84 Tbird project

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84 Tbird project

July 15, 2019, 10:21:51 PM

What's up everyone it's been a couple days! I've just been living family life, working, and playing with fox Fords.

And my latest project is this 1984 Thunderbird with a 3.8 v6 and C5.

It's pretty clean, runs and drives good. I drove it 20 miles back home. It has a small rust spot behind the back wheel on the passenger side, but the front frame rails and floor pans are still good.

I have a complete drivetrain out of a wrecked 89 Mustang 5.0 convertible that I'm gonna swap into this bird. The engine is already carbureted with a Edelbrock Performer intake and Edelbrock 600 cfm 4bbl with a TCI cable linkage for the AOD. I'm planning on swapping the E7 heads for a set of GT40s I have laying around.

I have a few questions about this swap starting out

The 8.8 rear end from the 89 Mustang will work if I just swap the tbird axles and drums on it correct?

I'm planning on running a duraspark ignition. I have a 1985 Mustang distributor and a blue connector duraspark box, but how do I need to wire this up in this car since it came with TFI ignition? Is there a diagram?

Also can I use a driveshaft from a Tbird with an AOD and does it have to be from a 5.0 or will a V6 AOD driveshaft work too?

Re: 84 Tbird project

Reply #1 – July 16, 2019, 05:41:38 AM

The rear should swap straight over without pulling anything off either of them. They're both 4lug with 9" drums and the v6 aod driveshaft should work to

Looks like a pretty nice start to a fun project!

Re: 84 Tbird project

Reply #2 – July 16, 2019, 08:44:42 AM

The Mustang rear axle housing is the same as that in the TBird, but you will need to swap the axles/brakes from the TBird rear to get the correct width. We have a sticky post about this in the "Drivetrain" section.

On the brakes, the internals are the same, but either the backing plates or drums are different to make up for the extra length from the axles. I think it's the drums. (It's been WAAAAAY too long since I messed with rear drums on one of these to remember).

Just check your DS length. The C5 one may be too long.

Re: 84 Tbird project

Reply #3 – July 16, 2019, 11:56:19 AM

Swap the 8.8 out of the Mustang into the Bird and get the correct offset wheels to match the Mustang rear end. It will move the wheels inboard 0.75" on each side and you can see this by dropping a plumb bob off the top of the rear fender and measure back to the center of the existing wheel on the existing rear end. Install the Mustang 8.8 and put your stock wheel back on and do the plumb bob again and that will tell you exactly how far in the wheel has moved. From this you should be able to select the correct wheels. If you want to go five lug then get the axles out from a 94-98 Mustang V8 or V6 rear end and that will swap you over to five lug, disc brakes, and it will just about be the same width as the stock Bird rear end (+/- a 1/16").

Gut the EEC-III out of the car and start over on wiring the new motor. This is what I did on my '83 with the 351W and it is carbed with an MSD ignition and distributor.

Put the motor and trans in the car from the Mustang. Put the car up on jack stands such that the suspension (front and back) is loaded and also safe to work under. A four post lift is the best but you will need to make these decisions based on your safety. Install the yolk from the drive shaft into the trans such that it is bottomed out on the tail housing seal. Measure back from the center of where the U-joint installs into the yolk to the face of the on the rear end that the DS bolts to. Whatever this measurement is you want a minimum of 3/4" less than that on the length of your DS. This allow for compression into the trans and for the yolk to slide back out of the trans for rebound. This is how the shop that built my aluminum DS told me to do it and it worked great. Here is a site that a lot of folks trust to build custom shafts and how they want you to measure for a DS:

https://www.dennysdriveshaft.com/how_to_measure.html

Re: 84 Tbird project

Reply #4 – July 16, 2019, 08:31:38 PM

Thanks for the help! This is gonna be a low budget production

so I'm trying to utilize parts from the Mustang where I can. I have the front brakes and spindles so I plan to put those on once I get it back on the road. I'm gonna use the sway bars too. I'm also gonna switch it to a floor shift and find a way to make the Mustang shifter work in the bird. For now, the wheels are gonna be 10 holes. I'll make sure to post updates. I'll probably start with swapping the 8.8 in and work forward.

Re: 84 Tbird project

Reply #5 – July 16, 2019, 09:18:46 PM

If you're going to use the 10-holes, swap the proper TBird axles/brakes into the 8.8. Otherwise it's going to look silly.

You can also avoid the custom-offset wheel route in the future. That is unless you have something special in mind. Mustang wheels are plentiful, though, and if you go 5-lug in the future, you'll have even more (affordable) options.

The '84 is going to be EEC-IV, not ECC-III, but you''ll be able to find the proper power wiring to power your DS module, etc in the harness.

Too bad the Mustang engine is already been carb converted, as you could probably have an easy-ish SEFI swap, as they are both EEC-IV systems.

Re: 84 Tbird project

Reply #6 – October 13, 2019, 12:52:53 PM

Project is underway!

Next is to pull the 8.8 and swap the axle shafts.

Re: 84 Tbird project

Reply #7 – October 13, 2019, 04:20:13 PM

Re: 84 Tbird project

Reply #8 – October 17, 2019, 10:16:54 PM

More progress today! Got the 8.8" out of the Zephyr, which has the drivetrain from a wrecked 89 Mustang.

Here are the axle shafts side by side. The left one is the Thunderbird that measures 30" and the right one is the Mustang that measures 29 1/4"

The axles side by side. They both measure roughly 54" from the outside of each backing plate.

Here is the 8.8" axle with Thunderbird axle shafts.

Next is hanging the axles under the car, making the brakes work, and installing the rear sway bar.

Re: 84 Tbird project

Reply #9 – October 26, 2019, 10:27:41 PM

Today we resealed the diff covers, hung the 8.8" axle in the Thunderbird and installed the rear sway bar.

Next up is getting the brake line hooked up and getting some KYB rear shocks for a Thunderbird because the Mustang shocks are too short.

Re: 84 Tbird project

Reply #10 – October 28, 2019, 08:08:00 AM

Coming along nicely!

One other option on the rear shocks is to get a set of Chuck's brackets that allows you to use Mustang shocks so you have more options. From what i understand Chuck doesn't make them anymore but these guys have been making them off his design: https://tbirdcougarparts.com/

Re: 84 Tbird project

Reply #11 – October 28, 2019, 08:58:04 AM

If the shocks that you have are good, just pick up a set of the brackets. The options for "good" shocks in TBird length are slim anyway.

Re: 84 Tbird project

Reply #12 – October 28, 2019, 08:25:15 PM

Thanks! Looks like the shock brackets are out of stock, but I can get KYBs for the Thunderbird cheap at work.

Re: 84 Tbird project

Reply #13 – October 29, 2019, 08:45:16 AM

I hated the Gas a Just kybs Way too harsh for me. I would get Monroe or Gabriel before them again.

Re: 84 Tbird project

Reply #14 – November 10, 2019, 01:12:22 AM

More progress today! The new shocks are on. We mounted the brake hose bracket to the body and ran a piece of brake line from the passenger side up to the rear hose bracket. Also hung the 7.5 axle in the zephyr so we can roll it around.

Also where is the resistor wire for the fuel pump? I unwrapped the wiring from the trunk to the fuel tank, but I didn't see it or I missed it. Is it in the trunk?

Next is putting the brakes back together and bleeding them. Then we start pulling motors!