Interior and Upholstery Preparation for Hot Rods and Customs

1956 Ford F100 Interior

Tips for preparing your hot rod or custom car or truck for interior and upholstery.


First and foremost, your wiring harness and all connections should be completed and fully tested before you start or bring your vehicle to an upholstery shop for interior work.

If your wiring is a mess, many upholstery shops will not touch the project until the issues are addressed and corrected. If the shop handles this work, this can add significantly to the cost of your project.

Areas to pay particular attention to:

  • fuse box (firmly mounted)
  • door locks, power lock switches
  • door poppers
  • power window, switches
  • windshield wipers, switch
  • A/C and heater controls
  • radio, amp, speakers
  • third brake light
  • dome light, courtesy and under-dash lights
  • any items such as switches or gauges that will be mounted in a console.

Always make sure there is a little bit of slack in the wires — wires should have enough slack under the dash to come up over the top of the kick panels and firewall panel at the bottom of the dash.

Hot rod wiring
Make everything neat, and tied up with plastic ties and securely mounted.

If you can run the wires overhead it will make your floor a lot cleaner and easier to work. If you plan on putting a console in the car you can run your wires down the middle of the car. 

Heat and Air Conditioning

Heater hoses should be fully installed and checked for leaks. Make sure they have a little slack in them. On some cars, the heater hoses run parallel under the dash, run down into the kick panels, and come out into the inner fender well. 

This makes your upholstered kick panels and firewall panel fit up nice and clean. The main thing is to keep your interior kick panels and firewall as flat and clutter-free as possible.

You should have your A/C and heating unit control panel in place, wired and working. If you plan on putting the A/C panel in the console, you can simply rest the unit on the floor for placement by the interior installer.

Heater hose spring
You may have to put a spring around the hose where it makes the turn from the kick panel into the fender well. This will keep the hose from crimping or folding up.

All the heat and A/C ductwork should be fastened to the unit and pulled to where the vents/louvers will go. If the vents/louvers are in the dash, everything should be in place and properly secured.

Windows and Moldings

All side and quarter windows should be in place and working. Power windows and door locks installed, wired, and working. 

Have all the window garnish moldings fitted well to the windows and either polished or painted? If you plan to paint the moldings the same color as the leather or cloth, have them in primer and make sure that the felting is fitted for the upholsterer to put onto garnish moldings after he or she has painted them. All window felting should be in place. 

You can leave the front and back glass out most projects — just ask your interior or upholstery shop.

Door panel

TIP: If your vehicle has power windows, locate the switches where they are convenient for you (not obstructed by your leg, for example). Often the best location for window switches in a custom car or truck are in the console or in a short drop panel under the dash.

Door Handles and Window Cranks

Have the door handles and window and vent cranks ready to install — it is best to have them when you take your car to the interior shop for proper fitment, but also because you’ll likely pay a premium for the shop to acquire them for you. 

OEM Dash Pads

Some cars and trucks had dash pads installed from the factory. You can reuse or recover the OEM pad. Sometimes shops can make custom dash pads. Another good idea is to fill up the holes in a metal dash where the pad bolted down and paint the dash. The painted dash often provides a particularly clean feel to an interior.

Radio and Speakers

If your radio is in your dash, ensure it is wired and working. If you plan on having your radio mounted above in the headliner area or in a center console, make sure to pull the wires with enough slack (generally, the longer the better).

Most shops will wire the sound system for you, simply ensure your harness is prepared with the required wires: red (ACC), yellow (HOT) and black (GROUND).

Console mount stereo

Must shops will make the speakers blend in with the upholstery as they build the custom interior (ensure ample wire length). 

Dome and Interior Lights

Ensure the power wires run for dome and interior courtesy lights are in place and with ample slack. 

Heat Shields and Sound Deadeners

It’s a good idea to use heat and sound insulation in your custom car or truck. The floor and firewall should be completely sealed with either a brush-on sealer or adhesive-backed sealer tape, or both. You can alternately use bubble-type insulation in your roof, side panels, or trunk to keep costs down.

We’ve found it best to use spray-on insulation in the doors because water can get behind the adhesive and cause stick-on insulation to peel. Additionally, adhesive-backed products, such as Dynamat, when used in the doors, add a lot of weight to the door, especially fiberglass doors. 

Heat Shield and Sound Deadening

Do not put adhesive backed insulation over package tray mounts or over areas where door panels clip on to the door.


Make sure that you have the carpet sill plate garnishes / moldings (where the carpet meets door-jam).

If you have an under mount master cylinder, consider using a remote fill on the exterior firewall or hidden behind an interior trunk panel. This will prevent the need for a hole in the floor.

Seats and Seat Belts

Ensure that the seats, if not mounted at time of delivery to the shop, have been pre-fitted and the slider tested ensuring there is no binding and they function properly.

Hot Rod Interior Seats

Ensure there is ample play between the seat and the door panels — check this with the seats in the forward most position. If you are using the original seat and it will need to be re-foamed, ensure that the seats are stripped and ready for new material.

Weather Striping

Have all weather striping in place in door and trunk jams ensuring proper fitment.

Convertible Tops

With a convertible top, make sure the tacking strips are in good shape. Ensure the top is adjusted to the windows and working correctly. Make sure to have all working parts and anything you may see painted. Contact your interior shop for more tips.

Finally, Plan Ahead

Experienced upholsterers will be glad to guide you through the details and styles available for your custom car or truck project. It is prudent to contact the shop well in advance allowing for plenty of time to plan and prepare. Be patient, all good things take time.

If possible, avoid rushing the project to make a deadline for a car show, for example, as this often leads to rushed work with lesser results.