Rear Suspension Photo Page

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Page updated April 21, 2017


Sway Bar Addition VP IRS Spindle Bushings Koni Adjustable Shocks Modified IRS Arms

Rear Suspension

This is what the IRS looks like when it all goes together. Without the aluminum panels on, it's much easier to work with. I had my hubs and rotors drilled by a friend and the rest I did myself. This is a real work of art. I also was able to install the pumpkin in without assistance. It's a little bit of a puzzle but it can be done. The last shot on the top row are the hubs after being re-drilled and the studs installed in one hub. The bottom row consists of the rear suspension after 4,000 miles.

January 2002

This is the latest improvement to the IRS. Installation of a sway bar. All I can say is, "What a difference a bar makes!"

Let's see, it's winter and time for those pojects we seem to start listing during the summer, to be completed now that the weather has turned a little cooler and wetter. I've been thinking about this project since last summer after putting some good mileage under my seat. By the way the car felt, it definately needed to be controlled for body roll. Although the Cobra squats nicely in the turns, too much body roll gives you the sensation of the car breaking out too early. When in reality, it could go just a bit further before the "feel" came to you. Adding the bar, puts this feel back into the handling of the car.

I purchased Craig Mapstone's sway bars Vintage Performance Motorcars and found them to be perfect for the IRS cars. The rear bar is a complete bolt in process. I was informed I am their first customer and believe me, this is an unbiased report on the installation and testing phase. There are a few things to consider but they are minor and will be explained.

The following photos show the installation procedure. I must admit they do a good job of packaging the parts for delivery. Everything is wrapped and the bars are well protected during their shipping. The directions are very well done and shouldn't cause anyone to have a problem installing the bar.

Taking the gas tank out is the biggest headache. I've had mine out so many times during the last few months, one more time wasn't going to hurt me. It does need to be "persuaded" for the bar to fit as explained in VP's directions. Also, having the tank out of the way makes it easier to fit the bar brackets and links. You should also remove the springs and shocks so you can test the travel after completing the installation. I had to trim the left rear bracket slightly to clear my lowered trunk box. I only trimmed the corner about 1/8".

The above thumbnails are as follows: picture before I started, VP's instructions, VP's parts, trimming the left rear bracket, left bracket installed, right bracket installed, sway bar bushing installed, fitment test of the bar for clearance and movement.

After removing the original quad shocks (you will not be able to reuse these in their current configuration) you can start by putting both left and right sway bar brackets on the frame in the existing two holes. Next step is to lube the bar and install the two bushings to mount to the brackets you just installed. As stated, make sure the bar will move freely without binding.

Now you need to drill the lower control arm. This is not as hard as it sounds. Just take your time to make a straight path through the arm. I plan on taking mine off next month and weld the bracket solid to the bar and re-powder coat them. The next step was to install the driving down-link and make sure the suspension will move freely without binding or hindering the operation.

The above thumbnails are as follows: using a center punch to mark for drilling, the punch mark on lower control arm, pilot hole, right side and left side with bar and driving link, checking clearance with the emergency brake cable, driving link, final look at the bar prior to test drive.

One note: the emergency brake cables may be in the way during the installation and should be removed for this purpose. Mine happen to have slight interference with the sliding bracket, but the bar can still be adjusted and it doesn't interfere with the operation.

Now you need to re-install the springs and shocks as well as the fuel tank. Make special attention to the fuel tank and make sure the bar does not contact the tank or the tank supports. I have my battery installed under the chassis and the "J" hooks do not pose a problem for the bar. Just make sure you have clearance when done.

I started with the stock FFR suspension package and set the bar at five inches. This is stiffer than what I would normally drive but it served as a good starting point for evaluation.

I'm also not using the quad shocks. I purchased VP's shocks but have not felt the need to install them at this time. I do not have any wheel hop but I will continue to test before making a conclusive deduction. Their shocks will fit and not interfere with the bar movement so I suggest you either purchase theirs or cut the originals down and fit them with heim ends on the shaft side.

I noticed an immediate improvement just down the road from my house. Very little body roll, but I was just getting started. On through a few more turns and then onto the highway. I took a few "supers" on the freeway interchanges and pushed it a little. Wow! This is going to be nice!! :) Even Jeanne said she didn't feel like she was being "thrown" about in the car. Yipee! Success!

The car really hugs the road now. I can push the car much further in the turns than before without the roll feeling the car had without the bar. I do not have any push in the front at this time either. The car will settle in the turn under trailbraking and putting the power down will keep the car planted. The car is much easier to control in my opinion even if this is all you do to your car. It is a different but secure feeling.

