Flexplate headaches

[Omie01]

I have purchased 2 different flex plates through Summit for my 351C, and neither of them have fit the bolt pattern correctly!! I bought a B&M SFI approved back in 2016 and had to "Modify" it to fit, but now I have a small vibration that comes and goes with engine RPM, so I decided to swap out the flex plate because it was the cheapest part, and it never sat right with me that I had to make it fit. So this time I spent twice as much on a TCI flex plate SFI 29.1, and guess what, SAME PROBLEM!! the bolt holes are just BARELY off, and we all know they only bolt up one way with the 28 oz. counterweight. I tried both of them on a different crank I have and same story. But get this, one was $75, the other $153, and they are both made with the same tooling, even have the same made in mexico stamp, just one has more welds and a different finish. Hmmmm!!!??? Anyway, I am returning the latest one, and now have a $209 ATI coming to me. Buyers beware! I just want to know, using ARP bolts, do I use a thread lube and torque to 75 ft lbs, or use loctite and torque to 70 ft. lbs? What have others done? I have the 12 point ARP bolts for my flex plate.

 

[Carolina_Mountain_Mustangs]

That is so strange that they got the bolt pattern off. 

On the fasteners. I always use red thread locking Loctite on crank bolts for flywheel or flex plate. Also fasteners on converter. Here is link to their web site listing all types and applications. 

https://dm.henkel-dam.com/is/content/henkel/threadlocking_capability_guide_brochurepdf-1

 

[Hemikiller]

FWIW, ATI makes good stuff.

A bolt pattern is a pretty basic item to make sure it's 100%. B&M and TCI are part of a "group", which typically means they're buying parts from other people.

Have you called either company with your concerns?

 

[turtle5353]

This is the one i put in my car. Fit great and pretty cheap. Been in there since 2016.

https://www.summitracing.com/parts/sca-fp302157sfi/applications

 

[jpaz]

I got a Pioneer 32-202 from Summit for my build last year and it fit just fine. No issues with it so far.

 

[Omie01]

The ATI is nice, but it is not offset like it should be, and the center hole is too big. Like it was suppose to have an adapter? Now waiting on another TCI just to see if I got a "fluke". Not even sure what to think now! If this don't work, gonna just return everything and buy from a different vendor! I'll keep you posted!! Thanks!

 

[Don C]

Is the crankshaft an original, or a replacement? If all of the flexplates seem to be wrong I would suspect there is something wrong with the crankshaft. I have 2 stock crankshafts and can take some measurements, if you would like.

 

[Omie01]

The crankshaft in my car is stock, plus an extra stock one at my shop, and the flexplates don't fit either, and get this, I had them send me another TCI to see if it was a fluke, but thats the second one that did not fit. They are barely off on 3 holes, I just don't want to grind the holes open. I did that on my B&M and I suspect that may be the cause of the vibration issue I am having. I just want a flexplate that bolts to a stock 351C crank!! Can't be that hard!! I have a 164 tooth, 28 oz. imbalance flexplate. Pretty common stuff!

 

[turtle5353]

What trans do you have? My flexplate is 157 tooth.

 

[Omie01]

FMX trans. I have counted the teeth twice, and my starter works with it.

 

[turtle5353]

Some weird ****! Good luck!

 

[Omie01]

I have a Hayes 12-030 on order, it doesn't look like the same stampings, but it is ASI certified, dichromite finish yada-yada. Ordered from a different vendor. lollerz Hopefully it fits!!

 

[SVO2SCJ]

 I have a small vibration that comes and goes with engine RPM, so I decided to swap out the flex plate because it was the cheapest part

I would have thought the the playing with the balancer would have be cheaper/easier to GUESS what would fix this !   1) they do go bad/slip. 2) a 1" bolt and nut to one of the holes allows you to see if the vibration is engine produced or a driveline issue.

My guess is you have done all the drive car/roll in netrual , check mounts etc etc etc !  It is easy to go the wrong way with a slight vibration - again I would be looking at balancer first

Mark

 

[AaronFord]

I had this but I was trying to bolt the flywheel in backward. That’ll mess ya up.

I’m sure that isn’t your issue, though. Hope you get it worked out.

Aaron.

 

[Omie01]

The reason I'm trying the Flexplate first is because the Harmonic Balancer I bought was REALLY expensive, and the flexplate was cheap, so I figured between the 2 the flexplate was more suspect. And I wanted to upgrade anyway. The Hayes I just got did FINALLY fit, and it's really thick, so it looks really heavy duty. It bolted in with no problems. I will keep everybody posted.