280zx rear control arms on a 510 crossmember

Suspension, including wheel, tire and brake.
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280zx rear control arms on a 510 crossmember

Post by abisel » 09 Aug 2018 14:34

Has anyone tried to install 280ZX rear control arms onto a 510 crossmember?

Will it work? If you go to coilover shocks it might, but what about track width and wheelbase, and half-shaft bolt up? The setup does give you rear disc brakes.
Datsun 510 subframe with 280zx arms brand new calipers new pads and drilled rotors
Culver City, CA

Datsun 510 subframe with 280zx arms
Has brand new calipers, new pads, and drilled rotors. Also comes with the e-brake cable. The subframe has been modified to fit an R200 diff.
The last couple of pics are with that rear subframe and 280zx arms on my car.
Please serious buyers only.
I saw that posted on the Datsun 510 (68-73) Parts for Sale FB page.

Here's a picture.
38519108_10157571409687388_3449449730482896896_n.jpg (65.42 KiB) Viewed 1653 times
Last edited by abisel on 09 Aug 2018 15:13, edited 1 time in total.

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Re: 280zx rear control arms on a 510 crossmember

Post by Byron510 » 09 Aug 2018 15:12

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.

that's it.....

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!

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Re: 280zx rear control arms on a 510 crossmember

Post by abisel » 09 Aug 2018 15:40

Thanks Byron.

So if someone wanted to do this kind of mod, they would want the late control arms from a 280ZX (82-83).

AND to add the crossmember mod to give adjustable camber and toe. Which "may" give you the adjustment needed to get an adequate toe/camber.

BUT what about track width? Would some offset wheels be needed to keep the wheel/tire combo under the fenders with or without flares?

Not to mention the additional mods to the front brakes and master cylinder.

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Re: 280zx rear control arms on a 510 crossmember

Post by duke » 09 Aug 2018 18:54

I seem to recall somebody saying that the track width with the 280zx arms is wider. By how much, I'm not sure. I think that a few people have done it successfully, albeit with a good amount of other modifications. I think the fairly well known car called the "Strutless Wonder" used 280zx trailing arms.
Duke Schimmer

'72 2-Door 510
"Simplify and add lightness."

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Re: 280zx rear control arms on a 510 crossmember

Post by icehouse » 09 Aug 2018 19:36

I'd rather but 510 arms on the ZX so wider rims would fit.
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Re: 280zx rear control arms on a 510 crossmember

Post by spriso » 09 Aug 2018 21:27

Yes— we put 280ZX rear control arms in the “Strutless Wonder”, but also narrowed the pickup points on the crossmember to compensate for the wider width. As I recall, it increased the track by 3/4” on each side before mods.

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Spriso Motorsports

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Re: 280zx rear control arms on a 510 crossmember

Post by StrutlessWonder » 11 Aug 2018 06:38

When I had TeamThump build a new rear x-member for the Strutless car in 2010, I bought a set of 280zx control arms to replace the ones on the car, only to find that the inner half shaft mounting flange length was different than the ones that were on the car (control arms themselves were the same). I determined that I actually had 1st gen Datsun 810/Maxima control arms under the car, not 280zx arms.

When I went to install a Wolf Creek CV half shaft kit, the relocation of the arms inward on the x-member was just enough for the kit axle length to be too long. I mounted them up, safety-wired all the bolts, only to find they bound tight as I moved the arms through their travel. Bummer. Still haven’t put a set of CV half shafts under the car, as they would have to be custom-length. About 3/8”shorter per side is what I needed, IIRC.
Kurt Hafer
'70 2dr VG30et "Strutless Wonder"

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Re: 280zx rear control arms on a 510 crossmember

Post by cambo » 15 Aug 2018 09:56

I have the 82-83 control arms on my 510. I always tell people don't do it. I did it 25+ years ago so I could have rear disc brakes and strong mounts for coil overs. It required me to build a custom Penultimate cross member to deal with the increased track width and toe difference of the 280ZX arms. Also the coil over mounts are high on the control arm requiring a really short shock body. Today you can buy disc brake kits, coil over kits, and adjustable camber/toe kits made to fit the 510.

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Re: 280zx rear control arms on a 510 crossmember

Post by freekwonder » 15 Aug 2018 17:13

Not sure what years it is from, can't remember think it was from a 79-81, but I've got the r180 and arms from a 280zx in my dime. Only reason I did it was my stock arms were beyond saving, and I couldn't find any arms in my area (at the time) and couldn't afford to get some shipped to me. As cambo said, it isn't worth it. Luckily I had already done the Penultimate crossmember, but for the other reasons like he says it isn't worth it I'd agree with. I'm actually in the process of trying to find some stock 510 arms to put back in her. And can't remember how much the track is widened, but stock 15x7 0 offset wheels where tucked, with the 280 arms they stuck out about 1/2-3/4".


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