nickmaris

Thanks for that very helpful guidance. My 'adjustable' perches have frozen solid (exactly 2 year un-adusted) but as soon as they are freed, I'll follow your suggestions. Do you have guidance on ride heights and where to measure them? with best regards Nick

Hi - of course you're right. Still say Monte Rally specs would probably be closest to the kind of use my car gets. I was under the car today, measuring the rear road clearance (and so indicating ride height?)per the service manual which is given "at the transverse link mount lower end" this is ambiguous - could be the outboard end of the lower wishbone/transverse link or it could be the inboard end where it connects to the cross member. Anyway they give 261 mm without load. I got 170mm outboard and 190mm inboard within +/- 2 mm or so. So if my measurements are correct my setup is lower than stock despite running 185/70 R15 tyres. This with 7 litres of fuel and a spare tyre and jack but nothing else in the car. I'd very much like to have a more comprehensive comparison of our two cars. Btw -have you looked at Tein suspensions? Nick

I'm very happy that JDMjunkies has invested the time and work needed to put together his really helpful article on S30 suspensions. It certainly helped me a lot. I've had my 240Z prepared for long distance rallying and it has an FIA HTP, with the work that lies behind that done. The suspension uses adjustable base spring platforms, and is modified with Bilstein inserts. Both the struts and the dampers were modified by Gartrac (https://www.gartrac.com/) The springs are 2.25 inch OD, front spring rate is 185lbs/in and rear 225lbs/inch. Lengths are 12 in (305mm) front and 14 inch (356 mm) rear. The car has done about 10,000 regularity rally miles with this setup, with one damper rebuild. But now the whole system including the insulator mounts, top bearings and bottom mounts are showing wear. Recently I weighed the car on Proform 7000 lb wireless scales. This is the result for the car with driver but no passenger aboard (I know, I know but full roll cage, extra electrics and no weight reduction because the marketing department thinks it looks good) all in kg: I must admit that the 80kg heaver front left than right and the 46kg heaver rear right than left was difficult to understand. The car is left hand drive so some of the front difference must come from the driver, the steering console/column, pedal box, plus the fact the carbs and manifold are on that side. As to the rear there is a built in fire extinguisher behind the pax seat. and the fuel tank is 'taller' on the pax side and the fuel pumps are also there. Still..... However taking these figures to be correct then with symmetrical spring lengths the car will not sit level. I assume there was always a weight difference left to right which is why the service manual shows different, as commented by JDMJunkies, front spring lengths each side (on page FA-20 on my copy) at 373.5mm LH and 386 mm RH uncompressed (note opposite heavier side to mine) to give an identical 201mm 'installed height'. The rears are shown identical. I guess that even if the lengths - or adjustable bottom mounts are set to bring the car level, the behaviour will be different on each side if the springs and dampers have to deal with significantly different weights on them, although with different lengths at least the spring travel will remain the same on the heavier side. So I'm trying to find out what to do. I'm looking at short term fix of fitting Eibach springs which have rates similar to the existing, but an inside diameter of the springs of 76mm, which I've been told 'are better'. But what I'd really like to do is redo the suspension from first principles. That is deriving the unsprung weights by weighing, work out the suspension frequency with different spring rates, and chose an appropriate damping rear in compression and rebound. Of course all this could be short circuited if I could get the information for the works cars in period, which must be closer to correct than anything I can calculate. So if anyone just happens to be sitting on this info and would share it, there is at a good meal with drinks waiting here in Switzerland

Another approach - welded in tubes to go with Evojack hydraulic jack. http://www.motorsport-tools.com/evojack-wrc-light-weight-in-car-quick-lift-hydraulic-rally-jack.html Only worth it if your doing a bare metal rebuild - and wheel changing speed is important. It works as advertised.

Dyno results (flywheel) for an L28 prepared for rallying - plenty of torque for street driving too. some weights and spring rates too. Combined DYNO, Weights, Spring, Damper files.pdf