Going a bit softer and compliant

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Chip Collingwood

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Oct 28, 2025, 5:45:54 PMOct 28
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I am contemplating changing the suspension setup on my VG car. Battery is located under the rear seat pan in front of the crossmember. so aprox. 40+ lbs no longer in the engine bay. Also have an aluminum radiator.

Currently running stock shortened struts with adjustable spring pan(collar), factory competition springs, Contour camber plates, Delrin TC rod bushings, Mulholland sway bar, 3/4" bump spacers......LCA's are set parallel to the ground. Rear is cut roadster springs with slotted crossmember, LSD Subi diff. 15x7 Rota's with 205/50 Dunlop Direzza.

I would like to do (3) things: Soften the ride a bit as I would like to be able to drive the car more often without driver fatigue from me soaking up the bumps. Possibly increase the ride height and increase the amount of suspension travel. And lastly optimize the front bump steer curve(ie: what angle should the LCA have in order to provide the least change in steering input from suspension travel) 

I have 2 sets of 280zx struts that I can use if needed. I have no issue spending a few bucks on a coil over setup as this would make changing spring rates easy. 

If I go back to a stock strut bearing and insulator can I use an adjustable LCA to set more camber, or is this a bad idea for the relationship of the rack arms. Is it better to set camber from the top? and how to do that while maintaining some isolation?

Thanks for any input, happy to answer any questions,
Chip



Dennis Hale

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Oct 28, 2025, 6:22:04 PMOct 28
to Chip Collingwood, Bluebird510


Dennis Hale


On Tuesday, October 28, 2025 at 03:45:56 PM MDT, Chip Collingwood <ch...@theukmotorsports.com> wrote:


>I am contemplating changing the suspension setup on my VG car. Battery is located under the rear seat pan in front of the crossmember. so aprox. 40+ lbs no longer in the engine bay. Also have an aluminum radiator.

How much does it really weigh? It doesn't matter how much it doesn't. You need to have enough travel to not bottom out or even hit the bump stops or things get harsh in a hurry. It's not really about harsh springs usually, it's about bump stop stopping the bumps.
You say nothing about shocks. Shocks slow the compression rate and make lousy bump stops. They are quickly destroyed if used as bump stops.

>Currently running stock shortened struts with adjustable spring pan(collar), factory competition springs, Contour camber plates, Delrin TC rod bushings, Mulholland sway bar, 3/4" bump spacers......LCA's are set parallel to the ground. Rear is cut roadster springs with slotted crossmember, LSD Subi diff. 15x7 Rota's with 205/50 Dunlop Direzza.

Stock springs were about 75#/" and traveled about 7" Factory competition springs were about 125#/" and traveled about 5". It all would be lower with the heavy VG motor I think. Rear springs gave about the same rates after the geometry is allowed for.
Less travel needs stiffer springs. Always. This is seldom done, I guess folks just want to look at it instead of driving it. Stock Roadster springs were no stiffer than stock 510 rears, only the rare comp roadster springs were different, and again they pretty much matched the comp fronts for the 510.
LCAs set parallel is very good. This will minimize bump steer. Bump steer spacers are better called roll steer correctors. They need to be about the same thickness as the lowering, even it that's mostly due to a heavier engine.
Solid camber plates can feel pretty harsh. Hybrid ones made by cutting down 240Z uppers and TIG welding on flat plates to mate to the slotted adjusters work well if you can do that.  
The sway bar loses effect as the spring rate goes up, pretty much one for one. 

>I would like to do (3) things: 
>Soften the ride a bit as I would like to be able to drive the car more often without driver fatigue from me soaking up the bumps.

Is the problem too much spring rate or too little travel? Big difference.

>Possibly increase the ride height and increase the amount of suspension travel. 

The problem is pounds of car over travel distance. More height helps, less weight helps, but you need a bit more information. 
You probably can't spend too much on shocks. 510 strut inserts are kinda skinny and not a lot of choices are out there. 510 brakes are obsolete and upgrades are expensive. You likely want to leave them behind.

