Fortune smiled on me recently. I was on the hunt to upgrade my task chair and I happened upon a used Herman Miller Aeron chair for around $300 on Craigslist. Since Herman Miller dealers provide new replacement parts, I set out to refurbish the old Aeron chair to nearly new condition. Here's a step-by-step guide for replacing a worn-out Aeron seat and back rest...
What You'll Need:
- 3/8" Craftsman clicker-style Microtork wrench with hex bit set
- Wrench for removing B-Links
- Allen wrench keys (for reaching tight area of B-link)
- 4, 5,and 6 mm hex bits
Preparation: I first contacted Herman Miller to discuss my plans and get some technical assistance and information before dismantling my new prized seating possession. Carla at Herman Miller gave me a tools list and the specifications for removing and tightening the hex bolts used to hold the Aeron together. A handy tool like this can aid you in removing the seat back's hex bolts.
Removing Back Frame: 4 seat back bolts are simple to remove with a 5mm hex wrench, but tightening them correctly requires a torque wrench. The torque wrench allows the greater control over the amount of tightening pressure being exerted on a bolt, highly recommended so you don't damage the chair. Once the torque wrench reaches the set tightness, it clicks into place.
Now that the seat back is off, the Aeron seat underside B-Links will be more accessible (see below pic). So, move onto replacing the seat before securing a new seat back. When ready, you can replace the old seat back with a new one using the same 5 mm hex bolts. For securing the seat back, 70-100 inch pounds of torque is required.
Removing Seat Frame: In order to remove the Aeron seat itself, a total of 4 bolts must be removed. I recommend removing the underside seat B-links first . Using a 4 mm Allen wrench hex key, hold the bolt in place with pliers while using a wrench to remove the locking nut (first upper left picture above). Then remove the underside B-link from the seat and do the same for the other side (a total of 2 B-Link bolts and nuts).
Now, you may remove the two B-Links under the seat. The B-links will swing free and can be placed down on the Aeron wheel caster base.
The hip bolts will require a 6 mm hex bit, and a long wrench will make removing these easier (i.e. the Craftsman torque wrench). Remove both hip bolts (a total of 2 of these) on either side of the Aeron seat. The hip bolts design did change around 2003-2004, so I recommend contacting Herman Miller for help in determining your model and if a replacement bolt may be necessary.
You may now remove the Aeron seat from the metal frame.
Replacing Seat Frame: So, now you have an Aeron skeleton. When you are ready to replace the seat, start with the hip bolts. Before anything, set the torque wrench to click at 200 inch pounds of tightness. Inserting each bolt one side at a time seems to work best. Afterward, determine that both hip bolts are secure and tightened correctly, then move onto the underside B-links.
These only requre the 4mm Allen-style hex wrench and a hand wrench. Just as in removing, hold the 4mm B-link bolt steady with the Allen key, and tighten the nut with a wrench. These underside B-link screws provide a little give from side to side, this is normal as the seat flexes when in use.
The company Office Designs ships Herman Miller Aeron parts at very competitive pricing. I was able to purchase a seat for $166.00 and a seat back for $139.00. Even replacement carpet casters are available for 19.95 (for all 5). Lumbar support, touchup paint, the list goes on. Just remember to make sure you order the right size seat frame and back frame, as the Aeron comes in 3 sizes (A, B, & C).
All you have to do now is reverse the process listed above to put your chair back together with your new parts, and voila, you've got a practically new Aeron for a discount!
Reversing the disassembly process and installing brand new replacement parts, the chair is almost as good as new.
While Aeron chairs are an expensive investment, buying a used one and slowly replacing parts can be a bit more financially viable than buying all new. Just be sure to keep them maintained and cleaned, and one should serve you well for years to come.
Do you all have any tips of tricks for maintaining a Herman Miller Aeron chair?
(Images: Gregory Han; Angela Kim)