Chamberlain 8 ft. Chain Drive Extension Kit-7708CB - The Home Depot
Message to Our Customers


Model # 7708CB

Internet # 100431682

Store SKU # 293784

8 ft. Chain Drive Extension Kit

Chamberlain 8 ft. Chain Drive Extension Kit

This item has been discontinued.
The Home Depot no longer carries this specific product.

$30.77 / each


Model # 7708CB

Internet # 100431682

Store SKU # 293784

The Chamberlain 8 ft. Chain-Drive Extension Kit is compatible with Chamberlain's chain drive garage door openers (Does not fit Chamberlain Model # HD220 Internet # 205215863 Store SKU # 1000053358t). It comes with a rail extension and replacement belt and can be used with garage doors up to 8 ft. high. Easy to install.

  • For use with garage doors up to 8 ft. high
  • Works with all chamberlain chain-drive models
  • Kit includes rail extension and replacement chain
  • Comes ready to install with complete instructions

Info & Guides

You will need Adobe® Acrobat® Reader to view PDF documents. Download a free copy from the Adobe Web site.


Product Depth (in.) 
Product Height (in.) 
Product Width (in.) 
Garage Door Part/Accessory Type 
Extension Kits 
Product Weight (lb.) 
5.8 lb 
Warranty / Certifications
Manufacturer Warranty 
1 year 


Rated 4.6 out of 5 by 23 reviewers.
Rated 5.0 out of 5.0 by 8 Foot Door Height Easy to assemble and install. Makes a nice difference to be able to open the garage door the entire 8 feet. Grade of steel not quite as high as the one I replaced on my 20 year old Craftman opener, but still gets the job done. May 12, 2015
Rated 5.0 out of 5.0 by Very Good Product Drive Extension arrived ahead of time and was installed by tech. Very good product March 3, 2015
Rated 3.0 out of 5.0 by Don't forget the rail extension! I purchased a Chamberlain garage door opener in store, failed to notice the fine print that an extension is required for doors taller than 7ft. Unfortunately they don't stock this particular extension in the store so I had to order online. The part worked fine, what I didn't like is that it simply replaced the entire chain assembly and one of the rail connection pieces, so two processed/manufactured items are now waste and only good for scrap metal. Not an environmentally concerned packaging system, adding to the chain link instead of totally replacing it would have been a more environmentally friendly option. Otherwise, does exactly what it needs to do. February 13, 2013
Rated 5.0 out of 5.0 by extension kit Works great. Wish the person at Home Depot who sold me the garage door and opener would of told me I needed this extension before my installer put it up and the door wouldnt go up all the way.. October 14, 2014
Rated 5.0 out of 5.0 by chain extension details in the instillation brochure could have been a bit more clear. product works great September 2, 2014
Rated 5.0 out of 5.0 by Needed part and arrived early Ordered online and had shipped to the nearest store. Arrived earlier than quoted, very pleased with the purchase August 5, 2014
Rated 5.0 out of 5.0 by Very good product. Easy to install. I bought this opener for a second garage. I followed the instructions exactly and got it installed in just a few hours. Had to buy the extension kit because my door ws larger than eight feet. My only complaint would be that all garage door openers are designed for a seven foot door. Who has a seven foot door? So you will need to buy the extension. Plan on another $30. Home Depot had the extension as well. This is the quietest garage door opener I have ever had. I highly recommend it. June 10, 2014
Rated 5.0 out of 5.0 by This product is well made. Works perfect .)my order was recieved before the promised date. May 15, 2014
  • 2015-05-21T12:03:25.889-05:00
  • bvseo_lps, prod_bvrr, vn_prr_5.6
  • cp-1, bvpage1
  • co_hasreviews, tv_23, tr_23
  • loc_en_US, sid_100431682, prod, sort_default
2 >>


Standard Shipping includes delivery by small parcel service. Processing time varies by product.

Orders for this item may be expedited for an additional fee.

Other Delivery Options:

Express and Expedited shipping options are also available. Estimated arrival times are available in checkout.

If product is eligible for shipping to AK, HI and US Territories additional transit time and remote surcharges may apply.