Irs into vk

[383 hatch]

The question is though, why would you?

 

[IMCRZY]

It won't pass an engineer. ADR stops that. No go other wise.

BS, i had a Vl with an R33 GTR 4WD coversion come in for a blue slip the other day & it was fully engineered, Approved by the RTA & emisions tested....

In other words 110% legal to drive on the road & 110% undefectable, When done properly anything goes

 

[soop]

The question is though, why would you?

Same reason people do most modifications I guess.
To get approval from interweb forum critiques. And a sence of validation from people who they've never met.

 

[Darren_L]

The question is though, why would you?

better handling ? A good IRS setup will outhandle any live axle setup
The panhard rod, live axle on Commodores isn't a great system, even a Watts link conversion would be a big improvement (something I've considered)
Sure the IRS on any Holden up to VZ is fairly crap
but I would adapt a VE IRS under the VH (if it is indeed possible), if I had plenty of cash to throw around

 

[sam5l]

irs

yeh thought i had seen it before yes well im going for handling ur right and i have 5 yrs till i get my license back so a big project is in order to role out the shed the day i get it back but i want to build something thats undone before so i have my resons u have yours no everyone wants a burnout car sure its fun but it just gets boring i love vks i just want a unique one that handles insanly after all there pre light and with good suspension dont handle that badly but with irs im sure it would make a big improvement

 

[Reaper]

Brock got an Opel system under a few VL's back in the day however none passed ADR's similar to a few other Brock modifications at the time. Anything can be done given enough time and $$$ but I suggest that if you have to ask, chances are its not something you should tackle. Beyond that, for a fast street/track car, it'd be very hard to beat a well setup live axle. Go visit Quatrant Billstein in Berwick (Vic), tell them you want a setup to make a VK handle and you will be amazed. Probably way cheaper than the IRS setup too.

Reaper

 

[383 hatch]

better handling ? A good IRS setup will outhandle any live axle setup
The panhard rod, live axle on Commodores isn't a great system, even a Watts link conversion would be a big improvement (something I've considered)
Sure the IRS on any Holden up to VZ is fairly crap
but I would adapt a VE IRS under the VH (if it is indeed possible), if I had plenty of cash to throw around

Holden Live axle is a better set-up than thier IRS IMO. The Commodore IRS is a pretty **** set up really, lot of work for no gain at all. I'd beg to differ on Holdens IRS set-up handling better than a well set up live axle. After all, how many purpose built circuit race cars do you see running IRS??

Atleast with live axle you don't need new rear tyres every 5 minutes...Unlike Commodore IRS.

Agreed that watts link is better than a panhard rod, but panhard rod isn't really that bad.

yeh thought i had seen it before yes well im going for handling ur right and i have 5 yrs till i get my license back so a big project is in order to role out the shed the day i get it back but i want to build something thats undone before so i have my resons u have yours no everyone wants a burnout car sure its fun but it just gets boring i love vks i just want a unique one that handles insanly after all there pre light and with good suspension dont handle that badly but with irs im sure it would make a big improvement

Who said anything about wanting a burnout car?

 

[Darren_L]

Holden Live axle is a better set-up than thier IRS IMO. The Commodore IRS is a pretty **** set up really, lot of work for no gain at all. I'd beg to differ on Holdens IRS set-up handling better than a well set up live axle. After all, how many purpose built circuit race cars do you see running IRS??

Atleast with live axle you don't need new rear tyres every 5 minutes...Unlike Commodore IRS.

Agreed that watts link is better than a panhard rod, but panhard rod isn't really that bad.

If live axles are so good, why did all car manufacturers progress from a live beam axle front suspension to independant front suspension ?

The worlds fastest rally cars all are fitted with IRS, the worlds ultimate road racing cars F1 and Champ Cars all run independant rear suspension. Only V8 Supercar and Nascar run live rear axle and then all your lower budget racers such as sports sedan, purely because of cost. Let's face it, if you have a 600hp race car, it's relatively cheap to setup a 4 link, 9 inch rear end (9 inch diffs are as common as Fords..) Compare that to the cost of custom building an independant rear end capable of handling the same power in racecar conditions.

