Suspension setup for dedicated drag car

Hey Guys.
So we all know that IRS isn't the best option for a drag car, but that's what I have, so im going to go with it, I don't plan on breaking records, but just to have good fun going in a straight line :br:
So im after a bit of a point in the right direction in regard to suspension set up.

I understand that there is a lot involved, pending on power, torque, tire size and all that, and its still going to be a fair way off yet, but, it will not be used as a street car, only used for drags, lets say 550-600 HP at the wheels, 2 Speed power glide and transbraked.

At the moment, as far as I have looked, the doner car suspension wise is pretty stock looking, but it has had the HICAS locked out.

So guys, any help, advice, opinions and ideas would be greatly appreciated,

Thanks heaps.

Col

 

Everyone will have their own opinion but with my own car, which is also being built for the strip, will be running factory suspension.

 

You'd want to flatten out your mounting points for the rear lower arm and iron out that anti-squat the zed is so (in)famous for. That for me would be your single greatest modification for off-the-line traction.

 

Thanks Guys.
AndyMac, what do you mean by flattening out the mounting points?

I understand that IRS cars need to squat to bring traction onto the rear, whereas solid axle cars "seperate" pushing the tires down.

But I'm guessing to get the best out of IRS it's just not a matter of running a soft ass end.

Cheers.

Col

 

JUN

JUN in Japan were marketing a rear subframe for drag racing.
Perhaps Rob260 could get you one.

 

The rear lower arm is mounted to the subframe at slight angle to reduce squat. As downward force is applied to the corner, the force is distributed down and back in an effort to reduce "squat". I suppose it's an attempt to reduce body roll without compromising ride quality.

I can't remember the angle, but it's significant, from visual memory it's about 5 degrees.

Ask Blackbeast, he's modified his.

 

Thanks AndyMac.
Yeah I think I remember seeing pics of that on his build thread.

 

Yeah I had a bit of a search, I have found what they call a "Drag Member" but nothing designed for the 300.
Only could come across S13 and R33 etc.
It does look like they have been getting good results with it though.

Cheers.
Col

 

Anti squat

For Drag Racing you need Anti squat , difficult to get enough with IRS , all cars need tyre body separation (powerful ones anyway) all you can do is try to reduce the IRS collapsing which is what the Drag member claims to do , but unless you are forced to run IRS ( class rules) probably a good idea would be to start collecting parts to build a 4 link , Powerglide 1.82:1 or 1.73:1 will help by reducing some start line ratio , or you can buy a valve body for the T400 that has a brake on 1st or 2nd 2.48:1 or 1.48:1 , something else you can do is 90/10 shocks in the front , but with that much power the front wheels should be off the ground anyway.

 

Thanks pmack
Yeah fitting a 4 link would be nice, but I'd have no idea as to where to start
By all recommendations id say I'll be going with a powerglide, but nothing is set in concrete yet.
Thanks again

Col

 

The stock irs comes alive with bias plys. Should be able to cut sub 1.5 consistently. 1.2x has been done before

 

Ok, sorry but what the hell is bias plys? Lol

 

Period correct street tyres for 60s muscle car ? That's my understanding

Must mean something else in the drag racing circles


Edit. I get it. So non radial tyres. No steel belts. Soft sidewalls

 

ahhhh yes, after a search.. The flex is transmitted to the tread,
So a purposely made drag tire