Hello David. Our cherished suppliers sell a purpose made bolt.
Regards
Stuart

Location: Staffordshire, the creative county.

I think the radius arm bolt is 5/16" and all replacements are the longer type with the later coil spring.

Cheers, Tony.

Location: Melbourne. Victoria, Australia.

Are you sure Tony, I thought it should be 3/8" waisted in the centre to allow roll where it passes through the Ball. I have also just encountered a reproduction Ball with a 3/8" hole through it, I have several loose originals in my parts bins and more on chassis ranging from 1928 to 38 in age range, all appear to have 7/16" holes through the Ball. Obviously we want the bolt to be a snug fit where it passes through the Arm and Cup but with sufficient clearance in the Ball to allow for suspension roll. Can anyone tell us categorically if there was a change at any point in the bolt / hole size, perhaps something that coincided with the change from solid to sprung loaded centre bolt?? I have not personally seen evidence of this but just asking as a result of this thread.

Location: NZ

Ian,

No I am not sure - my limited experience is with 1928 and 1929 chassis ball joints.

It is a bit cold to go crawling under but I think that I have tried a 3/8" bolt which wouldn't fit the hole in the radius arms on one of them.

I haven't seen a waisted bolt but that means nothing- most have probably been replaced.

The Spare Part books show a plain bolt but this means little - the spring with a longer bolt were introduced around 1935.

Cheers, Tony.

Location: Melbourne. Victoria, Australia.

Earlier cars had a 5/16" bolt with corresponding rods and cups, later ones 3/8" - the Service Journals or record cards may give the changeover date. It would appear that this car has acquired a mixture of parts and the practical answer would seem to be to open out the holes in the rods to 3/8" or get hold of a later pair, otherwise with a 5/16" bolt everything will be slopping about.

A short article/letter appeared in the Association Magazine about the changes to the design as described above - I cannot find it just now but it would have been around 2005-ish. From memory it was either written by Dvid Cochrane or Chris Gould, I think.

Purely for related interest, this is the drawing for the Prototypes that Stan drew up:

Thanks for that information.
I go along with Gadger's remarks. I think it likely that the arms are original & the balls later or repro. (one had a slight chamfer & the other an unbroken face where it entered the cup!)
I will grovel under the car with a sharp 3/8 drill....I'm not even thinking about taking the cups out...and clean everything.
I will use the 3/8 BSF bolt I have with a normal spring washer and lock nut it for good measure....the bolt is long enough.
It will interest me to see if this stops the front brakes coming on when applying steering lock....my original problem, before I found the radius arms to be disconnected!

Is the patent number someone else’s used, or an Austin one? Hard to believe the idea new.

As the assembly does not bolt up solid, the later nut and split pin (or locked nuts) seems more appropriate than a spring washer.

Davids description has me lost.

The bolt must be a very free fit thru the ball so it can tilt. Expect a normal fit thru cups and radius arms, but does not really matter if loose, as bolt only prevents the arms parting.

Normally, faces of radius arms should be flat and perpendicualr throughout length. May have become twisted, or been twisted to fiddle castor.

Location: Auckland, NZ

sorry to confuse you Bob!
The bolt is a free fit in the cups and the ball, but the hole diameter in the arms will not accept the 3/8 bolt.
I think the o/s arm may have been "adjusted" for some reason....the arm was under some tension, but could be persuaded to fit onto the ball. the N/S lined up ok. Both now have vertical faces.
I note your comment about the tightness of the joint & may forgo a spring washer
Been getting rusted & broken steel screws out of the hood front rail today, so maybe get underneath tomorrow!
David