3.8 to 5.0 using stock c5

[mobileaudio219]

I have an 84 ltd that I'm "building" on the cheap.

I'm going to start off buy throwing a 8.8" with 3:73's in it this weekend.

I'm hoping to finish the motor the motor in the next few weeks, and want to get it up and running. I still need to gather some t5 swap parts, but I figured I would drop the motor in and run it around for a while with the stock c5.

Anybody ever do a similar swap. carbed 3.8 to carbed 5.0. The motor is a explorer gt40p motor.

What flex plate and starter should I use?

[wraithracing]

I am not the automatic expert by any means, but my understanding is the C5 was nothing more than an aluminum case C4 with a lock up converter to improve fuel mileage. The 3.8 bellhousing pattern should be the same as the SBF, so a bolt up in that regard. I believe you would use the flexplate as listed a 5.0/automatic in a Mustang or Fox for the year model. I believe both are just over 14" in diameter and the matching starter should make it all work.

Not sure how well or how long the C5 will hold up behind the 5.0 with 3.73 gears, but should be drive-able for awhile at least.

[Haystack]

3.8 and 302 use the same sized flex plate, at least in the aod.

The balance of the 3.8 is 28 oz. So either an old 302 or 351 flex plate should work.

[Broncojunkie]

3.8 and 302 use the same sized flex plate, at least in the aod.

The balance of the 3.8 is 28 oz. So either an old 302 or 351 flex plate should work.

I thought the 3.8 was internally balanced? And if I read the post correctly, he'll be using a later 5.0 with v6 c5. He needs a 50oz flex plate (I would presume a 164 tooth) but I'm not sure if the v6 converter will bolt up.

Disclaimer: I'm even less of an auto guy lol

[Broncojunkie]

Had to do some reading and it appears that 3.8 didn't get internally balanced into 2001. I found 1 guy who stated that it was 28oz, but being completely different engines, I would have to guess that the bolt patterns are probably different than the Windsor. I looked up flex plates for both engines and there are different part numbers. Overall size is slightly different. No mention of balance weight on the v6 flex plates. Even if the size was the same and the balance, the v6 balance would likely be in a different position (again, only guessing here). But I suppose the argument is moot considering his engine is 50oz. I believe I would use a 164 tooth v8 plate (f150 5.0) and check part numbers for v6 vs v8 starters before choosing one.

Someone else will need to chime in on the torque converter bolt pattern. I'd bet a few bucks that bolt patterns are different than v8.

[Walking-Tall]

^ How many bucks? lol

Just went through this a little while ago, though with a 28.2oz-in imbalance situation for my earlier 302. A 164-tooth 50oz-in imbalance (mid-'80's F150 automatic should get you what you need) flex plate for your later 302 is what's needed. The C5's lock-up torque convertor bolt (studs/nuts) circle, at ~11-3/8", is the same as others that connect to a 164-tooth flex plate. Then bolt the car's "V6" starter, that's the same as a "V8" starter, right back into the C5 bell housing.

[wraithracing]

If the engine in question is an 84 model then definitely need the 50oz flexplate. I just went thru this exact issue in reverse when I accidentally installed a 50 oz flywheel and balancer on my 331 stroker when apparently I had my head up something. The wonderful vibration required me to pull everything again and swap on the correct 28.2oz flywheel and balancer to fix the issue.

[erratic50]

Interesting the automatics use 164 tooth. The T5 flywheels are 157 tooth.

I don’t remember seeing a starter or starter head on the list of stuff that needs to be changed when converting from automatic to T5, but I’ve slept many times since the last time I’ve read anything in-depth on that.

[gmatt]

Interesting the automatics use 164 tooth. The T5 flywheels are 157 tooth.

C4s came with either 157 or 164 tooth flex plates, depending on application. Both would need a specific bell housing for correct starter location. It's already been mentioned that the C5s are 164 though. It's my understanding that you can use a C4 bell on a C5 trans if you don't want the lock-up converter. You'd also need a C4 converter in that case.

[xctasy]

351 W and some Australian 302C's had Trucks had a C5 case. The C5 case is a Truck C4, with AOD flexplate.

The movement to 164 teeth is because that's the old FMX flex-plate, and every 351W, 351C, or the later 4 bbl or CFI 5.0's and 2 and 4v 5.8's were effectively M,Y, or S, H code 360/390 FT or FE truck replacement engines. The Fox bodies ended up with F trucks and Lincoln Mercury engines paying for the emissions certification. So they used a FMX/AOD/C4 Truck kind of gearbox, the C5.

