Transmission Swap

[smitty54]

The AOD transmission on my 84 GT convertible is leaking fluid. It's probably going to come down to a rebuild. It has a great running CFI which hasn't given me any issues. I prefer to still keep it stock, but I've been told numerous times that I should swap out the auto transmission for a 5 speed. My question is, should I keep it stock and rebuild the AOD, or swap it out for a manual. It's going to cost me money either way.

[xctasy]

Ford changed the CFi to operate only as an automatic. There are a few reasons, but mainly for safety, emissions and simplicity/ease of computer management. On the basis os safety, emissions and computer coding, its missing in all three facets, and you'd have to get into the EECIV and TFi coding to make it work 100% safely. The 5.0 HO CFi's idle tip in is a risky thing to have in a speed density Throttle Body engine with a stick shift.



Any time those 6 and 8 cylinder 78-85 engines were equiped with a manual SROD or T5, they then got a downgrade to a non feed back carb. Possible exception were a few 2.8 V6'S.

Fords prescription was to avoid any 2-BBL feedback system with a manual gearbox due to a critical safety issue to do with Air Con, Cruise Control, EGR or VOTM energising, and kicking the idle up and causing a runaway vehicle.

IIRC, all the 2-bbl based stand in systems, the 2150 Motorcfaft Feedback, the Variable Venturi 2700 and 7200, the CFi as well, it was all is just a transitional 2-bbl V8 and V6 induction used to ensure CAFE and EPA emissions compliance for 1978 to 1985.


The coasting idle and fuel metering off the MAP sensor might result in the engine "conking out" at various points. You can do it, but you may have other issues to deal with.



If you convert to Port EFi with your existing system, the EECIV unit is then calibrated for safety with a manual gearbox. 95% of your wiring allows that 86 system to be safely integated. Even with the earlier heads, and without the seperate four catalyst dual exhast system, the Port EFI can easily add another 60 hp at the boot becasue it doesn't come with the restrictive 2-bbl intake manifold the CFi does.

[supercharged347]

If it is all original I would rebuild the AOD. But if planning to build the motor in the future I would put a tremac TKO in it as it will handle more power, even though I am not one for originality, because a original fox engine bay is not very good looking.

[Haystack]

I've swapped several cars to manual and kept the auto computer. It won't know any different, except for one thing. A manual tfi actually starts sparking sooner and allows for a push start at low speeds. The auto tfi will not. Basically, the auto computer will shut off the car around 600 rpms because the auto setup isn't designed to go any lower. If you jump the nss so the car always thinks its in neutral, it will bump the idle up to 800rpm.

Basically, you won't want the engine rpms to drop hardly at all when starting out, or the car will die pretty easily. Tap of the gas or a bit of practice, you would never know the difference.

[smitty54]

Thanks for the info. I would prefer to keep it stock, but then again a 5 speed gives you a better driving experience. I'm going to have compare the costs, and aggravation involved of both before making a decision.

[richpet]

If it were me I would have the current trans rebuilt with a performance type valve body to improve the experience, but keeping all appearances as stock.

No computer issues that way, less work than any conversion, ... .

[smitty54]

If it were me I would have the current trans rebuilt with a performance type valve body to improve the experience, but keeping all appearances as stock.

No computer issues that way, less work than any conversion, ... .

That's probably the route I'm going. I'll have to save up some money and have it done late winter, early spring. I'll just put a pan under it for now while it's in storage to collect the leak.

[gr79]

Automatic with shift kit is fun to drive. Can feel like a different car.
Nothing wild, just firm the shift up a bit. More like for trailer tow than race.
Heavy duty parts in trans help it last longer. Updated internals, mods.
Auto is better in traffic and when cruising slow.
Way too much work to convert to manual and may never work right.
Sticks are fun to shift, but could do without the clutching part most of the time.

[Haystack]

If you drive the car for fun, its tour car, do what you want. I don't get why people are worried about a stock look. As long as you don't spend your whole tax return on the isle you shouldn't walk down at AutoZone, its your car. Have at it, and screw what other people think.

[Ourobos]

It's not a 3 speed C5?

[smitty54]

I'm going to keep the AOD transmission and rebuild, or improve upon it. I recently replaced the engine with a 306 crebs roller cam crate engine. The CFI on it runs fantastic with no issues at all.

[erratic50]

Unless the car is ultra low miles and super nice the direction I would go in is Gforce or Astro T5.

An Edelbrock Airgap intake and a carb would wake it up if that is your thing. Doing that very thing to my 85 because I haven’t had anything with a carb for 20+ years

port EFI could be done. Cobra ECU, 24 lb injectors, Typhoon intake, 65MM throttle body, 70 MM MAF.

The stock CFI and factory multiport intakes strangle a 302.

Upgrade on intake and exhaust these ares are WAY more fun to drive. Even an E6 head 302 is strangled by the intakes ford used.

Rev it up and pull the next gear.....