Hi guy's, I'm thinking about lowering the front end of my '55 pontiac even more (Static drop, no bags). I have heard stories about people swapping their uprights from left to right and inverting them. Now physically it can be done, but how is the steering geometry affected, and can it be brought into aligment by using the acentric camber adjuster bolt or does it require heating and bending. The reason i'm asking is if it can be done with little effort it would save me having to buy some FATMAN dropped uprights. Any imput on this would be great. p.s. I understand that the steering arms will have to be heated and bent down, but that will need to be done either way i go.
Without any idea of what '55 Pontiac spindles look like I'd be inclined to say it's not practically possible. Whatever the arrangement, you'll have a steering axis inclination angle - if not an actual kingpin inclination angle. Inverting the uprights would have the effect of reducing the camber by twice the SAI/KPI, and as SAI/KPI is usually in the order of 5°-10°, that would mean anything up to 20° negative camber! While there is a look doing the rounds these days, I don't think it's what you have in mind! There is an off-chance that, if you've got the sort of arrangement that has a spindle and kingpin riding on an upright (i.e. no ball joints) that the top and bottom pivots of the upright are on a line precisely parallel to the kingpin axis. That is the only situation where inverting the uprights would work. But with the kingpin-on-upright design it is often not that hard to fabricate uprights that would give the characteristics you want. My Morris Minor has the infamous threaded trunnions on its uprights (a detail that the Aero Willys shares) and I'm looking at fabricating uprights that have VW Golf Mk1 rear stub axles bolted to them. I don't know what your legislation says about making parts like that: I understand you can do all kinds of stuff if you can satisfy an engineer that it's sound.
There's another thread already about this http://www.jalopyjournal.com/forum/showthread.php?t=464030 If you look at the drawing the spindles are on a pillar, so flipping them left over to right [ to keep the steering arms correct ] doesn't alter the kingpin inclination on a pontiac as the kingpin appears to be at 90 degrees to the spindle. Whether there is a lowering gain ,I don't know
Even if the geometry works out, one additional consideration is that the loading of the upright is switched from the heavier section of the current lower end, to the thinner and weaker portion of the current upper section. The lower control arm and upright is where most the suspension loads are concentrated. The upper end/upper control arm carry relative little of the total loads imposed. Ray
Pull the kingpins and put a longer same diameter rod or dowel in the king pin hole. Then measure the distance from the rod to the edge of the hole top and bottom of the upright. If they measure the same they could be flipped with no geometry changes.
The Jalopy Journal
