AMC Eagle Den Forum

The Shop => Transmission Shop => Topic started by: shanebo on April 12, 2011, 11:41:07 AM

Title: Auto Trans with 4.0 upgrade question
Post by: shanebo on April 12, 2011, 11:41:07 AM
 :help:

I am working on upgrading my eagle to a 4.0 head and EFI. I am keeping the stock rebuilt trans. Do these Transmissions shift via electronic signal or do they shift on their own....I'm very transmission illiterate.
The reason I'm asking is cuz I will be swapping the eagles "computer" with the jeeps. I'm just not sure if there will be issues getting the trans to shift properly.
Title: Re: Auto Trans with 4.0 upgrade question
Post by: ericarmstrong on April 12, 2011, 12:11:57 PM
The eagles factory trans is hydraulic shift, no computer. If your using the jeeps EFI system forget about the AMC computer. The only thing it did was minor timing adjustments and fuel metering with the carter bbd carb. You will need to find a way to pair the transmissions throttle kick-down rod to the EFI jeep's throttle cable setup.  The kick-down rod is the rod that goes from your carburetors throttle linkage to the side of the transmission.
Title: Re: Auto Trans with 4.0 upgrade question
Post by: BenM on April 12, 2011, 12:50:55 PM
Lokar sells a cable for the transmision. Just set the system up like a manual, and the transmission will do its own thing.

Some computers had a separate transmission computer for automatics, and can be run either way, and others have an automatic controller built in. You'll need to get the 2-part cruise control cable and graft the electronic speed sensor in between or trim your floor pan to fit the larger sensor. You'll also need to replicate the crank sensor, many ways to do that.
Title: Re: Auto Trans with 4.0 upgrade question
Post by: mudkicker715 on April 12, 2011, 01:10:49 PM
Quote from: BenM on April 12, 2011, 12:50:55 PM
Lokar sells a cable for the transmision. Just set the system up like a manual, and the transmission will do its own thing.

Some computers had a separate transmission computer for automatics, and can be run either way, and others have an automatic controller built in. You'll need to get the 2-part cruise control cable and graft the electronic speed sensor in between or trim your floor pan to fit the larger sensor. You'll also need to replicate the crank sensor, many ways to do that.

Explain what that means. Set an auto like a manual.

That eagle trans tjrottle rod xontrols hydrolic pressure and is necessary.
Title: Re: Auto Trans with 4.0 upgrade question
Post by: BenM on April 12, 2011, 01:32:18 PM
The cable goes in place of the rod, and is designed for different carb/intake retrofits on 9xx and 727 equipped cars.

As far as the 4.0 computer is concerned, it needs to believe you have a manual transmission so it runs correctly and doesn't throw codes, since it will not get any feedback from the transmission except road speed.

The AW4 and modern Chrysler automatics both give a certain amount of gear and duty feedback to the computer, but your 998 won't be equipped to do it, so you set up your wiring like you're running a manual transmission, and it will work just fine.

Make sense?
Title: Re: Auto Trans with 4.0 upgrade question
Post by: mudkicker715 on April 12, 2011, 01:46:05 PM
Now it does. Thought you meant somthing else. Also I believe not certain, but an xj shift cable will work. Try that first
Title: Re: Auto Trans with 4.0 upgrade question
Post by: shanebo on April 13, 2011, 01:15:51 AM
Ill bet that would trip out the computer if its not getting feed back from the transmission it thinks should be there. Ill just have to get the computer out of a manual trans jeep to keep everything nice and simple!

Thanks for the input fellas Im finally starting to wrap my brain around this thing...Ive really never tore into something, to this degree, that was newer than a 72....every step of this project from here on out is a learning experience.
Title: Re: Auto Trans with 4.0 upgrade question
Post by: tougeagle on April 13, 2011, 01:28:25 AM
Quote from: BenM on April 12, 2011, 01:32:18 PM
The cable goes in place of the rod, and is designed for different carb/intake retrofits on 9xx and 727 equipped cars.

As far as the 4.0 computer is concerned, it needs to believe you have a manual transmission so it runs correctly and doesn't throw codes, since it will not get any feedback from the transmission except road speed.

The AW4 and modern Chrysler automatics both give a certain amount of gear and duty feedback to the computer, but your 998 won't be equipped to do it, so you set up your wiring like you're running a manual transmission, and it will work just fine.

Make sense?
That definitely answers a curiosity I had. thanks!

shanebo, as he said, set the wiring up for a manual, though you can from what I understand, retrofit an automatic 4.0 CKP onto your auto bellhousing....That would be much more reasonable than the hesco damper. Your vss can be done as I did mine, or if you have the extra money, I compiled some sites from members' advice that will allow you to get everything you need to set one up at the transfer case, as long as you intend to stick to the stock case. If not, you'll have to mount it onto your cluster input like I did.