Someone is bound to know this! Are the bolts securing mudguards,running boards, engine valances 2BA round head or hex and should they be fitted with repair washers(large outside dia.)? This is the second time I have restored it but the first time 40 years ago I just wanted to get it on the road so I wasn't so particular then and used 1/4 BSW hex. It's an AD registered Feb 1929.

We have an original 29 front wing and flitch panel in our spares shed and the bolts are definitely not ¼”, not sure about a BA size, I would have thought 3/16” they are cheese heads with washers about ¾” diameter. I will make a check the next time I am at the shed.

2BA is as near as makes no difference to 3/16 and are easy to obtain as well as being the likely original thread type. A good source is

www.ekp.supplies.btinternet.co.uk

who make proper turned screws, bolts and nuts in reasonable quantities and reasonable prices. Usual disclaimer.
Regards
Brian

I believe our '28 Chummy has the original bolts, and they are 3/16" coach bolts, with the thread right up to the square under the head. The square locates in square holes in the stays. After refurbishing the mudguards I put them back with head size rubber washers under the heads (cut from old black inner tube) to avoid possible damage to the now immaculate finish!

Having owned a very original 1926 Saloon and now a 1928 Chummy would agree with Ian and Robert re wing to flitch plate and wing to stay.Flitch plate to cow horns 1/4 BSF nut and bolt.Size of flitch plate to wing is confirmed by the 3/16 hole in wire clips on later cars.

Thank you all for your help. To summarise I think I should be using 3/16 BSF cheese head(or 2BA - hardly any visible difference)for wing to flitch plates and rear wings to body and 1/4 BSF coach bolts for front wing to wing stay. 3/16 BSF cheese heads for rad cowl to flich plates? Might as well do it right this time!
Cheers,
Dave

It should be ¼”x1/2” long hex bolts for rad shell to flitch plates, anything less will soon shake loose. The holes in an original shell are ¼”diameter and 1/4" slotted holes.

Thanks Ian. Yes they do shake loose don't they. The shaking causes fatigue cracks on a brass rad cowl also.