280ZX Rear Suspension - fixes??

[ecp48]

I'm probably dating myself, but I can remember someone coming out with a fix to reduce squat in the 280ZX rear. It seems like one of the Z vendors had a relocated or revised pivot point for the rear trailing arm they were selling. There was an article in Car & Driver or one of the other sporty car magazines at the time. I think, maybe in 1980 or 81.

 

Anyone remember this?

 

Thanks in advance.

[Modern Motorsports Ltd]

ECP48, I'm curious to here on that as well! I never heard tell of it ever previously and would have done it in a wink if I'd read it/understood and agreed with it. The squat actually makes for some great traction I quite enjoyed when setup with reasonably firm springs and good struts.

 

Our solution for this (required once 280ZX rear Illumina's were discontinued) is very complete, fully adjustable integral strut/coilover system package for the 280ZX rear.

 

You can read full spec's here, any questions at all drop me a line.

 

http://www.modern-motorsports.com/catalog/product_info.php?products_id=66

Cheers,

[tube80z]

I'm probably dating myself, but I can remember someone coming out with a fix to reduce squat in the 280ZX rear. It seems like one of the Z vendors had a relocated or revised pivot point for the rear trailing arm they were selling. There was an article in Car & Driver or one of the other sporty car magazines at the time. I think, maybe in 1980 or 81.

 

The one I remember required you to send in your crossmember as a core. They raised the pivots and added eccentric adjusters. I seem to recall later there was a bolt-in option like you mentioned.

 

You might try looking at dimequarterly.com for Kelvin Dietz's EP 510. I built a crossmember for the back of it that raised the pivots and changed the trailing arm angle to fix squat and lessen the rear camber and toe gains.

 

Cary

[johnc]

Design Products

(714) 892-1513

5462 Oceanus Dr # E

Huntington Beach, CA 92649

[BleachZee]

Slotting the rear crossmember is probably what you're talking about. The older 510 rear suspension is very simular. I've seen a tech article on slotting the rear not to reduce squat, but to correct toe and camber once the rear is lowered with lowering springs. The lowering springs should be more stiff, which helps reduce the squat.

 

http://dimequarterly.tierranet.com/articles/tech_crossmember_slotting.html

[Cody 82 ZXT]

If you serch on this site you'll find a couple of good post about the rear suspension for the 280zx.

[Modern Motorsports Ltd]

Slotting the rear crossmember is probably what you're talking about. http://dimequarterly.tierranet.com/articles/tech_crossmember_slotting.html

 

The 'penultimate' mod they call it, bit of work to accomplish properly but serves the dimes well as some reputable dime masters have reported (Dietz/Savage/Michael etc).

[slownrusty]

Or you can just coilover the rear of the ZX, like so:

 

 

Yasin

[JMortensen]

Switching to coilovers allows you to change the spring rate but it won't change the toe and camber change that is inherent with semi-trailing arm suspensions. Slotting the crossmember is different from the penultimate, which raises the pivots then slots the crossmember IIRC. That coupled with stiff *** springs is the best solution. Or just get a Z instead. I don't think any minor change to the crossmember is going to alleviate the squat entirely, but you can make it better.

[Phyxius]

ok...everyone says it squats because of the semi-trailing arms...but what exactly is it about them that makes it squat?

[JMortensen]

The way the suspension arms are hung at the front is what causes the squat. If they're hung from the middle of the car like a Z, then when you put power to them they don't squat by design (although the Z will still squat just by weight transfer).

 

Here's a real quick experiment. Jump in your ZX. Pull the ebrake, put it in reverse, and start to let the clutch out. Surprise! The back end will climb about 6" up. Opposite happens when you put it in first. The car will squat down. I distinctly remember my auto shop teacher doing this in when I was in high school and thinking the car was WAY broken. Do the same in a Z and there is no effect.

[ecp48]

Jon,

 

Got the Z! Three of them. I was just given a nice clean 280ZX, which will make a great grocery getter and daily driver, with a little massaging of the suspension.

 

That leaves my 78 280 available for the planned LS1.

 

I really want to clean up the suspension, just a bit for better handling. Less squat, lower springs and maybe some heavy sway bars.

 

Thanks guys,

[Phyxius]

The way the suspension arms are hung at the front is what causes the squat. If they're hung from the middle of the car like a Z' date=' then when you put power to them they don't squat by design (although the Z will still squat just by weight transfer).

 

Here's a real quick experiment. Jump in your ZX. Pull the ebrake, put it in reverse, and start to let the clutch out. Surprise! The back end will climb about 6" up. Opposite happens when you put it in first. The car will squat down. I distinctly remember my auto shop teacher doing this in when I was in high school and thinking the car was WAY broken. Do the same in a Z and there is no effect.[/quote']

 

so...the point at which the forward/rearward force created on the trailing arms by the wheels is above the trailing arm mounting points? This would tend to push the arms up during forward acceleration. I can see where raising the mounts would help this situation.

[Guest 81na ZX]

This thread is convincing me more and more to go through with a s13 rear subframe swap

 

Even after I just about talked myself out of it...

[Oleh]

am i the only person that likes cars that squat/dive

[Phyxius]

i like it for the fact that it helps transfer weight to the rear for launches, but other than that, it's somewhat embarrasing when it looks like you are hunting for racoons

[johnc]

This thread is convincing me more and more to go through with a s13 rear subframe swap

 

Why? Unless you're an expert road racer its not going to get you around a race track any quicker and unless you can cut a consistent fast light its not going to improve your 1/4 mile times. Remember, a lot of the discussion here delves into technical minutia (I call it Engnineering Masturbation and I'm one of the prime practitioners) that doesn't really matter much out in the real world once someone puts their hands on the wheel.

 

The 280ZX can be a fast car around a race track even with its supposedly "inferior" semi-trailing arm rear suspension.

 

http://www.a2zracer.com/page82.html

 

But, then again, this is HybridZ. If its something you want to do, go for it!

[JMortensen]

The 280ZX can be a fast car around a race track even with its supposedly "inferior" semi-trailing arm rear suspension.

Never seen a fast 280ZX on a race track in person, then again I've never seen a 280ZX on a race track period. I know that John is correct though. Seen plenty of fast 510s, and the suspension design is pretty much the same. Also seen plenty of fast Porsches which use semi-trailing arm design. Just toe in that rear suspension a bit and it'll stick just just fine. I think the reason you don't see the ZX more often is their weight disadvantage compared to a 240.

[preith]

Never seen a fast 280ZX on a race track in person, then again I've never seen a 280ZX on a race track period.

 

Ken Bonneau here in the Milwaukee region swears by his ITS 280ZX. He does pretty good in it and has considerable experience in S30 cars as well.

 

[Afshin]

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, 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.