Engine mounting bracket bolts

[Paul Coleman]

Somebody has made a right mess of the mounting brackets on my engine. Does anybody happen to know (long shot here) what the thread is of the engine mounting bracket bolts on an S1?

 

I reckon they could be 5/16" with 20tpi which is neither UNF nor UNC?

 

Thanks, Paul.

[Lou R]

Hi Paul,

 

I believe the S1 brackets are the same as the S2 brackets.  I have an S2.  When I tried to measure the bolt thread I couldn't determine if it was a 5/16 - 20 TPI (1 inch long) or an M8 - 1.25 (35mm long).  They both seemed to be right on the money !  I'll try to place a tap into the bolt hole in the block later today to see if I can get something more accurate.  Also, my car has allen head bolts which I'm pretty certain were not original (indicating a change somewhere along the line).  

 

Lou R 

[Paul Coleman]

Lou

 

Thanks for reminding me that sometimes I'm a complete idiot!! I don't know why I was convinced the bolts were imperial. The fact that I was looking for a non standard thread at 20tpi should have given me a clue D'oh!

 

I'm sure they're M8 1.25mm and I've run a tap through them which seemed to confirm.

 

My problem was that somebody had fitted a 5/16" 18tpi UNC bolt in one or more of mine in the past. Hopefully I'm sorted now. Thanks for your help.

 

Cheers, Paul.