260DET

The problem with compliance is that the amateur racer has difficulty in measuring and evaluating it. As I keep saying, the good modern sports type cars in stock form handle like something most S30 drivers can only dream of, as mentioned, Honda for one use compliance to improve handling. But all is not lost for us old schoolers, if our suspension allows, we can work at using dynamic suspension changes to improve handling eg toe in. If you don't accept that known and managed dynamic rear toe in could help then you are truly old school EDIT It's a pity that that Ron Sutton has little experience with rear independent suspension and is reluctant to advise on it, accordingly I would disregard anything he says about rear suspension. It's a pity because he seems very helpful and certainly seems to know the solid back axle stuff.

Technotoy are race proven.

Looking for info to help the suspension design process for the project car and ran across the cut paste para below, part of a Honda blurb about their five link suspension. Note their comment about dynamic toe in when cornering. Toe-in Characteristics Under Cornering The upper, lower and control arms are arranged to be true to the wheel longitudinal axis, which, coupled with a straight arm design, ensures high stiffness against lateral force. The wheel center to control arm span is longer than the one between the wheel center and the lower arm, allowing a greater displacement of the lower arm bushing to increase toe-in under cornering. This translates into improved handling characteristics and traceability.

Pics.

Yes, your triangle of behaviour and the grip apportioining pie, similar visuals. Of course final understeer is a good and common example of a manufacturer designing in handling behaviour for safety reasons but It seems to me that where sports type cars are involved they are designing in other characteristics that just make the car faster where the driver is keen enough to push it, this is the difference between a S30 and any modern sports car. The grip some modern sports cars display is just sensational, often ignored because power is an obvious factor in lap times and one most commentators seem to concentrate on. This is more for Jon but I came across some good comment on the racing use of HICAS by a former Nissan engineer. Apparently Nissan did race using tweaked HICAS, the standard version being too slow to react and not sufficiently aggressive for racing. Just shows how we can get a wrong impression, apparently the tweaking is beyond the capabilities of most although the electronics to do so are available.

The air intake from the throttle body to the upper plenum should be straight, put any bends in before the TB with a straight as possible immediate entry to the TB. Otherwise it's hard to tell much, looks tidy enough.

Brilliant and yet no interest, pfft, looks like you did a really good job here but apparently not fast and furious lol. Seriously, I can see lots of nice detail so bloody well done.

Don't forget engine management, an aftermarket ECU should be a priority because unless fuel and spark are correctly regulated then the rest is irrelevant, eg the best pistons will fail if fuel/spark are not right. And a tuner too of course who can set everything up during a dyno tune, problem to be solved is that not all tuners are good enough.

Yes, I'm aware of the HICAS deletion thing for racing, what I was getting at was that some manufacturers were sufficiently convinced that some dynamic toe was a good thing that they incorporated it into their sports production models. But once you go racing all suspension aspects are up for evaluation. I know bugger all about modern sports car suspension but they are so good out of the box that I'm sure that there are dynamic suspension factors at work, they have moved on from merely tweaking static settings like caster. As an example, the Honda rear suspension I posted about on Ozdat, clever.

To clarify what I advocate as far as rear dynamic toe in is concerned, firstly we are talking about only a small amount, maybe a mm or two in total, secondly it should be coordinated with the rest of the suspension design characteristics such as dynamic camber gain, all strictly controlled by the amount of roll which is allowed by considering roll centre placement, springs, anti roll bar and so on. Obviously different suspension types will dictate what they can and can't do, at present I'm considering the race Bluebird trailing arm with two lateral link type which, other than being a bit heavy, looks promising for the Z31. I was reading Fred Puhn's book, again, the other day and was struck by how conservative some of his comments are in 2017. Like on front caster and yes rear toe in. He would shake his head at using 10mm total toe in at the rear on a S30 Datsun but it works, I suggest by its effect on the outside tyres slip angle when turning in to get the back come around into the corner and joint the rest of the car. Not on corner entry cock itself up at the rear diagonally and then proceed to lose rear grip totally like so many standard modified type S30's do

The term 'bump steer' has by itself negative connotations and I think that we all agree that for the front bump steer = bad. And let's not forget that bump steer includes both toe in and out changes, having a front suspension change dynamically between toe in and out is simply to be avoided and that usually is what bump steer involves. But the rear is different, for a start we as drivers have no direct input there so any dynamic changes need to be predictable and for a purpose, just like when as some makers have done a car is fitted with a rear steer device. Also dialing in roll/bump steer at the rear is a common solution used by makers to ensure that a car will not oversteer at the limits. So what I have in mind, using dynamic toe in, is no different to what is commonly done by makers. In effect roll toe in induces a form of rear steer, the outside loaded rear tyre by toeing in helps the rear of the car point in the direction of exit. My new project is a Z31 but for S30's I'm sure that rear toe is not understood by most given their habit of spinning out However one of the S30 guns here is obviously aware of what rear toe in can do, he runs 5mm rear static toe in each wheel. I'm not here to convince anyone I'm right, whatever that is, I'm trying to run through the theory and it's application to make sure that something is not missed so all comment is great.

