Spring Rates for R32 GT-R (?)

[VSPEC32]

Hi All

Does anyone have any idea what the standard spring rates are for an R32 (1992) Skyline GT-R? I have a set of Whiteline springs as part of the Works package for that car, but the shocks were out of stock for some time, so had the std shocks rebuilt. Unfortunately the rebuilt ones still aren't cutting it with a lot of bouncing at the front (suspension guy says it's cavetating). Here's the details of the Whiteline spring rates that I got from Whiteline:

Front (Whiteline #83157) - Linear spring : 191 lbs/in

Rear (Whiteline #70191) - Progressive : 150 - 204 lbs/in

or (based on basic conversion)

Front (Whiteline #83157) - Linear spring : 3.4kg/mm

Rear (Whiteline #70191) - Progressive : 2.7 to 3.6kg/mm

Sydneykid, I know you're pretty cluey on suspension setup, do these springs sound about right. Application will be street and some track work, with about 350-400rwhp. Car rides on 18x10's (cause I like em - http://www.ipixel.com.au/temp/p1-qf-r32gtr/) that weigh in at 7.45kg sans tyres. Getting shocks rebuilt again to hopefully clear up the handling probs, feel the shocks just aren't heavy enough for the spring rates.

Cheers

Brendan

[Gav]

Brendo - I think that you should swap those QF rims and rubber for my new Bilsteins!

[VSPEC32]

Hehehe, PM me about it Gav. But don't expect a reply ; )

[VSPEC32]

OK, managed to find out the standard spring rates for the R32 GT-R, they're as follows:

Fronts - Linear spring: 134lbs/in or 2.4kg/mm

Rears - Linear spring: 151lbs/in or 2.7kg/mm

Here's the standard shock absorber ratings - ie. damping force (at 0.3m (1.0ft)/s):

Front Extension side: 1,746N (178kg, 392lb)

Front Compression side: 500N (51, 112lb)

Rear Extension side: 1,106N (113kg, 249lb)

Rear Compression side: 402N (41, 90lb)

These measurements are taken from the R32 GT-R service manual (Australian version I presume cause it's english).

Cheers

Brendan

[Sydneykid]

Hi Vspec32, as you can see they are a good, not drastic, upgrade on the standard spring rates. For circuit work, they work very well with the Whiteline stabiliser bars. I would also have the full set of bushes on my list and removeing the HICAS is a must.

You really need to do the shocks, or you going Koni or Bilstein?

[VSPEC32]

Thanks for replying Sydneykid. I actually have the Works pkg sans shocks of course. So that includes a few bushes and the sway bars. Unfortunately I've just found out I'm going to have to wait for the shock guy to do another more appropriate rebuild due to family problems. For me to get the appropriate Whiteline shocks now it's going to cost over $1200, but I've paid $1K already for mine to be rebuilt : ( Suppose it's going to have to wait.

Is there a simple way of shutting down the HICAS on the GT-R, or do I need to install something like a HICAS Locking Kit (eg. Tomei). Thought I had read somewhere that it was possible to route the hydraulics back around on to itself. Also, would the subframe bushes (pineapples?) be a worthwhile addition? Was going to do it before but was advised against it due to noise (this was when the wife was driving it with a coupla kids in the back).

Cheers

Brendan

[Sydneykid]

Hi VSEPC32

The noise is not a problem. I haven't noticed any increase with pineapples.

You should do a search on hicas locking, there are a few good long threads about it on here.

Hope that helps

[VSPEC32]

Thanks Sydneykid, will look into the use of pineapples next time I head into the workshop. As for the HICAS, not much about what I may have read, but found plenty about the kits and the advantages. Might have to save up for that one after a decent intercooler and cam gears go in.

Appreciate all the good feedback.

Cheers

Brendan

[Sydneykid]

Hi Vspec32, following are some of my previous posts on HICAS;

I believe that removing the HICAS is a good move for a couple of reasons...........

Firstly I like to be in control of the rear end via the throttle. The HICAS computer is slow and dumb, ie; it doesn't act very quickly and only has limited inputs. So it does things too late and sometimes they are the wrong things. It tries to help the rear traction by steering the wheels and this works OK, but only for as long as the car is within the traction limits of the tyre.

Secondly, rear tyres don't like to be twisted around when they are already under a lot of side load and scrambling for traction. The HICAS movement of the tyre is enough to break the contact patch on the road and the car slides. Sometimes a little, sometimes a lot. Then the HICAS tries to fix that by changing the steering angle and the whole thing starts all over again.

So, to answer your question, sometimes the HICAS adds to the oversteer and sometimes it doesn't. That's the killer, with the throttle and suspension setup, I have consistency. This gives the driver more confidence and consequently you can drive the car closer to the limits (ie; faster).

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we remove all of the HICAS stuff of our R32 road/race cars. We replace the rear rack with an billet alloy block, shaped and threaded to suit. This locks the rear wheels and stops them from steering. Just pulling the fuse will still allow some movement under load.

We remove all of the pipes, hose fittings, mounting blocks and the rear (1) and front (2) solenoids. We then take the hose that usually goes from the power steering pump to the front solenoids and re-route it so the fluid goes straight through the oil cooler pipe.

Removing all this saves almost 30 kgs (including the excess fluid) and the car handles much more predicably on the circuit and on the road. None of the GTR's circuit race cars I have seen anywhere in the world (including the Gibson ones here in Australia) ran the HICAS.

Simple HICAS bypass kits are available from people like Jun, Apexi, Tomei etc. They have a couple of washers that stop the rack from moving and an electronic box that tricks the HICAS computer into thinking the rack is still working and so the dashboard warning light doesn't come on.

There are other kits around that have a replacement for the rack and a small bypass hose that goes between the two standard hoses at the rear rack. This makes the HICAS computer think the rack is still working and so the dashboard warning light doesn't come on. Stillen make kits like this for Z32's.

There are relatively cheap solid rear rack replacements available (eg; Japanese Motorsport) but the HICAS warning light comes on when you remove all of the other stuff. Some people remove the bulb to fix this problem.

My suggestion to people when they ask about HICAS is to remove it totally cause it saves weight and the car handles better. If they don't want to go to all the trouble and expense that involves, then I tell them to use a Tomei kit. Takes under an hour to fit by an amateur with limited tools. Whatever way you do it, the car will need a wheel alignment when finished.

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This is the Stillen rear rack replacement in billet alloy, similar to what we use on the race R32's

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Hope that helps.

[justinfox]

Awesome! Looks like I am going to stuff my HICAS too!

[Gav]

I was happy with the results gained from removing the HICAS also, it does add to the turning circle a little, though.

BTW - on spring rates, does anyone know the specs for the King springs used in the GTR? I have King/Bilstein combo fitted and these are quite firm (almost too much).

Sydneykid - I also have pineapples fitted set up for traction (using the small/cut rings on the front). Do you use these in this configuation or as per all round performance (ie large rings on the front)?

[Sydneykid]

Hi Gav, re Kings spring rates, that's why I use Whiteline springs.

Using the small pineapples to lower the front of the rear suspension cradle decreases the anti squat, so you get better rear end traction due to the additional weight transfer. This is a good drag set up or for people who want to decrease the oversteer a little. On the circuit we find this setup increases the corner exit understeer, so we mostly run the large rings, underneath all round.

Hope that helps