5.0 Flexplates

[kaw550]

Are 5.0 flexplates interchangeable?

Is there something specific I need for the C4?

I have two. One is from a 91 F150 and the other is from an 80's van. I have no idea what transmission was used with either of the flex plates. They have different holes drilled in them but it looks like the bolt pattern for the crank and torque converter are the same. They are both 164 teeth.

 

[Viperwolf1]

You really need to know what you have because pulling all back apart is a PIA. A C6/E4OD flexplate won't work. Then you have the balance issue. A 302 from '81 and up is 50 oz-in. All 351W are 28 oz-in like the earlier 289/302. If in doubt on either of these issues buy a new one for $35.

There is also a possible problem with the converter bolt pattern. Some Broncos used the small 10.5" pattern with a special 164 tooth flexplate. Neither the converter or the flexplate is available now. So you may have to get a converter with the large 11 7/16" bolt pattern.

 

[kaw550]

I should be okay with the balance. They were still installed on the engines when I got them. I also compared the torque converter bolt pattern and that looks to be the same.

I will post up a picture of them tonight.

Although, I didn't realize they were only $35.

 

[tasker]

check the backspace....ask me how i know!

 

[kaw550]

I compared the two that I have. They both have the correct bolt pattern for the converter. The offset is the same on both. I am confident they are both 50oz.

When compared to the the 302 28oz flex plate, there is a 1/16" difference in the offset.

So what is right for a 5.0 with a C4?
Is there a production vehicle with this combination?

I attached a picture of the two 50oz flywheels.

 

[Viperwolf1]

Make sure the flexplate will sit all the way down to the flats on the converter studs. 1/16" is not enough to worry about.

The one on the left is different than all the AOD/4R70W flexplates I've seen. Might just be manufacturer differences.

C4 was phased out in '81, about the time the balance was changed. AOD/4R70W flexplate is the same dimensions (except maybe balance) as 164 tooth C4 flexplate.

 

[mattt]

They both appear to be 50oz imbalance, based on the window, & as long as the bar weight is 180* out from the window.

The one on the left appears to be a C6/E4OD flexplate though. The way I can tell is the stepped up rib where the ring gear is spot welded every 45* or so. That step up is the give away that it's probably a "big trans" flexplate with the different offset. I call C4/AOD/4R70W a small trans, & the C6/E4OD a big trans.

What did you measure when you came up with 1/16" difference in offset?

C4 & AOD use the same flexplate so compare your 28oz C4 flexplate to these two & pay special attention to the step up or step down right where the plate stamping attaches to the ring gear around the outside.

 

[kaw550]

To measure, I placed the flexplate with the mounting surface on the ground and measured from the ground to the top surface of the ring gear.

The steps on the plate to the right are a closer match to the 28oz plate, It just has more holes. The plate on the left has a round bead just before the ring gear.

 

[mattt]

The offset difference is made up at the "round bead just before the ring gear." You would need to measure from crank mounting surface to torque converter mounting surface to see the different offsets.

Think of it this way......the imbalance(28oz or 50oz) must be correct for the engine you are using. The offset(small trans or big trans) must be correct for the trans you are using.

That is why your 28oz flexplate looks more like the flexplate on the right in your picture....becuase it's most likely from the same family of transmission.

 

[kaw550]

Ok. I will remeasure.
If it is off, what should i use for an application? 91 f150 with a 5.0 and AOD?
This is the only think keeping me from installing the engine.

 

[kaw550]

The offset on the two 50oz flex plates are about 5/8" and the 28oz is about 1/2". It looks like I am in the market for a new one.

I found an old post that says to use a 86-93 mustang w/AOD.

Does that sound right?

 

[Viperwolf1]

http://www.bulkpart.com/2/product/FLYford/F209.html

 

[kaw550]

Wow. Great price. I really want to get thing installed this weekend. If I cant come up with one locally I will order it on Monday.

 

[skerrybronco]

Hi Guys
I have seen this link before in another post for my 92 5.0 mustang swap, I have the complete explorer setup for the front ( 50 oz. Balancer )
what confuses me is the application says C5, is this correct
thanks in advance

 

[Viperwolf1]

what confuses me is the application says C5, is this correct

Yes it is the correct flexplate for a large bellhousing C4 (Bronco & truck), C5, AOD and 4R70W.

 

[mattt]

It looks like the plate on the right in your pic above is the correct one for your application. Send a more close up pic of the two flexplates.....take the picture right where the two flexplate ring gears are meshed so we can compare one to the other.

 

[mattt]

Hi Guys
I have seen this link before in another post for my 92 5.0 mustang swap, I have the complete explorer setup for the front ( 50 oz. Balancer )
what confuses me is the application says C5, is this correct
thanks in advance

It's correct because the C5 is one of the "small trans" that I referenced above.

 

[skerrybronco]

Thanks folks
I have a 77 C4, so this is next on the list to order.

 

[mattt]

Thanks folks
I have a 77 C4, so this is next on the list to order.

Is your trans or engine '77 vintage? Or both?

 

[skerrybronco]

77 C4
Building a 92 mustang 5.0 block
afr heads, same year intakes and efi
Explorer front
Thanks