Thread: 68 Mustang Convertible - Some Unique Upgrades

My fabricator friend and long time collaborator, Sean O'Brien (forum name ESRinfo) posted some info on this project in response to a query in the Suspension section of this forum, but we have decided to post a full project thread, mostly for the benefit of the owner, who is slaving away half way around the world, and only sees his Mustang once or twice a year when he visits home. The car sat for several years because the brakes and steering were in pretty sad shape and it did not start and run well after sitting for long periods. My son suggested he have Sean do some upgrades to get the car into a more driveable state. After some research, Sean recommended conversion to power rack and pinion, four wheel disc brakes and ideally, fuel injection. The owner sent us a check and said go for it. We bought new front control arms and ball joints, and a Unisteer rack kit. The car had been poorly repaired form a previous fender bender, so Sean replaced the inner fenders and core support. He also installed some of the recommended reinforcements to the shock towers and suspension mounts, lowered the upper control arm mount as recommended, but decided not to install the stock type spring arrangement. Many of you will be familiar with the kits which replace the stock spring, which attaches to the upper A-frame, with a modern coil over shock which attaches to the lower control arm. Rather than spend $2600 for the kit to do this, Sean used a pair of control arm brackets that he removed from a Ferrari he was modifying several years ago, a pair of adjustable KYB shocks that our friend Peter removed from his 240SX after only a few thousand miles, and a pair of Mazda RX-7 springs. The brackets have about 2 inches ride height adjustment. Of course we have not yet driven it, but it seems to sit about right - there is always the chance we will want to change the spring rate after we drive it. The moral of this story has two parts:
1. Being a pack rat may annoy your wife, but it can save you money. 2. You may have scrap parts left over from just about any project, but you should NEVER throw away parts you remove from a Ferrari.



We wanted to use modern brakes, preferably with four piston calipers, and the better quality kits are priced at $1,000 and up. We went to our friends at Foreign Engines Inc, our local JDM source, and bought a pair of Nissan Skyline 11 inch front brake rotors and four piston aluminum calipers in good condition for about $200. Like most all top line Nissan and Toyota cars these days, they are 5 by 114.3 bolt pattern, which is close enough to 5 by 4.5 inch, so the wheels fit. We needed to space the wheels out about one inch for the more modern wheels we are considering, and I just happened to have some 1 inch spacers. Sean took some measurements and found that by putting the spacers INSIDE the brake rotors, the caliper adapter could be made from a piece of 1/2 inch aluminum plate, as shown in the photo. This required machining about 1/8 inch off the diameter of the spacers.



Installing the Unisteer power rack kit requires some grinding on the flanges of the frame to make it fit. The round tubular crossmember is replace by the mount for the rack. Sean welded in a couple of pieces that bolt to the lower control arm brackets to make the assembly more rigid.



Sean was planning to buy a rear disc brake kit for about $500, and install some extra half leafs in the front of the rear springs, maybe a Panhard rod to give better lateral support. I just happened to have a complete Infiniti J30 rear suspension, with a limited slip differential and large disc brakes, which I paid $200 for complete. This is almost identical to the Skyline suspension unit we installed in my 48 Studebaker project. It is mounted in a cradle which attaches to the frame with four bolts using rubber shock isolators. It certainly does not look as neat as the 2015 Mustang suspension (see attached photo), and I am sure the new Mustang diff will handle more power, but you can see the basic layout is very similar. The tuner guys say this Nissan diff is good for at least 400 hp, which is more than this 289 will ever see. I suggested Sean consider installing this unit in the Mustang, and after some measuring and a few mental gymnastics, he decided to do it. The owner was agreeable, so Sean just started cutting and welding, and after a few days it was installed.



When we were at Foreign Engines buying the brakes, Sean spotted a very nice set of coilover struts , aftermarket pieces for a Nissan 240SX. He said "I bet these cost at least $1200 new". The only marking was "Office", which meant nothing to us, but the price was good, so we bought them. After talking to Peter, our Nissan guru, we learned that these were made by a Japanese company called Kei Office, originally sold for about $1800. Sean modified them to use on the rear with the J30 suspension, with a mount attached to the frame which intrudes only very slightly into the trunk space.

Attachment 104976

The engine and trans are back in the car, and Sean is fitting all the required bits into the engine compartment. This car had unboosted drum brakes, so we need a booster and dual master cylinder. We just happened to have one we removed from a Skyline, and it seems to fit nicely, just need to drill four holes in the firewall and use a spacer to get the pushrod to the right spot.



We went to a local self service auto salvage yard and removed a complete fuel injection system from a mid 90s Ford pickup with a 5.0 V8. The intake manifold is a monstrosity, covering up the injectors and wiring and generally making maintenance access difficult to impossible without removing the manifold. Sean cut up the manifold and built a much simpler unit, which greatly improves access and simplifies the plumbing.





Lots of cleanup and cosmetic work to be done yet, and most importantly, the plumbing of brakes, fuel and steering. Then the real fun begins - figuring out how to hook up all those wires. We will continue posting our progress. I should say that Sean has done virtually all the work on this project, except that I did some of the painting and small details.

I am in the early stages of building a web site, and so far have only created build summaries for three of our projects in the automotive section as seen here - might be of interest to some of you.

stilettoman.info

Ben

xxx

I don't see any pictures.

Originally Posted by ochohill

I don't see any pictures.

Me too!

