IRS General Questions - 68 Camaro

[redefined]

It seems most people who upgrade the rear to go some sort of a link suspension and not to an IRS, is there a reason I'm missing as to this? Speaking for a street car that might see some road track time - coming from a guy who has road course experience in purpose built track cars. I'm really wanting the handling of say my M3 track car in this Camaro, but hey aren't we all?


To run the Heidts IRS it says it's bolt on, now I saw one guy doing it and he did a mini tub - is that needed? Must you do some version of a tub to run a good IRS setup? What about the Fast Track Roadster Shop IRS setup? This one does not appear to be bolt in and requires more customization and welding. With the width tires and rims they say this will run I'm assuming body modifications are required to accomplish this?


Any other solid IRS setups out there? Any reasons to pick one vs the other? One is bolt on but is the other worth the extra effort/time/money to weld it in? Keep in mind I'll be doing a front end as well, both of the aforementioned companies have 'matching' front ends also. I'd like to keep it all the same company unless 1 makes a better setup for one end then the other does.


Thought I had decided on the Heidts Kit but can't find a lot of information on the forums out there from individuals who are actually running it.


Thanks!!

[19,69camaro]

IMHO the Heidts irs should be used for street rods only. Its more show than go. Now Roadster shop is the real deal and they can make a full frame that you pretty much drop the body on, but its going to cost you a pretty penny.

There is nothing wrong with a well set up live axle. Just look up Mark Stielow and all the cars he has done.

[Todd in Vancouver]

In my opinion most of the folks on here are building the cars themselves and for myself I can tell you that I looked at it and then at the price and could not justify spending that kind of cash. It may very well be a bit faster on a track but, I'm not getting paid to race and this is a hobby. An expensive one, but a hobby. In an all out race there are other factors than IRS that come into play in determining the winner and all one has to do is look at the Red Devil vs ZL1 video to see what those factors are.

For myself the biggest investment to make my car faster will be me. I need to learn how to drive better and all the car technology in the world isn't going to help until I get better at what I'm doing.

If you got the coin and the time please do post lots of pics of the build because it is neat looking but I'm going to spend that cash amount getting my a$$ to some driving schools.

[redefined]

IMHO the Heidts irs should be used for street rods only. Its more show than go. Now Roadster shop is the real deal and they can make a full frame that you pretty much drop the body on, but its going to cost you a pretty penny.

There is nothing wrong with a well set up live axle. Just look up Mark Stielow and all the cars he has done.

Very interesting you say for street rods only. You say this because you think a live axle / link setup can be or is just as productive and less expensive?



In my opinion most of the folks on here are building the cars themselves and for myself I can tell you that I looked at it and then at the price and could not justify spending that kind of cash. It may very well be a bit faster on a track but, I'm not getting paid to race and this is a hobby. An expensive one, but a hobby. In an all out race there are other factors than IRS that come into play in determining the winner and all one has to do is look at the Red Devil vs ZL1 video to see what those factors are.

For myself the biggest investment to make my car faster will be me. I need to learn how to drive better and all the car technology in the world isn't going to help until I get better at what I'm doing.

If you got the coin and the time please do post lots of pics of the build because it is neat looking but I'm going to spend that cash amount getting my a$$ to some driving schools.

I 100% agree with your thoughts and I started in the same boat. My saying was "spend money on the nut behind the wheel". I have a lot of driving schools, track days, and racing under my belt. While this will NOT be a dedicated track car I want to take my time with this build and do everything once - don't want to mess with 100 diff suspension setups etc etc.

Good advice that every new track person should take though, 100% agreed!

With all that being said you're talking to someone that has only had more modern technology in his track cars. A solid rear axle is not something I've ever had to deal with which is why I'm asking these questions. To me a 4 link or 3 link setup seems to be 'dated' meaning other options would improve performance. Again I haven't dealt with this before so that's why I'm trying to soak up as much info as I can. I could be completely wrong and a simple link setup might be better for my situation.

[Ron Sutton]

As a race car designer, I don't see any of the rear suspensions as clearly superior over the other designs.

Each has pros & cons. I just look at the pros & cons for the application & decide which set of pros & cons fits the goals best.

[redefined]

As a race car designer, I don't see any of the rear suspensions as clearly superior over the other designs.

Each has pros & cons. I just look at the pros & cons for the application & decide which set of pros & cons fits the goals best.

Very understandable, thanks Ron. Based on my comments would you have a suggestion? Or happen to know of a good read to help me decide? Mostly a street car with a few road course events for fun per year (once completed heh). I'll stick to my kart for my wheel to wheel racing.

I'm also very interested in my questions on tubbing. Is this a must? Is there a line that is set in stone for tire size or goals where it just pushes you into having to do a mini tub or any type of tub in general?

[Ron Sutton]

Very understandable, thanks Ron. Based on my comments would you have a suggestion? Or happen to know of a good read to help me decide? Mostly a street car with a few road course events for fun per year (once completed heh). I'll stick to my kart for my wheel to wheel racing.

I am biased towards the solid axle, so I don't feel you'll get the whole story reading my side. I'll be as objective as I can be . After you read my points, hopefully someone who is knowledgeable, experienced & a proponent of IRS will chime in with their thoughts too.

IRS suspension pros:

Can isolate the harmonics from one wheel to the other, providing it doesn't use a transverse leaf spring.
Can be designed & tuned to achieve better tire contact patch & rear tire grip up to the car's cornering limits.
Less unsprung weight.


IRS suspension cons:

Must be designed & tuned to achieve better tire contact patch for the specific car.
Is complicated & tedious to tune, just like a typical double control arm front suspension.
Lot of work to move the roll center at the track.
More moving parts in drivetrain, lowering its capacity for power & shock loads.


Solid Axle pros:

Can easily provide more rear grip than the car needs.
Is simple, quick & easy to tune.
Easy to move the roll center at the track with adjustable panhard bar or watt's link.
Less moving parts in drivetrain, raising its capacity for power & shock loads.


Solid Axle cons:

Transmits a degree of harmonics from one wheel to the other.
More unsprung weight.





I'm also very interested in my questions on tubbing. Is this a must? Is there a line that is set in stone for tire size or goals where it just pushes you into having to do a mini tub or any type of tub in general?

This is outside my wheelhouse. Hopefully other people with knowledge & experience in this area can answer this.

[redefined]

Thanks Ron, I appreciate the info!

[Schwartz Performance]

Minitubs are recommended with any pro touring car, simply because you have more tire contact! There are many guys running 275s in the back of first gens that do great around the track.. But then you see DSE running 335's at every corner so there's something to be said there too.
Not to mention wide tires look killer, too. :)

-Dale

[shawnvan]

http://http://m.youtube.com/watch?v=jm8EvhX_2WM
If I did this correctly