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WTF with bells on... I am going out to look at my own flywheel (ABY). There is something silly going on there.
Totally understand few degrees skew on Dessie's flywheel with a bit of wonky welding - this is why the viking god of engineering invented adjustable camshaft pulleys !
Vems likes a stronger pulse than Motronic for the reference pin. I still a hole in a piece of steel and use the stock pin as a datum. But the pin is now wider.
Right so something doesn't add up... I have exactly the same 38.25 teeth on ABY flywheel as reported by Dave. So either the Audi docs we have been quoting at 62 deg BTDC from Cyl #1 for the G4 are wrong, or the little timing mark on the edge of the flywheel isn't 0 deg BTDC for #1.
I have never lined up one of these flywheels with the head off - do we know the mark for certain is 0 deg BTDC on Cyl #1 or some other cylinder (but that doesn't make any sense as the 40 degree difference wouldn't align with any other cylinder at TDC as we expect to see a spark every 144 degrees from 2x360/5 or 72 degrees for sequential TDC events ) ?
Could it be the G4 sensor position on the RR & 3B motor was 62 deg BTDC and Audi changed it for ABY onwards and forgot to update the manuals ?
But thats garbage too as we know people who have bolted 3B flywheel onto ABY Moronic ECU and not seen a timing problem.
Here is a pic. You don't need to be Pythagoros to see the angle from 12 o'clock (timing mark) to the trailing edge of the G4 lug is in 100degree territory.
Sorry the light is a bit poor and the measurement method isn't supposed to be deadly accurate.
Here is a pic. You don't need to be Pythagoros to see the angle from 12 o'clock (timing mark) to the trailing edge of the G4 lug is in 100degree territory. Sorry the light is a bit poor and the measurement method isn't supposed to be deadly accurate.
Lightened it up a bit so you can see the timing pin and 102 deg (or so) better. I think the literature has to be wrong, probably for all of them.
If the Cyl#1 timing mark is off by less than two teeth (and we know Hans und Franz struggled with camshaft mark alignment already) then my 62 degrees in HEX is pretty damn close.
I am imagining a German episode of the famous engineering Dilbert comic strip, where the really annoying guy form technical publications calls a meeting with the lead engine developer who thought it would be funny to tell him this crucial measurement in Hexadecimal... Who says the Germans don't have a sense of humour - we finally rumbled this joke about 25yrs late
Right folks here goes, the AAN has the flywheel ring gear on the back of the flywheel closest to the engine and has 135 teeth, unfortunately after numerous hours of searching the biggest flywheel clutch combination that I'm able to find due to the ring gear being on the clutch side of the T4 is 228mm and the flywheel only has 132 teeth on the ring gear, it has to be in this configuration as the starter motor enters the gearbox on the rear face with the nose pointing towards the front of the AAN engine.
The flex plate in question is the flywheel that came with my AAN engine from a automatic UrS6 and it is this that I'm proposing machining the ring gear from and getting fitted to my new single mass T4 flywheel rear face to imitate the configuration of the Audi engine.
From what I've read in the replies above I'm correct on the G4 timing pin position it's just the other two pins on the opposite side of the flywheel to the G4 pin that I'm wondering about now, are these needed and if so why are they there?
Thanks to everyone for replying.
Shaun
Are we forgetting that the timing sensor is at a different position arround the bell housing than the tdc window....
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You beat me to it mate.
I was just about to ask if the TDC mark and window were actually located at top dead centre or further around to the side of the engine?
That's true Des - by which the TDC mark might pass the G4 sensor window (say around the 2 o'clock point on the picture above) at 62 degrees after TDC.
That is trickier to measure but it's also clearly stated in the Audi docs that the G4 signal arrives 62 deg BTDC #1... So maybe something got lost in translation.
The location of the viewing window is NOT at TDC, it is off to one side. But that is irrelevant the location of the G4 timing pin is supposed to be relative to TDC (and the TDC) mark not the TDC viewing window.
RS2'd 93 UrS4 5 spd sedan
94 UrS4 V8 6 spd manual avant
Wouldn't be the first time the factory data is incorrect. On my engine not one of the TDC marks is accurate to actual TDC. They are only there as an assembly aid. Check timing and firing reference offset with a timing light they are kinda useless.
That is what I was getting at, the top dead centre mark must be off from actual top dead centre by however many degrees around the bell housing that the viewing window is, therefore the G4 pin location in relation to the TDC mark will in fact be more than 62 degrees apart.
I fully understand that the G4 pin should be set at the correct 62 degrees before TDC now though and I will go off actual TDC not the TDC mark on the flywheel.
Thanks for clearing things up for me though UrS4boy.
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