77 torque convertor and flexplate

[widowmaker77]

So I wanted to ask what you guys think or have run into in your own builds.
I am using my c4 and dana 20 out of my 77 in my 66 build for the time being. I’m using a 94 5.0 with explorer efi. Started installing the motor and the torque convertor studs wouldn’t line up with holes in flexplate. Pulled engine back out and found this.
Torque converter has a 10.5 bolt circle. Flexplate has a 11.5 bolt circle. I have owned this 77 since it was new. I have replaced the transmission and engine once but the flexplate is the original 77. So I haven’t had any issues with flexplate to torque convertor comparability. So to my mind it came from ford with the 10.5 164 tooth flexplate. From what I am finding (on threads here) ford went to the 164 tooth 11.5 flexplate by 1977.
I’m just curious if you guys have seen this before?

 

[77BRONKOTN]

Get a 157 50oz. Drilled for 10.5

 

[widowmaker77]

Get a 157 50oz. Drilled for 10.5

Yeah im doing that.
I’m just trying to see if anyone else has seen this also. From what I can find all 77 broncos should have came with the 164 tooth flexplate with the 11.5 bolt circle not the smaller 10.5 that was normally found in the 157 tooth car flexplates. Earlier c4 equipped broncos would have come with this 10.5 flexplate. Is this correct??

 

[Rustytruck]

Yes the small pattern flex plate was used from 1973 to 74 and very early 75 still a 164 tooth flex plate. then changed to the 11-1/2" bolt circle converter and a new flex plate. can't just swap in a a car flex plate and converter as the car flex plate wont work with the large bell housing and starter. the converter will be too short and ford welded on a cup spacer to make the converter spud longer where it fits into the flywheel. Just buy the right parts for your 1977 and walk away from the 10-1/2" stuff.

 

[widowmaker77]

Yes the small pattern flex plate was used from 1973 to 74 and very early 75 still a 164 tooth flex plate. then changed to the 11-1/2" bolt circle converter and a new flex plate. can't just swap in a a car flex plate and converter as the car flex plate wont work with the large bell housing and starter. the converter will be too short and ford welded on a cup spacer to make the converter spud longer where it fits into the flywheel. Just buy the right parts for your 1977 and walk away from the 10-1/2" stuff.

Yeah that’s what I’m seeing also. Have you ever seen a 77 come from ford with the 164 tooth 10.5 pattern flexplate?? Mine is original from ford.

 

[DirtDonk]

Yes, we’ve seen it. More often on ‘76 models, but a few’77’s as well.
But as said it was more commonly used a couple of years earlier. Unfortunately it is not uncommon to see inconsistencies where they may have used parts perhaps because the current ones were not available.

We found from experience here too, that while you can buy a torque converter for the smaller bolt pattern, you can no longer find a flex plate for the smaller bolt pattern. And since you need a flex plate specifically for the later model engine with 50 ounce imbalance factor built in, you are in a double pickle.
Whatever that is!

You will either have to precisely re-drill the smaller bolt pattern, which may not work due to other offset and sizing constraints, or bite the bullet and buy a new converter. You’re mixing and matching different generations of parts and having also to deal with the usual inconsistencies they threw at us back then.

Unless ford also installed a 157t flex plate when they built your bronco you still need the 164t version for a 50oz engine.

 

[Broncobowsher]

FYI, the 157 tooth flexplate advise is bad. The starter will never engage.
Keep the 164 tooth you have now and get an 11.4" bolt circle torque convertor.

Yes, there is always a lot of inconstancies in builds. Changes happen when they happen, not always at model year changes. To this day they still build stuff that way. Sometimes new stuff is ready before then next model year, or there are left over parts from the last year.

 

[widowmaker77]

Yes, we’ve seen it. More often on ‘76 models, but a few’77’s as well.
But as said it was more commonly used a couple of years earlier. Unfortunately it is not uncommon to see inconsistencies where they may have used parts perhaps because the current ones were not available.

We found from experience here too, that while you can buy a torque converter for the smaller bolt pattern, you can no longer find a flex plate for the smaller bolt pattern. And since you need a flex plate specifically for the later model engine with 50 ounce imbalance factor built in, you are in a double pickle.
Whatever that is!

You will either have to precisely re-drill the smaller bolt pattern, which may not work due to other offset and sizing constraints, or bite the bullet and buy a new converter. You’re mixing and matching different generations of parts and having also to deal with the usual inconsistencies they threw at us back then.

Unless ford also installed a 157t flex plate when they built your bronco you still need the 164t version for a 50oz engine.

Thanks! That’s what I was wondering! Just thought it was odd mine had the odd ball flexplate and it was one of the last built.

 

[widowmaker77]

FYI, the 157 tooth flexplate advise is bad. The starter will never engage.
Keep the 164 tooth you have now and get an 11.4" bolt circle torque convertor.

Yes, there is always a lot of inconstancies in builds. Changes happen when they happen, not always at model year changes. To this day they still build stuff that way. Sometimes new stuff is ready before then next model year, or there are left over parts from the last year.

