FYI FORD MustangSteve's Ford Mustang Forum / C-4 tranny question

**Posted by MS** 11/19/2024 3:30 PM

Anybody know if a 157 tooth bellhousing from a 1966 C4 will bolt up on a later C-4?

I have a C-4 with a 1977 bellhousing for 164 tooth flexlate that I would like to convert to the smaller 157 tooth size since I already have the 157 tooth flexplate that the engine was balanced to.

I have a 1966 C-4 tranny with bell. In the old days, I would unbolt the parts and figure it out, but I figured someone might already know.

**Posted by MS** 11/19/2024 3:31 PM

Now, I am wondering if the torque converter is a different size, too…

**Posted by Nos681** 11/19/2024 4:14 PM

I used the factory ‘65 C4 bell housing on the
80’s case C4 from TCI.

The factory 160 teeth flexplate was chewed up due to starter engagement, still worked fine.
A 157 teeth flexplate …WYAIT.

Both were “case filled” C4’s.

I also installed a Hughes C4 locking dipstick to minimize fluid contamination.

My stock C4 specs: factory 160 teeth flexplate (157 teeth is replacement), 24 spline input shaft, 24 spline torque converter

TCI C4 specs: 157 teeth flexplate, 26 spline input shaft, 26 spline torque converter

Last edited by Nos681 (11/19/2024 4:18 PM)

**Posted by RTM** 11/19/2024 4:18 PM

I recall swapping the bell housings around in my old 77 mustang II but I don't recall the years.

**Posted by MS** 11/19/2024 5:46 PM

Thanks, guys. Sounds like it should work

**Posted by RCodePaul** 11/20/2024 2:23 PM

I think you already have your answer - the small and large bells are different and look different, but you can bolt a small bell to a large case C4. Here is more information. Being an engineer, I'm thinking you like a ton of it.
This is from a post I made years ago on FordMuscle as "R Code". I asked all the C4 guys who were frequent posters to gin up their C4 knowledge and then I spent hours and hours and coalesced it all. It's got a lot of good info, but unfortunately a ton of dead links. 191,000 views and 82 replies.

C4 Monster Thread -
Bellhousings of course come in several versions. Case fills come with bells that bolt to the pump while pan fills come with bells that bolt to the case. C5 bells are deeper than either of the C4 versions. Most of the time, the case fills use the 157 tooth flywheel and the pan fills use the 164 tooth, but there are exceptions. The best tip I've seen to ID them is to measure the depth. If the depth is 5 7/8" it is a small bell 157t, if it is 6 1/4 is regular bell 164t and if it is 7" it is a c5 bell 164t.

https://www.fordmuscleforums.com/threads/monster-c4-thread-text-edited-way-long-version2.416584/

**Posted by MS** 11/20/2024 10:41 PM

Thanks for posting the dimensions.