I have a '85 F150 short bed with 4.9. Currently it has a three speed auto. I believe it's a C5. Now its getting weak after almost 330 K. When cold it won't go into reverse and won't shift into 3 until it warms up. My question is if I get a C4 (three speed auto) will it bolt right in without having to get a different drive shaft? Basically, is the length of the tranny the same as well as the bolt patterns on the bell housing? Can you change out the bell housing or is it one piece? Can I use the old torque converter or do I need to get a new one? What headaches can I anticipate doing this?

In the mean time, will adjusting the bands help for a little while or should I just leave it alone.

Any suggestions on a aftermarket C4 like TCI, B&M or PA? Sometime ago I got an estimate of around 1100 to 1200 to rebuilt this one. Seems a little high. I'm not going to race this truck, I just want something with some heavy metal that would make it more durable. Would appreciate any suggestions / info.

Butch ( the pusher behind ole blue)

 

Your local transmission shops could probably give you the best info on that.

 

According to thissy here:

https://www.ford-trucks.com/article/...ers_Guide.html

You should have a C6. There is id info in the text below the chart that will help you id it, with specifics to the C4, 5 & 6.

Here is what I would do, depending on my budget:

--flush, new filter, adjust the current trans and hope for the best
or

--swap for a like reman from a reputable builder, preferably local with a warranty. If he insists on the R&R to warranty, I'd do it.
or

--replace with an AOD from '88-'93 V8 or six in truck unit, maybe add some beef to it.

You can get C4 and C6 in the proper pattern for your engine. (same as 302/351w etc). C6 is longer than C4. C4 and AOD close enough for same driveshaft probably. C6 & AOD all one piece, C4 swaps bells, but you won't need to. Torque converter MUST be replaced--you going to pump all that old oil and debris through your new trans?

TCI shows $1000+ for a C6, double+ for an AOD. Half that from a local guy IF YOU CAN FIND ONE that meets the reliability/warranty requirements.

Headaches? Swap like for like and a mild headache awaits. Start swapping types, you my have drive shaft, shifter, cooler, crossmember issues to work out. Not impossible, just more quality time under the truck.

 

85e150, Thanks for the info. One thing I'm sure of is that I don't have a C6. I know that because a buddy of mine had one behind his 428 police intercepter motor. I helped him pick it up when he bought it. The pan is very different. Mine pan looks like a C5 and if I recall when I changed the fluid in the past I got the C5 gasket, but can't be for-sure. I read alot on how well the C4 performs and its durability. I'm not really want an overdrive, I'll just keep it simple. Thanks for the tip about the converter. Never considered the old fluid issue. I was considering cost savings. Once I get my intake issue fixed I think I will tighten the bands a smigen to see if that makes a difference.

 

how do you tighten the bands? i have a c6 in my old 78 that has a little slip every once in a while

 

C4/C5 use the same filter and pan gasket as a C5 is a C4 with a lock up converter. a factory style rebuild with a good shift kit, external trans cooler and filter and if u want to spend the $$$ a higher capacity fluid pan will be sufficent. keep the fluid cool and clean, and ur trans will live a long, healthy and happy life.

 

AUTO TRANS TECH MAINTENANCE - Do It Yourself - Trucks 4x4 @ Off-Road.com

as u can see, there is only on band adjustment on a C6 for the intermediate.

 

The durability of the C4 or C5 depends on whether it's a case-fill or pan-fill. I can't remember which off the top of my head is the more reliable transmission. C4 in an F-series is a waste of time, IMO, unless you have decent cooling. I'd go with a C6 or FMX - or go with an overdrive transmission as noted above.