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Trigger wheel on a 1500 pulley


sparky_spit

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When the rebuilt 1500 engine goes back in next year I might drag myself into the 21st Century and use Megajolt at some point. Now is the time to fit a trigger wheel in readiness for when that might happen.  2 questions:

I was going to weld the trigger wheel on, but am having second thoughts as the pulley is the embedded rubber anti-vibration type, and welding might melt and damage this. Is it best to bolt it on? What have others done?

Also, all the bottom end rotating components have already been balanced, including the pulley. As long as I use equidistant fixings, will the missing tooth be significant enough to upset the balance to any degree? I don't want to rebalance it all, as it was expensive enough as it is. Presumably a bent sheet wheel will have less impact than one of those thicker flat ones?

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On the Gt6 I bolted it the engine fan boss. This does mean that the trigger wheel is on the front of the pulley and if I need to change the fan belt I will need to remove the sensor to do so. I had the crank balanced with the wheel in place but didn't position it.  sods law says that when I came to fitting the Vr sensor the wheel needed to be rotated about 80deg .  This hasn't affected the balance as far as I can tell.

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339 wrote:
On the Gt6 I bolted it the engine fan boss. This does mean that the trigger wheel is on the front of the pulley and if I need to change the fan belt I will need to remove the sensor to do so. I had the crank balanced with the wheel in place but didn't position it.  sods law says that when I came to fitting the Vr sensor the wheel needed to be rotated about 80deg .  This hasn't affected the balance as far as I can tell.


The way to mount the sensor is to weld a bracket onto the timing cover so that sensor is inside the run of the belt.

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1381 wrote:
Don't remember seeing rubber anywhere on my 1500 crank pulley?

I bought a spare one off ebay that someone had welded a trigger wheel to. Whatever you do, it needs to be rugged.


I thought a standard 1500 Spitfire pulley had the centre part and the outer part bonded together with high density rubber.  It's this which sometimes, with age and deterioration, allows the outer part to slip round on the inner and thus making the TDC marker appear in the wrong place.

Can someone who knows for certain advise?  If I'm wrong I'll just weld it on.

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339 wrote:
On the Gt6 I bolted it the engine fan boss. This does mean that the trigger wheel is on the front of the pulley and if I need to change the fan belt I will need to remove the sensor to do so. I had the crank balanced with the wheel in place but didn't position it.  sods law says that when I came to fitting the Vr sensor the wheel needed to be rotated about 80deg .  This hasn't affected the balance as far as I can tell.


Yes, thinking about it, with all that mass in the crank/flywheel/clutch cover/pulley whirling around, especially around the periphery, a small bit of missing steel a few inches from the centre is going to be inconsequential isn't it?

Clive - with regard to having no rubber in there, what is it that allows the outer part to sometimes slip on the inner?

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sparky_spit wrote:


Clive - with regard to having no rubber in there, what is it that allows the outer part to sometimes slip on the inner?


I've only ever known this happen on 6 cylinder engines.  Have had more than a few 1500 engines and they all have solid pulleys.

To answer your original question, I had a small shoulder machined onto the back of my pulley and then machined the trigger wheel out so that it sat nicely over the shoulder ... I then held it in place with small grub screws loctited in.  I'll try to get a picture up later.

Mark


update - not so easy to photograph in situ but this gives the idea



You will notice that this is a 1300 not a 1500 but I think the same approach will work.  Also, as mentioned above, it is probably easier to mount the sensor on a bracket welded to the front of the timing cover.

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cliftyhanger wrote:
No rubber on the pulley. At least not on the ones I have here.....

Be good if somebody could get a batch of the sheet steel trigger wheels made up, ideally with the opening a snug fit on the pulley


I'm your man Clive.  Did a batch for the 6 cylinder engines a while ago.  Just need a 4 cylinder pulley sending to me for reference.

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I have welded one on a pulley already. One of the triggerwheels jobbies. Could probably do with balancing before fitting, when I get around to it.

I was thinking more for everybody else though. teh ones available are either a touch too large or small, so either careful fitting or machining is required. A made to measure would make life a lot easier.

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You win, I lose. Especially Nick as he got the A series bit right.  See attached picture, which shows a 1500 Spitfire pulley (on the left) and a 1275 A-series one off the Mini (on the right).  I must have noticed the Mini one a while back in the garage and thought it was the Spitfire one. Both engines are in bits at the moment, so that's my excuse.

Lots of excellent suggestions above. I've got a lathe so I'm going down MarkDeTriomphe's route of making a small shoulder on the back of the pulley to locate a Triggerwheels triggerwheel, and bolting/loctiting it on. This takes all the effort out of trying to keep it concentric whilst drilling/welding/whatever.

Then a sensor bracket welded on the timing chain cover, with enough scope for rotational adjustment. Job done, well, in my head anyway.

Thanks guys. 10/10 as ever.

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Gt6s wrote:


Is sensor position not covered by the software ? I know mine is but then I am not on Megasquirt.


I don't know but it would be good if it is. BTW this will be Megajolt, not Megasquirt. Can someone tell me?

All I need to worry about then is in/out  adjustment to cater for the air gap. I take it the sensor is threaded and has 2 locknuts?

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sparky_spit wrote:


All I need to worry about then is in/out  adjustment to cater for the air gap. I take it the sensor is threaded and has 2 locknuts?


That depends on the sensor, but the common Ford sensor is not adjustable in that manner.
                                                     Good luck,
                                                     Paul

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