>And lastly optimize the front bump steer curve, ie: what angle should the LCA have in order to provide the least change in steering input from suspension travel) 

The ZX struts are better, the brakes especially. Coil over 2 1/2" springs are easily available but require some cutting and welding. I bet you think you'll want 150# springs and I think you'll want 300# springs. Some experimenting is the name of the game. Try and find some really good bump stops to experiment with. MG, Mini, and Miata guys do a lot with them.

>I have 2 sets of 280zx struts that I can use if needed. I have no issue spending a few bucks on a coil over setup as this would make changing spring rates easy. 

And ride height adjustments, but beware and rear ride height change will change toe alignment and likely the lower mounts will need to be made double shear to handle the weight as well as the shock loads. Not cheap, not easy.

>If I go back to a stock strut bearing and insulator can I use an adjustable LCA to set more camber, or is this a bad idea for the relationship of the rack arms. Is it better to set camber from the top? and how to do that while maintaining some isolation?

I sorta explained that earlier with the custom hybrid mounts. Raising the LCA pivot is useful, a '69 crossmember gives you about 3/4", but a 3" lowering needs about a 3" rise and that's a big job, and both the steer arms and idler also need to be raised. 

Few builds get this far in but more is better than less.

Beware free advise. And the game goes on...

Thanks for any input, happy to answer any questions,
Chip

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Chip Collingwood

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Oct 28, 2025, 6:34:48 PMOct 28
to Dennis Hale, Bluebird510
shocks are Illumina adjustable front and Koni yellow in the rear.

Good to hear from you Dennis!

da...@datsuns.com

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Oct 29, 2025, 10:25:56 AMOct 29
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What Dennis said. Plus  “ I bet you think you'll want 150# springs and I think you'll want 300# springs”

Yep, the lower you are the stiffer you need. The heavier you are the stuffer you need. Lower and heavier you get double jeopardy (raises hand). I think the VG guys around here in OR run 175# front and 200# rear (wheel rate, the semi-trailing does the leverage multiplication thing).

In my heavier-than-most 510 (2450#) I run 200# front and cut Roadster comps in the ear (comes out to about 230# at the wheel) and am lower than stock but not “in the weeds” low (it’s my daily, so super-low would be dumb).  I never hit bumpstops (unless it’s something at would bottom normal cars too) and people who go for a ride (both car and non-car people) invariably comment “wow this isn’t as harsh as I was expecting, it actually rides nice”. The downside is at an auto-x I’d get beat by a Trabant. Tradeoffs…

 

As Dennis said you really, really want to avoid the bumpstops in any kind of normal driving.

Also to address harshness, you’ll want to keep rubber in the same places the factory does, going to Heim joints where there’s normally  rubber is going to add impact harshness. Yes replacing rubber with something stiiff makes things more responsive etc. etc. but seriously, unless you’re trying to be really competitive in something  (and I think by definition a VG 510 will never be, due to whatever modified class it will get thrown in and a Miata will beat you anyway).

 

Dave

nandjm...@bellsouth.net

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Oct 29, 2025, 4:33:28 PMOct 29
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Chip,

 

On the subject of Bump Steer, I have been on quite a journey in my efforts to get the bump steer minimized with a custom R&P project in one of my 510’s. You would be amazed at how little movement is required to make big changes in bump steer.

 

My advice, get the ride height, stiffness, and alignment where you want it on both ends of the car. Tackle bump steer last. Changing it at the LCA will be an easy place to adjust but start with shims and then cut the Roll Center Spacers to your ideal thickness. Naturally, re-do your alignment again after tweaking for ideal (or at least minimum) bump steer. Depending on your steering arms, you can also make corrections at the tie rod end. Depending on your wheel clearance, you may find that you have to make changes in both places.

