rear suspension arm upgardes??

[aarc240]

Here and there I have come across references to strengthening the rear suspension arm on the C110 but no details.

I have yet to simply bend one without a crash and am curious about what is the supposed weakness and where the failure area is.

Sure, they bend when you hit something going sideways but then there's usually plenty of collateral damage too.

Can anyone enlighten me ?

[Mat Big Hat]

well, i was hoping to do a rear coilover setup similar to what is sold for a 510, but taking a look at the rear of the c110, i realized that the lower shock mount is in a precarious position. odd that the shocks are upside down as most other datsuns i've seen are the other way round. in any case, not sure what to do there except leave it alone

[akwikz]

The rear suspension is actually a better design than that of the 510. The 510 has the shocks mount to the body sheet metal. On the C110 and C10, the shocks mount to a frame rail of the unibody. Definately a lot stronger. I have been thinking about the rear coil over set up myself, but I will admit the angle the shock sit at concern me. I guess it should not matter, but for some reason I don't like the way it looks.

Brian

[Mat Big Hat]

it was the lower mount that concerned me as well

for rear springs, in lieu 240k king springs, i wonder if 510 or 280zx rear suspension techniques springs would be sufficient?

i guess we really need to know the spring rates ... kent?

[aarc240]

FSM says

soft suspension

8.25 turns, 257.5mm (10.138") free length, installed height 200/617 mm/kg (7.874/1360 in/lb)

hard suspension

7.75 turns, 253mm (9.961") free length, installed height 200/612 mm/kg (7.874/1349 in/lb)

To translate those,

soft suspension springs are 600 lb/in

and hard suspension springs are 646 lb/in

Industrial Springs P/L in Adelaide (Aurora) do the rears at 680 lb/in in the shorter GT length.

I think (but not sure) that the 510 springs are smaller diameter and more than likely softer. 280zx are relatively soft.

How much are you going to save going that route???

[Mat Big Hat]

whoa! those seem pretty stiff. i know that aftermarket rear 510 springs are ~200 lb/sq inch, but it is a lighter car

btw, who makes and sells sport shocks for the rear (besides monroe)?

[jmortensen]

The 510 rear springs are not 200 in/lb unless they're seriously undersprung from the factory. That sounds like an aftermarket front spring rate, but the rear is not a coilover setup, and the leverage ratio is something like 3:1 IIRC, so that means probably a 700 in/lb spring would be about right to go with the 200 front in my estimation. Even when you convert them to coilovers they aren't linear rates because of the angle of the strut.

When you get into wheel rates then you can make a direct comparison of front and rear 510 springs, but that's wheel rate, not spring rate. If aarc240 is talking 600 in/lb wheel rate then that's really high, although it can be made to work. Takes $$$$$$$$$$$ dampers though, and a hell of a lot of chassis stiffening. While I don't know much about the 240K, the Z or 510 certainly can't handle those spring rates without a lot of chassis work.

[aarc240]

Spring rates not wheel rates.

The only Factory Service Manual (FSM) I've ever seen that included wheel rates came from Ferrari.

The leverage ratio is nearly 4:1 on the 240K

[jmortensen]

That makes a lot more sense. Just did a little digging and stock rear springs on the 510 are 320 in/lb and the "Safari" springs are 519 in/lb. Some of my friends who race 510s were running standard front roadster springs which are stiffer, and one ran comp roadster springs which are stiffer yet. Did a little check on these and it appears the comp roadster springs are testing in the 900 in/lb range!!! I think the one guy ended up going to a softer spring after he couldn't get it to work with the 900 lb springs. I think he backed off to the 700 lb stock roadster springs.

[Mat Big Hat]

my bad, 200lbs was rear coilover spring rates for 510

aftermarket 510 rear springs should work fine

no suggestions for 240k rear performance shocks?

anybody know the rate of 240k rear king springs?

[aarc240]

Aftermarket 510 rear springs are going to be too soft unless they are a LOT stiffer than even the 'Safari' springs.

Since roadster springs are like hens teeth in Oz we have little experience with using them.

It sounds like the stock roadster fronts would be pretty reasonable under the rear of a C110 and maybe the comp's would work for a REALLY stiff C110.

Rear shocks have been reasonable with Oz market Monroe Gas, much better with Koni double adustables. Haven't tried Bilsteins (yet).

You would need to ask King Springs to get a reliable answer on the rate.

[Mat Big Hat]

appreciate your imput, and there's certainly a lot of unknown territory here

i'm rethinking the king springs idea as alfadog has them and had issues with not being lowered enough

and that present problems of its own

i'd use coilovers in a instant if they didn't foul my wheels