Trigger Wheel thickness

MustangSix · Post by **MustangSix** » Tue May 04, 2004 3:41 am

How thick does a trigger wheel need to be? If I were to make one from scratch, thinner would be easier. But does that affect the quality of the sensor input?

oddcomp · Post by **oddcomp** » Fri May 07, 2004 12:44 am

look at how wide the actual metal portion of the sensor is ..
the thinner the wheel the more accurate you have to be with sensor placement
personally i would not go less that 1/8"
where as the stock wheel i think is 1/4"

Barry_D · Post by **Barry_D** » Fri May 07, 2004 3:40 am

Hello MustangSix,

I just bought a brand new Crankshaft Vibration Dampner Assy yesterday that was delivered today. To get a more precise measurement, let's use mm.

The Trigger Wheel is 6mm thick x 140mm in diameter measuring to the outermost distance 180 degrees from teeth ends. The teeth are 4mm between each, except for the space where the missing tooth is, which measures a 13mm gap. The teeth extrude 5mm in length. They are triangular shaped almost, measuring 7mm at the bottom, and 5mm at the top outer ends.

If you're going to have a wheel machined, I'm sure this is all the machinist needs to know, except possibly that once seperated from the Crankshaft Vibration Dampner, the thickness of the Trigger Wheel from its center to the top of the tooth is 17mm.

Think of it as being like a small ring gear as compared to one that is around a clutch flywheel.

I hope this answers all of your dimension questions... I suppose I could take some pics and upload them in a day or two when I get time if necessary.

1974 2002 BMW wide body w/many mods...
complete engine rebuild, f.i/turbo/MegaJolt
& MegaSquirt conversions starting now!
(=oo=)
Rock on Brent!

Barry Durham
barry@BMWupgrades.com
501 227-4365
http://www.BMWupgrades.com/
Coming soon...

MustangSix · Post by **MustangSix** » Fri May 07, 2004 5:36 pm

The harmonic balancer on the engine I'm using has cast iron pulleys with two sheeves. I'm only using one of them for a belt and was thinking of cutting teeth into the other sheeve to use as the trigger wheel. But at the point of the teeth, it would only be about 3/16 of an inch thick.

This is thinner than most trigger wheels I've seen, but would be the easiest way to add a trigger to this engine. If this is thick enough, how close should the sensor be to the wheel to get a good reading?

squirrelgripper · Post by **squirrelgripper** » Sat May 08, 2004 4:26 am

Barry (or others) - do you have the part # / price for the Ford harmonic balancer? Is the trigger wheel hollow in the center, like in this thread?
http://www.914club.com/bbs2/index.php?s ... f=2&t=9123

The reason I ask is that I ordered a trigger wheel, but it's a different design - instead of a large open center, it has a small center with a keyhole (like it was designed to attach directly to the crankshaft). On the plus side, it was $18.

Also, MUSTANGSIX - the clearance listed in the EDIS specs is 1mm.

MustangSix · Post by **MustangSix** » Mon May 10, 2004 2:28 am

Thanks all!

I think that machining the cast pulley will work based on your input.

Barry_D · Post by **Barry_D** » Mon May 10, 2004 2:55 am

Hello SquirrelGripper,

The Ford part # on the outside of the box I received is: 2M5Z-6312-AA, and as a description is says, Pulley. What I ordered is the entire assy that Ford calls a "Crankshaft Vibration Dampner Assembly" for a 91-96 1.9L Escort. And yes, it's exactly as pictured in the link on your previous post. Once the rubber on the front the the assy is heated with a torch, it seperates and the trigger wheel drops off the assy while prying, as what looks like a ring gear. No keyway, just a ring gear. Mine was $76.00 + shipping. If one of us would take one of these to a machinist, we could probably get the cost down to about $25.00 per gear.

Hope that helps!

1974 2002 BMW wide body w/many mods...
complete engine rebuild, f.i/turbo/MegaJolt
& MegaSquirt conversions starting now!
(=oo=)
Rock on Brent!

Barry Durham
barry@BMWupgrades.com
501 227-4365
http://www.BMWupgrades.com/
Coming soon...

bwells · Post by **bwells** » Mon May 10, 2004 5:05 pm

Squirrelzipper,

Hate to see you have to buy new parts. Here in Dallas, a used balancer/trigger wheel assy and pickup was $15.00 at the U-Pull-It junkyard. There were dozens of Escorts with all parts intact. This has the ring gear style wheel that Barry_D referred to. I am sure most other yards are going to have plenty of these vehicles. They are not that hard to remove, once the right front wheel and splash shield is removed.
I have pressed apart the three piece dampener assy into a hub, trigger wheel and belt pulley. The pulley was discarded and the hub will be used as a base to mount the wheel to my car's dampener. Since the inside diameter of the trigger wheel is about four inches, don't overlook using the iron hub as a base to mount the wheel to your engine. I have a small lathe and can modify it to fit. This will be a six cylinder Corvair application.

Good Luck,
Bill

Autosport Labs