Front upright geometry

[Ed McClements]

Hi all,

I already posted this question over on my build thread https://www.gt40s.com/threads/southern-gt-48.51480/post-545397 but thought I'd start a converation here, too. My SGT chassis comes with pickup points and wishbones to suit the John Wisher (?) style uprights and hubs, but there currently isn't money in the build budget for these very desirable items. I'm planning on building uprights from a couple of substantial aluminium alloy billets, with VW/Audi 5-stud wheel bearings bolted on (see post linked above for pics). I believe that the distance between top and bottom balljoint mounts is roughly 180mm, and the SAI/KPI is around 7 degrees? What's the distance outboard of the top balljoint to the 6-pin mounting flange on the hub? About 150mm or so?

(Actually, this might not be a John Wisher upright, but it was the best illustration I could see online of what I'm trying to determine).

 

[Terry Oxandale]

Glad to see this question, being I struggled with this a couple of years ago as well. I built my own uprights using a piece of billet, and the focus of mine was reducing the queried (flange) dimension as much as possible in order to decrease scrub radius, and increase arm length (for a given track dimension). This of course necessitated an wheel offset similar to what a FWD wheel has, but the driver feel is great. With my frame already "set", I focused on an upright height based on suspension design programs that set the lower arm pretty much horizontal, and the upper arm at some angle that made the upright (ball separation) taller than the height of the arm's pickup points (camber gain geometry). I eventually used the Corvette C4 bearing assembly to match the rear pattern.

Roughing in the upright:

 

[Doc Watson]

I will have a look at the weekend

 

[Frank Catt]

Really Terry, interesting but ----------, Frank

 

[Neil]

But what?