What do we actually know about Semi trailing arms???

[icehouse]

Marks car. He rebuild the tube frame part sometime after this. As you can see it's went threw a few iterations. This photo is from 2007

[510rob]

yes, that's the one!

[jeffball610]

So I decided to do some Googling. I found a very scientific paper about the topic with lots of fun math. If anyone would like to run the numbers, it might give us an idea of how the 510 suspension works.

https://www.researchgate.net/figure/Sem ... _258178438

You can download a PDF copy of the paper to see it in detail and full clarity.

[datzenmike]

50 years later...... the 510 is still a mystery.

[bertvorgon]

40 years ago I made the rear toe-in some, and, had GOOD shocks and spring rate, that controlled travel.....not touched it since..it is what it is....

[Tedman]

US patent 3,603,421 for the 510 rear suspension by Nissan. It gives the equations for the camber and toe curves. Their claim is that their design compensates for camber thrust with toe change to provide optimal straight-line stability.

[Byron510]

Tedman, that is so cool that a document like this come up today - as in 50 years later! Honestly, this is cool stuff. Maybe some of you knew this was out there, but I have never seen this before. I too would be interested in the actual science, liking fed to your analysis, Jeff.

I’m not sure how many of Kelvins Penultimate X members are out there, but I can tell you I have sold about 250 sets of my camber/toe brackets, a majority through Dave at Futofab. I’ve personally assembled 8 sets of the Datsport kits locally and know of a few more. And there are literally hundreds of people out there with old school slotted X members, still. Suffice to say, there are a lot of people who have done their best to correct their rides in some way - and all of these systems work to a different degree.

But practically speaking, as Keith mentioned, the easy solution has been around right from the beginning (BRE and Sharpe in 1969) regarding the additional camber and toe correction combined with the stiffer springs and of course understanding that a matched shock rate was needed.

It’s funny, when you do get it right, you know it. The Bronze works ok, but it’s never been “right”. My previously built car (road race/autoX suspension wise - because I was rallying at the same time) was my Grey/green 68 4 door. On narrower 14” tires R compound tires, this car was closer to ‘right’. And that was achieved with many attempts on an alignment rack with a slotted X member. But the ‘right’ had more to do with matched spring/shock rates and even how the front suspension was set up than it did about the types adjustment system that was used in the rear. I took second place in the regional west solo II the first year, won the series in my class the next in the 90’s. It was fun, but a hell of a lot of work, especially since I was dailying my car and my competition showed up on trailers!

Back to the Bronze for comparison, R compound tires, dry pavement. Take either two away or drop the temp from 20 to 5 degrees C, and it doesn’t work anymore. There are lots of factors, and it was fun to find them. A cold shock makes a hell of a difference even with an 1100 lb spring. Swapping from R compound to a street performance tire (ie 50 tread wear to 150 for instance) make a massive difference in how you load that suspension, again making the low speed (ie autocross) characteristics entirely different. A slightly harder tire can be loaded much differently at highway speed than in a parking lot full of cones, and that also makes a world of difference.

I’m interested to see your outcome, Jeff. Even if it’s just for fun after the fact.

Byron

[bertvorgon]

It's so funny to see this keeps coming back about our poor rear suspension.

It did not take me...and then Andy when I hooked up with him in 1977/78, as I was doing the most at that point in terms of Solo, specially in a 510.

The damn car had trailing throttle over-steer and other rear steer issues. So, we just took the spring out and ran it through it's travel......aaahhhaaaa...toe out...so.....with Andy's brackets we made, and at the same time realizing the spring rate needed a real rethink from convention of that time period, on my 510, we set the rear with a lot of static toe IN, really upped the spring rate game for that time period, and experimented with a few shocks to get the right combo.

Whammo Danno.....over-steer was gone and I put 4 back to back championships on my shelf. I never told ANYONE what I ran for setup, each to his own and never discussed spring rates for a ton of years, plus a few other tricks. The competitive edge so to speak.

As Byron said and I talked about in the "suspension" thread , there is NO magic one solution, it becomes what do you do with your car. I set mine up for racing and never looked back nor have I touched that last setting for the last 25+ years!

[jeffball610]

we set the rear with a lot of static toe IN

How much toe in are you talking about? I don't have a ton; running about .10"-.15" in the rear. I'm not sure I can get much more with my current setup. I feel like my car has a ton of on throttle oversteer. I've always blamed it on the narrow tires and power level. I'm running a 1.5 way LSD as well to help tame things. I'm not experienced at all, so I'm trying to glean as much knowledge from the community as possible to make my car more enjoyable to drive on track while still being streetable.

