9 replies to this topic

[Arthy]

Hey guys,

 

I'm currently in the process in modifying my throttle shaft (Vizard style), and need to get button head type screws instead of the standard countersunk ones (AUC1358)

 

Does anyone know what size/thread they are? 

 

Thanks in advance,

Arthur

[Swift_General]

Try these people.

http://sucarb.co.uk/...bdchq6nvggkl1f5

[carbon]

I am fairly sure they are 1/8 whitworth

[Drydave254]

1/8” diameter. 5ba

[carbon]

Dave - are you sure the spindle screws are 5BA? SU typically use whitworth.

 

5BA is almost identical diameter to 1/8 Whitworth, but different thread pitch (40 vs 43BA) and thread angle (55 vs 47.5BA). If you use wrong screw it will chew up the threads in the spindle and is also more likely to drop out.

 

(apparently the reason the SU spindle screws have the splayed legs was bad experience at a race in the 1930's, and they have used this type ever since)

[Drydave254]

Hi Carbon,

To be honest I was modding the spindle on an hs2 a short while back and 5ba was what came up a number of times on internet searches.
Ended up removing upper half of spindle, cutting a small chamfer in butterfly disc and re-using the original screws cut down with a dab of loctite.
The 5ba are marginally bigger than 1/8 whit on both outer and core diameter, so would probably bind if wrong. Not much thread on spindle for it to lock up solid, so likely to still screw fully home. Either way I wouldn’t use either without loctite.

Regards, Dave.

[Drydave254]

Apologies.

Email confirmation from Burlen, is that the screw they supply (AUC1358) is 1/8th witworth

[Retroman]

I always use stainless 5BA domed allen heads loctited in and have never had an issue, they feel nice as the go in.

You will struggle to find any 1/8 Whit other than from Burlen.

 

[hhhh]

North American #5 might be a better match. It's 0.125" X 40 tpi, but of course the thread form is different. I'd sooner have the tpi match and the form not than vice versa.

[Arthy]

I ended up using 5BA dome head brass screws. Couldn't find any stainless ones! Was a nice fit and a bit tight, but thats probably down to me using a bit too much loctite