I've got an 1986 and routinely see 6000 and once a month 6500. Had it up to 7000 once. Guess I should back off a bit . . . .:scared:
 

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But Mad North-Northwest
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There's a thread in the Spider forum with instructions for the monopod cars.

http://www.alfabb.com/bb/forums/spider-1966-up/2902-how-fix-your-slow-reading-speedometer-tachometer-91-94-spiders.html

Or you can pull the tach and take it to a speedo shop. They can put in a new potentiometer to replace the crappy original one and calibrate it.

Or you can just see how far off it is using an external tach and just make mental note of the difference between actual and indicated. This is the simplest way and will keep you from over revving the motor.
 

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There's a thread in the Spider forum with instructions for the monopod cars.

http://www.alfabb.com/bb/forums/spider-1966-up/2902-how-fix-your-slow-reading-speedometer-tachometer-91-94-spiders.html

Or you can pull the tach and take it to a speedo shop. They can put in a new potentiometer to replace the crappy original one and calibrate it.

Or you can just see how far off it is using an external tach and just make mental note of the difference between actual and indicated. This is the simplest way and will keep you from over revving the motor.
Thanks Gubi!!
 
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