DIY: Coilover installation for 1-series

[shemmy]

H&R Street Performance Coilover kit DIY

Thanks to eurotuner.com for the pics and write-up

Please review our DIY disclaimer before attempting to perform modifications to your vehicle.



Tools required

• E12 screwdriver bit
  
• 21mm, 18mm, 17mm, 16mm, 13mm socket
  
• 18mm, 16mm, 13mm open-ended wrench
  
• 10mm Allen socket
  
• Screw jack
  
• Spring compressor
  
• 4 jackstands and a floor jack (or preferrably a lift)
  

Safely put the car on jackstands using the proper floor jack points or use a lift, if you have one available to you. Never use a hydraulic jack as the primary means of supporting a vehicle.

Rear suspension



Use an E12 screwdriver bit to release the bottom of the rear damper from the aluminum suspension arm that supports the stock damper and spring. Use a 16mm socked to undo the top mounts on the dampers inside the trunk, carefully removing the trunk lining to access them.

Use a screw jack under the suspension arm to raise the rear suspension and release the tension on the damper. A 21mm socked is needed to undo the bolt that secures the aluminum suspension arm to the brake hub. Lowering the jack slowly, you can then remove the damper and spring from one side of the car and then the other.



With a 17mm socket, remove the bottom mount from the original equipment (OE) damper and transfer it to the replacement damper. You also slide the plastic sleeve and bump-stop from the top of the OE damper and refit these on the replacement part.



The next job is to install the adjustable spring perch in the aluminum suspension arm. This will give you the ability to adjust your ride height. To do this, remove the circlip from the threaded section of the new spring perch and remove the center section of the perch (it screws off the main thread). Fit one half under the other inside the suspension arm. Use the supplied C-wrenches to tighten the two halves together, clamping the arm between them. You then poke the threaded shaft through the top section and wind its threads into the center section. You should now replace the circlip onto the end of the thread. Lubrication is supplied to allow the threaded shaft to be screwed on and off more easily.



A top spring perch is also supplied in the H&R kit. This is a simple disc and it pushes into the OE upper spring perch. With both perches in place, you can fit the coil spring and its red assister spring. The assister spring simply prevents the main coil spring from dislocating when the car is jacked up.




Insert the damper and use the jack to again raise the suspension arm so you can bold the arm to the hub. Finally, bolt the damper into place, top and bottom and replace the trunk liner.



It is suggested you set the lower spring perch in its middle setting, to give you a starting point. In reality this set the rear really high. We ended up winding the perch all the way down, using a 10mm Allen socket in the bottom of the threaded shaft. This lowered the car 1 3/4".

Front Suspension

Start by disconnecting the ABS, brake pad and headlight sensors from the front suspension strut. This is done to prevent them from being stretched when the suspension sags during this process. Support the brake hub with a jack to avoid dropping suddenly when the strut is loosened. This will prevent damage to brake lines and most importantly injury to yourself.

Remove the sway bar end link from the hub using a 16mm socket and an open-ended wrench on either side.

Use an 18mm socket and open-ended wrench to remove the pinch bolt that secures the strut to the hub. Once this bolt is removed, use a small chisel to gently pry the two sides of the hub apart, allowing the strut to be pulled from the hub.

Limited suspension movement due to the supporting jack means that the hub will not drop enough to free the strut, so remove the three 13mm nuts that secure the top of the strut to the suspension tower. You can do this without removing the strut tower brace if you use a 13mm open-ended wrench on one of the nuts. You may need to loosen the steering arm linkage to jiggle the strut free.



With the strut out, the top mounts are needed for the replacement strut. The plastic sleeve and bump stops are not needed. Releasing the top mount is a dangerous task since it holds the coil spring under tension. You must safely compress the coil spring using a spring compressor before you attempt to undo the 21mm top mount nut.



The new dampers are labeled left and right to help you, so place the top mount assembly on the new strut once the replacement coil spring is in position. The body of the strut is threaded and the spring sits on an anodized perch that can be screwed up or down the body to change the ride height. Again, it's suggested you place the perch in the middle position on the thread. We did this but had to raise the front slightly to get the car where we wanted it once the wheels were fitted.

When refitting the top mount, you don't need to compress the spring again. The 22mm nut supplied in the kit will fix everything into place once it's tightened down. However, ensure the spring is properly seated in the top mount before you proceed. Align the narrowest portion of the spring with the area adjacent to where the wheel will be. This will give you extra clearance if you opt for wider tires.



While reassembling the H&R coilovers, it was noted that the 135i strut bolts to the dead center of the top mount. On previous BMWs, such as the E46 3-series, the bolts were offset, allowing some degree of negative camber to be added by simply rotating the position of the top mount. However, the 135i will require an additional camber plate in order to gain negative camber for improved cornering ability (although it does increase tire wear).

The OE strut has two locating pins to ensure it's refitted correctly to align with the sway bar, steering, sensors, etc. However, the H&R damper doesn't have these so observe its position before removal (although you are able to rotate it slightly before bolting everything in place). So refit the front strut by inserting the bottom into the hub. You may want to lube the strut tube and pry the hub open to help this process. Then use a crowbar to lever the suspension down so the top of the strut clears the fender. The whole assembly now needs to be lifted into the suspension tower so the three nuts can be secured to the top mount (the top mount rotates to ease alignment and there's a locating pin to ensures the mount is in the correct position).



Provided the strut is positioned correctly, you can now attach the sway bar end link, but don't tighten it. Now use a jack to raise the brake hub and ensure the strut is properly seated. Recheck the sway bar link. Now tighten the pinch bolt to hold the strut before tightening the sway bar, refitting all the sensors and reconnecting the steering.

Height Adjustment

It's possible to adjust the H&R spring perches without removing the wheels. Use a 10mm Allen socket in the bottom of the threaded shaft. It's all about trial and error but after a couple of attempts the car was lowered to where we wanted it - which turned out to be the maximum amount the rear spring perches would allow the car to be dropped. After measuring we discovered it was 1 3/4" lower than the stock ride height. It left the tires nicely tucked under the fenders.



The front needed to be raised. This was achieved by turning the adjustable perch on the threaded strut using the C wrenches supplied by H&R. Unlike the rear, the thread on the strut is very fine and moving the perch one inch will alter the ride height approximately one inch.




Stock vs. Lowered

[2fast4u2]

Thanks for the DIY!