Wanted it right, did it myself - Tightening up the rear suspension

[Bwahl602]

So Ive been really tired of all the clunking, creaking, squeaking etc coming from my suspension -- especially since none of its very old. Today, I took care of the rear.

Heres my setup:
MM LCAs (less than 2k miles)
New factory UCAs
Bilstein HDs
Steeda Springs
Stock sway bar
No isolators

While finishing up my fender roll last week, I peeked under at the LCAs to see how they were doing. Last year ish, MM sent me new LCAs because the urethane front bushing was annihilated for some reason with less than 5k miles on them. Since installing those, my car has seen less than 2k miles. Its a street car with just bolt ons. I can clearly see that the bushing has been allowing the LCA to move forward and back quite a bit. The debris and grease inside the torque boxes is pushed clean around the bushing, 1/4+ inch in each direction.

Now, this is the type of significant deflection I saw last time when I found that the bushings were split inside. So I tore apart the rear suspension, popped the bushings out and surprisingly, they were completely intact. Either way, I'm unhappy with what I see and have been experiencing, so its time to look into some different arms...

A quick web search shows me that replacements with spherical joints at both ends are gonna run me a lot of money. And... Im not 100% sure theyre what I want.

Fortunately, Ive had some special bushings clunking around in my toolbox for some time. And, I've got the tubing lying around to tackle this.. Time to build some LCAs

The joints at either end are made by Currie Enterprises. They have a 2.5 inch DOM shell, a ball pivot encased in two small urethane bushings. They utilize a 9/16 through bolt. The whole assembly is pressed together and secured with a snap ring. These are strong enough for full size jeeps and SUVs that are rock crawling, they will do just fine for this application.


Now, I know what you're thinking.. "But the stock bolts are 14mm not 9/16" ...
9/16= 0.5625 inches
14mm= 0.5512 inches
The 9/16 bolt is bigger, a difference of 0.0113 in diameter (0.00565 radius). For some perspective, thats about 1/90th of an inch difference in diameter.

So I decided I was going to move forward, drill out the factory holes and install 9/16" grade 8 hardware for the new joints.

I picked up some 9/16 hardware and to my surprise, it dropped right through both joints on the MM LCAs that I had. Even more surprising, the 9/16 bolt required no modifications to the axle side mount. It again, dropped right through.

Im not expert, but if we consider a 14mm bolt, in a 9/16 sleeve on both ends, each with .0113 of difference in diameter. And then add on the axle side that had at least that much. Were looking at 0.0339 in slop across those 3 connection locations. Thats 1/20th of an inch. Not a huge number, but significant. This sealed the deal for me for sure. Of all the cobras and mustangs with clunks, I wonder how many of them could be corrected here.

Any who, ran a 9/16 bit through the body side LCA mount. Notched some tube, welded the ends on. Added a spring plate and sway bar mount. Voilla!


This is before welding, you can see the 9/16 hardware chilling in the MM arms. And It wasn't forced in them by any means

I didn't take any great pictures of the new arms after pain, but this is the idea. I moved the spring perches forward a little to better aligned them vertically with the upper spring retainer with a car this low.

These eliminated all of the bind that occurs in the LCAs. They have pivot capabilities at both ends

I did consider that since both sides could pivot, what would keep the LCA from rotating on the joints and dumping the spring. I did some searching online and found several suppliers who sell LCAs with flex joints at both ends that use standard springs (some with sway bar and some without) so I figured I was safe to move to a testing spot.

Once installed for a test fit, i mounted the springs and put weight on the car. I kicked and pried on the sway bar mount (no sway bar attached) and could not get the LCAs to rotate with the spring pressure on them. Additionally, the sway bar will keep them upright once installed. I do not believe there is an issue here at all. To be safe, the center of the lower coil cup was doubled in height to prevent the coil from taking a walk off.

So now with bolts in the right holes and tight tolerances all around, with spring isolators back in and everything buttoned up.... Wow. The car feels totally different. Not a noise, its solid and handles beautifully. The rear still wags a bit since I haven't yet built a pan hard bar, but its much more predictable and consistent. Theres definitely more noise transmitted into the car with the different bushings

50 hard winding road miles on them and no issues with the springs.

Now I'm not saying that everyone should build a set of control arms. But at least if you do, know that the modifications are minimal to use 9/16 hardware and there is a plethora of 9/16 through bolt poly, spherical, heim etc joints out there to use as replacements.

Thanks for checking in, ill post more pics when I can

And BTW, kudos to Maximum motorsports for great parts and phenomenal customer service. Ive got a ton of there parts on this car and I really like there stuff. These just weren't doing it for me

Bill

[jbrad88]

Great Write up.

Necessity is the mother or invention...or innovation as it were...

hope that works well for you...looks like you did a great job...

[Mach828]

Awesome! Great write up, and high quality fab work.

Post up your panhard bar build. I've been wanting to build my own for a while, and may follow your lead. I can surely build one for far less than the $400 for the aftermarket units.

[TKat13]

awesome job! A friend has the mustang clunks in the rear as well. I use the wolfe LCA and they have the spherical joints, no clunks at all but I know what you mean with the added NVH. It is there but I would rather have that than the clunks.

Those look really nice and your write was great!

[lcaptmorg]

Very nice work.