I only have the rear bar in at this time but will soon have the front bar on as well and will continue to do more testing with both and then add the poly bushings in the rear spindle supports.

The bottom line as of this writing is the bar IS A MUST if you intend to do some aggressive driving and want better control of your car. There are alternatives out there for putting a bar on your car, but from my point of view, it was worth the money spent. You can drop $$$$ in your engines but if you can't control the car, it doesn't do you any good. Just my opinion. Good luck on your choice.

Updated report on July 1, 2002.

I have had both front and rear bars installed for over five months now. They have both been a very good upgrade for handling characteristics. I'm currently running the front bar at the softest setting 174# with 450# springs and stock Pro Shocks at 4/6. The rear is 160# with 550# springs and revalved Pro Shocks at 5/7. It feels good and the cornering is extremely predictable with rotation if you really want to push it.

I'm trying some shock upgrades at the moment and hope to have some information by mid August. I think this will be another plus to add to the already nice feel the car has. I have not lost any "comfort" asthetics with ride. It is still a good riding sports car. I just tend to want a little more at times.

I've tried different settings on the rear bar and seem to have found a happy medium for the time being. Once new shocks are installed, I'll have to recheck all I've done. After the bar had been tested for a few months to make sure nothing would interfere with anything, I removed the bar and brackets to have them all powdercoated for protection.

After our incident with a rear heim breaking, I've installed the steel FK bearings and shims. My rear alignment is 1/16" toe and 1 3/4° camber. I've found that about two full turns of the upper heim is equal to 1° of camber change. Adjusting the camber in the rear isn't hard. You just need to take a little weight off the car on the side you're doing and remove the heim bolt and shims and then make an adjustment. Reinstall and go test to settle the car. Because I have a rack it's much easier and I'm not crawling around on the garage floor, but it can be done in about 15 minutes time. The shock/spring package will keep the wheel in place while you adjust. You can push or pull the tire to help realign the heim bolt. Having someone to help won't hurt, but you can do it by yourself.

See my Front suspension page for information and pictures on the front sway bar installation from Vintage Performance Motorcars .

IRS Poly Bushing Installation

February 2003

I finally got around to installing the rear bushings from Vintage Performance Motorcars . They've been sitting on my shelf for a year, yikes!!, and I just waited until I was done driving for the year and ready to do my upgrades. I had a few more things besides the bushings so it really didn't matter to me.

The installation was a breeze. I have access to a hydraulic press so it didn't take long to press out the old bushings. Installation of the new ones was done in a vice. I won't know how much difference they make until I put it on the road for a good test run.

After taking the car out, I can't honestly say I noticed a big difference. The rear is much tighter than it was for sure and I can't think they won't do any good. My rubber ones were worn so this has got to be an improvement.

Koni Adjustable Shocks

March 2003

I started doing research for some gas filled monotube shocks in January 2002 when I purchased the sway bars from Vintage Performance Motorcars. I knew there had to be an alternative because someone on the east coast was running Bilstein shocks.

I contacted Bilstein and finally talked them into sending me a "dummy" shock so I could do a test fit while I was installing the sway bars. I gave them dimensions and travel of the Pro Shocks that were on the car and the total drop and compressed suspension settings. The shock they sent would NOT fit, no matter what I did. They were not amiable to making a special heim fitting to clear the FFR suspension either. I decided not to dwell on the subject with them and re-installed my Pro Shocks so I could use the car and moved on.

Next choice was Koni Shocks. It took a long time to get a hold of someone but I was persistant. While waiting for a response from Koni Shocks, I also took a look at Carrera. Carrera had something that could work, but they didn't want to send a test shock out and their pricing was a little on the steep side. I don't remember at the time of this writing but it was definately more than what I wanted to pay.

Koni Shocks finally returned my call and I went through my ordeal with them. The person I connected with, Anthony Miller, was very helpful and very understanding. He asked what my intentions were, i.e. racing, autocross, street driving, etc. and then we got into details.

I gave him the valve settings I was running with the Pro's along with suspension compression and extension measurements. I sent him scaled drawings of the Pro shock and what was needed to clear the FFR tubular suspension. Lucky for us, all of the shocks use the same setup for clearance.

Upon recieving the shocks, I knew they weren't going to fit in the suspension. We need long heim ends or a spacer setup like the Pro Shocks in order to work. I took pictures and posted them on my site for him and gave him a call. Both of us looked at the pictures while we talked (ain't the internet great!) and by having a Pro Shocks laying beside the Koni Shocks, he was able to see what I meant by the heim and spring perch. I boxed them up and sent them back along with a Pro Shocks setup.

I recieved the replacement shocks about two weeks later (September 2002). These things looked great!! I couldn't wait to try them on for size. Koni Shocks made a special heim end in which they welded the needed extension and cut a special spring perch so it would accomodate their setup.

