I converted my rear suspension to a three link set up. Car is 1" lower then factory ride hight. (Stock rear is 14" from the center of the axle to the finder line, I am set at 13") The lower arm mount on the axle was cut off and lowered so the control arm are level (no roll steer). Upper link is 18.5" mounted 4.5" to the right of center line and angled down to provide approx 55% anti-squat that is biased to the right to counter the lift on the right under acceleration. Panhard bar is level with the bottom of the diff. Stock sway bar.
175 Lb/In spring rate, 1.93hz measured frequancy on the rear. Rear shocks are KYB 343161 (Mustange foxbody GT stock replacment shocks)
I have been driving this for 7 years this way. The 343161 shocks are slightly lacking in rebound, Compression is ok, acutally the only problem is when hitting a hi speed midcorner bump is when you would really start the pucker factor.
If it matters in the front I have KYB 363046 rear for a 1985~mid1986 Toyota mr2, 225lb/in springs (and they are a perfect match since the mr2 uses iirc 200lb/in rear springs)
I have a set of KYB KG4644a Gas-A-Just monotube shocks speced for the fb rx7, brand new been sitting upright strapped for 14+ years, made in Japan. I know these are much firmer then the stock rx7 spec but will it control a 175lb/in spring?
Also in my inventory are (gas monotubes) KYB KG5551 (foxbody 5.0 with the 8.8" axle) and KG5559 (foxbody 2.3 with the 7.5" axle)
The kyb KG shocks I have take ~40ish lbs to compress to ride hight, 80lbs total and will raise the rear 1/4 to 3/8 in.
This is my street car.. I am looking for some advice (without spending huge $$$ for custom shocks) for thouse who have use 150~200lbin rear springs rates. I have searched and cannot find any info on the above mentioned shocks. I belive the Tokico blues are not made anymore and may of worked in my application.

 

I used the B6 Bilstein shocks for Fox body Mustang (part no. 24-021487) on my racecar with 200-250lb/in rear springs. Worked great. I think they are the sport version of what you have now.

Carl

 

How is the compression, is it harsh? I am also looking at rear shocks for the BMW E30's, compressed and extended length are almost the same and the bottom sleeve is 12x40mm, (fb is 12x32mm)

 

I used the KONI adjustable rear shocks for the fox body with I believe 200lb. fox body springs with a three link. They seemed to work well for the short time I drove it. (edit: scratch that, went out and checked. I gave them away already)

 

You can use any rear shock that fits a 79 to 2004 Mustang. I think shocks for 94-2004 Mustangs may be a little shorter. So, lots of options to choose from. I have used KYB AGX shocks (on my 85 Mustang) and well as single and double adjustable Koni shocks on my race car. All of those shocks will handle the spring rates you are using.

Retail sources for Fox/SN95/New Edge mustang rear shocks are plentiful. I use LRM.com, AmericanMuscle.com, Steeda.com and Summit Racing. Also eBay because you never know what you might find

 

This is what I did. Fully adjustable and very streetable. https://www.rx7club.com/1st-generati...my-sa-1156704/

 

Any experance with the Koni 8050 1033 STR.T orange shocks

 

Koni STR.T are for stock replacement. I have them on the rear of mine with 150 lb/in springs and I think they're a little soft, bouncy in the wrong way.
I thought that since the Mustang was a little heavier they'd be a little stiffer than a stock RX-7 damper.

My car is a 99% street car which is where they're mostly fine, but I do track days and that's when I wish I had the Koni Sport on the rear.

 

My coupe has Koni Yellow externally adjustable shocks. The car handles very well although the ride is a little firmer. If you go onto the Ausrotary facebook trade/sell page a vendor is selling a set of rear Koni Red internally adjustable shocks which have done less than 2000klms for $300. You'd probably get them for $200 and postage from Aus to US is much more reasonable.

 

The only non-adjustable shock I would try is the B6 Bilsteins that Carl mentioned. Maximum Motorsports (a reputable Mustang suspension tuner/manufacturer) recommends the B6's over anything short of an adjustable Koni sport.

 

That is my experance also with the kyb twintube for the foxbody gt.. mostly fine untill you hit a mid corner bump and then you really feel the lack of rebound dampening..

 

I found a set of Koni reds, adjustable. I belive you have to compress the shock to adjust.. I am waiting for conformation that they are the 8040 1026 part number, for $60 a pair I may take a chance on them. Any experance with the Koni reds for a fox body.?

 

Yes, they were OEM on the 85 SVO I owned in the 90's. They worked fine but having to compress them to make a shock adjustment was a pain. Also note that adjusting them stiffer also made them allot harder to compress to make an adjustment later. I set mine to full stiff once and had to use a floor jack to compress them to change them to a softer setting.

