English French German Italian Spanish

Big 4 cylinder hold down nuts

Submitted by chris_howard on Sat, 02/06/2018
Forums
Singles

Hi there following the much welcomed advice regarding the cylinder to crankcase studs, now replaced with the correct ones, I have another issue someone out there may be able to help me with.

Having replaced the studs I just fitted the piston and cylinder and spun on the new cylinder base nuts. The outer two nuts, drive side, no problems but the inner two, next to the valve chest, a different story. No matter how I try I can't get a spanner, socket or any other device onto the nuts to tighten the.

Is there a special tool of technique for tightening these nuts as I'm not sure that grinding a spanner down will allow it to retain the strength needed to do the job.

Thanks in advance

Chris

Submitted by steve_adkins on Sat, 02/06/2018

Permalink

Hi Chris, on Norton twins, some cylinder base nuts are reduced hex, so you may have the wrong parts. Its a long time since I took a '53 Big 4 to bits.......

Have a look here:

https://drive.google.com/file/d/19fYgcNjkFZ1Ldb9WJSTbuiolIPPdqUX6/view

https://drive.google.com/file/d/0B_5ev0g65Xk6MHRjYmt5bkJRdFE/view

You still may have to modify a spanner, but not too drastically.

Good luck!

Rgds Steve

Submitted by ian_soady on Sat, 02/06/2018

Permalink

I've seen and used reduced hexagon 5/16" nuts eg for magnetos on twins etc but haven't seen 3/8" ones (which is what I assume you have). Having said that, a quick look at Nooky's Nuts website shows he has them!

I have an old double cranked ring spanner that I cut in half and ground down which I used for the inaccessible Commado rear head bolt. It was quite strong enough.

Submitted by richard_cornish on Sat, 02/06/2018

Permalink

Hi Chris,

Just to back up Steve's and Ian's answers, yes the nuts next to he valve chest are reduced hexagon but have a slightly larger round shoulder on the bottom to bear against the cylinder flange. If you can get the right onesanordinary1/4" Whitworthring spanner should fit, but might be one spanner tooth at a time.

Regards, Richard.

Submitted by chris_howard on Sat, 02/06/2018

Permalink

Thanks for the help and advice on this problem it definitely sounds like the reduced hex is what is needed. I'll have a look around for some original and if none about it'll be reduced hex with a thick washer to spread the load.

Thanks again

Chris

 


Norton Owners Club Website by 2Toucans