260DET

My brakes are around the same size, the 2+2 booster works well with them.

Don't know much about 280ZX's but don't they have a similar rear suspension to the Datsun 1600 (510)? If so you may be able to use similar mods because that rear suspension can be a problem if left stock.

The basic problem for us with lowered cars is that we lose a lot of suspension travel so cars like BMW have an advantage there. But the Z's basic suspension design is good which is a plus. Other than sorting out spring and anti sway bar rates and suitable (adjustable) front/rear alignment specs, which is a challenge to say the least, a set of remote cannister fully adjustable shocks would be the key. That plus the retention of those stock suspension components or systems which contribute significantly to insulating the body from NVH and which don't significantly degrade suspension performance. So, other than the suspension travel limitation, there is no real reason why a Z can't be setup to be reasonably comfortable and to handle better than most. It just involves a lot of attention to detail, a methodical approach and testing, lots of testing. Oh, and money.

So when turning the knob clockwise you should be able to feel an increase in resistance as you go? Mine is not like that, the knob spins around quite freely for quite a few turns until near the end when you can feel just a bit of resistance. It just does not feel like its doing much at all. All the right things have been done with my setup including removal of the stock valve. The caliper effective piston area is around 2:1 front to rear which in theory as I understand it should be about right, assuming that with the sliding rear calipers you double the piston area for calculation purposes. The fronts are Nissan four spots, the rears ex (Aussie) Ford Falcon which have similar sized pistons to the Nissan's, which is why they were chosen.

Anyone had any problems with these valves? I just cannot get sufficient rear brake, they work but not enough to provide sufficient balance for the fronts. A question, the Wilwood knob is turned clockwise to increase rear brake is'nt it? The label is missing on mine. So, it looks like the valve will have to be bypassed using a jumper connexion, see whether the rears can be locked up then. If mine is faulty, are these valves serviceable?

The problem in making specific recommendations is that both the cars I've been involved with are reengined and so don't have the same weight distribution, etc as a standard Z. However, with good shocks, the original spring top insulators retained, stock anti roll bars and tyres no less than a 55 profile, I'd be looking at trying two 250lb springs and two 275's on yours. Put the 275's on the front first and try it, if you don't like that put them on the rear. It is all very subjective but if you're prepared to experiment and note the results of each change you will end up with what you want, eventually. Another benefit of the heavy springs route is that both nose dive under heavy braking and squat under heavy acceleration will not be a problem. Sway bars of course have no effect on those two conditions. Then when it is finally sorted you may wish to tell us all about it.

Generally the best approach with a Z is to go up with the spring rates but not with the sway bars. Heavier than OE sway bars will destroy your ride quality quicker than anything, except perhaps the replacement of the stock spring top insulators with something solid. With suitable uprated springs and poly bushed stock sway bars, check out the various stock sway bars available, you are on your way to having a firm handling and reasonably comfortable car.

Take 2. That is what we are now going to do for the next test. Once the springs are sorted out then look at sway bars, then tweak the other adjustables.

Thought you might say that John. Did some measurements on the apparent actual suspension travel used during the track test and the available suspension travel that are interesting, jacking up under one suspension unit until that particular unit just takes the load of the relevant car end, front or rear, and using that as the 'available' measurement. NB the measurements are up to contact with the soft bumpstops which compress a further 20mm approx. Front: 65mm available, 50mm used. Rear: 50mm available, 50mm used. So, both front and rear used 50mm suspension travel on the test, NB 50mm equals 2". So, given the good overall handling, power down and braking performance during the track test the springs will stay the same, for the moment anyway. Alfshin, both front and rear suspensions are fully adjustable and in excellent condition. Tyres are Dunlop RA1's soft compound 205/55R15, a great road legal tyre, better IMHO than Advan's or Toyo's which have been used in the past. And yes, a slightly wider tyre would help. Present sway bars are 22mm front, 14mm rear. Subject to the industrial estate test, I'm looking at going up a bit on the rear sway bar size as well as tweaking the front end as previously mentioned. Another item, Dave Weitzenhof's US website states that at low speed more front shock rebound reduces power on understeer. Something else to think about as I'm using adjustable rebound Koni Sports.

