G28 engine speed sensor for AAN conversion

[Shaun-P-C]

Hi folks, I'm doing an engine swap into a VW T4 and wondering how critical the number of teeth on the ring gear is?
I know that the ring gear on the AAN URS6 flex plate has 135 teeth but I'm not sure that I can get a flywheel with this number of teeth for the T4 gearbox flywheel.
Will this matter or can I get away with a lesser number of teeth?
Thanks in advance
Shaun

[UrS4boy]

Crank Position (G4) and Engine Speed Sensor (G28) Info - Function , Location and PNs



Other than going to VEMS, you are going need a 135 tooth flywheel for Motronic to work.

Crank Position (G4) and Engine Speed Sensor (G28) Info - Function , Location and PNs:
http://forums.quattroworld.com/s4s6/msgs/20986.phtml

[Shaun-P-C]

Thanks for your reply UrS4boy (please excuse my ignorance, I'm sorry I don't know your real name).
Right so I've bought a steel flywheel for my conversion and I'm thinking my easiest solution is to get it machined along with the flex plate so that the ring gear from the flex plate can be fitted to the new flywheel, while its at the machine shop I will also need the pin for the G4 trigger fitting, am I correct that the pin needs fitting at 62 degrees before top dead centre?
Also on my flex plate it has 2 more pins fitted, what are these for and do I need to get those installed too?
Thanks in advance.
Shaun.

[UrS4boy]

AAN G4 Timing Pin Location Details

So when you say "Flex plate" and T4 I am thinking that you are going to mate an AAN to a T4 automatic transmission (?). *IF* so, good luck. I doubt that the autotrans will last very long dealing with the torque of the AAN. Definitely don't chip it or add a bigger turbo.

As for the "62 deg" thing, you need to measure the location of the G4 timing pin relative to the TDC mark on the AAN flywheel as you make up a new flywheel for your application.

Other details regarding the G4 timing pin can be found here:

http://forums.quattroworld.com/s4s6/msgs/51259.phtml


Photo courtesy of V6quattro on the S2 forum

[Shaun-P-C]

No absolutely not mating it to an auto box, I'm actually fitting it in to a VW T4 Caravelle with a 6 speed manual gearbox.
I'm thinking of having the starter ring gear machined off the flex plate from the UrS6 and getting the new T4 flywheel machined to accept the ring gear from the UrS6 on the rear of the flywheel opposite side to the T4 ring gear.
Unfortunately my Ur flex plate has no noticeable TDC mark but the new flywheel does so do I set the timing peg at 62 degrees before TDC then?
Also like I say the two other pegs on the opposite side of the flex plate? Will I need these or not?
Thanks again
Shaun

[S2central.net]

Right I am going to ask the dumb question as I know nothing about Caravelle's - what is this 'flex plate' that you speak of ?

Also - rather that trying to modify the Caravelles original flywheel for the AAN motor... why not use an alternative gearbox with the right shape input shaft to accommodate the AAN clutch... or assuming the Caravelle gearbox does bolt up to the AAN motor - just get a custom clutch made with splines that match the Caravelle input shaft ?

[UrS4boy]

No absolutely not mating it to an auto box, I'm actually fitting it in to a VW T4 Caravelle with a 6 speed manual gearbox.

Then you don't have a flex plate. You have a flywheel. Probably single mass.

Also - rather that trying to modify the Caravelles original flywheel for the AAN motor... why not use an alternative gearbox with the right shape input shaft to accommodate the AAN clutch... or assuming the Caravelle gearbox does bolt up to the AAN motor - just get a custom clutch made with splines that match the Caravelle input shaft ?

Are sure that the AAN flywheel doesn't work without modification? Where are the folks who have used T4 2.5L engines for AAN strokers? They must be able to comment here.

[S2central.net]

Very good point Dave - the gearbox used in the 5cyl T4 must bolt right up the 2.5 block - which we know is same bolting as the AAN... so there must be a 240mm clutch that suits the T4 gearbox shaft even if that is different from 01E that the AAN clutch would expect.

[Error404]

From memory the crank reference trigger angle is 58deg BTDC

[S2central.net]

Its deffo 62 degrees BTDC for crank reference position - as seen in numerous factory manuals from 3B-->AAN-->ABY-->ADU

[UrS4boy]

Its deffo 62 degrees BTDC for crank reference position - as seen in numerous factory manuals from 3B-->AAN-->ABY-->ADU

As posted above

[diesel des]

My vems seems to think it's at 59 degrees from memory. This is by using a timing light and setting timing to 0 then moving the reference angle to align the tdc Mark. I get 58.5 deg I think....

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[S2central.net]

Wtf

[diesel des]

Could be due to me welding on a bigger pin on the flywheel....

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[UrS4boy]

Wtf

This will really make your head hurt Paul:

I have a new in a box (NIB) LUK DM AAN flywheel. Off topic, I am disappointed and shocked that they left the edge like this. Another local to me one that I saw the other day was the same.

Back on topic: One tooth = 2.67 degrees (= 360/135). TDC is supposed to be 62 degrees away from the G4 timing pin = 23.25 teeth (nice, counting 0.25 teeth). (Not sure if that is center of the G4 pin or edge)



Eventually found the timing mark:

Found the timing mark on the NIB DMFW. Not 23.25 teeth from G4 pin. 38.25 teeth
Not sure why the literature says the G4 is 62 degrees away from the TDC mark (= 62/360 x 135 = 23.25 teeth). 38.25 (ish) = 102 degrees. (!!??)