510 scrub radius and wheel fitment calc

Suspension, including wheel, tire and brake.
User avatar
Boy Blunder
Posts: 117
Joined: 18 Oct 2012 18:02
Location: Terre Haute, IN

Re: 510 scrub radius and wheel fitment calc

Postby Boy Blunder » 07 Mar 2015 21:48

bertvorgon wrote: The biggest thing on my 510 was getting rid of the rear positive toe change, THAT just transformed the car back in the early 80's and has now benefited most on this site, to keep the rear inline with an imperfect independent suspension.

These two books were my bibles for a lot of years, long before the Internet came along.



Thanks for chiming in again.

If I may kick this horse again.. Remind me. What did you do back then to get rid of the rear positive toe change? I have discussed this inherent issue often with the previous owner/builder of my car. My 510 is " dampened stiff as hell" with not-kidding-you Koni 30 series circle track spec shocks. The shocks are monsters.. yet running a 250lb AFCO spring. Im fairly convinced on my setup that the shock is doing more work than the spring. I know I'm not getting mathematical here, but I can tell you the solution on my cars build is to limit the travel of the rear suspension by the force of the dampening itself.

User avatar
bertvorgon
Supporter
Posts: 9562
Joined: 04 Aug 2003 20:45
Location: White Rock, B.C. Canada

Re: 510 scrub radius and wheel fitment calc

Postby bertvorgon » 08 Mar 2015 10:39

Let me re-phrase that...I have made sure the rear does NOT toe out.
We fixed that back in the 80's by making the rear camber/toe brackets ( which Byron now sells ), so that we can run static toe in, and enough that as the suspension goes through it's travel, it does not ever go to toe out. That I/we run quite stiff springs also helps with the AMOUNT of suspension travel. As you say, we all try to eliminate the large travel, but, at the same time, we do need some travel to be compliant with bumps. The balance becomes running enough rear toe-in, that in the largest real world bump in a corner, you do not toe-out.
The shock issue is just that...an issue. re-read the suspension thread where I talk about the need for proper valving to compliment the spring. I never liked the Koni shocks, just found the bump/rebound was way too stiff, so that I got "jacking" in lineal slaloms, etc.
Yes, by making the shock/travel as minimum as possible will work of course, the ability to have some compliance and feed back as to what the rear is doing is important. I slalomed for a ton of years, so I did not care about the large rear toe in I run, as tire wear was not an issue. The ability to not have the rear steer the car was the all important criteria. Even today, where all my driving is on the street, on our high speed drives, I still run the same rear toe-in. I want nothing to do with high speed oversteer, for all the reasons.
"Racing makes heroin addiction look like a vague wish for something salty" - Peter Egan

1973 2Door Slalom/hill climb/road race / canyon carver /Giant Killer 510
1968 Vintage 3HP Mini Bike
1971 Vintage 13' BOLER trailer

User avatar
SteveEdmonton
Supporter
Posts: 397
Joined: 27 Aug 2010 13:20
Location: Edmonton, AB

Re: 510 scrub radius and more calculator..... Needs YOUR hel

Postby SteveEdmonton » 23 Apr 2016 09:57

kayakdude07 wrote:I have done some reading on the bluebirds list and it seems like the 280zx strut spindle angle is slightly disputed...
http://www.datsun510.com/bbmail/2006-2/5878.html

This image from datsun510.com also supports your findings....
Image

I have 2 sets of zx struts. 1 set with 510 perches that I ran on the car before with the 14" early 200sx rims and the set I'm am running now that are done up with coilovers and zxT snowflakes.

The first setup with the 200sx rims and 510 perches/random springs suffered visible from positive camber issues (no camber plates first year).

After doing up the coilovers on my other set of zx struts and installing them with camber plates and everything this year, I am maxing out my camber plates (positive) to give me front camber of between 0* and -0.5*.....

I am thinking that I may be a victim of crazy angle zx struts. :shock:
When I get home I will most definitely take them all apart to compare and try to get to the bottom of this


Jordan, did you ever get to the bottom of this "positive camber with 280ZX struts" issue? Anecdotally, I thought I observed the same thing when I installed the same setup you're talking about, a month ago. 280ZX struts, 510 perches & springs. It looked like I had positive camber. So I pulled that setup, popped in my old 510 struts, and ordered a set of coilovers to deal with the problem.