V8 Supercars are going to independant rear with the future racer series, because it is a superior setup. The reason V8 Supercars have remained so long with the live rear axle, is because the series rules dictate they must. When the series was first developed back in the early 90's, most Commodores and Falcons were fitted with live rear axles. In an effort to avoid the cost of redeveloping an independant rear setup capable of meeting the requirements, teams could continue using the very same Ford 9inch based, camber adjustable hub, Harrop setup that the Commodores were using under the old Grp A rules. Nascar are primarily an oval circuit car, and the series has intentionally kept the cars simple eg carbed engines, live rear axle

Consider the worlds fastest, best handling factory street cars - Bugatti, Ferrari, Porsche, Lamborghini, GTR..... even GM's own Corvette, all run IRS - for good reason.
A good IRS setup will always be superior to a live axle. A basic fundamental concept of a good handling car is to maintain maximum tyre contact with the road. With a live axle what happens on one side of the axle, directly effects the other - eg l/h/s hits a bump lifting the axle on one side and pushes the axle down on the other, causing one side of the car to dip and the other to lift. IRS, each wheel is independant from the other, so this problem is minimised significantly.

Commodore IRS up until and including VZ is ****. It's a 30 year old, semi trailing arm design that was originally intended for an Opel with significantly less power. Even with the bandaid solution, toe control rods introduced in VT/VX, the wheels still toe and camber in excessively when the suspension compresses, due to the poor design.
However the double wishbone VE system is leagues ahead of any live axle setup on a factory car. Yes it will end up with uneven tyre wear compared to a live axle, but no more-so than front tyres wear.

The panhard rod system is terrible. How can a system where an axle moves sideways as the suspension moves be a good thing when it comes to handling ? Even the old Grp C Commodores were changed to a watts link system to avoid the bump steer issues associated with a panhard rod setup

 

[383 hatch]

Woah man, i can't be bothered reading all that... I skimmed over it though.

I'm aware there are cars with better IRS set-ups than a Commodore, however, the OP is intending on using a VT type set up which is rubbish to put it nicely. I can't see the point of going to all that trouble to end up with a crap IRS design, there is no point at all. Might aswell just stick with the live axle and make it handle (even if that means going to watts link, which will be a lot cheaper and easier).

If you are going to all that trouble, you would want to make sure it's going to be streets ahead of the current set up, with pre VE IRS is not.

You simply can not compare Commodore IRS to the likes of the Bugatti, Ferrari, Porsche etc., its no where near even in the same league as those set ups. Sure, if OP was saying he was going to fit one of those set ups (or custom fabricated) then by all means, go right ahead, but Commodore IRS? Come on....

I'd choose any live axle over Commodore IRS, any day of the week.

 

[Darren_L]

Woah man, i can't be bothered reading all that... I skimmed over it though.

I'm aware there are cars with better IRS set-ups than a Commodore, however, the OP is intending on using a VT type set up which is rubbish to put it nicely. I can't see the point of going to all that trouble to end up with a crap IRS design, there is no point at all. Might aswell just stick with the live axle and make it handle (even if that means going to watts link, which will be a lot cheaper and easier).

If you are going to all that trouble, you would want to make sure it's going to be streets ahead of the current set up, with pre VE IRS is not.

You simply can not compare Commodore IRS to the likes of the Bugatti, Ferrari, Porsche etc., its no where near even in the same league as those set ups. Sure, if OP was saying he was going to fit one of those set ups (or custom fabricated) then by all means, go right ahead, but Commodore IRS? Come on....

I'd choose any live axle over Commodore IRS, any day of the week.

I wasn't suggesting any Commodore IRS or Commodore for that matter, is comparable to Bugatti, Ferrari etc. Nor is your comparison with a race car. However as you are questioning the advantages of IRS over live axle, I'm pointing out the obvious advantages of IRS. OK let's compare Holdens to Holdens. An IRS VE vs a live axle VK with a similar power to weight ratio, on a twisty racetrack. My money would be on the VE, despite it's extra size disadvantage

The VE IRS is superior to any street car live axle setup. You may prefer the crude handling characteristics of a live axle (I'll certainly admit it's fun having the back end skating around, wheels spinning) but that doesn't make for fast cornering.

And agreed, I personally wouldn't bother with a pre-VE IRS conversion either (if I was going to that much trouble, I'd want something better) but set it up right and it's still going to out-handle a live axle Commodore. IMO that's a logical enough reason for the OP to give it a go.