bakuro117

iTrader: (5)

Hey guys,

I thought I would share this with everyone since is caused me quite a bit of time and work to correct it.

I recently did the balance shaft elimination on my engine. And despite hearing that I would experience a lot of vibration I havent noticed any more vibration than what I already experienced with solid front and rear motor mounts. But this thread isnt about that. Its about the sprocket on the crank shaft that spins the small timing belt and thus the rear balance shaft.

This would be labeled #20 in the Timing Assembly diagram.



Now when I was following Mitsuorder's 4G69 Experiment, he states that he uses Mitsubishi Part Number "MD128107" from a 1.8l mirage (which has no balance shafts) to replace the sprocket and free up some rotating mass.

I thought, "Great! I'll pick up this part for when I do my balance shaft delete." So I hopped on MitsubishiParts.net and ordered it. Here is a picture of the two side by side.



So I noticed something didnt seem right. But I went ahead with the install thinking that maybe it sorted itself when everything was finally back together. I was wrong.

I turned the key. No spark. The Crankshaft Position Sensor couldnt pick up the timing disc (part 15 in the diagram) therefore it wouldnt provide any spark to the engine. SOOOooo... lucky me had to pull everything down to the timing belt back off. Found out what I noticed was indeed the problem. The part from the mirage is thinner than the timing sprocket. Meaning that there was a tiny bit of play between the stack of sprockets on the crank shaft, and this allowed the timing disc to be back just too far for the sensor to pick it up.

Picture Evidence:






So there you have it. If your doing a balance shaft delete on our 4G69 engines dont bother picking up this piece its too thin. Now in saying that I dont know if this is different if you are using Evo parts. It apparently worked for Mitsuorder so that must be the case. But with factory Ralliart/4G69 parts it doesnt work.

Thanks for reading guys.

I hope this helps someone out there keep from making the same mistake I did.

CrAnSwIcK

iTrader: (5)

invaluable

Raikiri

iTrader: (21)

I'm pretty sure I just left the sprocket in there.

Pal215

iTrader: (12)

Just confirmed that this part MD128107 will only work for the 4g63t. This brings up the question now, why is the balance shaft sprocket on the 4g69 so thick?

-pal215

CrAnSwIcK

iTrader: (5)

to make up for its weak pistons

roni4g63

iTrader: (1)

lol

Pal215

iTrader: (12)

bakuro117

iTrader: (5)

Could have something to do with the sensing plate on the 4g69 being a different style than on the 4g63. The 4g69 just senses the 33 teeth as they pass by, and on the 4g63 has two large blades that pass through a sensor.

Its not just the balance shaft sprocket that is a different size either. The main timing sprocket is also more narrow on the 4g69 than the 4g63t sprocket. Discovered that earlier this year.