Monday, July 13, 2020

DIY - Eibach Lower Performance Springs - Rear Spring Install

Fair warning: If you are not mechanically inclined and have no experience working on cars, just don't do this. If the car is jacked unsafely or the torque is set wrong on suspension components and wheels, it can leave you dead. Just hire a shop to do it. This DIY is at your own risk.

Arguably doing the rear is easier because of the lack of need for specialized tools such as Torx bits and spring compressors. However, I did learn half way that removal of the rear diffuser is important to release the springs and to set the torque of bolts properly, so be prepared for that and see the approparite instruction here.
Eibach and Stock Springs side by side

Let's get started. The tools that will be needed are shown below.

Add caption
The list includes but is not limited to: 
- 10 mm socket, wrench and ratchets and extensions
- 21 mm socket and wrench
- Breaker bars and various extensions
- Additional jack or 1 jack if using jack stands
- Torque Wrench
- Flat screw drivers
- Jack, Jack Stands, Chucks and Jack pad adapters for Tesla 

Step 1. Jack, Chucks and Safety

Chuck front and back of the opposite wheel to the one that is being worked on, in my case front left wheel.
Chuck Opposite wheel - front and back

Remove the Lug Nut cover by using fingers to pry and 2 consecutive sides of the black cover. Using a 21mm socket or tire wrench loosen the lug nits in the order as shown. Tightening will be in the order shown as well- always a star pattern to ensure even pressure.
Loosen and tighten lugs in a star pattern always

Jack up the car using jack pads adapter so as not to damage the frame or battery shell. A quick note here. I only had 1 jack adapter so I was limited to not being able to put the entire car up on jack stands. I own 4 jack stands. I recommend that you use jack stands. To do that, raise the car from the front right side high enough that the right rear jack point clears the stand+adapter. Put the jack stand and a jack pad adapter on the rear jack point and then lower the car from the front so that the rear rests on the jack stand or use a jack with the stand built in. Don't be dumb like me.

Using a Jack Pad to jack up car safely.

Raise the car up using the jack. Place the jack stands and remove the rear wheel. You can now see the spring that needs to be removed.

Wheel removed

So instead of removing the lower control arm bolts as I did at this point, instead I recommend removing the rear diffuser as per these instructions.

Removing the diffuser gives us clear access to loosen and more importantly properly torque these bolts after the new springs are installed. Do not loosen this bolt yet. I am just illustrating the bolts that need to be accessed by removing the diffuser.
These bolts must be loosened to remove spring from control arm

So now that we are back from the detour of removing the rear diffuser, let's get back to the steps of removing the spring. Remove the 10mm bolt on the control arm plastic cover.
Remove bolt and cover

Note these two rubber nubs on the spring mount. They need to go back exactly into the holes when assembling, otherwise you are gonna have a bad day.
Note rubber nubs on spring mount

Using a 21 mm socket & breaker bar and a 21mm wrench loosen these bolts, do not remove them yet. Just break them free.
Loosen but don't remove these bolts.

Also loosen the 21mm bolt which connects the control arm to the subframe, but do not remove it. It will allow the control arm to easily swing down further allowing for the spring to come out easily.
Loosen this bolt too.

Next you need to jack up the lower control arm to put remove the tension on the control arm. I prefer a block of wood such as a strong 2x4 and a scissors jack because I can finely control the height unlike a hydraulic jack. After you jack it up a bit, all the bolts will be easy to remove.
Jack up the control arm.

Next remove the the two 21mm nuts bolts completely, remove the bolt that hold the rear rotor assembly knuckle and then the bolt that connect the strut. The strut is easy enough to compress my hand to ease the bolt out.
Remove nut and bolt that connects wheel assembly arm

Remove the nut and bolt that connects the strut to the control arm. Let the strut expand out. No harm done.
Remove the struct nut and bolt.

Next lower the jack slowly so that the spring uncompressed. It is at this point that I could not remove the spring completely because of the bolt that connects the control arm to the subframe. But since the rear diffuser has been removed, it is easy to loosen that bolt and allow the control arm to swing down more releasing the spring. DO NOT remove the bolt that connects to the sub frame, it just needs to be loosened.
Spring will not come out unless the bolt behind the rear diffuser is loosened

After the bolt is loosened then the control arm drops more and the spring comes out easily. Move the brake line out of the way push the spring down and also remove the rubber lower mounts of the spring to install on new spring.
Removing rear right spring

Comparing the two springs side by side.
Tesla OEM left, Eibach right

I noticed that the Eibach was considerably heavier, so I weighed it and found that it is ~5.2lb heavier than the stock spring. I guess that is the price for dual rate springs. 
5.2 lb heavier than stock

Install the rubber lower spring mount and align it.
Align the lower spring mount
Replace the spring into the lower control arm making sure that both the top and bottom rubber mounts line up and you must ensure that the little nubs of the lower mount go though the holes on the control arm. This is important or it may cause problem. The trick is to also make sure that your 2x4 does not push those nubs out of place.

Once the spring is in the control arm, jack up the control arm so that the wheel/rotor knuckle assembly arm is lined up exactly. This is why I prefer a scissors jack as shown below. Be careful there is a lot of energy in that spring at this point, don't force anything sideways to cause the jack to slip.
Line up the bolts by using jack.

Slide a bolt through the hole and hand tighten the nut. Next compress the strut with your hand so that the holes line up and slide a nut through it and then hand tighten the nut again.

Using a torque wrench and closed/open wrench tighten the two bolts to 115 Nm or 85 ft-lb. slowly release the jack and then finally tighten to the same torque the control arm mount to the subframe, which hopefully you did not remove completely.
New spring installed.

Replace the control arm cover and tighten the 10mm bolt, but not over tighten.

There is one more piece of the instructions, to trim the bump stop. Many do not want to do this, but I trust the manufacturer has some intention when requiring this.
Trimming the bump stops.

Fairly easy to do. Slide the bump stop up slightly, feel behind the struct dust cover and pop the bump stop down. Push the strut dust up and out of the way.
Release bump stop.
Measure 25mm from the bottom using a stright edge and mark it.
Mark 25mm from bottom

Using a very sharp box cutter or utility knife cut along the bump stop and then cut the piece vertically to remove,
25mm removed

The bump stop should look like this and then simply slide it back up until it attaches to the top behind the dust cover.
Modified Bump Stop

Replace the Wheel. Hand tighten each lug nut. Then torque the lug nuts to 175Nm or 125ft-lb. This must be done in a star pattern. I always prefer to torque with the car up in the air to ensure even pressure on the rotors and re-check one the car is down.

Jack up the car and remove the jack stands. jack down the car. 
Move the chucks to the other side front wheel, then repeat the entire procedure (minus diffuser removal) on the other side. The other side should go quicker :)

Reinstall the diffuser per reverse of the diffuser removal instructions.

Take a break before starting with the front because that is a completely different story, easier in some ways, harder in others.