 

In my case, I had adjustable coilovers. Dropping the spring seat way down makes it easy to move through the full travel range when looking at bump steer. A laser pointer on the hub face pointing back at the garage door made an easy way to plot the alignment change through the travel. I was eventually able to make my setup “not worse than factory” but my R&P setup and wheels limited my adjustment range leaving perfection out of reach.

 

Let us know how it goes!

Nathan

Dennis Hale

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Oct 29, 2025, 6:09:40 PMOct 29
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Then again if you just drive like Peggy and me, with one front wheel up, it mostly doesn't matter anyway....

Dennis Hale


Ward Hill Press

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Nov 1, 2025, 2:50:48 PMNov 1
to nandjm...@bellsouth.net, Bluebird510, Chip Collingwood
Front spring travel is limited by shock travel. (Spring travel needs to be less than shock travel) How does this effect consideration of spring rates?
I plan to use ZX struts with an adjustable 510 spring perch.
Previous owner cut the stock 510 springs. The front springs sit in the ZX perch with welded in spring retainers.
I'm currently trying to decide spring rates and ride height, front and rear.
Current ride height at the rockers is 7 3/8" F and 8 3/8" R. The rear will be lowered with an adjustable crossmember.
I've been sidelined from this project by family matters.
Steve


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Carter Boad

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Nov 1, 2025, 3:36:10 PMNov 1
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Ward Hill Press

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Nov 4, 2025, 12:57:50 PMNov 4
to Dennis Hale, blueb...@googlegroups.com
At 04:54 PM 11/1/2025, Dennis Hale wrote:
>On Saturday, November 1, 2025 at 12:50:48 PM MDT, Ward Hill Press <ward...@rcn.com> wrote:
>Front spring travel is limited by shock travel. (Spring travel needs to be less than shock travel) How does this effect consideration of spring rates?

Springs are linear. If you cut it in half it will be twice as stiff, but the remaining travel will be zero so that means it won't work. If you have 5" of travel with a 10" spring about all you can drop is about 2", leaving 3" of travel with a spring 20% stiffer. Not good. The stock stuff did not have any extra travel for normal use, let along more spirited use. If you want more or less stock behavior with half the travel you need at least 40% stiffer springs.
Softer and lower is not possible using the strut and control arms design you have.

I am not looking for "softer". I was looking to balance my springs front and rear. I would like to have neutral or slight understeer handling. I think I will have more travel than I have now, which may result in a better ride.  I need to figure out the rear spring rate first as I will be putting in an adjustable rear crossmember with a bigger exhaust hole than in this picture. read on.

>I plan to use ZX struts with an adjustable 510 spring perch.

Maybe OK but you really want 2 1/2" x 10" race springs. They are available in 25#/" stiffness increments where stock diameter springs are not. Few tires will hit the small springs and perches.
The best thing now about ZX struts is the 510 brakes are not available, the ZX ones are still available, for a little while....And they last a lot longer....but they need a larger master cylinder, the early 240Z ones are better than the ZX ones for balance. It all adds up. Still.

Previous owner put ZX struts on the car, I have a second pair that I will be putting on adjustable perches *if* one of the pairs of springs I have will work with my rears. Or as you suggest going with coilovers. I am thinking about the Hyundai springs but I also have Datsun "Upgrade" Springs 54010-U0110. (I also have Canadian springs, but I think they are useless). I have not done the calculations of the Comp Catalog suggestion of cutting 1 1/2 coils front.  Here is the answer I got when I asked about these springs 6 weeks ago (thanks Ted and Jason):

Fwiw, the  "hard suspension" 510 F/R spring rates are 116.5/443.1 #/in.  Stock are 89.5/357.2. This per '72 Service Manual. A note in the 2001 Comp Catalog suggests cutting 1 1/2 coils front and 3/4 rear for a nicer look.

