I have an 85 302/AOD with a 164 tooth flexplate. What changes will I have to make to remove the AOD and bolt on a C4. I think I need to use the 164 tooth flexplate because of internal engine balancing (50 oz). Is that correct? I think the C4 was originally bolted to a late 60s 289 which used a 28 oz balance flexplate. I'm pretty sure the AOD and C4 driveshaft yokes are the same and I think the AOD/C4 transmissions are about the same length. Can one of you Ford gurus confirm this?

 

I have not had much experience with the C4, sorry no help. I imagine some one here can help.

One question though, is the AOD bad or you are not happy with it, why the change? I have been steered clear of the C4 by fellow hot rodders around here.

 

Vern, the size of flywheel/flexplate you need is dependant on the bellhousing on the transmission case. You're right in that you need the 50oz flexplate for your 85 302, but 157 tooth count plates are available in the 50oz balance if you need one. You might need to check with a Muastnag parts supplier to find one, though. And that's as much as I know this morning. ;-)

Last Chance, I'm not sure who would have steered you against using a C4 trans? Other than not having an overdrive gear, it's one of the best, lightest and most compact 3 speed transmissions ever made. They can be built to withstand the rigors of big block drag racing, if necessary. It sure does fit a lot easier around the transmission crossmember and floor pan of an F1 than an AOD.

 

you will need to use the 85 flywheel or an aftermarket flywheel with 50 oz weight. you shouldnt have any problem with them as long as you get the same bolt pattern convertor..11 7/16 is most common on both of those. you just need to ck the convertor distance free play when bolted up. at least an 1/8 to no more than a 1/4..preferably 3/16..
and i have to ask this also..why are you going to c-4 versus aod??..your final drive ratio with c-4 is going to be much higher and turn considerable more rpms.
i have access to an aftermarket flywheel(164 50 oz) which has multiple bolt patterns if needed(11 7/16, 10 7/16, and a powerglide(3 bolt) which you would have no need for). thanks eddie

 

Just to add to the confusion, all the parts need to match. Some C4 bellhousings are smaller and have the starter bolt holes closer to the engine, so the flexplate diameter/toothcount need to match the case, and the torque converter needs to match, as well. Once you determine which flexplate you need, the rest will fall into place.

 

ya why no overdrive?

 

Vern, the flexplate tooth count/diameter has to match the bellhousing for the starter to engage it correctly. Most C4's used the 157 tooth plate up until the late 70's when some of them got a larger 164 tooth plate in some trucks. The surest way to know for sure is to look at how the bellhousing mounts to the transmission. If the bellhousing attaches with the front pump bolts, it's a 157 tooth bell. If it attaches with a separate ring of 5 bolts OUTSIDE the diameter of the pump, then it's a 164 tooth bell. If your C4 is really out of an early Mustang like you had mentioned awhile back, then you're probably going to have to order a 157 tooth flexplate in the 50 oz. imbalance factor to work with your combo. The factory never used this combination, so it's only available through the aftermarket. Here's one:

TCI Auto 529610 - TCI Flexplates - Overview - SummitRacing.com

 

I installed a 66 c/4 behind an 84 302, the flexplate,50 oz. was for the AOD . Thats what the napa store told me. The c/4 had the big housing and is in operation now with out any problems. I am looking for a AOD now to replace the c/4,i think i would like it better.

 

Okay to clear up a few questions. No way to tell for sure but the AOD is probably junk since it came out of a car that may have been driven with no throttle valve cable so I don't want to take a chance on it and I don't have the money to have it rebuilt. I will be running a 3:08 rear gear so the AOD transmission would not shift into OD untill about 55 MPH anyway (been there and done that).

The AOD has an integral bellhousing so I will be using the late 60s Mustang bellhousing. I don't know if it's the big bellhousing or the small one...didn't know there were two sizes. Am I correct in assuming that if I have the big bellhousing (attaches with a separate ring of 5 bolts outside the diameter of the pump) I can use the 164 tooth AOD flexplate but if I have the small one (transmission attaches with front pump bolts) then I need a 50 oz, 157 tooth flexplate? I don't know which I have and will have to look at it again when I can get back out to the garage. Will the present starter work with either bell housing or flexplate? Will the Mustang torque converter bolt to the 164 tooth flexplate or only the 157 tooth? The C4 came with a flexplate but I haven't checked the number of teeth on it. I assume I could not use this flexplate with the 85 engine because it is probably a 28 oz or neutral weight plate. Is that correct?

The is very confusing for an old Chevy guy!

 

85 302 will be 50 oz.

 

try the bell housing on the C4 to see if it fit's, you lost me when you said assuming

 

It isn't that bad to keep track of. It's just different. You just have to get used to the fact that Ford "tinkered" a bit more than GM did. I've ran into more than a few oddball little differences while wrenching on GM stuff too, though.

 

10-4 merc, just have not tinkered with them just mostly the C6, AOD, and E40D. I understand his issue about the tranny tv cable being missing and if you got extra parts laying around. Good luck guys.

 

c-4s in a very general sense came three ways,
big bell that mounted to pump 164 dipstick in case
big bell that bolted to case 164 dipstick in pan
small bell mounted on front pump 157 dipstick in case...
this is very general for the cases/bell hsg,most all 164 are 28 oz,157 mostly were 50oz ,usually the 157 have 10 7/16 bolt pattern conv and the 164 had 11 7/16 pattern conv
remember none of this is written in stone.....there are alot of variables
if you want to call me and i can discuss this with you in person,call me at my shop 804 648 8737 eddie
if you have an oddball setup i should have the flywheel to fix the problem..
hope this helps

 

Eddie,

Thanks for your offer. Right now I'm just gathering information since it's winter here and I can't work on the truck until Spring anyway. I may have an oddball setup so I may need a different flexplate to make the 67-68 C4 work with my 85 engine. I currently have a 164 tooth flexplate that came with the AOD that was bolted to the engine AND I have the flexplate that was bolted to the C4 (don't know the tooth count - came out of a mid to late 60s Mustang). I'm hoping that one of these will work. I'll keep your number though and call you as the need arises.