280ZX Rear Suspension - fixes??

[JMortensen]

280ZX in competition (practice vs. theory):

 

1979 Newman wins summit point then another 6 out of 8 races and then won national championship at Road Atlanta and breaks track record' date=' including that of the Sharp Z. Logan Blackburn was second in another ZX and Leitsinger got 3rd place, showing a clear dominance of the ZX. The Sharp prepared 280ZX breaks the Sharp prepared Z record, hehe (not that I have any biases . Newman takes overall win for C-production class that year.

1979 Devendorf wins 9 of 13 races and gets IMSA GTU championship

1979 Posey wins several IMSA races, including Lime rock

1982 Electramotive turbo competes in GTO class against the mighty BMW M1 and Porsche RSRs and won 6 of 10 races to take the overall title.

1982 Sanches takes overall showroom stock A class

1983 Hendricks takes overall showroom stock A class

1983 Sanches takes showroom stock GT class with 280zx turbo

1983 Kawahara wins RAC rally privateer’s prize

1983 Newmann wins several individual GT1 races

1983 Devendorf/Adamowicz win 4 consecutive GTO wins

1984 Hendricks takes overall showroom stock A class, again

1984 Clement wins SCCA GT2 class

1987 Clement wins SCCA GT2 class, again

(There are many other individual wins and track records that I have not summarized)

 

Some benefits of 280ZX platform:

Significantly stiffer chassis (which in my opinion makes more of a difference than the benefits of rear strut vs. semi-trailing arm design. But then it does add weight), engine further back in bay resulting in perfect 50:50 weight distribution, wider track, and much better aerodynamics.

Personally, along with Dr. Ferdinand Porsche, while not my favorite design, I have no serious problems with semi-trailing arms. On or off the track.[/quote']

Couple that with the 510 history (probably a lot longer list of wins) and you've got plenty of evidence that the Nissan semi-trailing arm cars can be plenty fast. I never meant to insinuate that they weren't or couldn't be fast. I just said I haven't seen it in person and gave a little explanation of why semi-trailing arms do what they do.

[tube80z]

280ZX in competition (practice vs. theory):

 

Some benefits of 280ZX platform:

Significantly stiffer chassis (which in my opinion makes more of a difference than the benefits of rear strut vs. semi-trailing arm design. But then it does add weight)' date=' engine further back in bay resulting in perfect 50:50 weight distribution, wider track, and much better aerodynamics.

Personally, along with Dr. Ferdinand Porsche, while not my favorite design, I have no serious problems with semi-trailing arms. On or off the track.[/quote']

 

I guess we have our own little chevy versus ford debate. A good chunk of the cars you mention above really share little or nothing with their production versions. I think most of why the ZX is good is in the last little bit you mentioned. Balance and aero being key. And a lot of these were based on the 2+2 platform.

 

Trailing arms can be made to work. I have plenty of practice in 510s over the years. Keep the arms at or near level and never lower the car so that the pickup points are under hub height. When you do that you get into an area of extreme toe change. Camber is a simple straight line for these beasts.

 

If you wan to make it better you need to change the swept angle. A good candidate for stealing info from is the BMWs. Take a look at what I helped a firiend build if you want ideas, http://www.datsun510.com/photopost/showphoto.php?photo=4420&sort=1&cat=3187&page=2

 

Cary

[260DET]

According to Ray Hutton's book The Z-series Datsuns, the Z31 rear end pivot points were inclined inwards to promote negative camber through most of the suspension travel. The semi-trailing arms were inclined at 18 degrees to the wheel axis, instead of the 23 degrees of the 280ZX.

 

Apparently the rear end was borrowed for the Z31 from the then current Silvia.

[Drftn280zxt]

I think coilovers would be your best bet. But I'm no engineer...yet!

[ecp48]

Thanks Guys,

 

Its been an entertaining thread. Ross's coil over package is nice, but overkill for a basic street car, that I want a little better handling out of.

 

The 510 type slotting is a good approach, but after installing the lowered springs and noting the relation of the pickups. I may want to modify a second set of trailing arms to raise the pickup point.

 

I'll try to review some old magazines I have hanging around and see if I can find anything as to how much the pickup point was raised.

 

Changing the direction a bit, has anyone tried raising the front inner arm pivot point, ala JTR for the Z. I've done that on my 280Z.

 

thanks,

[JMortensen]

The bumpsteer issue is totally different on a 280ZX than a 240/260/280Z. You'd have to measure where the bumpsteer is in order to correct it. The nice part about the steering box setup is that you can drill out the holes in the drag link and the steer knuckles to 5/8" then just run 5/8" rod ends on a piece of 5/8" tap tube and use a common bumpsteer spacer kit on the outboard end to adjust the bumpsteer.

[Calico]

So is there any definite solution to correct this problem?

[johnc]

No.

[HowlerMonkey]

Tube9z is correct in his post on the first page.

 

There was a company who altered the shape of the rear control arms.

 

The best way to describe the mods is to make a fist pretending that the fist is the mounting point and your forearm is the trailing arm.

 

Bend your wrist up or down about 45 degrees to get an idea of how they changed the articulation of the arms.

 

I haven't seen one in a few years but I saw more than a few on 280zx turbos that were modded for high horsepower in the mid to late 1980s.

 

As far as racing......I think sanford sliverberg still holds at least one SCCA ITS track record with a 280zx.