Editing Rear Camber

[[Category:Steering & Suspension]]

The IRS system in S13 & R32 is completely different to the R31.

R31 = semi-trailing arm independent rear

R32/S13 = multilink independent rear

The R31 shares the same setup as a number of oldschool cars... 910 bluebirds, datsuns 280Z, and Z31 300ZX, even VP commodores have this style of IRS system, though the VP's arms are fitted straight so the wheels don't camber when slammed out.

This system consists of a crossmember at the back that is fixed to two big threaded pins that stick down off the body (with bushes), and fixed to this crossmember is a Y shaped trailing wishbone on each side containing the hub & brake assembly etc. The long nose of the R200 LSD is bolted to the top of the crossmember, and the back of it is mounted to the chassis. Lastly, the trailing wishbones each have a mounting point for the struts.

Due to the shape of the crossmember (it's a bent shape) & where the wishbones bolt on, the wishbones are on a diagonal pivot. This means that as the car is lowered, the crossmember lowers, and the wishbones pivot upwards. Because of this diagonal pivot, the wishbones tilt up and slightly inwards too, thus negative camber results.

The inside mounting point of each wishbone uses a cam bolt which can be adjusted to change the toe by a couple of degrees. The bolt passes through a slotted hole, and an offset (cam) washer sitting inside of a couple of retainers is what pushes that part of the wishbone back or forward.

[[Image:Camber_9.jpg]]

The simplest way to get camber adjustment, is to perform the same cam bolt mod to the outside wishbone mounting point on your crossmember, only spin the design 90 degrees so the cam bolt provides vertical adjustment. This would then provide the required camber adjustment... it would be a relatively cheap mod to do. Just get a local engineering shop a box of beers and 50 bucks on a friday morning, so they can do it during the day and give it back to you after work & have a beer !

I've been offered a relatively sophisticated mod for pretty cheap over here... a race engineer has offered to modify my wishbones, cutting off the tops of the Y arms, and replacing them with adjustable tierods & modifying the crossmember to have the vertical adjustment at each point. This will allow me to fully adjust toe and camber in two different places, on each side, by a large amount ! This is superior to the R31 House adjustable rear wishbones which only have this setup on one arm of each wishbone, and will cost less than 1/6th the price of their exorbitant product !

[[Image:Camber_8.jpg|thumb|200px|R31 House Rear Camber Adjustment.]]




The trailing IRS system is not bad, it just doesn't provide much adjustment. When you floor it around corners, the added negative camber from the weight transfer can be beneficial to digging the wheel in and pushing you around that corner better !

R32/S13 on the other hand, have a big four-point mounting subframe, with arms and rods and links and adjustment all over it. I haven't really played with one so I'm not that qualified to say... but basically it's a different and more complex design, with a lot more adjustable aftermarket parts available for it.

From a technical standpoint, multilink is better... from a performance & street perspective, you'll notice very little difference if at all, in the handling of both generations. Some of the 31s on here with the mad coilovers and good bushings etc (like mine will be  Cool) will absolutely dick on R32s in the handling department... it's only when you start getting to the serious competition modified level that you'll really get differences coming through... but a well set up street trailing IRS R31 will be just as potent as a later model multilink.

^^ Hope this helps

==Pictures==

Ok I have taken the liberty of modeling in 3d an example of what I'm talking about... the inside of your crossmember already has this, but turned 90 degrees to create forward/backward movement for toe. What I have modeled is to show what needs to be done on the outside flange of your crossmember to allow for camber adjustment.

===One Extreme===

[[Image:Camber_1.jpg]]

[[Image:Camber_2.jpg]]

===The Middle===

[[Image:Camber_3.jpg]]

[[Image:Camber_4.jpg]]

===The Other Extreme===

[[Image:Camber_5.jpg]]

[[Image:Camber_6.jpg]]

[[Image:Camber_7.jpg]]


'''Compiled by:'''

Mettler


'''Pictures by'''

3D modelling from Mettler, Rear Crossmember from Dave 31GTSR