Th400 help

[reaperz1]

So long story,short version lol, I have been restoring a 1972 c10 with the stock 402 and th400 for the past 8 years. Due to my divorce and having to move I am missing the bolts to transmission mount connecting it to crossmember and can’t seem to find any, so does anyone know the size of bolts and grade I should get, also is there supposed to be a plate between cross member and transmission mount if everything has stock brackets and mounts if so do you know where I can get one there was not one on this truck that I know of.
Thank you for your time

[71CHEVYSHORTBED402]

Originally Posted by reaperz1

So long story,short version lol, I have been restoring a 1972 c10 with the stock 402 and th400 for the past 8 years. Due to my divorce and having to move I am missing the bolts to transmission mount connecting it to crossmember and can’t seem to find any, so does anyone know the size of bolts and grade I should get, also is there supposed to be a plate between cross member and transmission mount if everything has stock brackets and mounts if so do you know where I can get one there was not one on this truck that I know of.
Thank you for your time

You want those bolts just the right height due to the threads in the transmission. I believe the bolts are normally GR 8, but can't swear to it. The replacement bolts probably are, I bought new to fit just so. The energy suspension kit sits the transmission 2" above the crossmember. You can compare that to your original for any drive line concerns, but my guess it's good. In my case it doesn't matter, because the drive shaft is being rebuilt anyhow.


My notes for the transmission mount are below, 402/400TH.


See page 835 in assembly manual.

Transmission mount to transmission crossmember: The transmission mount secures to the transmission crossmember using two (GR5) 5/8" hex bolts, washers and lock washers. The bolt threads are 7/16-14 x 1. The bolts insert from below. NOTES: One bolt is stamped "M" and the other a faint "C". The washers are 3/16" thick and 1.1/4" wide.

Transmission to transmission mount: The bottom of the transmission mount is rubber and has two female threaded inserts. The transmission was mounted using two 3/8” shims (spacers) between the mount and transmission. The transmission was secured to the mount using two 5/8" hex bolts and lock washers. The bolt threads are 7/16-14. NOTE: The bolts weren't factory and varied in grade and length.

Assembly order on the original mount from the bottom: Bolt > lock washer > mount > two spacers > transmission.

NOTES:
The mount was replaced with an Energy Suspension mount and (GR8) 7/16-14 x 1.1/4” bolts and washers. The mount sits the transmission 2" above the crossmember.

The female threads in the transmission are approx. 7/8" deep. Per the transmission shop the bolt should insert at least 3/4" into the threads in the transmission. If they're too tall they'll damage the transmission.

[reaperz1]

thank you so very much, going to get them tomorrow after I get off work.