Edit....looking back, I believe these were mono body shocks because of the way they expended as soon as they were unbolted from the axle. The Sports are twin tube design and don't do this. Not sure if the new version of mono or twin tube.

I don't know how they compare to the single adjustable Koni Sports in terms of how compression is changed when rebound is adjusted. However, the ability to adjust the Koni Sports with a **** is a game changer.

Frankly if you want to risk money on an old shock, find a set of Tokico Illumia shocks. They are WAY better in my experience. They were made for RX7s as well as Mustangs from 79-2004.

Edit....looking at the AmericanMuscle.com site and am noticing allot of shock options. Including their "house brand" SR adjustable shocks. So more to research.

 

After a lot of looking and learning more then I wanted to about shocks and the math. 175lbin springs 1.9Hz approx 481 lbs on the spring. I came up with some numbers ..
4 in/sec lb330–360 lb rebound 110–135 lb compression (compression is usually a digressive curve, it initally rises thenflattens)
I am getting a pair of Koni 8040-1026sport shocks. The only other sutible shock that hits thoese numbers are the B6 Bilstien.
Critical damping coefficient (c_crit)≈ 41.8~42.6 lb·s/in This is just the spring with 481lbs on it.. theory, in reality it is more like 420ish 4in/sec, @ 100% the sprung and unsprung mass is much higher.. and gravity plays apart also momentum
typical is 70~85% in rebound and 25~35% in compression at 1.85~1.95hz

 

Wow! I got a headache just reading the your post, but mad-props for the skill in doing the math!

 

I ran the Mustang AGXs with a similar setup (175lb and 3 linked) mainly because I could adjust them.

Interestingly, I had a set of actual FB Bilstein Yellows on my other car, and I switched that car to AGXs also because the Bilsteins felt too soft. The ride control was OK but they didn't control the unsprung weight very well. I THINK the rear springs are 125 or 150lb, stock 4 link setup.

 

Sounds like you have a full race set up in the rear, drive mostly on the street but also track it as well. You will always be compromised trying to have good track performance but also have street manners, particularly in our antiquated factory suspension configuration. I would suggest that since you are sensitive enough to recognize subtle differences in the rear, you should probably commit to an adjustable shock, and one that can be easily adjusted btwn sessions at the track. I've never had a street RX or run non-adjustable shocks, so the best I can compare would be wet vs dry set up. Just like on a wet track, I would dial out the settings if I were to drive my racecar on the street; then turn it back up for the dry or track. I run the single adjustable Koni 8041-1026 on my ex PRO7( now ITA) car. I think that I would be too lazy or busy for the effort req'd to make changes to the 8040's at the track. So for the extra bucks, I would suggest something externally adjustable. If you only drive your car on the street then I would guess the 8040 would serve you well.

"the only problem is when hitting a hi speed midcorner bump is when you would really start the pucker factor. " My experience is that you will experience that no matter what while driving our chassis hard. That's part of the charm!

 

100% street..

 

Cutout for the upper link

Upper link as you can see is much longer then the stock upper links.

Panhard bracket before drilling, you can also see the upper link

Checking at full droop

boxed in upper link mount

Gsl axle, 5" spring perches, upplink mount and panhard mount (not really seen), also the lower link mounts have been dropped down so they are parallel at right height.

Upper link mount before being boxed in.

Screen shots on setting the geometry.

 

You can see the upper link in this pic.

Upper link

 

FYI, the problem I found with the panhard bar and the three link was that with wider tires it would force the axle off center and the tire sidewall into the sheet metal when it cycled too far. I ended up building a Watts link to keep the axle centered. I don't know if you experienced this problem or not, but worth keeping an eye on. Not a big concern for a track car, but definitely so with a street driven car, wide tires, and stock sheet metal.

 

Nice fabrication!

 

Merry Christmas to myself.

 

My panhard bar is as long as possible with no bends in it so the arc it travels is minimal. Also the mount to the body is very rigid. Most bolt in panhard conversions I have seen are abominations in particular the one from T3.

 

So a few notable things about the konis 8041-1026s shocks. The upper stud on the shock is 12mm, the oem is 10mm, The hole in the shock tower is 13mm, so with a 12mm stud that leaves 0.5mm clearance around the stud and the shock does move around during suspension travel. I enlarged the hole with a 5/8" drill (nominal 16mm). The koni rubber upper mounts have a 21mm stepped edge that I reduced down to 16mm.. The shock lower mount steel sleve has to be trimmed down to 32mm. Shock diameter is also larger so I had to clearance the mounting ears.




In this pick you can see how the mount was lowered to keep the lower control arms level at ride height (so not to induce any roll steer effects)



You can see how long the panhard bar is in this pic