The BSA A7-A10 Forum

Technical => A7 & A10 Engine => Topic started by: beezer barry on 28.12. 2007 14:01

Title: connecting rod torque
Post by: beezer barry on 28.12. 2007 14:01
Hello, everyone

   I recently purchased a 1958 A-10 golden flash. It has been sitting since 1967, and has 6700 original miles.  The engine was seized when I bought it, and I assumed it was the pistons. Unfortunately it was not. rust had invaded the bottom end and was the source of the seizure.  Luckily the engine had never been run in this condition. The crank cleaned up nicely at .010 under.
I am very confused about the connecting rod bolt torque specs. The engine number is DA10-310 and according to my haynes manual, torque should be 22 ft/lbs. Here is the confusing part. My engine has the castellated nuts and split pins, and I've been told this is incorrect for a 58. My 58 parts book shows the castellated nuts as well.  I cannot believe that this engine has ever been apart. When I disassembled the engine the nuts were very tight, they had to have more than 8.5 ft/lbs on them. What is the correct torque 8.5 ft/lbs or 22 ft/lbs? I dare not guess at something so important. I ordered new bolts and nuts thinking this would resolve the issue, however upon receipt they were of terrible quality. I got three different bolts (sligt differences in length and head thickness) and two of the nuts have extremely loose fitting threads. I will not be using these. Also on my conrods there is a 1/4" recess where the castellated nut can fit into the larger locknuts will not fit into these recesses. Any help would be most welcome, Barry
Title: Re: connecting rod torque
Post by: a10gf on 28.12. 2007 14:34
Hello, and welcome to our friendly little corner of the internet.

You may find something here to start with:
Title: Re: connecting rod torque
Post by: trevinoz on 30.12. 2007 20:48
Barry, according to my literature the first '58 Flash was DA10 651. Yours may be the last of the small journal type cranks, you can confirm by measurement.
Service sheet 208 states that early 22TPI bolts are torqued to 10 lb. ft. 26 TPI types are 8.5 lb. ft. Post '56 it is 22 lb. ft.
Early large journal bolts use a castle nut which was changed to a nyloc type, not sure when. Nyloc nuts can be used in place of castle nuts but rod cap needs to be spot faced to clear nut.
As a matter of interest, what type of fuel tank is on your bike? Is it the round badge or the winged badge type?