The shocks are monotube rebound adjustale only. The front were 3014-5 B23 and the rear were 3014-5 B34. My front springs were the stock 450# 10 inch and I upgraded the rears to 550# 8 inch springs which I was running with the revalved rear Pro Shocks. The 5 means five inch stroke.

I drove the car with these shocks for five months and I must admit, they were the best thing I did to the suspension since adding the sway bar. while I was doing some work during February of 2003, I sent my rears back to be revalved. The reason was the compression in the rear was too soft for my liking and I wanted them valved at least the same as the front.

Jump forward to March 2003.

After finishing the re-installing all my suspension upgrades, the front competition upper arms, rear IRS poly bushing spindles, my revalved Koni Shocks shocks (Yes, I had the rear shocks revalved) and setting my alignment, the wife and I took the car out for a test run to settle the suspension and get a feel of the rear shock revalving. I noticed a difference right away. The car felt firmer on the road and when I hit those compression turns and bumps, the car just settled right down and there was no bounce like I had felt before.

All my suspension settings remained the same so I could get a good test. I kept my ride height the same, springs were the same and sway bar settings were the same. This way, all I needed to note was how the car behaved, compared to how it was previously. Now the fronts are B23 and rears are B22.

I believe I'm through testing the shock setup and feel confident that anyone who has the IRS and front lower tubular arms, could use these.

These shocks can be adjusted while the car is on the ground. There's no need to jack it up. I've done all four corners in less than five minutes. The shocks can be converted to dual adjustable shocks. To adjust the compression side (if you decide to get them), you have to raise the chassis and let the shock hang at full droop. This is fine if you have a jack with you and have the time, but for everyday driving it might be too much to deal with. Once the compression is set, I don't think it's necessary to mess with unless this was a full-on racecar. You'll be suprised how little you have to adjust the shock in order for it to respond.

Cost each of the Koni Shocks at the time of this writing (March 2003) are: $350.00 plus $20.00 for the heim end and perch, plus any taxes and shipping.

The pictures above show the new poly urethene bushings installed, a comparison between the Koni and Pro shocks, Koni shock installed on the front, Koni shock installed on the rear and a bottom shot looking up from the rear bottom.

Modified IRS Contol Arms

February 2017

During my major overhaul of FFR1812, I needed to do some work to the IRS control arms. My biggest concern is the amount of heim joint thread that shows. Or, in my case, how much doesn't show.

I have been running the same Compomotive wheels for almost 15 year and never needed a spacer becasue they were custom made so I could have a deeper dish wheel. All that was fine, but when I went to the Team III wheels, things changed.

Using the Team III wheels required me to use a 3/4" spacer to make them fit and not rub. Not a problem, but another problem I had was running my track wheels and tires, which required a 1" spacer. So,everytime I changed combinations, I had to change spacers as well. My spacers ARE NOT the slip on type, but rather an Eibach aircraft aluminum spacer that bolts to the hub and the wheel bolts to the spacer. I didn't want any problems with the spacer so I decided to modify the IRS arms to meet my needs.

Knowing the heim joint has about 1.5" of threaded end is nice, but I like most of it inserted into the rod end. Although Factory Five rod ends only have about 1/2" of threaded insert and means much of the heim isn't in threaded material, I still don't like to have a lot of the heim thread showing. My IRS was a bit different due to the Compomotive wheels and I wasn't going to change my IRS setup by threading out more heim end. This prompted me to look for a solution, and I found one.

I searched for the correct rod end for a 1.20 wall tube, which is what the IRS arm is made from. I found some for about $8.00 each and ordered six from FK Rod Ends for a 1 1/2" OD x 1.20" wall thickness x 3/4" thread, part number 3108. Perfect! These rod ends are 2 1/4" long and are threaded the entire length. The next part was to determine how much to lengthen the arms.

I needed to extend the stock IRS arms about 3/4" on the outside, which calculated to about 9/16" to be lengthend overall with the new rod end. This worked out perfectly and allowed me to make my toe and alignment adjustments with at least 3 to 5 extra threads showing AFTER the jam nut was on. Plus, the entire heim joint is threaded completely into the rod end, unlike the Factory Five stock ends. I was very pleased how this turned out and now can use either my street or track wheel combinations without any issues. I also plan on doing a partial "315 mod" to the chassis side once I take the body off next month.

Took all the suspension back out and took them in for powder coating. While at it, the IRS carrier was removed so I could go through it and replace the clutch pack and if needed, new gears.

Below are some pictures of the variation of the two joints, plus a stock and modified lower IRS control arm.