Flathead(8BA) Automatic Transmission Options/Question
 

Good morning all. First, I hope you are well. I’m looking to swap my 3 speed manual column shift transmission out (which I like driving) with an automatic transmission (just needs to happen). I am looking for a good, cost effective, bolt up match to my 255 8BA Flathead with Dana 41-3.92. My tires are 205’s instead of the 215 radial equivalents. I would like to maintain this rear end if at all possible. I typically do not operate this vehicle over 65-70 mph if necessary, but most of the time just cruising to spots on average 50-55 mph or less. Most of the threads (tons of helpful info, thank you…definitely got me started in this endeavor and right direction) I’ve searched mention these options…C4, C6, AOD, etc? My humble question is, which one without breaking the bank and will be safe, to operate within normal drivable limits. My apologies for all the rambling. Thank you kindly in advance for your knowledge, experience, and input. Stay safe, blessed, and be well.

Re: Flathead(8BA) Automatic Transmission Options/Question
 

C4 is the easiest and sucks less horse power (25hp) to run and will handle 400hp. With the smaller converter from the earlier 170 inline 6 there is minimal to no trans tunnel modifications. The c6 is too big and the aod sucks lots of HP (50hp) to run
The other option is a c5 which is just a c4 with a lockup converter which will give better fuel mileage on long drives.
The c4 will give you close to the same top speed as your 3 speed. The OD of the AOD has the potential to give you a higher top speed but you most likely will never get the benefit unless you are flogging your engine assuming it’s stock at 85 hp minus the 50 to run the aod gives you less driving power than my lawnmower. But you can go full manual on the C4 C5 and AOD which will cut down the HP needed to run the trans but you will have to be shifting the gears and activating the OD and converter while you try to enjoy the drive.

I put a c4 in my current build with 3.55 diff and 31” tires will give me 70 at 2700rpm

Re: Flathead(8BA) Automatic Transmission Options/Question
 

Good morning…Sorry for the delay and thank you kindly for replying. Stock I’m at 110hp. This is great, just what I needed. Thank you so much for the assistance. I appreciate it. Have a safe and blessed rest of your day @ActionYobbo.

Re: Flathead(8BA) Automatic Transmission Options/Question
 

I'm not quite ready for an automatic yet, but power steering sure would be nice.

Re: Flathead(8BA) Automatic Transmission Options/Question
 

@Tubman…Definitely PS in the hopper on the to do list for sure. I just figured going auto now will give me some convenience. I just purchased my vehicle in March so I’m still going through it. Just recently finished a 12V conversion trying to plug away here and there at things.

Re: Flathead(8BA) Automatic Transmission Options/Question
 

Another option is a 2 speed powerglide. I have one in my totally stock 64 impala and is a pleasure to drive. The 2 speed sucks the least HP of any automatic and is also an option for the ford flathead with adapter kits available

Re: Flathead(8BA) Automatic Transmission Options/Question
 

@ActionYobbo…Thank you kindly for the follow up info. I did see that in one of the threads. I’m leaning more toward the C4 with my 110hp. Hopefully it’ll be ok. I’m definitely not trying to race or be speedy, I like hot rods in the mix, but not for this one. I had a 2 speed PF in my previous 1956 Dodge CR and it actually did great IMHO. I was going about 70ish and don’t recall ever having any concerns or complaints. It would zip down the interstates 😎. Never had the chance to dig into the ‘40 Plymouth transmission, but is was original, just don’t remember much about it. I think my top speeds were about 70. I appreciate your assistance.

Re: Flathead(8BA) Automatic Transmission Options/Question
 

If you decide on a C4 you have a couple of options as far as the bell housing, flex plate, and torque converter
164 tooth flex plate v's 157 tooth. They are not interchangeable so you must stick with one style.
I have a 164t in a 1948. I love it!
What year is your car?

Re: Flathead(8BA) Automatic Transmission Options/Question
 

Good morning @69a. This was going to be my next question. As you can see novice in the transmission stuff. I have a 1950 Mercury. I think it has the 112 tooth but I’ll need to confirm this, I’m not sure. Thank you kindly for the information. I need to figure out what additional parts I’ll need should I pull this plug on a C4. Thanks again.

Re: Flathead(8BA) Automatic Transmission Options/Question
 

Here in Salem, Or is the C4 fellow, Nice building and location for these conversions. Google him. Good local rep. Newc

Re: Flathead(8BA) Automatic Transmission Options/Question
 

Good afternoon…First, I’d like to say thank you very much for the responses, your input, experiences, and knowledge. I purchased a C4 from a ‘65 Mustang. I am planning on still utilizing the column shift, well I’d like to. Now, to gather the “additional” items I’ll need. Thanks again, I’m grateful for the assistance and so quickly. Stay safe out there, blessed, and be well.

Re: Flathead(8BA) Automatic Transmission Options/Question
 

@Newc …Thank you kindly. I will do that. I appreciate the info.

Re: Flathead(8BA) Automatic Transmission Options/Question
 

Good afternoon. I tried searching him, but nothing came up with that name.

Re: Flathead(8BA) Automatic Transmission Options/Question
 

Hi. I'm fairly certain that you have a 157 tooth bell housing. Bolt the bell to the block and make sure the starter fits. I think you have to grind a little from the block (or starter) to allow it to fit perfectly. Once you have the flex plate bolted to the crankshaft do a trial fit with the torque converter and make sure it goes all the way in so that there is no gap between the studs on the torque converter and the flex plate.
There is a lot of information on a website called pigseye.com pm me if you can't find it and I will email you the info.

Re: Flathead(8BA) Automatic Transmission Options/Question
 

Oh, ok copy that. Thank you kindly for the instructions. This is great and will surely get me started. I appreciate it. I was just searching how to install and column linkage stuff. Thank you.

Re: Flathead(8BA) Automatic Transmission Options/Question
 

I did several customer A/32/33-34 chassis over the years with 8BA motors my local machine shop built and either the C4 or AOD kits from Speedway. Both the motors and the trans worked good, no comebacks. Mostly used 3.25 rear gears for the C-4's and 3.78's for the AOD's.

Re: Flathead(8BA) Automatic Transmission Options/Question
 

Am I missing something? All the responses seem to indicate that the C4 will just bolt up. No mention of a install kit. Now I never did a C4 to flathead but I have done a C4 to a Yblock, and it will not just bolt up. A conversion kit is needed and the only one I know that has it is Flat-O-Procucts. I believe Speedway carries the same kit.


Am I wrong ?

Re: Flathead(8BA) Automatic Transmission Options/Question
 

Awesome…I appreciate hearing this. I am hoping at some point once installed, I won’t have any comeback either 😌. I’ll check out speedway. I think I’ve come across the SW once at some point searching for other non related parts. Thank you.

Re: Flathead(8BA) Automatic Transmission Options/Question
 

I called Gene from Flatomatics about a C4 conversion kit for a 1950 Mercury 255 8BA and left a vm. I couldn’t find anything on a website for them. Speedway, I will surely check out. Thank you kindly. I appreciate the info.

Re: Flathead(8BA) Automatic Transmission Options/Question
 

No

It needs a Flathead to C4 flex plate, a bellhousing spacer and a starter adapter. Speedway sells a kit with those bits. Look up Flathead C4 kit and you will find what you need. Also depending on what you are fitting it into there is rear mount/crossmember modifications needed.