Link to the Ozdat thread http://ozdat.com/forum/viewtopic.php?f=30&t=10296

Hmmmm, it could be a coincidence of course Jon but it looks like someone may have 'borrowed' from a pretty extensive suspension discussion on Ozdat including the Bluebird suspension, hence my query. No real problem but one of the reasons for putting different ideas out there is to get some constructive comment, at least one fellow in that forum you linked did acknowledge Ozdat which is good. I'm not a suspension guru but I know what I like when driving, one rear suspension characteristic I like for a powerful rear driver is some dynamic toe in the corners. So I find it strange when people talk about dynamic toe as undesirable.

Wow that is interesting Jon, how did you find that? Lols aside, for a road car working the stock setup is the way to go. That may sound simple but for a start there is virtually no aftermarket support so it's either capable DIY or whatever assistance is available to you. If you want current chassis dynamics then there are plenty of off the self solutions involving modern cars, otherwise with the Z replacing all the suspension consumables is a good start, these things handled pretty well back in the day, modern tyres and suspension bushes take that further. As for the Bluebird trailing arm twin lateral links suspension, I'm going to give it a go just for the challenge and because race car and because well thought through stuff sometimes works in the real world. BMW used that suspension type on a couple of models, E38? Something like that.

OK, I'm convinced, bar links to terminate at the LCA's. To use longer links it might be an idea to mount the bar on top of the chassis rails, am going to have to fabricate mounting spots anyway and all that would be otherwise required are holes through the inner guards for the bar to go through. Thanks for the constructive comment chaps.

Interesting point, hadn't thought of that. But if the links are aligned parallel to the struts then such side loading would be negligible? The reason why I like the idea of strut connected links is that they can be long and so allow acceptable angularity when their location on the bar is adjusted in or out.

My application is for a project Z car, anticipate making up and welding mounting plates to the chassis rails. Certainly for a S30 this would be necessary. Other than that my preference would be to use long links connecting to the struts which, if possible, will dictate the length of bar required.

Well 1speedway have a 32mm OD hollow bar, the same OD as my JDM one. Mine has a 3.5mm wall thickness, 1speedway have a 3.2mm wall option. This is a great guide for what may suit mine, for anyone else my JDM bar is pretty stiff, no rear bar used, so if you want a stiffy the 1.25" hollow .125" wall 1speedway option may suit you. Mine is soft mounted which is not good, one of the reasons for going this way is to have hard mounts.

Great find, thanks. My race 280ZX has a OE big hollow bar on the front off some JDM Nissan sedan, so much lighter. It works well, will measure the OD and wall thickness and post them up.

Do you do overseas orders without charging $50 shipping for a couple of gauges? Should be, what, $20?

The bar itself is straight and usually splined each end to accept the bar ends which are essentially levers that connect via links to a unsprung part of the suspension somewhere. There are versions made for using on the rear suspension of a drag car which look like they could be adapted to work on a Z car, at the front of course. But finding info on the wall thickness of the hollow bars used is like a Wikileaks exercise only harder. Maybe someone here is using something similar on their race car that suits, if so tell us about it. I'm plain researched out. EDIT Maybe a mod would like to move this to suspension.

At really high speed it's all about aero, particularly where the track undulates or has peaks, anything that lifts the front of the car up. Alignment is only relevant when the car and particularly the front is on the deck and particularly when it comes back down from a aero fail induced front end lift incident. Then it is crucial and can make the difference between a safe 'landing' and disaster. Ask me how I know that from experience. Ask me also how aero is king, it's always about keeping the car with a bit of rake on the deck no matter what the track is trying to do to upset that crucial balance.

Classy video, particularly the first part.

My Cherokee diesel tow car is comfy, that's it, Z cars are for racing stuff.

Stitch welding is good as is oxy welding right around the door opening flanges, the rest is a bit hit and miss mainly because it all gets complicated and very much an individual's opinion. I had a good look at a MX5 the other day because cars that do well in racing are good chassis examples. One thing I noticed when looking down from the engine bay was the horizontal bracing from the rails to the bottom of the firewall which is going to be incorporated in the Z31 race car project. Then, with the front guards removed, a 45 degree brace from the front of the rockers to the upper front body towards the strut towers is useful, did this with the 280ZX plus a triangular strut firewall brace. The best advice is to look at modern cars like the MX5 and Toyota 86 and consider why they did what they did and use your imagination as to what loadings the 280ZX chassis will have to handle when racing.