Valuable Manual Resources

Chilton Manual
Chilton's Ford Mustang, 1989-93 repair manual : Free Download, Borrow, and Streaming : Internet Archive

Haynes Manual
Ford Mustang ( 79 92) Mercury Capri ( 79 86) Haynes : Free Download, Borrow, and Streaming : Internet Archive

Offical 5.0 Tech Manual
The official Ford Mustang 5.0 : technical reference & performance handbook, 1979 through 1993 : Kirschenbaum, Al : Free Download, Borrow, and Streaming : Internet Archive

Initial Maintenance - Power Steering Fluid

I noticed the power steering makes a slight bit of noise on the Mustang when turning at low speeds.  It isn't anything significant so I really did not think much about it.  When putting in the steering limiters, I was turning the wheels side to side in the garage and fluid squirted out the overflow hole in the power steering reservoir.  This caused me to look a little closer to see how bad the power steering fluid looked and I thought it best to look into a bit further.

I have a large syringe that came with a hydraulic clutch kit that I used to pull a little fluid out of the reservoir.  It was a fairly dark brown color that makes it appear rather old.  I checked the receipts I was provided and the owner replaced the steering rack in October 2024.  When that happened, they charged him to flush the power steering.  Either they didn't do the job or there is something else going on with the system.

I decided that I would just use the syringe to get all the fluid out of the reservoir.  As I did so, I noticed that in the fluid seemed to be something black suspended in the fluid that didn't fully dissipate.  The lower the fluid level, the more of that black fluid was in what I removed.  I'm not sure if it is black from deteriorating hoses, wear inside the pump, or residue from the back rack that is still in the system.  

Rather than get covered in fluid, trying to fully pump it all out, I just added new ATF.  I then drove the car around a little expecting the new ATF would clean the system a bit and I'd just keep repeating this until the system looks clean.  After driving it for a few miles, I used the syringe again and the fluid looks even darker now that before.  Before, the fluid was a little translucent when held to the light but this really isn't.  Perhaps that is due to everything circulating as I had not driven it lately when I first pulled some from the system.  

With the color of what is coming out, I think a full drain is in order.  If the older, darker stuff is setting at the bottom, a full flush might be the only way to remove it.  To do that, i really should replace the hoses.  Since I don't have hoses, I'll refill it, drive it some, and maybe repeat the process to see if things get any better before deciding how much I want to invest in this project.

Initial Maintenance - Throttle Cable Adjustment

I recently learned the throttle body doesn't open fully on the Mustang when I have the pedal to the floor.  The pedal was originally restricted by the floormat but once that was fixed, it was still not near opening fully.  As shown below it is open only 85-90% of the way.  It is actually restricting a large amount of airflow which is no doubt hurting performance.

After looking everything over, I expect the problem is just that the throttle cable is stretched.  I'd buy a new one but I've already spent a fair amount this month so I decided to go with a quick fix.  That is a .2" thick black spacer that I used to space the cable further away from the throttle.  With it in place, the throttle is fully closed when the pedal isn't pressed and fully open when it is to the floor.

As shown below, I now have full throttle.  This is far better than the starting point and took just a bit of time in the garage.  I might take the throttle body off and clean it but I've not decided if I want to go that far right now or not.  I'll just be glad I have full throttle range of motion for now.

Initial Maintenance - Mass Air Flow Sensor Cleaning

I decided to remove the Mass Air Flow (MAF) from the Mustang and clean it.  While the previous owner installed a cold air kit from SVE, the MAF looks like it has never been cleaned as it is covered in grime.  Once removed, I found the inside didn't look back but carried on with the cleaning.

I removed the sensor itself and cleaned it with CRC MAF cleaner.  There are two small little wires that resemble the filaments inside a light bulb but smaller.  I sprayed them with 10 blasts of the cleaner as the can suggested and made sure to touch them with nothing.  With that part removed, I then cleaned the exterior of it with some carburetor cleaner.  

With the exterior clean and the sensor removed and clean, I decided to work on the inside of the MAF.  I removed the protective mesh screen and cleaned it with MAF cleaner.  I also sprayed down in the hole were the sensor resides with the MAF cleaner and all around the inside.  This is probably overkill but it is worthing doing well since it is out of the car.  

I measured the opening of the MAF and it is 55mm.  The sensor itself has the following part number on it.  It all looks to be the stock equipment setup for use with the 19 lb injectors.

