Here is the factory rear suspension. Notorious for breaking the outer "stub axle" where the axle bolts to the hub.

 

Here's a member here Stony's 240z project. I really like this design and would do something similar on my project if I decide to get away from IRS.

What determines "squat" with a 4 link setup? Could I limit squat and how much would be reasonable? I'd really like to run different fenders, but this would limit the amount of travel I have available. The last picture shows the rear fenders I'd like to run. Is that feasible with a 4 link setup?

Justin

 

Oops, Here are the rear fenders I'm planning on:

Justin

 

sounds like one hell of a project, i love that black car and the fenders.

seems like you will be putting down some serious power, so most likely the 4 link is the way to go.

however maybe you should consider swapping to a different IRS if you want to keep the handling aspect?

i recently did a corvette C4 IRS swap into the back of my bmw. so far its working out well. And i'm scheduled to take it to the track next weekend

 

I currently have a Nissan 9.05" lsd diff and axles out of a 300zxtt. I can use this setup, but I'm really unsure how much power it will handle. It would be nice to be able to keep it IRS for handling, but realistically I am building a drag car that I drive around on the street. Solid axle is probably the way to go.

Justin

 

Usually, dragracers prefer the presence of "hit" or "separation" which occurs with a bit of rise...not squat...at the rear during launch. Unfortunately, this is very difficult to achieve with the geometry associated with an IRS. Not impossible, but very difficult.

So, you'd want 100%...or a tad more...of antisquat with a 4link adjustment. You'll find a spreadsheet at my site to help you with the setup.

Those sacrifices in handling...associated with a live axle...are very small and usually only detectable on a very rough road surface. One other matter: Rear wheel hop during braking is more common as you remove the squat. This is not a safety matter, as most of the braking is accomplished at the front, anyway, but is the reason why roadrace cars are usually set up with some squat.

 

Thank you for the information regarding squat. I will read through your site There is a ton of information there.

Can I stay with 4 X 4.5" bolt pattern?

What rear end assembly would you recommend for my power goals (1200-1500)?

Looks like RJ 4 link brackets would be really nice for this conversion.

Justin

 

I went 6.0's with a completely stock rear suspension and 26x8.5's hundreds of times in a 240, which is the same as yours. The only thing it would ever break was the u-joints in the half shafts if I got aggressive with it. Even had a welded diff too.

 

Back from the dead. car is almost done... hoping to take for a trip down the track this summer. will let you know how the rear-end works out. First 2 are videos click the pic to start.