Boom's Boosted Bullitt

[Boom]

Got my new filter in. They had a 9" and 12" tall option. I got the 9" since it was in stock. I don't forsee needing the larger one realistically. I like that not having the maf in fender well moves the filter up a good bit so it's not as close to the ground.



Car fired right up and idled smooth. I drove it home, was raining quite a bit so I didn't romp on it at all. Maybe in the morning ill get on it a bit more to see how it runs.

 

[Boom]

Car has been running smoothly. Decoded to move on with installing the next parts. I know some of you probably won't like it.

My calipers came back from the powdercoating shop. Here's a shot getting ready to reassemble them.



This was my first time rebuilding calipers, so I was a bit nervous. Seemed to go back together without issue.




I decided to install them today. I am reusing the stock 13" rotor, I have new pads and hardware of course.

There's not much to the install. Since I had already replaced the bushings, these literally just bolt right onto the car. Even uses the same banjo bolt. Stock brake hoses fit and everything. I grabbed some new copper washers and mounted everything up.




The wheels are close in spots, but I had already verified they'd fit.

The toughest part for me was bleeding everything. I'm not good at using those lil vacuum pumps. I prefer to use the old two person pump pump hold method.

Car has a bit more pedal travel now but does stop firmer. I'll drive around some more to hopefully bed in the new pads to the old rotors.

 

[Grabber70Mach]

Nice, it's looking good. Is there someone that sells a kit to adapt the CVS brembo calipers to the sn95 spindle?

 

[Boom]

Nice, it's looking good. Is there someone that sells a kit to adapt the CVS brembo calipers to the sn95 spindle?

Thanks!

I don't think so. I believe the CTS caliper has a solid design with the holes all cast into the caliper itself.

The ATS and XTS calipers have a bushing that you can press out and then press in one designed for the sn95 caliper. Thays what i did with this setup here.

The ATS uses the stock 13" Cobra rotors. The XTS is bigger and runs the 14" GT500 rotors.

Here's the place I got the bushings amd spacer from. They make a kit to allow a bigger rear rotor too.
Caliper bushings

 

[Grabber70Mach]

Thanks!

I don't think so. I believe the CTS caliper has a solid design with the holes all cast into the caliper itself.

The ATS and XTS calipers have a bushing that you can press out and then press in one designed for the sn95 caliper. Thays what i did with this setup here.

The ATS uses the stock 13" Cobra rotors. The XTS is bigger and runs the 14" GT500 rotors.

Here's the place I got the bushings amd spacer from. They make a kit to allow a bigger rear rotor too.
Caliper bushings

Thanks. I don't see a link if you posted it.

 

[Boom]

Shop | S&S Engineering

www.ssengineeringllc.com

 

[Boom]

Another boring project commencing!

I am going to be replacing the rear suspension with the IRS from a 2001 Cobra. I want to get a smoother ride and have always liked the Cobra IRS.

The setup I'm getting is from a place in Florida called Butler Auto Parts. It's a salvage yard, they have an ebay store and a website. I've found their ebay store easier to search tho.

Interesting thing about them is they offer free shipping. They arranged to have my suspension shipping up to PA for me for free. Almost couldn't believe it.

Suspension is set to be delivered to me Monday.

Here is a pic of the car it was pulled from and some pics of the setup still on the donor car.









One thing I found mildy annoying. The shop took the halfshafts off. Those were extra . I decided to just order new ones off rockauto for a bit cheaper then they wanted to see me the original ones.

No brakes either. Not a big surprise there. Debating on just using the caliper I have now on the solid axle or getting new ones for this setup. Theyre the same calipers and bracket that my Bullitt came with.

 

[kb3]

How much work will this swap be? I assume the cars are very close in design, but may not have all the necessary brackets?

 

[Boom]

The car bodys are identical. The IRS has a subframe that bolts in place where the traditional four link and shock mounts go. So it "should" go right in.

Picked it up today! Met the truck driver at a Lowes and just slipped it right onto the bed.



Looks as good as to be expected. I had already been researching the various options to replace all the bushings. Not only are they the weak link on the stock design (rubber) theyre all 20+ years old.

I have new half shafts on order already. I also ordered new subframe bushings, new mounting hardware, amd sway bar bushings. Needed to hit a magic number for free shipping. Adding sway bar bushings actually saved me money vs paying shipping.

I also plan to order a new crossmember to replace the one here in front of the diff. In 03-04 models Ford ties this into the diff mounts for added rigidity.



I may need a new driveshaft. Some debate there. I need to see what I have on the car now and measure it.

 

[kb3]

I have seen quite a few guys mount the S550 IRS under other vehicles. If my wife keeps having people run into her 2015 GT I may have to scavenge the motor, trans and rear end out of it!

 

[Boom]

I have seen quite a few guys mount the S550 IRS under other vehicles. If my wife keeps having people run into her 2015 GT I may have to scavenge the motor, trans and rear end out of it!

