IRS to Solid Axel Swap

[HIGH ROLLER]

Is there a link or website that someone can direct me to see what all i need to complete the swap.Any input is appreciated!!

 

[Soap]

--Joe

 

[trey193]

TTT for ya!!

 

[bassin247]

I asked Dana these questions..

bassin247 wrote on 11-11-2003 10:10 PM:
Hey Dana,

There is a local Bullitt owner that wants to swap his solid for my IRS. I'm going to do it but I have a few questions if you don't mind.

The guy offered to replace my gears because I don't want the 3:27s. Should I stick with the 3.55s or user something numerically higher? My car isn't going to be a dedicated drag car, but it will make it's fair share of passes.

Since the rear is going to be opened and I don't want to be replacing broken parts after it is installed I was planning on getting a setup similar to yours.. Eaton Posi with 31 spline Strange axles. Should I replace anything else? I have not had a rearend apart, but I can figure pretty much anything out. I just don't want to make any mistakes while I have everything apart.

Can/Should I use the Bullitt springs/shocks? I wonder how the Bullitt suspension is going to effect my car's ride height. What are you using for rear shocks and springs? how much?

The rear brakes from the Bullitt are the same as my cobra so I'm not going to need the brackets, but I think the lines need to be swapped.

Am I going to need a pinion flange to reuse my driveshaft or can I get it off of the Bullitt?

Am I missing anything? Any questions, comments, concerns would be greatly appreciated.

Thanks,
Mike

and he replied..

Ok, I put 3.73's in mine after many sleepless nights trying to decide. I don't regret it. These motors really don't need the extra torque they provide, but the 3.73's will allow it to wind up just a little faster and the motor will carry the 3.73 through the quarter mile easily. There are still a few hundred RPM's left.
I would go with the 3.73.

Sounds as though you have the insides of the housing covered pretty well. There isn't much more in there. The Eaton Posi survived my brutal attack on it with the T/C being left on all day one day at the track with no problems. That's another story.
The Strange axles are decent and although I bent one, I think it was because of the tremendous amount of torque that was being applied to it by me leaving the T/C on.

I have built rear ends before, but they can be a rear pain in the ass if you are not very good at it. I elected to have someone set up the Ring and Pinion for me. I did the rest.

As far as suspension goes, I used the Strange 10 way adjustable shocks. They are reasonably priced.
I am pretty sure I screwed up on the springs though. I used aftermarket Moog springs for a 4 cylinder Mustang. The problem was that they were Cargo Coils ($75) and the weight transfer isn't happening right. I plan on changing them this winter or spring to something else, I don't know what yet. Maybe Eibach or something from FRPP. I want the rear about one inch lower than stock and the weight to transfer properly.

In your case, I would get the adjustable shocks and use the springs from the Bullit for the time being. See where it sits and how it rides. Changing them is no big deal and can be done in a few hours easily.

What you have to keep in mind is that when you install the solid axle, your car effectively becomes the car that the suspension is from. In you case the Bullitt. In my case, it is a 2002 GT. You buy the parts to match the suspension that has been installed.

Although I am not familiar with the Bullitt, I don't see why the brake lines or anything else should have to be changed if they have the 11.7 inch Cobra rear brakes also. Just leave your calipers in place for the swap(reuse your own calipers). I would also reuse your own rotors since they are worn to match the pads in the calipers on your car. The ABS stuff should plug right in too. Just watch the routing of the cables and emergency brake lines afterwards. They can get a little close to the tire. I repositioned the front bracket where they exit the floor pan and that was sufficient.

With the D/S, you can go several ways. Swap in the entire D/S, and you don't have to change pinion flanges. It is supposed to fit ok, as far as length goes. I didn't do this so I can't give you a definte answer.
What I did was reuse the Cobra D/S and install a 5 inch Cobra pinion flange on the rear end.
You can also install a GT (or Bullitt) end on your D/S. That should work also. You may have to scrounge up a u-joint that will work though.

Don't forget you need a GT CatBack and the hangers to match. They mount right behind the mufflers.
While it is down, I would consider poly bushings for the control arms, at least. If not adjustable arms.
I don't have sway bar, I use a anti-roll bar, so I can't help you there either. But use good bushings there too.
All the suspension upgrades can be done at a later time, so if you don't get it right at first, don't panic.

Use LockTite on everything, particularly the brakes. They will loosen up on you. The only place not to use LockTite is on the bolts that hold the caliper to the clamp, where the rubber boots are that slide in and out.

Anyhthing else, let me know.

Good luck.

Dan

I decided to go with 3.73s and I am very happy with them.

I kept my DS and got a new U joint and swapped DS flanges.

I ended up replacing the Bullitt gears/diff/axles/diff cover with 3.73s/eaton posi/31 spline moser axles/mac hd diff cover.

I did use the Bullitt springs/shocks. The ended up dropping the car ~3/4 of an inch. (going to be replaced soon)

I kept my brakes because he had a Bullitt (same rear brake so I didn't have to buy the 98 cobra bracket).

We swapped stock catbacks and I took he exhaust hangers.

If you are going to get new catback, springs, shocks, lower control arms, upper control arms now is the time to do them.

If you are going to do this yourself have a lot of tools, jacks, jackstands, and be prepared to work!

If you have any particular questions post them and I will do my best to help you out.

 

[bassin247]

I highly reccomend getting FMS upper control arms and MM lower control arms. With this stock stick it feels a little shakey when you corner fast (like doing 50 on an on/off ramp).

This summer I will most likely have a MM torque arm and panhardbar installed with coilovers.

 

[davidmax]

I use HAL coilovers in the rear,god prices/480-517-4969.
Dave Smilovic

 

[bassin247]

ttt

 

[2kbill]

Originally posted by bassin247
I highly reccomend getting FMS upper control arms and MM lower control arms. With this stock stick it feels a little shakey when you corner fast (like doing 50 on an on/off ramp).

That is the setup I have, and I am very happy with how it tracks on uneven stuff while cornering. Click on clunkless! below for pic.


Bill