Yes John, it was a bit of a surprise to see that she had been on the rear bump stops because there was no dramatic oversteer. The stops are those soft foam poly ones though. The present springs are 300lb front, 275 rear with a reasonable amount of suspension travel. So we are going to take the car to an industrial estate, hopefully deserted over the weekend, and try a few things. Use a video camera to study suspension angles and body attitude in slow corners.

The common adjustable tension rod conversion where I live is to adapt some Ford Falcon strut suspension adjustable rods to fit. They have to be modified a bit at the suspension arm end then redrilled to bolt on but they are long enough, stiffer (heavier in section) and cheap from a wreckers. Maybe in the US you have something similar you can adapt?

Thanks all for your suggestions. A touch more toe out and more castor it is then. The more rear sway bar suggestion is pretty perceptive because on looking at the small cable ties I'd put around the shock shafts it appears that she has been on the bump stops at the rear, presumably during cornering. So the rear bar will go up a bit in size too, even though the aim has been to keep the rear as soft as possible to aid power down.

After another track test day to see how the handling has changed as a result of various mods, the results were quite encouraging. The only substantial problem now apparently remaining is some mid corner understeer. The car brakes, turns in nicely and feels well balanced. But in slower corners of 90 degrees or more there is some understeer in the middle part of the corner, before the last part of the exit line when full power can be applied. The present front alignment specs are 2.2 degrees castor, 3.1 degrees camber and plus 1mm toe. If my understanding is correct, more castor will induce more turn camber, at the point when a bit more camber is required to aid front grip. Correct? On faster corners which require less steering input the car is fine, if it starts to run wide a little when the line is not quite right, backing off the accelerator just a bit brings the front in tighter immediately with no loss of overall stability. So the setup is just about there. Any suggestions?

The Toyota front conversion is OK, depending on what you want from your brakes. If you want really outstanding brakes and don't mind spending more money, consider an upgrade using four spot aluminium calipers and around 290mm (11.5"), or bigger, diameter ventilated rotors. Better to think about it now than later on after you have spent money on the Toy conversion.

The old oil seal can be used as a buffer when putting the new one in. Sit the new seal in place, put the old seal on top of it and gently tap the old seal so that it pushes the new one into place. Or, even better, you can put a small piece of wood on top of the old seal and tap that. Make sure that the new seal goes in straight. Tapping around the circumference in varying places helps.

The Nissan four spot calipers won't bolt up to the Z, the four spot caliper has wider hole spacings. Given the apparently excellent big brake conversion kits available in the US, a Skyline conversion attempt hardly seems to be worthwhile, I looked at it a while ago and for reasons I can't now recall rejected it.

Seeing we have drifted off topic I recall that there was an article in a long ago US magazine, Road & Track?, where they tested the fitting to a 240Z of a flat, angled alumium plate fixed at the back of the hatch. Apparently it made a significant improvement without any additional drag. Can't recall the size, angle, etc but it was about the size and angle of a whaletail.

Thanks all for the useful info. I did do a search first but it didn't turn up much for some reason or other, hence the query. Incidentially, the Torsen website provides a list of cars that had/have Torsens fitted as standard.

Anyone using one of these gear type 'LSDs'? If so, how do you find it? Out of a what? John, apparently Mazda MX5's (Miatia's) have a Torsen diff so you should know all about them.

For something different an acrylic etch primer by itself is working for me and mine. The theory was that as it wouldn't be exposed to direct light it would not degrade. And having a thin coating would reduce chipping due to stones etc impacting, plus of course an etch primer sticks like s**t to a blanket. Has to be sprayed on of course but it dries quickly. The matt finish looks good too.

Big guess, it could be the pressure plate slightly out of alignment. But, you know that you should pull the box out and do it all properly, don't you. We all at some time or other 'forget' things so don't feel too bad about it.

Thanks all for that, most useful.

Consider the effect of having a solid front diff mount in combination with a flexible rear mount.

As we know, the stock front sway bar has shorter arms than the rear bar and is thicker. So the amount of leverage on the front bar is less than on the rear which means that the difference in effect between the two is exaggerated. My question is - are there tables of calculations or graphs available which enable you to work out the effects of various bar thickness/leverage measurements? To clarify the question, how do you work out the amount of resistence offered by a particular bar taking into account the length of its arms and its thickness? I've read a few books on suspension and have never seen anything specific on this. But I'm sure that amongst the brains we have around here someone will know.