7A Flywheel Timing Pin

[Rusty]

I've read that the 7A and 3B FWs have the timing pin a few degrees different... is this correct and does it affect the stock ECU operation?

[GazzaG60]

didn't know that also interested as i have a 7a flywheel to fit. where did you hear that andy

[here2learn]

I have a 7a on mine un modified and have no noticeable effect. Would like to know if this is a potential issue,wouldn't the other sensors help to determine correct timing to counteract this?

[A1QSHIP]

I've read that the 7A and 3B FWs have the timing pin a few degrees different... is this correct and does it affect the stock ECU operation?

It depends on which 3B flywheel. I purchased a "3B" flywheel, P/N 034 105 271F, to use to replace the dual mass unit in my S6. I had thought that it would fit straight on but it did not have the center spigot to mount the pilot shaft bearing. I ended up using a lightened & balanced (not shown) 7A flywheel P/N 034 105 271 C instead. I took pictures but do not have the one on this computer that shows the timing pin difference of the two flywheels. The distance is essentially "two ring gear teeth". Keep in mind the pin location is between two adjacent ring gear teeth.
Here is what I have to show now.





I believe that the 034 105 271F flywheel is used with a 3B engine & an 016 transmission.

Just for kicks here is a picture of a AVK 6 cylinder flexplate on a 7A block. Another project for the future.





Chris

[quattro-nick]

i have used the 3b flywheel 034 105 271F on my AAN engine and made a centerplate to mount the pilot shaft bearing.
I have the timingpin compared on the AAN flywheel and 3b flywheel and they were just on the same place.
I've just welded a bigger piece of the pin to get a better crankshaft signal for VEMS

[pasbogdan]

It depends on which 3B flywheel. I purchased a "3B" flywheel, P/N 034 105 271F, to use to replace the dual mass unit in my S6. I had thought that it would fit straight on but it did not have the center spigot to mount the pilot shaft bearing. I ended up using a lightened & balanced (not shown) 7A flywheel P/N 034 105 271 C instead. I took pictures but do not have the one on this computer that shows the timing pin difference of the two flywheels. The distance is essentially "two ring gear teeth". Keep in mind the pin location is between two adjacent ring gear teeth.

Have you measured the timing setting the parts with the crank mounting holes concentric 100%(not using the mounting screws,but with 0.00mm deviation from holes ID made pins to insert in the holes of both flywheels) or used an engine to mount one flywheel,get a mark for the pin position,mount the other one get the mark for the pin and compare?Because aligning the flywheels using starter gear teeth as reference seems not a good option.From my point of view starter rings can be mounted in any position,as rpm and crank position are independent info that ecu uses and not only one is a position sensor.
Very interested in this supposed angle difference.Soon i will get a 7a fly to compare with a 3b one.But maybe someone already has the correct measured thing.

[andy10v]

I never thought about the 3B 016 flywheel, I only think of the 3B 01A flywheel as we never got 200 20vt in the UK.

Where did you get your info from Andy?

[Rusty]

http://www.s2forum.com/forum/showthread.php?t=16954&highlight=7a+flywheel

http://www.s2forum.com/forum/showthread.php?t=46293&highlight=7a+flywheel

[andy10v]

Interesting.

[A1QSHIP]

Have you measured the timing setting the parts with the crank mounting holes concentric 100%(not using the mounting screws,but with 0.00mm deviation from holes ID made pins to insert in the holes of both flywheels) or used an engine to mount one flywheel,get a mark for the pin position,mount the other one get the mark for the pin and compare?Because aligning the flywheels using starter gear teeth as reference seems not a good option.From my point of view starter rings can be mounted in any position,as rpm and crank position are independent info that ecu uses and not only one is a position sensor.
Very interested in this supposed angle difference.Soon i will get a 7a fly to compare with a 3b one.But maybe someone already has the correct measured thing.

Both flywheels shown were bolted to the block in the pictures. They can only be fitted one way. The TDC mark for both flywheels was in the correct position on the block & corresponded with #1 piston at TDC. I counted the ring gear teeth from the 0 mark on the flywheel to the timing pin. Starting at the 0 mark on the flywheel; The 7A pin was 37 ring gear teeth from the TDC 0 mark & the 3B pin was 35 teeth from the 0 mark. The ring gears had the same diameter & the tooth count (135) on both 7A & 3B ring gears.

[A1QSHIP]

I never thought about the 3B 016 flywheel, I only think of the 3B 01A flywheel as we never got 200 20vt in the UK.

The advert for the flywheel said it was for a 3B & I bought it because it looked lighter than a 7A & had enough mass to suit the AAN engine in my S6. When it came to the pilot shaft bearing I never thought that there was a difference between the 016 & the 01E or 01A transmissions. I overlooked the fact that there was no pilot bearing mounting provision. Blinded by a "Good Deal" I guess.

[A1QSHIP]

Delete double post.

[vidar skotheim]

So what is then correct ? i also have a 7a flywheel that dont have the original pin , and looks like not balanced , also missing some machining around the pin , so need do machine before possible to put in a pin , not sure were this came from , have same part nummber as normal flywheel ..

[A1QSHIP]

So what is then correct ? i also have a 7a flywheel that dont have the original pin , and looks like not balanced , also missing some machining around the pin , so need do machine before possible to put in a pin , not sure were this came from , have same part nummber as normal flywheel ..

Pictures would help.

[driftin jo]

I checked the location of the pin on 034 105 271 C flywheels that I machined and it was in the same location as the ABY, don't know about the 3B as I've never had one in my hands.

As for part numbers of flywheels and I’ve said this before , I personally taken 2 flywheels from 7A engines and they were all 034 105 271 C not 034 105 271 K as AUDI list them!
I'm not saying there aren’t any with the K suffix but all the ones I have bought have also been C suffix.