Hey everybody, I have looked through this site for a long time for references and help but never created an account or posted.

I have a 1995 F150 with a 4.9l Inline Six and a ZF5 trans. I recently went to get an alignment and found a 6.5inch crack in the crossmember than runs underneath the motor. It runs pretty close to a motor mount and worries me a lot. The 300 is really 'torquey' and I know it will pull apart even more. It is split pretty good and rather than re welding it, I got a nice, clean one from a scrapyard.

These are riveted to the frame, not bolted. My frame is pretty straight and still good and I'd really like to keep my truck.

My question is what would the torque specs be when I put the new crossmember in? I plan to use Grade 8 all around and having to re-torque these later down the road will be a pain.

Any recommendations are appreciated, thanks!

 

Bolts were not used in this application, so there is no factory torque spec to my knowledge. However, every bolt size and grade has a torque spec. Just google the bolt size torque spec. Use blue or red loctite if you want to keep them from coming loose. (Red only if you don't care about removing them normally in the future.)

 

The engine crossmember is WELDED to the frame. Rivets on the top and bottom but welded verticality. V the crack and weld it, never worry about it again.
My 80 F350 had a large piece MISSING where the TTB bolts to that crossmember. I simply cut the piece from another frame and welded it back in. The truck had been pretty much a dedicated pulling truck with a 429 and manual valve body C6. I have yet to have an issue with it since I repaired it 25 years ago

 

No harm in welding it so long as it’s done properly. Besides cutting a vee into the crack with an angle grinder, you can prevent it from spreading after repair by drilling a hole at each end of the crack.

If you really want to bolt in a new cross member, use the largest size bolts that will fit into the holes (I’d guess 1/2” or 5/8”) and use the recommended torque according to a generic chart (easily found with an internet search).

 

maybe this posted by Freightrain

 

If you use prevailing torque nuts, you will never have to retighten them. Fastenal has them as well as the grade 8 bolts and sae washers.

 

I know the thread is dead, but what did you end up doing? installing the new piece, or welding the broken one?