C4 to AOD swap on a 250 cid engine. Help.

Hi I´m writting from Venezuela. I have a couple of questions:

1°- Is it worthy to swap my c4 tranny for an aod? I use my car daily, y make about 85 miles every day going to and coming from work. My car is a 4-door ´76 maverick, a family car, I´m not a racer or anthing like it, but I want to increase my engine´s milleage. The gas´prices here are just too low (0.11 US $ per gallon. Hehehehehehe, sorry, I had to tell it ), but I would like to have about 90-100 miles per hour without killing my engine.

Is this worthy?

2°- My c4 sometimes just falls on reverse when my car is parked on a levelled road. When the parking pawl isn´t holding the car it sometimes gets on reverse and rams over what is behind it. Recently it rammed on my ´78 country squire...!!! I´ve checked the linkage and looks just fine, but I´ll check it again if i have to.

I hope to get some help with this. Thanks.

 

I think the AOD is a good trans and for a stock or near stock motor should be a good swap without having to strengthen the transmission.

Theres even a guy on here who makes a KILLER aod crossmember to make your swap that much easier.

As to your second question I dont have an answer. Someone will though

 

i hear the AOD's eat alot of HP though and the 250 doesnt really have that much to spare. theyre also heavier so i guess youve got your pros and cons to think about

 

Thanks guys, but how is that the AOD eats a lots of HP? Newtoford, you mean heavy because of the weigth...? My C4 is a good trans (I overhauled it just like a stock one), but I just want to let my engine to go slower on high speed (not too high).

Hey Chinguschild, I`m bass player too!!!

 

thats just what people say. i havent done the swap so I dont know. but just like accesories and such rob engine power the AOD takes a little more power to turn then a C4 would. theyre also a little heavier so you have more weight to carry around with a AOD then a C4. so the engine will be putting less power to the wheels (since its lost in the trans) and have to work a little harder to carry the weight. so your only real avantage will be the much lower RPM's on the highway. in the end i dont know it it would be a net gain or net loss in mileage. Thats just the opinion ive come to after reading a few things, i may be wrong tho. ive heard estimates as high as 20hp that the AOD will rob from your RWHP #'s. thats not really a big deal on a 300hp v8 but on a 70 HP 6cyl 10-20hp really means alot

if your paying 11 cents a gollon though why bother? if you were up here paying $4.10 i could understand lol

 

Thats sweet! What equipment do you have?

 

The AOD has a set of clutches that run backwards under all positions except when in that gear. It turns backwards which loads the transmission in the other gears. It uses more power to turn that part backwards - it calls for .080" to .120" clearance for that reason. If the clearance is as tight as the C4 clutches it would burn up in a short time. It isn't just heavier than a C4 the AOD is almost twice the weight of the C4. It may lower your RPM but not at high speed. When the throttle is pressed to the floor (or even close) the AOD will shift back to 3rd and you are right back where you started from. It is an expensive swap if you can't do the majority of the work yourself and the transmissions are expensive to build.
If you decide to go ahead with the swap start off with a '93 AOD from a truck or full size car as they have the best parts in them.

You have a PM -

 

Thanks guys, you´re really fast here!!! Hehehehe

Hey newtoford, the gas is not the matter, but the engine is. Here the 250 cid is almost a rare engine to find on the junkyards... and the import ones are rarers...
But the gas is cheap...!!! Hehehehehehehehehe

Ok, so far I´ve decided not to do the swap, but there are some questions left:

1°- What can I do to improve my C4? So far it works just fine, but I have 2 spare C4´s at home (again, hehehehe) and I want to prep one of them to be bulletpoof (not for racing, again, but to make it "happier" or some like that).

2°- What can I do to get my car a little faster or give the engine a little rest on the highway? I dont remember the rear end ratio (that may be because we never, I repeat: NEVER had to tear it down), but mya be changing the rim from 14" to 15" with a sligthly wider and taller tire? I don´t Know if that will be any good (other than what about the look can be)

3°- PaulS: On the Tranny matter, what do you think about swapping a C6 for a AOD behing a 400 cid? I have a ´74 Fairlane (Starsky and Hutch model, here they call it a fairlane, not a Torino or Grand Torino) and I use sometimes on the highway (and it´s a pleasure, the engine behaves like the gas pedal is endless... Hehehehehe). The engine was overhauled like stock one, just 0.020" overbored because it needed to be.

