Kingpin sizes

[spannerman]

Can anybody help me please 
I'm looking for the size of a seven 
Kingpin and  size of a big seven pin?
Building a special so would like to fit 
The big 7 axle and will need some hubs
To fit ?

[Ruairidh Dunford]

My recollection is that Big Seven king pins are 5/8" - standard A7 ones are 1/2".

[Alan]

The other thing, I think, is that on a seven, the camber is achieved in the stub axle - the bearing spigot is at an angle to the king pin axis. On a big seven the king pin eye in the axle is inclined, and the stub axle is “square” , if you see what I mean. The two aren’t interchangeable.

[Ian Williams]

Yes 5/8" kingpins and the stub axles are not interchangeable with normal seven ones. The hubs are virtually the same and can be interchanged but Big seven hubs don't have wheel dowels and they have a small register that locates the brake drum, this means that the brake drums are not interchangeable across hub types. If you use a Big Seven axle on a special and want a lower ride height than std you will run into other complications, modification of the radius arms will require some ingenuity in order to meet the crossmember ball. To over come the problem some people bring the radius arms to a pair of ball joints one attached to each side of the chassis, however this causes the front axle to twist when cornering and in my experience adversely affects handling.

[spannerman]

This information is good I've got some good information
On the axle and hubs? fitting 17" wheels
Anybody done that on big 7 axle I think the steering
arms may hit the spokes on the wheel will. I have to modify them ?

[Stuart Giles]

I heated and bent the steering arms on my special which has 17" wheels and a Big Seven front axle. some of the Ackerman is lost as a result; haven't noticed any bad effects of this in the last 35 or so years of driving it with this arrangement. I bent the steering arms when it had the original style track rod ends which protruded past the steering arms, I don't think this would be necessary with the spherical rods ends i'm using now on the track rod.

[spannerman]

That nice to know that 17" wheels will fit
And steering arms just need reshaping
A bit I will be using rose joints on the end
Up to now the parts I've been using have
All been secondhand parts and no restorable
Cars have been used the chassis had been
cut up Into 3 pieces when I got it and now is
One but a 1 1/2 shorter than it should be?
I'm lucky in that I'm a good engineer as
I've worked all my life in maintenance and
Design of machines for manufacturing industry
But I'm still learning at 67

[Mike Costigan]

This Big Seven is for sale at the moment - it looks like it's on standard 17" Ruby wheels:


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