Britbike forum
Posted By: Raymond Smith BSA Gold Star Head Bolts Stuck - 05/04/21 3:57 pm
I have a DBD34 that has been resting for 40 years and needs to be revitalised. All eight bolts, four Cylinder to Head and four Crankcase to Head are stuck. Valves are free to reduce pressure. Please Help with best ideas to undo bolts without damaging head and barrel. Keep Safe Ray
Posted By: Andy Higham Re: BSA Gold Star Head Bolts Stuck - 05/04/21 7:22 pm
Will the sleeves unscrew out of the crankcases? If so you can remove the whole head/barrel assembly as one piece.
Then while the wife is at bingo/shopping/drinks with the girls, place the assembly in the oven and let it soak at around 150 - 180 deg C for half an hour. the studs should unscrew easily
Posted By: Stuart Kirk Re: BSA Gold Star Head Bolts Stuck - 05/04/21 8:36 pm
Hi Raymond,
Welcome to the forum. There's lots of good advice to be had here.

Your cylinder to head fasteners screw into bronze thread bushings so are not likely to be seized, just good and tight. They are counter clockwise rotation to remove, looking from the underside. I would try a good quality box end wrench (ring spanner) and an extender on the short bolts. The easy way is to link two wrenches together, open end to box end. You will need to apply 30, maybe 40 foot pounds of force or even more. You will have to use an open end on the long bolts so it needs to be a good, stout one or maybe two weaker ones used together. (Same force as the short bolts.)

One small word of caution about removing the abutment sleeves that thread into the crankcases. They will usually be tight and often require heat to get them to turn. A further hazard is this. The threads are undercut under the ledge that seats on the surface of the crankcase mouth.

This undercut can act to break the edges of its hole while being unscrewed such that it can't be properly tightened in again without a level surface to seat against. That ledge is quite narrow.

Repair is a machining operation so it's not the end of the world, but you won't be happy about it.
Posted By: chaterlea25 Re: BSA Gold Star Head Bolts Stuck - 05/05/21 1:31 am
Hi Ray
Removing the Magdyno gives better access to the rear bolts
I bought a copy of the special BSA angled head spanner on ebay, its laser cut and about 10mm thick to get a good grip on the hex's

Posted By: Raymond Smith Re: BSA Gold Star Head Bolts Stuck - 05/05/21 7:34 am

Many thanks for all your valued advise and information, I have only worked on B31/33 cast iron so did not know about the Bronze insets, that is good news.

Thanks to all for your adise and help.

Stay Safe

Ray Smith
Posted By: Stuart Kirk Re: BSA Gold Star Head Bolts Stuck - 05/06/21 4:51 am
Best of luck with your project.

Let us know how it turns out.
Posted By: Raymond Smith Re: BSA Gold Star Head Bolts Stuck - 05/06/21 9:41 am
Present position is that I have managed to release 7, the back head stud (Mag) is stubborn and worn. Plan is to get engine out before causing more damage to the stud. Just waiting on Clutch center removal tool to move on. Thanks for all you advise and help. Cheers Ray
© Britbike forum