Has anyone with a '74 seen this type of crack in the plastic lower panel? It is such a straight line crack I think it was caused by the excessive weight added by the seat belt yellow box assembly. The seat belt interlock has been bypassed by the previous owner so I would just remove the box but the damage is already done. Plus, not knowing what they did to defeat it I'm afraid if I just unplug the box I may cause issues.
Your lucky if that is the only crack that you have in the lower panel, the panels are known to crack in that area and not from the seat belt box all years do it. The crack can be repaired but not easily and will require the panel to be taken off but that is a task in its own. Cant hurt to unplug the box and see if it causes any issues
Thanks and yes, I also have a small crack developing to the right of the glove box door as well. I was planning on removing this panel so I could repair the cracks from the back side using epoxy putty but as you said this is a task. I think it would probably create new cracks or it would break in two at this large crack during removal. So I think I may leave it alone. Might look into either removing yellow box or providing support to it from the rear with a velcro strap just so it doesn't apply more stress to the panel than it already has.
I would agree....the yellow box has nothing to do with why it cracked. Pretty common for them to crack.
45 year old plastic has likely shrank. More likely vibrations from radio contributed to the breakage.
Have you ever removed one? I'm pretty sure that if I could get it out without further damage that I could repair the cracks with epoxy putty on the backside. Looks like about 6 sheet metal screws along the bottom plus a couple in the glove box but my guess is it's more involved than that. I checked my Detroit Iron manual and no mention of it there.
I have removed lots of the lower dash assemblies. Several phillips screws along the top where it attaches to the metal dash, and then some 3/8" bolts on the bottom on the ends.
I had repaired one. I used two part epoxy and glued pieces of coat hanger as reinforcement in spots inside where the repairs could not be seen. I also glued washers in where tabs for the screws were broken. Drove the car for several years and the repairs worked well.
I had planned on using two-part epoxy, but the coat hanger rebar is a really great idea! I will be sure to do that. Did you have trouble removing it without making the cracks worse (or breaking the part altogether)?
The heaviest thing attached to it is the radio and its bezel. After that, it is very light. I unbolted it and was careful in handling mine. I managed to do it solo, but another pair of hands may help. Also, you could tape a yardstick to it with painter's tape as a brace if you are concerned. If I recall right, there is metal bracing in key parts behind it. If the car has air conditioning, there are hoses attached at each vent. The glovebox liner is cardboard, so be careful not to damage that on removal. Also, there are two sizes of glove box liner. Non a/c cars have a bigger glove box. A/C cars have a duct taking up room behind them and the liner is smaller.
ok thanks for the tip. The only major crack is just below the right side of the radio, you can see it in the photo at the top of this thread. I got to thinking maybe I should just remove the radio then repair it from the back side with the lower dash still in place. May just need to loosen the screws temporarily to allow some movement to align the crack together. I'll take a closer look this afternoon.