F1ZF-12B579-AA

AFH55-03B

2E20

I'll set this aside now as I'm going to keep on moving up towards the throttle body cleaning and adjusting the parts as needed to address the full throttle issue I learned of yesterday.

Dragy Performance Meter - Initial Testing

I purchased a Dragy GPS Performance Meter as I wanted a way to do some level of baseline testing before I started making modifications to the car.  At this point, it is stock with a few exceptions.  Those are that is has a full header back exhaust system and a cold air intake.  The cold air intake is a cheap SVE version that has a small generic filter on it.  The exhaust is a BBK equal length shorty header, 2.5 midpipe with H, and then a Flow Master 40 cat back setup.

I was largely growing familiar with the tool so I don't know that my runs are really fully representative of what the car could do.  I had the A/C on low the whole time, an 1/8 tank of gas, and it was a morning which wasn't sunny and 84 degrees.  I didn't particularly find smooth roads and just stopped and went to 60-70 MPH.  

I left at 2,000 RPM and went to 5,500 RPM in each gear up to 3rd.  My best was a 2.96 second 0 - 30, a 7.98 second 0 - 60, and a 10.4 second 1/8 mile.  That really isn't fast at all.  That leads to an estimated quarter mile time of 16.1 - 16.6 seconds.  I'll try it again on another day without the A/C on and I'll see if it is any better.  This was my best of three runs and it was also the last run.  I think the first few I was just getting the hang of it a little. 

The performance is somewhat below what I expected so I started searching for the reason.  Once option is that the throttle body isn't opening completely.  I decided I'd start there as it is easy to check and I found it is indeed not opening fully.  The floormat was stopping the pedal from going to the floor.  Even when that isn't the case, it still isn't opening fully.  

I took the above picture and ran it through ChatGPT to ask it to estimate the percentage the throttle is open in the above picture and the amount of the obstruction considering the obstruction covers a large section of the middle of the air flow path.  ChatGPT indicated it appeared to be 12% open which would mean it is obstructing 21% of the airflow.

I'll need to work on correcting this but for now I wanted to post my initial results using the Dragy meter.

For reference, I used the Dragy in my truck and it went 0-60 in 7.52 and the 1/8th mile in 10.06.

Initial Maintenance - Sway Bar Bushings and End Links

I expect that I'll ultimately replace the front sway bar but I don't know when I'll find that to be the most reasonable next upgrade.  Until that time, I want to continue the maintenance to make the car run and drive as close to its original ability.  With that in mind, I'm going to swap out the sway bar bushings and the end links.  

The end links I decided to use are made by Energy Suspension (Part# 9.8167G) which have two different size bushings allowing it to be set at a few different lengths from 6 3/8" to 5 7/8".  They are polyurethane and made in the USA which is nice.  The nut on the existing sway bar end link looked as if it has been removed before so I'm not sure if what was on the car was stock.  However, measuring from the center of the end links was 6.5".  Since the car is slightly lowered, I removed the end links, put the car on the ground, and measured with the sway bar end parallel to the ground and found I need the new ones set to their lowest length of 5 7/8".  

The stock end links are in the middle of the picture below.  The new end link on the left is set to the 5 7/8" length.  On the far right, you can see the configuration that makes it the longer 6 3/8" size.  I ultimately set them both to match the one on the far left.  

The bushings I'm using for the way bar are 1 1/4" in diameter and are also made by Energy Suspension (Part# 1.51408G).  These are also polyurethane but there isn't anything on the packaging to state if these were made in the USA.  The bushings I removed were still quite flexible and looked fine except for the inner surface that touched the sway bar.  That inner surface had worn off the sway bar coating, caused some rust, and the inside seemed like it was coming apart a little.  

It wasn't my original intention but with everything removed, I decided to clean up and paint the sway bar.  I cleaned it with some super clean, sanded down all the spots were the existing finish (which seemed to be powder coating) had chipped or was rusty.  I then sanded the whole sway bar with 220 grit, then used a red Scotch-Brite pad on the whole bar, painted the ends with Rust-oleum Rusty Metal Primer (as they were a little rusty to start with and it seemed like good insurance), and then coated the sway bar with VHTs Roll Bar & Chassis paint (#SP671 - Satin Black).  The paint takes 48 hours to dry so there was a bit of waiting involved to reinstall the sway bar.