Thanks! Yeah a new 11.5 torque convertor seems to be the only way to go. Found one 164 tooth 50oz 10.5 flexplate and it is right at $300. So I’d rather just buy a new converter

 

[Rustytruck]

You may need a new flex plate too for your 5.0 motor as they usually have a 50 oz balance and the 289/302 had a 28 ounce balance point. send Viperwolf a direct mail and he can advise with part numbers. He is more deeply involved with the C4 than anyone I know.

 

[DirtDonk]

So somebody is finally making a small bolt flex plate? That’s great, but I guess the low production volume is reflected in the price.
And then you have to confirm proper offset and stuff. I suppose that 300 bucks isn’t too bad for someone who already has a specialized, or otherwise big buck converter though.

 

[widowmaker77]

You may need a new flex plate too for your 5.0 motor as they usually have a 50 oz balance and the 289/302 had a 28 ounce balance point. send Viperwolf a direct mail and he can advise with part numbers. He is more deeply involved with the C4 than anyone I know.

From what I’m seeing I believe I just need to buy a new 11.5 converter and use the original 50oz flexplate that came on the 94 motor I’m using.

 

[widowmaker77]

So somebody is finally making a small bolt flex plate? That’s great, but I guess the low production volume is reflected in the price.
And then you have to confirm proper offset and stuff. I suppose that 300 bucks isn’t too bad for someone who already has a specialized, or otherwise big buck converter though.

https://www.summitracing.com/parts/jpt-n93002xx this is the only one I have found. If you scroll down towards the bottom it gives all the specifics of it. Too pricey to me for a flexplate.

 

[jamesroney]

From what I’m seeing I believe I just need to buy a new 11.5 converter and use the original 50oz flexplate that came on the 94 motor I’m using.

I thought that all 1994 Fords would have been 50 oz, 164 tooth, 11.5 pattern and AOD depth.

I though that you said you were using a C4 from an Early Bronco.

Remember that there are 4 things that have to be right:
1. Number of teeth.
2. Balance weight.
3. Torque converter bolt pattern.
4. Torque converter depth.

So I think that means that your original 50 oz flexplate will be the wrong depth for your C4.

...but everyone knows that I hate automatics.

 

[widowmaker77]

I thought that all 1994 Fords would have been 50 oz, 164 tooth, 11.5 pattern and AOD depth.

I though that you said you were using a C4 from an Early Bronco.

Remember that there are 4 things that have to be right:
1. Number of teeth.
2. Balance weight.
3. Torque converter bolt pattern.
4. Torque converter depth.

So I think that means that your original 50 oz flexplate will be the wrong depth for your C4.

...but everyone knows that I hate automatics.

Yes sir. In 82 (I think??) ford went to 50oz balance flexplate on the 5.0.
The 94 flexplate is 164 tooth 50oz 11.5 pattern.
The 77 c4 I have came from ford with a 28oz 164 tooth flexplate with the 10.5 pattern. By 1977 ford had changed to the 11.5 pattern.
So that’s why I was asking if anyone else had seen this. Because it’s somewhat of a anomaly and one more thing I have found that is different on my 77. My assumption is ford was using leftover parts to finish production on these later 77’s and some things are different.
The 94 flexplate should bolt directly to a c4 11.5 convertor.

 

[Broncobowsher]

I thought that all 1994 Fords would have been 50 oz, 164 tooth, 11.5 pattern and AOD depth.
...

There is the odd 302 E4OD combo out there. The high GVW F150 package or odd 302 F250.
The E4OD flexplate has the C6 offset. This is the wrong offset for the C4/AOD/4R70W transmissions.

 

[widowmaker77]

There is the odd 302 E4OD combo out there. The high GVW F150 package or odd 302 F250.
The E4OD flexplate has the C6 offset. This is the wrong offset for the C4/AOD/4R70W transmissions.

I’ll have to look to be 100% sure but I believe the trans code on this 94 truck I got the engine from is U which is the 4r70w I believe.

 

[Rustytruck]

as far as I know Ford used the odd combination for 2-1/2 years in the Ford Bronco and in the 73-74 Ford Econoline Van.I do not understand the thinking for using the small converter in the big bell housing. Seems it should have been the other way around. Its not like they built a special converter for the Bronco they just adapted a car unit to fit the big bell by adding the spacer on the snout.

 

[widowmaker77]

as far as I know Ford used the odd combination for 2-1/2 years in the Ford Bronco and in the 73-74 Ford Econoline Van.I do not understand the thinking for using the small converter in the big bell housing. Seems it should have been the other way around. Its not like they built a special converter for the Bronco they just adapted a car unit to fit the big bell by adding the spacer on the snout.

Yeah it’s pretty weird

 

[widowmaker77]

So I’m not really wanting to put much money in this c4 since my plan is to go 4r70 BUT I need to get this rig running. So does anyone have any experience or knowledge of one of these convertors?
https://www.oreillyauto.com/shop/b/...a6be/v/a/4952/automotive-suv-1977-ford-bronco