Ball Joints
The SL-C can generate very-high suspension loads which can cause the stock ball joints to wear out quicker than you'd normally expect. In fact, one builder noticed much For this reason, I decided to upgrade all four lower ball joints. The fronts are race-grade ones manufactured by QA1 and the rears are stock because the QA1s won't clear the the rims. The ones from QA1 have the following advantages over the stock ones; heavier duty, completely rebuildable, and adjustable pre-load.
QA1's rebuildable ball joint; sscrew-in housing shown, I have the the bolt-in housing
“I liked the concept that they were rebuildable, but I wasn’t expecting to rebuild them before they were installed! ”
I bought model 1219-103 and discovered that the stud was 1/2" too short. Because they are rebuidable, this was easily fixed by buying the 9029-203 ball stud and installing it (note that I should have bought 1210-203B which comes with the appropriate length stud). My friend Will also figured out that everything was off by 0.25" so he designed a custom spacer, I 3D printed a test for him and then he had several sets water jet cut out of aluminum. This is what they looked like after a little sanding.
The top of the ball is 0.25" closer to the ground which will lower the roll height a little which doesn't seem like it will hurt anything.
Setting the pre-load or rebuilding the ball joint requires custom tools which are demonstrated in the video below.
Custom 0.25" aluminum ball joint spacers
| Qty. | Part Number | Description | Unit Price |
|---|---|---|---|
| 2 | 1210-103 | QA1 Rebuildable Ball Joint | $44.97 |
| 2 | 9029-203 | QA1 0.5" Longer Ball Joint Stud | $19.97 |
| 1 | 1891-106 | QA1 Ball Joint Socket Style Spanner Kit; Includes a Spanner Socket and Allen Hex Key | $25.97 |
| 2 | Custom 0.25" Aluminum Ball Joint Spacer | $ | |
| 4 | Custom ??? Castle Nut Spacer | $ | |
| 2 | TBD | Moog Ball Joint | |
| 16 | 5/16"-18 x 1.75" Grade 8 Screw | ||
| 16 | 5/16"-18 Grade 8 Nyloc | ||
| 16 | 5/16" Grade 8 Washer |
Stock ball joint on the left and QA1 ball joint on the right
The ball joints have a tapered stud which is installed clean (i.e., no anti-seize) in the lower ball joint plate. A custom spacer is placed under the castle nut. It is critical that the spacer is sized so that it enables the cotter pin to be properly installed. The castle nut is then torqued to is 55 ft. lbs. and then tightened until the castle lines up with the hole so that the cotter-pin can be installed.
The hex screws are then torqued to 24 lb/ft. Note that the screws on the front hub should point down and the rears should point up.
As can be seen in the picture to the right, the QA1 ball joint requires a lot more space under the control arm. This isn't an issue in front, but NFW will they fit in the rear. I plan to see if the Moog ball joints will work there.
Removing the Ball Joints
Similar to most cars, the ball joints use a standard tapered fit and tend to get stuck. After doing a little research it seems that many people beat on them with a hammer or use a pickle fork or some combination of both... not on this suspension! I found this Ball Joint Separator from Harbor Freight. While it's not something I'm going to use very often it's worth $21.99. This video does a great job explaining how to use it.