Well, for a start there are two different 280ZX control arms, and neither are the same geometry as the 510.
-Yes a 280ZX and 510/610 share center to center pivot dimensions,
-Yes a 280ZX and 510/610 have the same function as a semi trailing arm.
I did document the differences between the 280ZX early and late arms here - there never was a need to compare them to a 510 arm.
I've seen a couple people install S130 trailing arms on a 510, but those people have never stuck around to actually document the alignment specs. Maybe my camber/toe adjusters that I sell can correct things - I've not known of someone who's tried.
Anyways, here's the documentation that I did comparing the early and late S130 trailing arms from a facebook post of mine of 280ZX Drivers about a month ago - click the link and you'll also get the photos;
https://www.facebook.com/groups/1646904 ... 030627838/
First up, I’d like to thank Raymond Anderson for starting a post that clearly shows that there is a difference between the early and late rear S130 cross members. And it kicked me in the ass to get a more accurate assessment of the situation. At first I wanted to call them a Series I and Series II suspensions (cross members and Lower control arms or X-members and LCA’s from here on in), but I’m not so sure that is fully correct and I will leave the actual designation to the guys who really know the chassis codes as there are a few experts here in that department.
What we do know is that there is an early and late version of the X-members, and it involves a different X-member and different matching lower control arms (LCS’s). The geometry was changed starting with the ‘81 Turbo model as far as I can tell, with the intension of improving the handling (source Kurk and Matt over the years). With the change in rear suspension geometry also came a brake design change, and this in itself has not only stopped people from easily swapping from early to late LCA’s without making any other changes – it also makes it easy to for rest of us to identify which control arms are which by a simple glance. Both design changes (x-member and brakes) were eventually incorporated into the N/A versions somewhere in 82-83 – again I’ll need the experts’ confirmation on exactly when this happened and whether this change always coincided with the exterior trim upgrades (F&R bumpers extended to wheel wells, NACA duct hood ect). Don’t post unless you’re absolutely sure – everything is easily changed after 35 years!
Let’s start with the X-member itself. To be honest, I had to stare at the X-members for a while before I could evaluate exactly how we should accurately measure and compare these two X-member variations. As a machinist, I do own a number of actuate measuring tools, so that helped to begin with. I do have a granite surface plate, but unfortunately it’s 2x3’, not quite big enough to place the X member across, so I was forced to use the concrete. Thankfully I built the garage myself and was able to control the building aspect – the floor is reasonably flat, and certainly good enough for this purpose of this measurement.
Establishing a datum and reference point to measure from was the first job. Turns out the top side of the X–member a good datum point. Both early and late X-members share the same distance from the rubber isolator mounting holes back to the differential mounting holes. When I placed the X-member on a couple of precision parallels placed on the diff mount (upside-down) and measured the top x-member mounting surface back to the floor at the outside isolator ends of the X-member, I found that both early and late designs are identical in mounting geometry in this regard. So confirmed that the diff is at the same position relative to the mounting studs and at the same height for both early and late versions. Also the actual X-member stamping itself appears to be the same in all regards – with exception only to the LCA mounting brackets. And lastly, the LCA brackets are spaced identically between each other on both early and late X-members.
Now onto the comparison of the OEM LCA mounts on the X-member. Measuring from the center of the X-member outer body mount stud back to the center of the LCA pivot mount hole, the early X-members measure 96mm, the late X-members measure 103mm. Now measuring from our mounting face at the top side of the X-member at the body mounting stud (the steel, not the rubber isolator bushing) down to the centerline of the LCA mounting hole, the early X-member measures 14mm down where the late version measures 23mm down.
Moving to the inner LCA mount, measuring from the top of the differential mount face down to the center of the LCA pivot hole, the late style X-member is 7mm lower than the early X-member, and measuring perpendicular to the centerline axis of the LCA pivot to the rear the X-member, the later style outboard side of the inner LCA mount appears to be 2mm further rearward when I compare the two versions.
So in conclusion, the late X-member LCA mounts are further rearward and lower down compared to the early x-member on both inner and outer pivot points. The outer pivots having been moved 7mm rearward and the inner pivots only being move 2mm’s rearward on the late version.
One other note, I have three late X-members (and 2 early x-members), two were from turbo cars, the other from an NA car. The turbo X-members do have additional braces welded in. The turbo inboard LCA mount have a triangular brace welded on each side at the top of the LCA bracket. The outboard Turbo X member LCA mount has a double plate welded across the bottom and the X-member to the LCA bracket. Just something to note that was different from the late NA X-member which did not have either additional bracing, but did share the same late style LCA geometry.
Onto the LCA’s themselves; First, identification…
The early LCA’s can be identified by the deeper rotor hats and the brake caliper was secured through threaded mounting ears on the LCA bracket. The distance from the outboard face of the stub axle to the backside (inboard side) of the caliper mounting bracket is 78mm. In case this caliper bracket has been removed for some reason, the distance from the centerline of the stub axle (outboard face) to the centerline of the outboard LCA pivot bracket on the X-member is roughly 449mm (plus/minus 1mm).
The late LCA’s have the shallower brake rotor hat design, the caliper mounting ears are through drilled holes (no threads), the distance from the stub axle face (outboard) to the inboard side of the caliper mounting flange is 69mm and the distance from the centerline of the axle (outboard face) to the centerline of the outboard LCA pivot bracket on the X member is 438mm (give or take 1mm)
So it should be evident (even if using a tape measure) to identify which LCA you have – no need for accurate tools or any jigs in this case – to make note if your components are early or late style LCA’s or X-members.
Certainly mixing and matching the early and late parts will cause alignment issues. With this much difference in the LCA’s you’ll end up with something quite strange if you try.
The math above would tell us that the mounts were moved further back on the outboard side than on the inboard side, so, placing a longer, early arm on a late X-member would net you more toe out, and vise-versa if you mounted a late LCA on an early X-member.
Given that both inner and outer x-member LCA pivots were dropped 7mm suggests that the actual LCA pivot axis angle relative to the ground was not modified, just that its static position was changed lock, stock and barrel when viewed from the front/rear to change the dive and toe changes when cornering and braking. However when viewed from the top, the outer x-member LCA pivot was moved rearward 7mm while the inner as moved only 2mm rearward, and this certainly changed the pivot axis geometry of the whole LCA itself relative to the angle at which the stub axle/bearing housing is affixed. The effective angle between the mounts when measured at the outer sub axle face would be increased on the later, shorter LCA’s making it a larger triangle.
The actual angle of the stub axle and bearing housing between early and late styles relative to the centerline of both LCA pivots has not been determined. Sorry – I didn’t go there, there wasn’t the need at the moment.
Anyways, I hope some of you find that information useful. I have 4-5 hours into this between measuring, taking the photos and writing this report – time flies!