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Trigger wheel 36-1 balancer


davek

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Staring at my L28ET in 100 pieces last night I started thing about how I was going to mount the trigger wheel for crank angle sensing.

Then I noticed the harmonic balancer looking right back at me. This is a balancer right?? There is plenty of meat on that back side flange/disc I could easily machine the 36-1 notches. I have access to CNC mills and wire EDM.

Of course this changes the balance of the unit right? Well doesn't mounting a seperate 36-1 wheel on the crank change the balance as well?

Am I thinking way to far out of the box? Anybody done this?

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I could save a little machine time. The real question is this a good idea or not.

I see the trigger wheels have a balance hole in them opposite the missing tooth so my original post is not correct.

I'll call the engine shop and ask about rebalancing.

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I used the flywheel method and it pretty well. The flywheel is large and stable so theoretically should give the best signal if the divots are positioned correctly. I just had problems with my sensor and possibly the positioning of it in relation to the divots.

 

Currently I'm using a 30-1 wheel made out of the '81 l28et's 90 tooth wheel with a hall sensor, I think this is probably the easiest way to go with stock parts. Just have to remove the pulley and grind two teeth for every one. I think there's enough material and it sticks out far enough that you could grind down all the teeth and make wider teeth like an OEM 36-1 wheel has. I haven't had any issues with the little nubs losing the signal though.

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I used the flywheel method and it pretty well. The flywheel is large and stable so theoretically should give the best signal if the divots are positioned correctly. I just had problems with my sensor and possibly the positioning of it in relation to the divots.

 

Currently I'm using a 30-1 wheel made out of the '81 l28et's 90 tooth wheel with a hall sensor, I think this is probably the easiest way to go with stock parts. Just have to remove the pulley and grind two teeth for every one. I think there's enough material and it sticks out far enough that you could grind down all the teeth and make wider teeth like an OEM 36-1 wheel has. I haven't had any issues with the little nubs losing the signal though.

 

Can you elaborate on the issues you had with the crank sensor and position. I have not tested mine yet, but I am hoping it will work. If you are still at assembly stage on your engine, this method of using the flywheel is the cheapest and easiest in my opinion. A 20$ sensor and a drill press. Granted-you should have the flywheel balanced afterwards which adds to cost.   

post-1083-0-98869500-1387567064_thumb.jpg

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I think the problems I had were my own.

 

I would lose the signal over 5800rpm and that might have something to do with the specific sensor I was using. My dad gave me a stainless steel Caterpillar VR sensor. It looked nice, so used it. Originally it was made for reading the teeth of a flywheel to get the engine rpm. I don't know the specs on it, but it might be possible that 5k+ rpm was outside its operating range. Up until that point, it was fine. It was really finicky about the gap too, I pretty much had a 1/2 a turn range where it would and wouldn't work.

 

There's also the chance I mounted it slightly out of position on the cover plate.

 

By easier, I meant you don't have to drop the transmission, it's my least favorite thing to do.

Edited by Metro
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  • 1 month later...

Back to my question--Balancing the unit becomes very simple. I'll make the depth of 2 teeth deeper opposite the missing tooth to make up for the missing weight. Correct??

 

2 more questions.

a) Using the hall effect sensor from DIY--Will it matter if I leave the crank angle indicator knotch on the harmonic balancer. I would like to leave the notch on a tooth to be able to strobe the ignition angle. I don't know if the small notch would have any affect on the hall effect sensor readings.

b)What is the length of line for a tooth? The edge the sensor is reading. I'm thinking the space between teeth is more important. And depends on size of the sensor. The Teeth on the harmonic balancer I draw up are 0.26" with 0.35" between teeth. looks good but I'm no sensor engineer.

post-40993-0-25878800-1391271791_thumb.jpg

Edited by davek
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