I've seen that too. The IRS from those is drastically cheaper to acquire too since every car had them.

I have looked occasionally at wrecked S550s and considered getting one for the engine and trans.

 

[Boom]

Took some time today to remove the differential from the IRS. Kind of a pain. Really just the rear bolts. Very limited space to swing a wrench or ratchet.

Been reading up on what some of the upgrades and improvements are for the IRS. One that caught my eye was a few places offer a lowered mount for the rear of the diff. Apparently the Cobras came from the factory with a pretty lame driveline angle. The lowered rear mount and optional front shimmed mounts allow you to angle the diff upward to hopefully get to the ideal 0*

Need to look and see if the mount fits on the stock diff cover. It's sold separately, but everyone seems to machine the Ford Racing cover for its use.

Here's a shot of the cradle with the diff removed. Not very exciting, but we all love pictures. The lowered diff mount would replace that bracket just off of the center there



I also got the new halfshafts in. Much heavier then I expected. Makes sense though.

 

[kb3]

That thing is just crying for a spray paint overhaul! When you say the ideal 0* angle, is that specific to IRS set ups? Most diffs want approximately 3* angle for the ujoints to be happy, maybe since the diff does not move 0* works? I have never studied that...yet.

 

[Boom]

Yes it is definitely getting cleaned up and repainted!

From what I've read, from the factory, the transmission exits at 2* down, the diff pinion is also at 2* down. Ford added the heavy weight block mounted under the pinion to minimize any driveline vibrations.

I know the diff is rigidly mounted so the driveline angle shouldn't change much, if at all, while driving. With so many rubber bushings in the factory setup I can see why some folks had vibrations though. The ideal angle is 0*, this helps prevent u joint stress and shaft vibrations. Though most places agree that anything less then 3-4* is acceptable.

I plan to replace most of the bushings die to age at a minimum. Been reading up on all the pros and cons.

 

[Horseplay]

Driveline angle is not as much a mystery as some think. There isn't really any magic degree angle other than there must be some angle. U-joints don't like being inline. Zero degrees is bad.
What is important is to align the two angles of the transmission and the rear end. If the engine/trans is sloping down 2* then your rear end needs to angle up that same 2*. It's when these two don't match that you can run into problems with vibration, etc.
You can also have the rear offset (left/right) of the trans centerline without issue, contrary to what some might tell you. U-joints are made to work in that situation as well.

 

[Boom]

Yeah, that's what I meant for the angles. Not for them to actually be at 0* but rather to counter each end's angles like you said.

 

[kb3]

Yeah, that's what I meant for the angles. Not for them to actually be at 0* but rather to counter each end's angles like you said.

That was my understanding on solid diffs, I was not sure if it was the same for IRS.

 

[Horseplay]

As far as diff and trans angle alignment, there is nothing different about a IRS vs a traditional solid (floating) axle. The nice thing about the IRS is the diff doesn't move up down or even a slight bit sideways like the other does. It sits stationary the whole time. Makes driveshaft length calculations that much easier. Add in a 4-link and things get a bit more difficult as the pinion angle can move up and down as the axle moves through its arc. Whole lot of math and angle measuring needed when one goes that path.

 

[kb3]

As far as diff and trans angle alignment, there is nothing different about a IRS vs a traditional solid (floating) axle. The nice thing about the IRS is the diff doesn't move up down or even a slight bit sideways like the other does. It sits stationary the whole time. Makes driveshaft length calculations that much easier. Add in a 4-link and things get a bit more difficult as the pinion angle can move up and down as the axle moves through its arc. Whole lot of math and angle measuring needed when one goes that path.

I never gave IRS driveshafts much thought, but from a theoretical perspective both the transmission and rear end are locked in place and you should be able to use a solid shaft, no u-joints. I assume the little bit of play in mounts, etc make the joints necessary.

 

[Boom]

I never gave IRS driveshafts much thought, but from a theoretical perspective both the transmission and rear end are locked in place and you should be able to use a solid shaft, no u-joints. I assume the little bit of play in mounts, etc make the joints necessary.

They shouldn't move much in theory, but they aren't lined up enough to have a solid shaft. The cars flooring would need a trans tunnel for that to work.

The irs does float around a bit in stock form, thats its main drawback. It has rubber bushings literally everywhere. Rubber holding subframe to the car, rubber mounting diff to the subframe, rubber control arm bushings, rubber holding the spindles to the control arms.

Replace those bushings with stiffer material and it tightens up the rear end tremendously. Ford tried a bit in the 03-04 models by increasing stiffness of the diff mounts, but the NVH team vetoed replacing the other bushings from the factory.

Scored a good deal on the exhaust kit. Was browsing online and found some random site, Elite race fab, had the same Borla kit everyone else had but for almost a $100 cheaper. Hit up the chat on AM and it told me a person would call me. They actually did have people working on the 4th. They price matched it and shipped it already, says it'll be here tomorrow.