Rear suspension diferences 240z -280zx

[col]

Does anyone know why they changed the rear suspension from 240z to 280zx?

Is there any real advantage one to the other?

datsun 1600-180b- early skyline etc had very similar suspension to the 280zx. So they went to the 240z design and then went back.

I know the 280zx design had toe out in compression problems ,and both have excessive camber change, but how does one really compare to the other?

[Savage42]

Big difference! The 240-280Z has a chapman strut with rear A arm, where the 280ZX went with the semi trailing arm like that of the early 510s. The ZX/510 rear suspension works alright, but is inferior to the early Z setup, due to the fact that the semi trailing arm setup has huge amounts of squat under acceleration which results in camber & toe changes. The most likely reason is that the semi trailing arm setup allows for a lower floor, hence, more cabin space. It's all about packaging, not about being better.

[JMortensen]

My guesses are ride comfort and ease of assembly.

[col]

It is semi trailing but the main change from the 510 is that it too runs a chapman strut instead of having the captive spring with seperate shock.

I have found a lot on modifying the 240-80 rear but not much on the 280zx.

I have one I am going to rally and was hoping to get some mod info.

I intended to lower the axle mount on the swing arm to get the push angle down so as to ilmit squat.

I was also going to move the outside pivot back to reduce camber and toe change.

Any thoughts?

[260DET]

This video shows what a rear semi trailing arm suspension can do in the real world of competition, if you are prepared to do the homework and spend the $. Which 99.9% of S130 owners are apparently not, tightarses.

 

[col]

That car handles great ,no squat and it appears not too bad for camber change.

I would love to see the actual mods don to the suspension.

I was talking to a guy on another forum with a bmw and he is looking to do something similar to me as well, because he has the squat -camber-toe problems too. So obvoiusly the suspension on that car has more than a set of hard springs, which is the most common way to keep angles under control. Hard springs limiting travel may be the most common way to run but not the best.

That is why I was hoping someone had been there done that and save me some time and mistakes.

260det,are you running a 280zx? If so what mods have you done to the rear suspension?

[woldson]

This video shows what a rear semi trailing arm suspension can do in the real world of competition, if you are prepared to do the homework and spend the $. Which 99.9% of S130 owners are apparently not, tightarses.

 

 

 

HEEEYYYYY!!

[Savage42]

There are really only a couple ways to fix the problem. You either need to raise the pivot points upward (which is very limited due to clearance issues with the floor pan) or design a new arm/crossmember where the arms are more of a full trailing arm design. I ran 280ZX rear arms on my 510 w/ VG30 turbo and we modified the crossmember, which raised the mounting points upwards 1" and also allowed for camber and toe changes. This also allowed me to run poly bushings without getting bind when those changes are made, as the mounts swivel. Many 510s have this crossmember, as my buddy made/sold them. Here's my setup:

 

 

Here's what my fried did to his 510, which basically had no trunk area, but as least will give you an idea of what can be done. Very little camber/toe changes with this setup!

 

 

[zcarnut]

To respond to the original question: I’ve read that Nissan wanted to increase the cargo area in the rear deck. The S30 rear shock towers protrude into the passenger compartment. You still have shock towers with the semi-trailing arm suspension, but they are less obtrusive.

 

Nissan just took the rear suspension parts from the 810 (except the change to rear disc brakes) and used it on the 280ZX. Commonality perhaps? Nissan also used most of the 810 front suspension on the ZX even using the same re-circulating ball power steering.

[col]

Thanks for the pic's .

I can't go as radical as your mate , but I do intend to raise the pivots on the crossmember, lift the diff as much as possible, and move the outside pivot back to reduce the camber-toe change.

Does anyone know what camber increase on roll would be a good amount to aim for?

I will be aiming for about 10 deg anti squat if possible as it now has about 10deg squat.

[260DET]

Yeh I did have a bookmarked US private BMW site that had tech info on the competition spec rear end but can't find it now. Bit of a google should turn it up though.

 

Z31 rear end may be worth checking out too, I believe the sweep angle was altered on it to give less camber change, compared with the S130.

 

From the research that I did a well setup semi trailing arm suspension will give excellent power down on corner exit, better than the strut rear end on the S30 for example. The video I linked above is worth a good look. That BM rockets out of corners although it is laying rubber on a lot of the exits. A bit of squat can help power down, the Nissan multilink rear end on my project has been tilted forward to nullify anti squat for that very purpose.

[col]

Yes I agree a bit of squat is ok as long as the geometry is stable. Although too much and the car, by changing pitch every time you hit the throttle, can upset the handling , or moreso give the feeling that it does. Then if you react to the change in pitch you only make things worse. I have seen a well sorted mx5 with soft suspension go around the bitumen motorkhana course, it was set soft for road and track. The guy kicked the arse of most other mx5's that were set hard to stop all the roll. Thing is the mx5 can keep geometry under roll ,and the guy was not put off by the roll. However most poeple would have gone faster in the harder cars because they seem more predictable and are easier to catch on flip flop.

I intend to leave slight squat but if possible make it adjustable so I can try other setings.

I also intend to have some dive left in the front for some transfer to the front brakes, also adjustable.

The rear pivots will probably have to be decided on and fixed, so opinions on the amount of camber gain in roll would be apreciated.

So far it has been sugested to have about 1 degree for every 2" of travel and start with only 1degree static to maximise take off geometry.

The static does not matter as it can be changed.

So how much do you guys think the camber change should be for every 2" of roll travel?

[260DET]

Of course with strut front suspension there is the same camber change problem that you'll get with a semi trailing rear. I can't comment on your camber change/travel ratio question except to suggest that perhaps, and only perhaps, the amount of camber change at the front may be relevant to what would be an aiming point for the rear.

 

Another way to look at it would be to ensure that at all times there is toe in at the rear, then setup the rest with that in mind. Don't know about you but a nice stable predictable rear end is a very important asset, perhaps more important than always getting maximum power down.

 

Afterall, it no going to be a straightline (drag) car is it

[col]

It's not a drag car and I don't want to compromise other aspects of handling. But really isn't every race car a drag car part of the time. Sure you want to get around the corner as fast as possible, and in no way will I make the car unstable just to be quick off the mark. That said once you get the car straight it is a drag to the next corner. Straight line traction is just as important as cornering traction.