7A Flywheel Timing Pin

[Error404]

Lots of folk with 3B flywheels on ABY software, so they must have the same pin location

[Rusty]

Well that's grand, as mine was from driftin jo

I have 3B on there at the mo and it's been fine...

[elaw]

If the pin was 2 teeth off from the wrong position, the engine would probably still run, just the ignition and injection timing would be about 5.3 degrees off the correct value.

That number is small enough that many people probably would not notice, or would attribute the changed performance / knock tendency to other factors.

[zpix]

Alittle off topic

I have a 034 105 271 C Flywheel from an NG whitout pin, and I looked around and found that the 7A is the same number "034 105 271 C" just with a pin

My question is were is the pin placed? between which tooths? what's it's diameter and heigt? (I Swaped the NG with a 7A)

"Starting at the 0 mark on the flywheel; The 7A pin was 37 ring gear teeth from the TDC 0 mark" is that correct?

Because if i put the flywheel onto the gearbox and put 0 at the gearbox mark and count to the sensor hole its only around 20ish???

Hope you guys can help, sorry if I went abit off topic (:

[GazzaG60]

from looking at my aby flywheel compared with my 7a one the pin on the 7a is smaller in both height and diameter. its the same height as the teeth and sits tight to them. it has 2 pins on the other side the same height and size as aby. 1 in the correct spot plus another. it also has 2 skinny longer pins.


with the extras removed to summarise one pin is the same size and diameter the other is not. i feel especially for my vems application it will need working.

i will get a machine shop to lighten it slightly, skimming the back surface flat and then welding on an aby style block. that way it should have no issues. there must already be a good few kg different between the 2 but the extra kg or so removed should make it a little but not too much lighter

[UrS4boy]

from looking at my aby flywheel compared with my 7a one the pin on the 7a is smaller in both height and diameter. its the same height as the teeth and sits tight to them. it has 2 pins on the other side the same height and size as aby. 1 in the correct spot plus another. it also has 2 skinny longer pins.

Might be off base here but are you confusing the G4 crank sensor pin with the clutch pressure plate location dowels?

[Tille]

The timing pin always has the same position. Only the "0" mark is different. This is because the transmission window to set TDC at C Chassis transmissions is at a different location than the B Chassis transmissions.

[diesel des]

Really? How with same 01e gearbox?

[GazzaG60]

Might be off base here but are you confusing the G4 crank sensor pin with the clutch pressure plate location dowels?

maybe, not sure but dont think so. the aby does't have these pins any flywheel ive seen on here doesn't either. if they are dowels they are the same as the timing pin exactly? also i have lined them up with the aby pins and they match other than 1 extra one and the long thin pins??

the others are long think sticks rather than dowels.

i was gonna remove them and match it to aby pattern as others i have seen have done.

is mine another weird flywheel setup? same pn as the ones listed everywhere.

[elaw]

On all the 7A flywheels I've seen, there are 3 kinds of pins.

The timing pin is small (about 3mm diameter and 10-12mm long), solid, and is on the "back" of the flywheel, meaning the side that faces the engine.

The pressure plate locating pins are on the "front" (transmission side) of the FW and are about 6mm diameter and 10mm long. There are 3 of them, assuming none are broken or missing.

In addition, on the front of the flywheel there are two hollow pins - in the USA they're usually called "split pins" or "roll pins", not sure what the UK term is. They're around 6mm diameter but long - I'd say 25 or 30 millimeters.

As far as I know, the latter pins (the two hollow ones) don't actually have any function in the car - they're used for factory testing of some sort. So it's okay to delete them (actually sometimes they break off) - the only effect will be on the flywheel's balance.

[UrS4boy]

These are the clutch pressure plate locating dowels on an ABY (and ADU) dog-dish flywheel. The G4 crank position timing pin is on the engine side of the flywheel.

Just to be clear.

[GazzaG60]

thanks for clarification.

i have all 4 pins on the front of mine 7A. 2 dowel and 2 longer. the longer are a lot tinner than the dowel. the rear pin is small in comparison to the aby

on aby i have mistaken one dowel as a pin. seems im missing a dowel.

that clears that up. i only need the rear pin sorting then for the sensor.

o

[zpix]

I've read that the 7A and 3B FWs have the timing pin a few degrees different...

The timing pin always has the same position. Only the "0" mark is different. This is because the transmission window to set TDC at C Chassis transmissions is at a different location than the B Chassis transmissions.

Can anyone confirm?

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.

Was the gearbox mounted and did the 0 show on both flywheels in the the transmission window?

[etsola]

Quick question off a little off topic :

I have a 3b flywheel from a '91 200 TQ, does this mean it is single mass ??

Also, anyone knows if it has the same amount of tooth for the starter - engine speed sensor ? Because my RPM's are off and trying to figure out.

Cheers

[elaw]

Quick question off a little off topic :

I have a 3b flywheel from a '91 200 TQ, does this mean it is single mass ??

Should be! They're pretty easy to tell apart: if you look closely a dual-mass FW is clearly made of multiple parts (some of which can move relative to others) whereas a single-mass FW is just a single machined hunk of metal.

Also, anyone knows if it has the same amount of tooth for the starter - engine speed sensor ? Because my RPM's are off and trying to figure out.

It certainly should... I think all I5 flywheels of that era had the same number of teeth.

How much is your tach off at different speeds? If it reads 25% too high, it may be configured for a 4-cylinder engine rather than a 5. If it's off by less or just has an offset (like always reads 200 RPM high), it's probably just a little inaccurate. Dashboard tachs aren't exactly sophisticated scientific instruments.