Bolts

[Howard]

Hi, I want to refit the sump plate to my 1951 A7 however I see that there are 2 normal bolts and then 2 studs with nuts does it matter where these are postioned ? Also I want to rebolt the gear box to the motor but same situation, 2 normal bolts and 2 studs with nuts, which go where ? (guess I should have taken better notes when dismantling)

[BSA_54A10]

You should have 4 studs and nuts, not bolts.
Having said that, the world will not stop turning because of your missing studs.
Measure the length of the bolts to make sure that they will not go through the cases so far as to foul on the crank.
Bolts usually need a copper washer under them as oil will wick down the threads.
Studs otoh are driven home to the end of the thread so that effectively makes them oil tight

[trickytree]

The gearbox however has studs at the bottom and bolts at the top....perhaps to aid removing one or the other while still in the frame?

From an engineering veiw point for aluminium, studs are prefered. Use the apptly named studlock to fit the studs into the case. Use coppaslip and locking nuts, or spring washers, for the fastening nut to minimise the risk of a seized nut pulling out the stud.

[groily]

Might be worth thinking about a plate with a drain plug in it while you're on Howard? SRM do one and there are quite a few comments on here on the subject, the options, and the best way to point the plug for easy oil drainage from the cases at oil change time. I quite like my SRM one, but didn't use the allen bolts supplied, preferring to make longer studs for the 2 good reasons given (oiltightness and 'into alu'). Choices, choices . . .

[RichardL]

Howard,

Having just discovered the presence of bolt and studs, take a close look to be sure that they are all of the same thread type. The idiosyncracy of my own sump plate is having three metric helicoils and one remaining original thread. This is my own idiot fault, but I  know to keep track of it when disassembling. Next engine rebuild, say, in fifty years, I intend to correct this.

Richard L.

[fido]

Yes, for the sump plate if they are all the same thread they can go in any positions as long as none of the bolts bottom out in their holes.

[Howard]

The Forum comes to the rescue once again....many thanks guys....Regards Howard