On September 20, 2025, at 12:02 PM, "jason datsuns.com" <ja...@datsuns.com> wrote:
AI says;
The Nissan part number 54010-U0110 corresponds to a heavy-duty rear spring with a rate of
116.5 lbs/inch. 
 
This part was designed for the S12 chassis, which is the Nissan Silvia/200SX from the mid-1980s. It is part of Nissan's "HARD" spring lineup, a designation used for their performance-oriented parts."
 
Stock 510 fronts reported as around 90#/in.

>Previous owner cut the stock 510 springs.

Sure, we all did. It was for sale for a reason.....


>The front springs sit in the ZX perch with welded in spring retainers.

I doubt that, ZX perches hit almost any tire on a wheel that fits a 510.

195/60-14 on ZX wheels. Are you saying my tires and wheels aren't wide enough? :-D
To be clear, there are cut 510 springs up front being held in place with tabs on the larger diameter ZX perch.

>I'm currently trying to decide spring rates and ride height, front and rear.

Wheel rates of 200#/", spring rates depend on what rear mount you use. Stock location divide by 3.8, coil overs add 10% to get wheel rate. Ride height maybe 2 1/2" lower. Zero front toe (more chews tires) and 1/8" IN rear toe (toe out will back you into the guard rail). 2* front Camber, maximum Caster. 1* rear Camber (again, more will chew up tires).
I'm pretty sure you ask this stuff every year. Buy once, cry once.

My health and family health issues have stalled this project. Thanks for the alignment settings. I have no idea what the stock ride height was. I have D50 springs which I thought I was going to use in the rear. I didn't realize cutting them would give me 6 1/2" ride height, I would prefer about an inch higher.

>Current ride height at the rockers is 7 3/8" F and 8 3/8" R at the rockers. The rear will be lowered with an adjustable crossmember.

The adjustable rear crossmember will not lower the rear, it will allow safer alignment settings.

Sorry, my poor wording. Lowered with springs, adjustable to correct toe out. I think this crossmember will work.

Who in New York will machine up this crossmember? Flame cutting is Not acceptable! Both inner and outer need to be machined and some sort of locking provided.
Ride height is dependent on the tire, this really means nothing. Any change in rear ride height makes a big change in rear toe and that will be unstable to you. Every change will require an expensive realignment, if your new crossmember will allow it.

Dennis

I'm trying to ask questions to get it right the first time. If I understand what you wrote I am looking for 200#, as you wrote it 200#/" (200# per inch?)
Thanks
Steve
X-member 3.jpg

jason datsuns.com

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Nov 4, 2025, 3:26:13 PMNov 4
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Quick check of the at-wheel effective spring rates that you have now, have two large frients sit on each of the rear corners of the trunk and measure the change in rear ride height. Have them move to the front and each sit on front fender or (core support w/ hood open), & again measure the drop in front ride height. Take their average weight (say 200#) and divide that by the ride height drop at each end to calculate approximate spring rates. Not perfect method but it should give you a good idea of the comparative front & rear effective spring rate and you can then work on changing springs at one of the ends to closer match the other to get the front rear rates balanced like you want. 
-Grayjay
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Ward Hill Press

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Nov 4, 2025, 5:30:18 PMNov 4
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Jason, Sorry for any confusion I may  have caused by my poor wording.
I want to start with a clean slate. I don't want to use anything I have. FWIW, the rear bottoms out with a 110# person sitting in the middle of the rear seat with 2 people up front.
The cut front stock springs sit on a higher than 510 perch.
I have a combination that will give me 6 1/4" F and 6 1/2" R, but that is too low for obstructions* I may have to drive over here.
I think ~ 7 1/2" front and rear would give me the ground clearance I need.
I would like to stay away from rear spacers in the rear if I can.
*NYC speed humps are not the problem, only one pair of wheels is on them at a time.
I think I have the spring rates for the D50, Hyundai springs with a drop to 6 1/2" somewhere.
Steve

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