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oldtuckunder

Trigger Wheel Mounting Vitesse

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Hi Wise Ones

Have the Radiator out of the Vitesse, and am contemplating Trigger Wheel mounting options for the contemplated Electronic Ignition. I have some options and also some issues, and wondered if anyone had any thoughts. Now as anyone with a Vitesse or GT6 knows there isn't that much room in front of the crank pulley, and especially if like me you have an electric fan engine side of the radiator, so my Crank Shaft Bolt is already one of the short ones on a short mounting spacer. I would also like to mention that with everything else installed I just have room to get a long spanner on that bolt head to turn the engine for setting tappets etc, so I don't want to loose that.

As you can see from the pictures there isn't room to mount a Trigger Wheel on the back face of the pulley well not unless I can get one about 2mm thick, and as I'm not sure how much the teeth need to protude it might also foul the timing marker (which it would be nice to keep). Also bolting/welding to the extremities of the pulley also probably isn't a good idea as its of the rubber harmonic type, and whilst the rubber is good, if it did start to slip or fail it would be a bugg.r to have the timing move with it.

So I'm thinking the only option is to look at holding it on with the crank shaft bolt, or rather as if I need to remove it (and undoing a 100ftlb bolt with anything other than a long persuader and a fair amount of room is impossible), actually put a small 5mm thick collar under the bolt to centre the trigger wheel, and then drill and tap the boss under the bolt (it is dowelled to the pulley) and bolt the trigger wheel to the pulley. 

OK so I may have somewhere to bolt the trigger wheel, but then we get on to the next issue, mounting  the sensor, I know it has to go somewhere so that it aligns with the missing tooth "n" degrees before TDC, I know it varies by engine type but can I find out what it should be for a straight 6 no I can't!   But any way assuming its somewhere between 20 and 180 BTDC It looks like I have plenty of room to make/fit a bracket that will mount the sensor, and also a selection of useful bolt heads to attach the bracket to.  OK so here is my real problem, now I understand that the sensor head has to be within a few mm or thou of the trigger wheel, so I make a neat bracket that comes off and positions the sensor next to the wheel that is mounted on the front of the pulley (like most of the example pictures you see everywhere. HOW DO I GET THE FAN BELT OFF?

As far as I can see the only options are 1) Unbolt the sensor bracket and risk not getting it back in the right place on a damp night, or 2) Unbolt the Trigger Wheel in a very confined space.

As a fan belt has to be one of the most likely failures (Oh alright I can't remember when I last had one) so do I keep a set of spanner just for this job always in the car, or can a bit of sideways thinking solve it?

Oh I have measured and I can't mount a trigger wheel on the front of the pulley but behind the belt pulley as its not deep enough and the belt would be rubbing on it.

Alan

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Hello Alan

                 I machined a TR6 crank pulley for the teeth it was an after market one and the inner part of the vee groove was bigger than the front I will find a photo if I can

This may help and its the same for Microsquirt

  • EDIS-4: missing tooth is exactly nine teeth (90°) ahead of the VR sensor,
  • EDIS-6: missing tooth is exactly six teeth (60°) ahead of the VR sensor,
  • EDIS-8: missing tooth is exactly five teeth (50°) ahead of the VR sensor.

Roger

Edited by rogerguzzi

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I turned down the centre weight of the pulley ever so slightly, enough to let me mount the wheel flush to the pulley face , and tap 4 holes for my wheel.

The mount for the sensor has channels in the back to sit flush on the cover, and is tapped from behind.  Three o-ringed and loctited machine screws hold it in place.

The wheel only adds 3mm to the face of the pulley this way.

 

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With Megasquirt you can dial in the exact degrees of offset.  It's a good idea to be in the 60 degree region still though, as it puts it out of the compression squeeze area that can confuse the ecu.

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Duh!  of course it only took the first Sideways Genius to point out my error, I was foolishly looking at mounting the sensor on the outside of the trigger wheel in the 6 o'clock thru 10 o'clock position to get the missing tooth offset from TDC, forgetting that the missing tooth can of course go anywhere in relation to TDC as long as the sensor moves also. And of course in the above the sensor is still on the outside of the trigger wheel, but inside the belt loop. Now I'm feeling stupid!

Many thanks, especially as my centre boss is already turned down so the Trigger wheel will sit flush and I can just bolt to the boss. Just got to work out a mounting bracket for sensor!

Alan

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What Craig has is more or less the same as I had on my PI - except I used the trigger wheel sawn off the pulley of a Sierra 1.8CVH.  I even managed to get the mechanical fan back on afterwards (and that even still missed the radiator - just).  Working out how to get the fan bolt holes in the right spot and still have the missing tooth in the right place did lead to the smell of burning hair though.

Vitesse has the same trigger wheel arrangement as the PI, but a detachable sensor bracket that bolts to the front plate.  It's a stupid design as the bracket has to come off to change the fan belt - but it does the job.

Nick

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Someopne was selling a thin trigger wheel a while ago, so this is what I did with it as clearance was so tight.

The red nose cone was turned down from the original cylindrical spacer, to clear the electric fan motor.

 

But since then, I've moved the engine back, by putting the support brackets behind the turret mounts, clearance is not a problem any more, and the first whel is on a another project.

So I have a convenetional thick wheel, like this.

 

John

 

 

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Thanks John

I had seen pictures of those fold over wheels, but on a quick search I couldn't find any, were the mounting screws into the outer or inner ring of the damper pulley. I had wondered if I might just squeeze one in at the back if I used counter sunk set screws to keep everything as thin as possible.

Alan

 

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I think it might have been Tim Ward (Club Triumph Forum) made a batch of those.  Was quite a while ago now.......

He's been poorly but did pop up on the CT forum a couple of months back.  He's Worcester way too IIRC......

Nick

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Hello Alan

                  These photos may not help but rear mounted is Spitty and front mounted is TR6 and the temperature sensor is were I fitted it on the TR6

 

Roger

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3 hours ago, oldtuckunder said:

Thanks John

I had seen pictures of those fold over wheels, but on a quick search I couldn't find any, were the mounting screws into the outer or inner ring of the damper pulley. I had wondered if I might just squeeze one in at the back if I used counter sunk set screws to keep everything as thin as possible.

Alan

 

Ooops!  Forgot!

Yes, those hex-head screws fouled the timing cover, just.  Made a terrifying noise on start-up!   I was sure all big ends had gone at once!

Modified with counter-sunk head screws - fine!

 

My sesnor mount v.similar to Roger's.   Lower mount hole circular, upper slotted on a radius, to allow distance adjustment.

JOhn

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