Its replacement clutch is the issue...no longer serviced, and it survives okay on a 137-140 hp 5.0, but not on anything stronger, and certainly not on an f150 truck.

Get a non lock-up clutch replacement, is my advice. Everything else about the C5 is really good.

[Broncojunkie]

Interesting the automatics use 164 tooth. The T5 flywheels are 157 tooth.

I don’t remember seeing a starter or starter head on the list of stuff that needs to be changed when converting from automatic to T5, but I’ve slept many times since the last time I’ve read anything in-depth on that.

Another interesting bit is that the fox and sn95 5.0 v8 cars used 157 tooth flywheels while the 94-04 v6 cars used 164.

[Haystack]

The starter is the same, 164 or 157t.

There is a different offset to flywheels though. I did a sn-95 t-5 using the 3.8 bell housing on an 87 f-150 flywheel and clutch on an 87 5.0. The truck flywheel stuck out a bit more. Off the top of my head, its 3/8" or 5/8" offset.

To make it work, I had to do the truck starter, but otherwise the whole thing bolted up.

Sorry, I confused the whole 3.8 flywheel thing thinking you were going to stick to a 3.8 for some reason.

[at_the_junkyard]

Not sure if this is any help but i'll put it out there for info sake.

FWIW when I was messing around and rigging up a 302 on my test stand I used a 50oz flexplate from a 1982 302 automatic (pretty sure a 164 tooth) with a 95 mustang 3.8L manual T5 bellhousing and its mini starter. It all meshed up fine and turned over the motor nicely.

So it would seem at least the later model 3.8 flywheels are the same diameter and teeth as the 80's 302 auto flexplates (14.25"). I'm not sure what diameter the 80's 3.8 flywheel would be however.

Of course for this project I was only concerned with getting it to turn over and start on the stand with the correct balance as opposed to actually work in a car so just a weird combination of junkyard parts fitted together LOL.

Also as a side note the 95 mini starter will also bolt directly up to a 302 SROD or T5 bell with 157 tooth flywheel as well. It works well and the starter is much smaller and lighter.

[xctasy]

The C5 had its lock-up clutch removed on the 115 hp 2.8 Bronco II's and the reason it wasnt found on the High Out out engines and only the Standard Out put 5.0s was the lock-up clutch burn out in service. Its probably the only weak point. As soon as the torque was over 220 lb-ft or it was in the 3000 Bronco with 154 lb-ft, the lock up clutch C5 was not an option. The rest of the transmission should take to a bucket load of torque with ease. The C5 is an exceptionally good "slushbox".

[gmatt]

The C5 had its lock-up clutch removed on the 115 hp 2.8 Bronco II's and the reason it wasnt found on the High Out out engines and only the Standard Out put 5.0s was the lock-up clutch burn out in service. Its probably the only weak point. As soon as the torque was over 220 lb-ft or it was in the 3000 Bronco with 154 lb-ft, the lock up clutch C5 was not an option. The rest of the transmission should take to a bucket load of torque with ease. The C5 is an exceptionally good "slushbox".

So you should be able to swap to a V8 bell housing and non-lock-up converter, correct?

[mustangxtreme]

I had a 302 in front of my c5 originally. The issues I was coming up with a kickdown linkage. Well that and theCc5 received it's 302 at 194,000 mi. If the transmission is in good shape, it should work. I also remember reading an article about building a bullet proof c4 and they used c5 internals in the build.

[xctasy]

Not sure on the part numbers.

Down at der bottom oft der welt, most of our C4s have a Cleveland 302 bellhousing which copies the FMX, and the Truck C4. The US C4s were exported with a special C8/C9 or C10 cast iron or alloy bellhousing to suit 157, 160 or 164 teeth flexplates. The US C5 can only take a specific kind of bellhousing for pan fill C4s...I cannot quickly find the part number. Best bet if you have a C5 is to just use the replacement unlocked C5 torque converter assembly. The defect with the C5 is just the lock-up part. The 2.8 V6 part in the Bronco is 138 teeth, and the converter might not fit. If it does, youll get a higher stall ratio, non lock up C4 style C5 converter.