Bolts for transmission mount brackets

[Christopher A.]

Couple of questions:

1. Should the M headmark bolts for the rear transmission bracket to mount be black oxide or cad plated? Also, should all four bolts have the M headmark with 3 lines?

2. What should the headmarks be for the two bolts that secure the bracket to the frame-the two small ones at the rear that keep the bracket from swiveling downward?

3. What should the headmark be on the bolt that secures the transmission bracket to the frame at the bottom and should this bolt be black oxide or cad plated? The one that passes parrallel to the crossmember. I have seen one that has a double circle with RSC headmark inside the cirlcles i have found an identical bolt that came with my cars parts, but it has an "N" headmark in the middle of the two circles.


Thanks

[Timothy B.]

Re: Bolts for transmission mount brackets

Christopher,

On my 63, I used M headmark grade five bolts at all four locations. I believe they are black plated and the two that attach the bracket to the rubber mount use those big flat washers, I believe the other two just have lock washers.

I can't remember what the other bolts are that attach the mounting bracket to frame except that the horizontal longer bolt is grade eight. (I think) I can go out and look tomorrow if someone else does not post.

[Gary S.]

Re: Bolts for transmission mount brackets

Maybe these pictures will help. The car is a well known Bowtie car from Texas. The loose bolts are from an original 65 365 car I worked on. I think all five bolts, lock washers and thick washers were black finished The three crowned locking nuts were zinc/cad plated. You can make your own guess, but I have several pictures of others and this is what it appears to be. Maybe someone can find the factory spec. I have seen several other head markings and any of the "era" should be acceptable as long as they are the right grade. However the "M" is very common for the two mount bolts used with the thick washers.

TransMountBolts.JPG

TransMount.JPG

TransMountMufflerClamp.JPG

TransMountHardware.JPG

[Gary S.]

Re: Bolts for transmission mount brackets

To add more pictures to my previous post, here are pictures of original bolts I bought at Carlisle last year. Also, I have found a common head for the pivot bolt (left to right in the frame bracket) does have circles in it, but again can be any bolt of the era I think.

NutsBoltsHeads.JPG

BoltLengths.JPG

[Christopher A.]

Re: Bolts for transmission mount brackets

Thanks for taking the time to reply and post photos!!!