[Byron510]

Old school talk - I've run between 1/8 and 1/4" total toe in with good success.
I know - that seems like a wayyyy too much.
But here's the thing - getting out of the throttle even halfway through a hard corner where you may have been steering with the throttle a bit... and the back end tucks right in.
That inspires confidence at the limit.
You'd also think that this would wear tires. And I will admit the car does not roll on a flat surface, even in my garage without some resistance.
I run about 1/2 degree of negative camber on 1000 lb springs, and tire wear is dead even.
Now I use to drive it as I stole it, whenever the opportunity presented itself. But over the last 10 years, those opportunities are very rare with the traffic even on back roads these days. And maybe I'm getting a bit old. But I still don't see any uneven tire wear.
A few thoughts from my side.

[bertvorgon]

Morning Jeff,

Kinda like Byron said, I run 1/4" total or 1/8" a side or a tad more. It takes away that penchant for our cars to have trailing throttle over steer. Now, this must be seen in the context, if you go back and read my posts in the suspension thread, I run 1,100 inch/lb rear springs WITH a shock that controls that.

It also was set at the time when I ran real Goodyear qualifying tires with 9.5 inches of rubber on the road, so on power ON throttle, I could do these wonderful and controllable slides, but, like anything, there is a point where you must know where the final traction limit is. THAT is part of being a fast driver.

That today's...or at least for me...the Yokohama brand of their 001,008, 032, 048's have been so good with my setup..STIFF sidewalls, so it is very easy to 'feel" the car. I only have 250-260 to the rear wheels, which in my car we kept ( max boost 16 PSI) as a wonderful balance of traction vs power. I beat many a high powered car, as I had such a good balance to come out of a corner and feed the power on, with just a hint of being at the loss of traction. No good having 400 HP and not really be able to use it where it needs most to be used!

And, as Byron also said, doing a very fast lineal slalom, where I could snap out of the throttle, to help rotate the car, I did not have to worry about the dreaded oversteer. That is why most of us here DO NOT run a rear anti-roll bar, we have very BALANCED cars that can truly be driven with the throttle.

In all of this, one must remember that the rear is a sum of the front too, I ran 6 degrees of castor, so in those tight turn in's, the induced negative camber gave wonderful bite at the front. So, the sum total of the ability to use and understand WEIGHT transfer in our cars, is very important to being fast. KNOWING, when you lift throttle, as to how much front bite you will have, will help load the front outside tire and then at the appropriate point, back ON the throttle to transfer the weight back onto the driving wheels, still requiring some subtle feels for the traction limit, will make you very fast.

That the Yokohama setup works so well on what is still my "race" setup, says something about how far out tire technology has come. I decreased my front castor to a round 5 degrees now, as the real world driving now into parking lots, etc, made 6 degrees a brutal bear to try to steer at slow speed. I have a brace in the driver side toe well ( for the steering box) that does not help either, as my turning radius is a bit limited, I have learned to live with that.

In terms of tire wear...I could care less...I don't rotate tires, so I get at least 5,000 miles out of set of 048's at the moment, if I truly rotated then double that but at the same time, they harden up anyhow, so why bother. Handling to me is not about tire wear. I see so many on this site spends 10's of thousands on all the trick suspension stuff and then put tires on that will NEVER let the car see it's real potential.

In terms of real world street driving now, again as Byron said, it is very hard now to really zip along, compared to some of our drives at truly silly race speeds, those days are DONE..at least for me. I survived as did a contingent of other like minded drivers here in our group.

My take at any rate.

[DADZSUN]

You'd also think that this would wear tires. And I will admit the car does not roll on a flat surface, even in my garage without some resistance.

Funny, after playing musical Datsuns in my garage last night, I finally realised that the aggressive rear toe is why my 510 is unreasonably difficult to roll around. Comparatively, pushing my larger VQ powered 620 is like playing with a large skateboard (Infinity G35 multilink under the rear, hehe).

Like you Byron, wear hasn't really been an issue. I run some pretty aggressive camber but I guess the light weight keeps that in check.

Thanks to the 510 community graciously sharing key alignment numbers, I never found my car difficult to handle in Solo2.