Gaz Shock and Spring selection.

[Eternal]

Hello All!

Long time no see :D
I'm looking at getting my shocks organized for the Skyline Roadster and could do with some advice. As most of you know it's got a rather large engine(300kgs with gearbox), a 135mm chassis stretch, and 2mm wall with welded 3mm steel floor so its quite a bit heaver than a normal Haynes Roadster. Can anyone please give me some advice as to what spring rates I should be using and also what shock to use? I'm using the standard Sierra build from the book so I think its 14" shocks that are required.

So far I think I should be using this... from Page 15 here. http://www.gazshocks.com/images/downloads/GAZ_2015_catalogue_V2.pdf


4x - 140/095B12 shocks
2x - 2.25'' x 8'' x 350 lbs springs (Maybe higher i.e. 400?)
2x - 2.25'' x 9'' x 250 lbs springs

[wylliezx9r]

I'm running an s2000 engine and box which is considerably lighter than yours. I run 350 springs up front and 250 at the back. The front feels right but the back to soft [I'm going to change to 300's over the winter]. If I were you I would go at least 400 on the front and 300 on the back. Obviously thus is just my best guess.

[ozzy1]

Firstly i would say pay the extra and get the protech shocks, much better quality.
I would speak direct to them and tell them what you are building and they will have a better knowledge of what you will need.

[alga]

I'm running an s2000 engine and box which is considerably lighter than yours. I run 350 springs up front and 250 at the back. The front feels right but the back to soft

I'm curious, how do you judge that the rear is too soft? Understeer?

[wylliezx9r]

I'm curious, how do you judge that the rear is too soft? Understeer?

Slight understeer and lots of roll at the back, confirmed by photos taken at a track day.
My engine is set very far back in the chassis I don't know if that makes it worse.

[alga]

Slight understeer and lots of roll at the back, confirmed by photos taken at a track day.
My engine is set very far back in the chassis I don't know if that makes it worse.

Hmm, I would think that since the chassis is rigid, the amount of roll is the same front and back...

[Eternal]

So going to put the order in tomorrow with Gaz.

What I'm thinking is this.

G140/095B12-2
Front - 2x 8” 375lb 2.25”
Rear - 2x 9” 275lb 2.25”

How does that sound to everyone? I know its quite a bit harder but then again with the steel floor,18" wheels, full cage, chassis stretch, 7.5" diff and bonker 6 pot block I think it makes sense.
http://s29.postimg.org/dqa1qny4n/12449258_10155632302284619_139544626_o.jpg
All advice more than welcome!!

[wylliezx9r]

Personally I would go for 300's at the back. But it's all a bit of a guessing game.

[baz-r]

the only way you can tell is to calculate it form weights and shock ratio to be sure.