However, when I mentioned this in another thread a few days ago, members of the brain trust assured me that all 280ZX struts have 10 degrees of spindle angle, just like the 510 struts. So I finally did what I should have done a month ago: I pulled apart both my 280ZX struts and the stocker 510s, to compare angles. And sure enough, they're both 10 degrees.

That leaves me puzzled, though, about why I thought I saw positive camber with the Frankenstrut combination (ZX struts, 510 perches & springs). What was up with that? Something installed wrong? Optical illusion? Plain old mistaken-ness?

This isn't just an historical question either. I haven't actually installed my coilovers yet, and so going back to the 510 perches & springs remains a live option. No caster / camber adjustability of course (my camber plates are the ones from DP racing that have some built-in caster), and if I run with the stock 510 springs I'd obviously not be upgrading in the handling department the way I would be with the 300 lb coilovers. If I cut them by a coil, I'd be getting a bit of an improvement, but clearly not the same as with the new springs.

So anyway: Did you ever account for the positive-camber issue you encountered with 280ZX struts and 510 perches / springs (your setup #1)?
Last edited by SteveEdmonton on 23 Apr 2016 10:56, edited 1 time in total.
'71 4-door
'74 MGB-GT
'04 Miata

User avatar
Byron510
Moderator
Posts: 11441
Joined: 01 Jul 2003 23:06
Location: Maple Ridge, BC

Re: 510 scrub radius and wheel fitment calc

Postby Byron510 » 23 Apr 2016 10:28

Just for reference, I put a lot of effort into this spreadsheet years ago, it's a good time to post it again.

The illusive 12 degree strut has never to my knowledge been recorded, only reported many years ago but someone and it somehow became gospel. If it exists, that it need to be documented. But I have measured over a dozen ZX struts, turbo, NA and through the whole 4 year production run.

Byron
Attachments
Datsun Strut Comparison2.jpg
Datsun Strut Comparison2.jpg (413.67 KiB) Viewed 447 times
Love people and use things,
because the opposite never works.

User avatar
SteveEdmonton
Supporter
Posts: 397
Joined: 27 Aug 2010 13:20
Location: Edmonton, AB

Re: 510 scrub radius and wheel fitment calc

Postby SteveEdmonton » 23 Apr 2016 11:01

Thanks Byron. I guess it wasn't clear, but my goal was not to perpetuate that myth of 12 degree struts, which I think contributed to my own "perceived issue." :? My actual measurements, when I finally did them, confirmed what you have documented much more fully.

Rather, I'm curious why both Jordan and I seem to have had unexpected camber with this particular combination of parts: 280ZX struts with 510 perches springs. Simple coincidence? In particular, if he learned something as a result of his experience, I'd be glad to know what it was, to help me in my present situation.

Maybe the combination of your data-table and Jordan's and my experience can help others avoid this problem in the future.
'71 4-door
'74 MGB-GT
'04 Miata

User avatar
Byron510
Moderator
Posts: 11441
Joined: 01 Jul 2003 23:06
Location: Maple Ridge, BC

Re: 510 scrub radius and wheel fitment calc

Postby Byron510 » 23 Apr 2016 14:55

Hi Steve,
Understood. The chart was posted more for general interest as the original post from somewhere before 2006 seems to be non-exist anymore on the site.
You didn't by chance change the steering arms as well to the 280zx did you?
I didn't see it mentioned, but I thought I'd ask.

Byron
Love people and use things,
because the opposite never works.

User avatar
icehouse
Posts: 2957
Joined: 17 Jul 2005 17:06
Location: Everett Wa

Re: 510 scrub radius and wheel fitment calc

Postby icehouse » 23 Apr 2016 17:24

The 300z struts have the same strut angel as well. I just checked a set I had laying around the other day.

Steve adding caster with your camber plates will add some bump steer to your setup. Just to let you know.
I liked Hainz better...... Can we trade back?

User avatar
duke
Supporter
Posts: 1780
Joined: 26 Oct 2005 14:21
Location: Santa Rosa, CA

Re: 510 scrub radius and wheel fitment calc

Postby duke » 23 Apr 2016 22:30

Another thought on scrub radius. I recently swapped over to 280zx steering arms (for a faster steering ratio). Because of the location of the ball joint hole in the arms (further outboard than the 510 arms), wouldn't this reduce scrub radius? I know that I had to lengthen my LCA's 1/2" to keep the same front track. In doing this swap it does feel like I lost a little bit of feeling from the steering. I'm wondering if this is because of the loss of scrub.
Duke Schimmer

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


Return to “Suspension”



Who is online

Users browsing this forum: funwithmonkeys and 3 guests