Rear Brake Anchor Bolt

[morningside]

Reference my 1948 Flying Squirrell : I would like to remove the rear brake anchor bolt and domed nut. The domed nut cannot be removed from the frame lug as it appears to be captive. Was it originally swaged after being inserted through the lug ? Is it possible to remove it ? Does anyone make both the domed nut and the 1/2″ bolt with flats which engage in the brake torque arm?

Thanks/Regards

[dave bushell]

The original “bolt” was removable and wasn’t swaged over to retain it.

Dave

[Johannes Hofmann]

Dave,

Thanks for your response. I have removed the domed nut part of the assembly by filing off the ‘peened over’ end and inspected both parts. The ‘bolt’ part (with the flats) appears to be both original and in good condition. The domed nut part also looks to be original but may have been ‘modified’ hence the peening over. On re-assembly the two parts appear to assemble o.k. with the flats engaging correctly in the anchor plate. There is a gap of approx. 1/8″ between the anchor plate and the frame lug. Is this correct ? Also the diameter of the hole in the frame lug is bigger than the outside diameter of the domed nut (which is 11/16″). The result being that when the rear brake is applied the domed nut moves forward/backward in the lug and is audible. Something is not correct here. Has the hole in the lug become oversize, is the gap correct, is the domed nut part correct ? I need to get this right. Any help/advice would be appreciated. A photo or dimensions would be very helpful.

Thanks/Regards

[dave bushell]

Hi Johannes

The “bolt” head is 3/4″ diameter with no spanner flats, relying on flats engaging with the brake anchor slot to prevent it rotating. The threaded portion of the bolt is 11/16″ long and is 1/2″ diameter with a 1/2″ cycle thread. The long shanked domed nut is 1 1/4″ long and 3/4″ diameter on its shank. It also has an undersized head that takes a 7/16″ BSF spanner. The hole in the frame lug is 1/2″ dia. and there shouldn’t be a gap between it and the brake anchor plate. Check your rear wheel alignment.

Dave

 

• This reply was modified 2 years, 9 months ago by dave bushell.

[morningside]

Dave,

Many thanks for your response and time taken to obtain the dimensions – very helpful. My ‘bolt’ conforms with your dimensions. The ‘domed nut’ is 1-3/16″ long x 11/16″ diameter and frame lug hole diameter approx. 3/4″ diameter – so here lies the problem. If anyone has a spare ‘domed nut’ for sale please contact me.

Many thanks/Regards/Ian Moorey

For Info and to avoid any confusion : The above post dated 22nd April was from myself and not Johannes – Do’nt know how this happened !

 

 

 

[dave bushell]

Obviously the frame lug hole is too large at 3/4″. I think I would make a top hat bush to reduce the lug hole to 1/2″. Your existing dome nut could then tighten down on the larger diameter surface (outer) part of the top hat bush.

Dave

[morningside]

Dave,

Thanks again for your response. Your suggestion looks like the way forward. I can turn up a top hat bush on my mini-lathe. Onwards we go !!!

Thanks/Regards/Ian Moorey.

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