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Black Shadow rear brake drums?

kick69

Website User
VOC Member
A question for the masses, our '50 Shadow , which seems original, has finned drums on the front but plain on the rear. Does that seem right,? or did they come out with finned on the back as well. The books have conflicting suggestions, Cheers Jonathan:confused:
 

john998

Well Known and Active Website User
VOC Member
Would agree with you there, but I always find the the front wheel worst.
Have used allen cap screws for years, so most of the work can be done easily.
This set up has worked well, even with a sidecar.
 
F

Flatout

Guest
Would agree with you there, but I always find the the front wheel worst.
Have used allen cap screws for years, so most of the work can be done easily.
This set up has worked well, even with a sidecar.

I'm getting my Comet rebuilt and I've been advised to go for M8 s/s allen cap screws and M8 s/s Nyloc nuts as it's a huge saving.
The grade is 304 I think. Probably wreck a few blades in the process!
 

Len Matthews

Well Known and Active Website User
VOC Member
Metric cap heads & nuts-oh dear! I appreciate the cost cutting factor but as long as Imperial fasteners are still available let's use them. Besides, 8mm
and 5/16ths are not the same thing. The original brake drum bolts are "fitted" bolts for good reason because they are in sheer when braking and, in the case of the rear hub, under acceleration.
 

john998

Well Known and Active Website User
VOC Member
Brake drum bolts

Hello,
Just been out in the cold garage to measure some bolts.
The bag of about 100 original ones has two types. One has a round eccentric head and is .311 under the head. the others are hex head with 2 reduced sides, these are .309 under the head.
The round head type appears better quality, if you will forgive the pun all round.
5/16 is .3125, 8mm is .3150 so I would think unless some malefactor opened out the holes it would be no go, but I do not have any to measure to check.
Imperial allen bolts have served me well for more than 30 years, ideally they should be bolts not set screws. The only drum failure so far has been the sprocket flange coming clean off at Cadwell. John.
 

john998

Well Known and Active Website User
VOC Member
Brake drum bolts

Hello,
How sad is this, had a better look at my bag of bolts in day light, and discovered more flavours.
The hex head with flats comes from two makers one type is marker Newton, and has a thin head. The other with a slightly thicker head is stamped with a capital D.
Also found five bolts with a round head that is not eccentric, but has a taper with two flats.
Must try and get a life. John.
 

Len Matthews

Well Known and Active Website User
VOC Member
Yes John, there is a bewildering variety of hub bolts. I think those with a taper and two flats are very early ones. An ex-Argentine "B" I worked on had those and because it had pressed steel brake drums they were slightly shorter. Whatever, they've got to be better than metric Allen screws!
 

A_HRD

Well Known and Active Website User
VOC Member
Metric Hub Bolts

Actually, I just measured some stainless 'M8 A4-80' allen bolts with plain shanks on which I got a while ago for my Ducati. They are just the right length for hub-bolts with the overall length cut down a bit. The shanks are consistently 0.311 - 0.312 diameter which is a perfect fit for hub-bolts, I'm sure Len would agree. (The collection of standard/original 5/16 BSF hub-bolts I have collected over the years have shanks varying from 0.302 to 0.313 inches - deplorable!!). The M8 heads need a flat to be milled or filed on; so locking as std is guaranteed.

Just as good, the stainless M8 Nylocs I have for them have a nice black nylon insert (not the gaudy blue inserts which are the mark of cheap imported nuts). The 13mm across flats is only about 10 thou down from that of the nominal 0.525 of 5/16 BSF Nyloc nuts; so no-one would know. :p

For those who remain totally allergic to metric threads, you can buy longer M8 allen bolts with a plain shank at least 1-1/8 long, cut to length, thread 'em 5/16 BSF on a lathe and file the flat on the head.

Either way, the cost-saving is huge and the all important fit is probably better. Use A2-80 or A4-80 in preference to A2-70; they're a little stronger.

I promise I'll get out more.....

Peter Barker
Bristol, UK
 

john998

Well Known and Active Website User
VOC Member
Brake drum bolts.

Hello Peter,
I like the sound of those bolts, as they will as you say be a better fit.
The heads on metric cap screws must be larger than the nearest imperial,
as they fit without any machining or filing. A clean out with an 8mm reamer, if necessary will probably be an improvement .
The main reason for using cap screws is ease of assembly, most of the tightening can be done using an allen key. With lock nuts and a final pull up with a spanner I have never known one to back off.
If I used 8mm cap screws I would probably turn down the head so it would turn in the drum.
Regards John.
 

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