PaulS, my C4 have been a very good tranny, but is it that good? is really a though tranny compared to others?

 

My bass is a bbg series, 4 strings, active mics... YEP!!! The power is from a Peavey plant, an old Combo 300... not too much, but it rocks!!! I´m not like that guys that appear to have 10 fingers on each hands, but people appear to like our music hehehehehe

 

Hola CC.

Basic shift kit will help. B&M or Trans go are decent. Make sure the bands are good and consider a full seal job to avoid any leaks down the road.

The AOD would be good for your application. I think Trans go makes a kit that will keep it in overdrive at full throttle.
Gear Vendors OD will also work well. I think it has about .78 gear (expensive though).
1" taller tire will help a bit to bring the rpms down.

I would keep the c4 over the C6 for Mavericks/Comets. The 6 is big and also takes more power to turn. But yes, for a larger motor/car, the c6 would be a good choice.
A c4 can take a suprising amount of abuse and hold up well.
I've been torturing mine for amost 2 decades (including nitrous runs) and it's still ticking.

 

1. Look in the tech Articles section on this board. On the second page is one called "How to Hotrod your C4 Transmission" I explain how to do everything you need to do. Under NO circumstances use a B&M shift kit - I have heard nothing but complaints from people who have used them, The TransGo 40-2 kit is the best one on the market and is widely available. To make it bullet proof you will want to have six and five clutches instead of the five and four clutches that the factory uses. The stock input shaft should be fine for any stock engine up to about 350 HP. You will need to add a big cooler and use both the radiator cooler and the auxillary cooler in series. (front cooler line to the radiator and the rear cooler line to the auxillary cooler. Then you just connect the two coolers together.

2. Higher rim, bigger tires or slightly taller gears - you probably have 3:1 and could swap in some 2.92 gears without a big drop in performance.

3. The C6 is a larger C4. It is capable of taking the same 1000+ HP as the C4 but the case on the C6 is the weak point. Swapping in an AOD is a step backwards in strength. It is hard enough to make an AOD take 350 -400 HP which would be enough for the 400 but it is at the top of what it can take. It would give you 30% more speed at the same rpm as long as you were easy on it but you could break it just as easily by using the gas pedal hard. The AOD is fine for 302 hotrods when modified correctly but when you step up to the 400 it is on a par with what the AOD can handle. It will work - and I am very conservative - but I don't have broken transmissions coming back. In my opinion the AOD is a risky bet for the 400. If you are a gambler and have the money to lose then go for it. Hang on to that C6 though, you may want to put it back in.

 

Well, it looks like I won´t change any of my transmisions. I will read about hotrodding my C4 and let go the idea of swapping to AOD. I dont want a weak tranny on any of my cars (I do a lot of highway and need a really reliable car). On the maverick it will eat my HP´s and on the fairlane I will brake it with the gas. It doesn´t look like a bad transmision, but it´s not for the specific applications I want to use it. I will see what can I do here about the C4 since it´s really hard here to get the kits for upgrading it. Thanks guys, I really appreciate the advices.
I´m thinking seriously about getting bigger tires on 15" instead of 14" rims, it`s easier and cheaper to do than almost every other thing (and my car will look better).
Thanks again, really!

 

Look at the "How to Hotrod Your C4" article in the Tech Articles forum.
It lists all the changes to make a "bullet proof C4" for up to 450 HP.

 

Thanks Paul, I´ve already read that, I will e-mail you soon to ask you for all of the pictures about that article... and I have some questions to ask you about it too.

I have very good ideas (or I think that they are good... hehehehe)

 

I will wait - be sure to identify where you're from and who you are.
I get a few emails so it helps to know who I am talking to.