Flex plate help

[krisx125]

My 1976 had a 74 302 with a c4 in it when I bought it a few weeks back. Motor started to tick and was tired. Yanked it and a friend gave me a clean low mileage 90 5.0 out of a gt. Bought a 50oz balancer three Bolt, and a 50oz flex plate for an AOD mustang. I was an idiot and didn't check to see if the TC bolts lined up with the flex plate prior to dropping the motor in. And now of course seems like they don't line up...am I losing my mind? Or do they just not line up?

 

[DirtDonk]

Well, it'll be both pretty soon working on a Bronco!
But no, you're not crazy yet. It's not only a common issue, but yours being a '74 is particularly vulnerable to the dreaded Bronco-pattern (smaller I think?) torque converter bolt pattern.

Not sure if it was a Bronco-only thing, or if any other Fords had this uncommon size, but members here run afoul of it all the time when swapping trans/engine combos.
Not sure the best solution, but you will need to check a couple of factors.
One is the bolt pattern. You could re-drill (VERY CAREFULLY!) the flexplate to match the TC, but you need to verify that the offset is correct too.
The other is to find a more appropriate TC to fit the new flexplate.
I don't know of a modern 50 oz flexplate that has the correct offset OR bolt pattern for the old converter, since it was likely never used on a modern engine. Would have to be an aftermarket custom most likely.

Gonna have to do some measuring for both offset and pattern. And yes, you're gonna have to take the engine back out. Or at least the trans out, but I prefer the engine myself as long as I have a hoist and a buddy handy.

Good luck. I'm sure others will have advice. Hopefully some that can save you the trouble and dry off the parade that I just rained on.

Paul

 

[Broncobowsher]

Yep, that screwball mid years early Bronco convertor issue. 164 tooth flexplate is needed since you have the truck C4. But the original convertor is the small bolt circle. But the convertor is also the long snout due to the thicker bellhousing. And the 164 tooth, small bolt circle flexplate that was only used on a few years of Broncos is no longer a service part.

What others have been doing, even without the engine swap, just getting a good flexplate, is get the '73 or '77 large bolt pattern torque convertor. That will work with the AOD flexplate.

I do NOT recommend drilling the flexplate. Unless you have access to a turntable and a mill to accurately make the 4 holes in the right places. The convertor indexes into the holes. The convertor is the mass of the flywheel to keep the engine rotating (since there isn't a flywheel with an automatic). You need that accurately attached to the engine.

 

[krisx125]

Thanks for the info guys! However my truck is a 76, shouldn't it already have the bigger bolt pattern? I'm going to yank the motor out in a few and see what's going on.

 

[Broncobowsher]

You have a '76 with a '74 motor and expect that the previous owner put everything back to stock '76 specs? What year is the transmission? They may have swapped in the whole package. What has happened in the past with untold owners is always a huge mystery.

Who really cares how it should be. You now know what you have. That is what really matters. Lots of "you should have..." stinks compared to "what I have IS..."

 

[krisx125]

Old owner just came and bought the 74 motor off me last week. Crawled around and said everything else was the way he left it. Trans is 76. I'll measure it all in a few

 

[krisx125]

Pulled motor back out, flex plate lines up with studs. Studs seem aprox 11 1/2 apart. My question is, do I need to remove the pilot bearing from the crank? Stang was a stick. something seems to be keeping it from mating correctly to the bell housing

 

[Broncobowsher]

Yes, remove the pilot bearing. All else is good.
The convertor pilots into the back of the crank where the pilot bearing goes.

 

[krisx125]

Awesome, thanks for the help! I guess ill get to cutting it out!

 

[Butros]

Easiest way to get a pilot bearing out that I have found is to fill the center of the crank with grease by putting it thorough the center of the pilot bearing. Next take a dowel or something else that will fit snug in the center of the pilot bearing and start taping it with a hammer. The dowel with press on the grease and build pressure behind the pilot bearing and press the bearing out of the crank shaft.

 

[krisx125]

Ill try that, the bearing its self is hammered. Looks like someone tried to pull it out already. Ill have to cut the bearing out (whats left of it) and try the grease trick with the rest.

 

[Broncobowsher]

The less you hack the bearing now the better the grease trick will work. You want as much surface area inside as possible. And don't screw up the bore that the pilot bearing goes into, that is the crankshaft and the convertor needs to moves smoothly in that bore. If it hangs it can destroy the thrust bearing on the crank.

If it was a roller bearing and it came apart, remove the loose bits first.
Take the largest bolt that will go through the center bore. wrap the threads with electrical tape until it is snug in the bearing. Pack with grease. Insert wrapped bolt. Hit with a hammer. Remove bolt, add more grease, repeat as needed. It is way easier then trying to cut chunks of bearing out.

 

[krisx125]

Yea, its just the roller bearing that is broken up. Ill get that out then try the grease trick.

 

[krisx125]

Motor has gone in and out 5 times today. I'm losing my mind. Balancer is a 50oz three bolt from professional products. And the flex plate is for a 90 mustang, also 50oz. Well bolted it all up and the weights hit the spacer plate between the motor and bell housing. Took motor back out and cut the raised pieces off the plate. Also took torque converter out and bolted it all together out of the truck. It was fine and didn't rub. Now out motor back in and tightened up the bell housing and sure enough the weight on the flex plate hits. And will also hit the side of the block....anyone ever have this issue?