Cart 0
Cart 0

Your source for 1973-1978 GMC Motorhome sales, service, and parts

GMC Motorhomes - Repairs and Service

OUR SHOP:  Vintage GMC Motorhome Service

We are a complete GMC Motorhome maintenance facility specializing in factory-built GMC motorhomes.  Vintage RV Service at its best!  We love the GMC coaches and will do everything in our power to keep your Classic GMC on the road, with safety and dependability.

Our Facilities  
Our shop is equipped with all the parts, tools, and expertise needed to restore, repair, and maintain your GMC coach.
Our lift is specially specified to safely lift our GMC coaches.  This is important when rebuilding suspension and chassis components.

We have several service bays for heavy mechanical work such as engine and transmission rebuilding.  

  • We have a specialized lift designed to handle the special weight distribution of our front-wheel drive coaches.

  • Complete air conditioning service - Dash (driver compartment) A/C repair and upgrade.

  • Body repairs and paintwork can make your coach look new or better than new!  New paint schemes can make your coach really look original or ultra-modern.

  • Brakes - Repairs and Upgrades

  • Front End repair and alignment

  • Air suspension repair, rebuild, update.

MECHANICAL UPGRADES FOR YOUR GMC 

Our engineering team is always looking for new product solutions to keep our GMC coaches functioning as well or better than new.  We have created several new parts that improve the safety, handling, or performance of the GMC coach.

Air Suspension Upgrade

Air Suspension replacement Airbags. The original GM factory air suspension air springs (airbags) are no longer being manufactured so we are currently using available off-the-shelf airbags from Daytona. 

Replacement Air Bags: Single Airbag System (Ferrara bags) This replacement is one single chamber bag with a waistband for each side.  The waistband keeps the airbag from “bulging” in the middle and helps maintain load capacity. This solution provides:

  • Direct bolt-in replacement for original air spring.

  • Firmer suspension feel.

  • Slightly larger in diameter than the original.

  • Reduced suspension travel compared to the original provides a firmer ride for better control.

  • Same operating air pressure as the original.

  • The same ride height on your coach as the original.

  • Larger spacers provide limited collapse distance if the airbag fails.  Your coach can be driven a limited distance on “flat” bags.

  • Same load carrying capacity as original. o Readily available replacement airbags are available. NOTE: An isolation kit is included with each set of new bags.  The kit, shown below,  allows ride level to be maintained in the event of an internal air suspension control system or compressor failure.

Hub Extenders for Front Wheels

  • Provides a wider stance with the proper wheel offset for the front wheels.

  • Allows front track width to be equal to rear tract width.

  • Especially important when using upgraded aluminum wheels.

Complete Braking System Upgrade

Brake system parts are engineered for direct replacement or upgrade

Front Brake Parts

  • Upgrade larger diameter brake calipers

  • Front Stainless steel brake hoses

  • Severe duty brake pads - fit original and upgraded calipers

Brake Distribution Valve

Disc Brake Rotor

Disc Brake Caliper

Stainless Brake Lines

Rear Brake Parts

  • Engineered replacement brake drums

  • Upgrade wheel cylinders. Install these on the front set of the rear wheels. Use standard wheel cylinders on the rear set of wheels for improved balanced braking

  • Severe duty brake shoes. These work with standard and upgraded wheel cylinders

  • Stainless rear brake hoses

  • Upgrade to rear disc brakes. Complete kits are available.

Severe Duty Rear Brake Shoes

Rear Brake Drums

Stainless Rear Brake Lines


Front Steering Knuckle and Hub

  • Steering Knuckle and Hub. Core Required. May need to be replaced if the hub or knuckle is worn.

  • Wheel bearings - re-packed when brakes are serviced, replaced if worn.

  • Grease seals for wheel bearings

Wheel Bearings

Front Steering Knuckle

Wheel Bearing Seals

Front Wheel Hub

Emergency or Parking Brake

  • Note: Emergency or parking brake is designed to operate on rear drums

  • New brake actuator cables are available, as well as all fittings

Brake Booster and Master Cylinder

  • Engineered brake booster. We use original factory booster cores and rebuild to original factory specs. Core required.

    • Standard duty booster

    • Sensitized booster for same braking pressure with lower pedal effort.

  • New master cylinder engineered to match original equipment fit and performance

Major Mechanical Upgrades: Engine and Transmission Rebuild

We feel that one of the strong points of the GMC Motorhome has always been the 455 (403) engine. Over the years we have seen that most GMC engines go trouble-free for much more than 150,000 miles. We offer a complete engine rebuilding service. We are always preparing rebuilt engines so that one can be ready to install on short notice.

 Coaches for Sale

Enjoy vintage RV’ing in your very own GMC motorcoach. 

We keep a variety of Vintage GMC coaches for sale on our lot. 

Some coaches are ready to drive across the country, some are beautifully refurbished and upgraded, and some are restoration projects. 

We are glad to do restoration and upgrades for you, or you can do your own work according to your abilities. Our restoration shop is preparing several coaches for sale…if you buy while the work is in progress, then you can choose the final details and updates such as color scheme and interior style.

Mechanical upgrades are our specialty.  We can make any coach safe and road-worthy…just let us know how far you would like to take your restoration.

Click here to see the coaches we have for sale.

Contact Us

Please email or give us a call to inquire on price and availability for any items not listed in our online store.

 Sirum GMC proudly supports the GMC Motorhome Forum