Don't know what button I pushed,but somehow my original post had two sets of the photos, one set imbedded in the text and another set at the end called "attachments". I deleted the attachments, and I could still see the imbedded images, but apparently no one else could. I finally figured out that my browser cache was fooling me. Now I think it is all straightened out.

Went back to Foreign Engines Inc again yesterday and bought a set of 17 by 7 wheels with really nice tires, mostly used up but good enough for testing the car. They made me a really good deal and I think they look good on the car - still waiting to see what the owner thinks. These wheels are from a late 90s Nissan Sylvia S14, and are in excellent condition, never been curbed.

If it helps, I can see the photos. Very interesting take with the Nissan parts, and lots of fun to watch!

Sean has now done most of the engine work and fuel system is essentially complete except for the fuel injection computer. The Skyline brake booster and master cylinder are installed, still looking for a couple of brake line adapters.

Sean decided to use a pair of the stock 5.0 Mustang stainless exhaust headers, since this is just a stock 289 motor with no intent of increasing the horsepower. The exhaust is all stainless with the headers collected into a single 3 inch pipe to the back, then a custom made ovalized tube across the back with dual outlet tips and a modification to the lower rear panel, giving a similar appearance to the dual rear outlets on some Shelby cars.

Following this closely. Love the front suspension ideas. If I may ask, what year Nissan shocks and Mazda coils? I might have to try this on my 65 Falcon.

The KYB shock strut is from the rear of an S13 version of the Nissan 240SX, don't know if it fits the S14 or later models. The springs are from a 2nd gen RX-7, probably an 87 or 88, I think from the front, but I will confirm this. After a few weeks we should be test driving the Mustang and then we can report on the handling and if we think the spring rate is stiff enough.

https://www.ebay.com/itm/KYB-AGX-Spor...-/171642278928

Sean says you should be able to get a shock bracket from anyone who sources NASCAR suspension parts, and just weld on a bolt. This is assuming your local Pick-n-Pull salvage yard is not parting out any Ferrari 308s this week.

Thanks for the info. Seriously considering this setup, just for the availability of replacement parts. Not sure about the Pick&Pulls near you but the highest end car I might see in south jersey is a Lexus, maybe a Benz....

Double post...sorry

I love your approach to this build. There's no doubt the site sponsors here make some OUTSTANDING parts which are well worth considering, but I love innovation worked out on the garage floor from the best of what you have available.

I like the repurposing of parts, but your front strut is a little scary.

With the original setup the weight of the car was supported by the upper control arm that was designed to carry the weight. With your strut the weight of the car is now being carried by the lower control arm, that was never designed to carry that weight, and worse yet, all of the weight of the car is being supported by the small little stud that goes through the lower control arm (the clevis on the far left of the picture).



Andrew

Andrew -

Your concerns are legitimate, but you have apparently not examined the geometry in detail. We spent considerable time discussing this issue when we first decided to use these parts, and in our view the only item of concern is the lower ball joint. The strut load on the lower bracket is almost straight down. Sean has a couple of large nuts under the bracket to get approximate ride height. When the entire car is assembled, he will machine a spacer of appropriate thickness to adjust the ride height. The load pushes the bracket down against the control arm, so the stud sees no tension load. The only significant load on the stud is shear, from hard braking or when the tire hits a nasty pothole, curb or whatever. If this stud is equivalent to a grade 8 commercial bolt, it will carry shear of about three times the weight of this car. If Mr. Ferrari used a better quality material, equivalent to an aircraft grade bolt, it will carry more. Note that this stud replaces one of two bolts attaching the tension rod to the control arm.

The bracket is attached to the control arm about 2 inches from the ball joint, so the bending load on the arm is pretty small. Our main concern was the axial load on the ball joint, which would tend to pull the ball out of its socket. We talked with the supplier and were told that this is the same ball joint they use on a Mustang II style suspension, which is loaded exactly like our design. We took one of the original lower arms and sectioned the ball joint as shown in the attached photo. You can see the thickness of the socket and the amount of wrap it has around the ball. We decided to go ahead and finish the car and do our testing to determine if we like the spring rates, etc. My only concern would be after much driving and when the ball joint is worn. I plan to consult with a couple of friends who are aircraft stress consultants before I recommend the use of these parts in this way. Worst case we will replace the ball joints with something more robust - Sean mentioned some of the Mopars have a very robust ball joint that can be easily adapted.

If you look at the design of the TCP Mustang suspension, you can see it is pretty similar to what we are doing.

I have been so busy with my Studebaker project I have neglected to update this thread for some time. The Mustang is running and driving now, and some very knowledgeable people have driven it. They all think the steering, cornering and stopping ability are excellent, and with the fuel injection, the throttle response is good. Even with the old original 302 and stock cam, it will spin the wheels easily. It will be great around town, but it is geared pretty low, with a 3.9 diff, and we may need to find an overdrive trans to make it comfortable on a long freeway trip.

Sean built an all stainless exhaust system, with a dual outlet that had the appearance of some Shelby models, even though the exhaust was actually a single 3 inch from the dual cats back. It has a very nice tone. I should note that Sean has been building custom headers and exhaust systems for about 40 years, and actually ran an exhaust shop for many years.

The paint job is not the greatest, and was badly oxidized. My friend John and I spent a good part of a day polishing it , and it looks pretty good. We found some Honda wheel center caps that fit the wheels perfectly, and some Mustang emblems that were the same size. Peter used his fender rolling tool to get some more tire clearance with these wide wheels.

The wiring under the dash is a real rat's nest, and Sean is slowly getting that sorted out, between working on other projects.

Looks great, how does it drive?