I was going to work through cleaning the original sway bar mounting brackets but after soaking them in Evap-O-Rust overnight, I decided it would just be better to buy a new set.  The originals are rusty and it will take quite some time to get them to look reasonably good.  I also need new hardware which comes with the new bracket.  Since I'd already be waiting two days for the sway bar paint to dry, I ordered a new set of sway bar brackets (LMR branded LRS5486A).  They come with a nice, solid mounting block to use in place of nuts which made what was a challenging installation by yourself a little better.  

I debated cleaning the mounting points on the car but decided to wait.  There is much more to clean and taking forever on these little mounting spots would do little good right now.  As is normally the case, I scratched up the bar a little getting it into the car.  However, I touched it up so that it isn't visible but I'm sure plenty of rock chips will show up soon enough.  

I drove it around the block a little not expecting much of a difference but the responsiveness when turning is much improved.  It feels quite solid so this was worth the time.

Clutch Cable, Quadrant, & Firewall Adjuster

The clutch pedal feel has been rather inconsistent with the Mustang.  I expected the clutch cable was worn and stretched which was contributing to the problem.  The Mustang also retained the original plastic clutch quadrant which also wasn't helping the situation.  Today, I handled both by replacing the clutch cable (Ford Performance #M-7553-C302), clutch quadrant (Maximum Motorsport #MMCL-6), and added in a firewall clutch adjuster (Maximum Motorsport #MMCL-3).

I started at the transmission and worked my way up to the clutch quadrant.  I was surprised to find the clutch fork cover was in horrible condition and had rust holes through it completely along the bottom.  With it removed, it was rather easy to remove the entire clutch cable including the connection just above the gas pedal.  There wasn't anything visually which made me believe the cable was bad or excessively worn.

Removing the original clutch quadrant is a little challenging... even with the front seat removed.  This is mostly due to a spring designed to hold the adjuster into place on the pedal.  What was then more challenging was the installation of the new clutch quadrant.  The mounting hole was slightly too small.  After considering options and trying a few different things, I ultimately put some 320 sandpaper on a 3/8 extension and it slide into the mounting hole which allowed me to just slightly expand the opening, so it fit perfectly.

With the quadrant installed, I worked on the firewall adjuster.  I'd considered using the LMR adjuster that came with the firewall brace I purchased but prefer the black anodized one from Maximum Motorsports (see below). I was going to install the LMR firewall brace but found that it doesn't really match the contour of the firewall and leaves a gap between it and the firewall.  I decided I'd just install the Maximum Motorsport part without the firewall brace and return the LMR kit.

The firewall adjuster requires almost nothing to get it into place.  The original stock cable retaining screw is removed, That same screw is used in one of the two mounting holes with the new adjuster.  You then drill another hole for mounting the other side.  I'm typically opposed to drilling any holes in a car but did it anyway and mounted it with some #8 - 3/4" black screws.  

I ran the cable from the transmission, mounted it to the driver side frame rail area using the integrated bracket, and then ran it through the adjuster.  There is a unique spacer you need to install on the cable according to Maximum Motorsport so I took care of that job.  The cable then easily slid onto the quadrant.  I've mostly adjusted the clutch just using the stop nuts at the transmission end leaving all the adjustment at the firewall for later use.  

I then a Maximum Motorsports document on how to setup the firewall adjuster.  They suggest you spin it all the way in, leave the frame rail mount off, fasten the clutch cable at both ends, and pull on the cable towards the front of the car.  As you do so, the transmission side of the clutch cable sleeve is mounted so it stays in place.  You will find a gap form at the firewall adjuster, and you need to adjust it out to fill that space.  I did that and adjusted a little at the transmission and now the pedal starts to engage at 2 or 3" off the floor.

While I was at it, I the speedometer cable was leaking at the transmission.  I checked and found that I still had an O-ring for the transmission in my '67 Mustang parts.  I cleaned up the area a bit tonight and swapped out the O-ring.  The leak wasn't bad but I expect it was the O-ring as it was a little on the hard side and seemed to have shrunk slightly compared to the new O-ring.  

I drove the car for a day or two and all seems reasonably well.  That also gave me time to get a new clutch fork cover as mine was in horrible shape and actually had small rust holes.  I picked up a E6ZZ-7513 which is made by Daniel Carpenter.  These never fit great as I used two on my '67 and they generally need some metal forming on the front to fit into the bellhousing.  On the positive side, it included the screw which normally isn't included (LRS-55981S2-1).  With it now in place, this project is wrapped up and the clutch works a bit better now.  

The car now has 81,927 miles on it which is 301 miles more than when I purchased it.