Flex Plate

[demon69]

Hi all

I have a 69 Mach1, 351W with FMX, pretty much stock.  I'm replacing the torque converter with 2500 stall.  I removed the flex plate and it has to be replaced, the ring gear is shot.  First I purchased a Pioneer 164 teeth 28 oz external balance but the bolt hole alignment is not matching, I can get 4 of the 6 bolts in but the other two are too tight.  I took the plate back to the supplier, he pulled out a 351 crank and the plate bolted up no problem.  I changed to an Aeroflow AF89-302ESFI 164 teeth 28 oz external balance, I can get 5 bolts in okay but the the 6th bolt does not fit, I would have to enlarge the bolt hole on the flex plate slightly for the bolt to fit.  Has anyone experienced a problem like this, any suggestions???

Thanks
Peter

[6t9m1]

The chances of placing the flywheel on the crank shaft and all six bolt holes lining up first time is very unlikely.

Have you tried turning the flywheel one bolt hole at a time until the holes line up?

You may need to try this up to 5 times.

[Reborn67]

 It's my understanding ( and i could be corrected ) that the flexplate will only go on one way, this is to ensure the balance on the flex plate aligns with the crank, so the holes are deliberately out of line, try as 6t9m1 says, keep rotating until the holes line up,  the supplier should have known this.....,

[GEOFF289]

It's my understanding ( and i could be corrected ) that the flexplate will only go on one way, this is to ensure the balance on the flex plate aligns with the crank, so the holes are deliberately out of line, try as 6t9m1 says, keep rotating until the holes line up,  the supplier should have known this.....,

Yep, it'll only go on one way.

[demon69]

Yes absolutely, that is correct, it will only go one way.  And that is my problem, I have it aligned it correctly but still have the issue of the one hole being slightly out.  Cant figure it out, its like the crank is out of whack.

[HAMBURGLAR]

Yes absolutely, that is correct, it will only go one way.  And that is my problem, I have it aligned it correctly but still have the issue of the one hole being slightly out.  Cant figure it out, its like the crank is out of whack.

Don't want to sound condescending or anything disrespectful , but are we positive its a 351 Windsor and not something else. Just saying !

[barnett468]

Yes absolutely, that is correct, it will only go one way.  And that is my problem, I have it aligned it correctly but still have the issue of the one hole being slightly out.  Cant figure it out, its like the crank is out of whack.

As was mentioned, you need to rotate the flywheel by 1 hole at a time until all the holes line up PERFECTLY, and this may require rotating it up to as many as 5 different holes. This is because the holes are intentionally not evenly spaced. This is so it can not be clocked incorrectly which would place the external weight in the wrong position. It is a very annoying design.

[GEOFF289]

Yes absolutely, that is correct, it will only go one way.  And that is my problem, I have it aligned it correctly but still have the issue of the one hole being slightly out.  Cant figure it out, its like the crank is out of whack.

I also don't want to come across as condescending - I sure ain't no expert - but we are all trying to help.

As has been suggested, have you rotated it around a hole at a time and gone all the way round, i.e. tried it in all of the positions it can be? Unless you have I don't think you can be sure it is in fact aligned correctly.

Satisfy yourself the bolt pattern is the same as the one you've removed, or that it's different, by putting one on top of the other and poking the bolts through. You'd still need to rotate one of them a hole at time but could be doing this on the bench rather than lying under the car.

[mwizz]

I had my flex plate changed for a new one but when I got it back there was a lot of vibration and it drove like a dog. The new plate had not been balanced when it went in. Luckily I kept the old flex plate so that the new one could be removed and balanced against the old one and now the vibrations are gone. I know that this is not your issue but keep your old flex plate just in case.

[demon69]

Yes, done all of the above including rotating the flexplate until the bolt holes align.  Its not like I have just started playing with this stuff, I have a bit of experience with engines etc. That's why it is frustrating, it doesn't add up.  I can put my old flexplate back without any problem.  I have now tried another Aeroflow flexplate and I can get all the bolts into the crank.  This shows that there are inconsistencies in the punching (manufacturing) of the plates from the same manufacture, in this case.. Aeroflow.  These flex plates cost under $100, I wonder if they are so cheap the manufacturing is inferior.  I would like to try a more expensive plate to see how that matches up.  But the main suppliers I have found only carry Pioneer and Aeroflow.   

[Reborn67]

That could be explained why you can pay less than $100 to twice that for a flexplate..,

[barnett468]

Yes, done all of the above including rotating the flexplate until the bolt holes align.  Its not like I have just started playing with this stuff, I have a bit of experience with engines etc. That's why it is frustrating, it doesn't add up.  I can put my old flexplate back without any problem.  I have now tried another Aeroflow flexplate and I can get all the bolts into the crank.  This shows that there are inconsistencies in the punching (manufacturing) of the plates from the same manufacture, in this case.. Aeroflow.  These flex plates cost under $100, I wonder if they are so cheap the manufacturing is inferior.  I would like to try a more expensive plate to see how that matches up.  But the main suppliers I have found only carry Pioneer and Aeroflow.

Take your flex plate to a shop that sells them and have them match it up or make a pattern of the holes on a manilla folder and take that.

I have not seen ANY inconsistency in pioneer plates in 40 years.

[shaunp]

Never had an issue with Pioneer plates.