IRS Camaros - Lateral-g Forums

mfain · #1 09-22-2010, 01:26 PM

I've seen several built or "under construction" Camaros with C5/C6 Corvette IRS's (like Tyler's 50/50 project). Does anyone have any reliable, real world performance comparisons between that configuration and a well prepared 3-link set-up. I'm looking for road course comparisons as well as braking performance. I am curious whether the lower rear roll center and the associated higher rear spring rates along with a further-aft center of gravity are making a significant difference in turning performance. Thanks.

Pappy

mfain · #2 09-23-2010, 01:02 PM

Looks like I need to narrow my question. Has anyone seen a first gen with C5/C6 independent rear suspension run on a track or autocross, and if so, what was your impression of the performance? Is anyone currently driving or building one of these cars with the intent of serious track time? Tyler?

Teetoe_Jones · #3 09-23-2010, 03:35 PM

I've got nothing to go on. You and I have been building our cars for a long time. I will say the reason I decided to do my chassis based on a C5 was because of the Mallett prepped 1999 Corvette that placed in the top 5 in the One Lap of America. I got to drive that car when it got traded in on a Porsche at the dealer I worked for.
That car was stupid fast, handled amazing, and was all I thought a race car should be.

That said, I'm going for an all out race car on my 50/50 project that I drive on the street. I hope that in time I can show cars like Bad Penny, Finch's yellow 70 Camaro, and Shipka's One Lap car some tail lights.

I don't know of any C5 based 1st gens running on the track that we could compare numbers on. There are at least 3 of them on the road though.

Tyler

mfain · #4 09-23-2010, 04:58 PM

Thanks Tyler. I'm getting closer -- built some longer LCAs for your ATS spindles and used a deeper offset front wheel -- that gave me a better scrub radius and allowed me to get a 315 on an 11 inch wheel up front with good turn radius. Also some interesting duct work for the oil cooler (inlet, diffuser, and air extractor/nozzle) and I'm finishing the underbody CF tunnels and belly pan. I'll get an update on my build thread soon. We need to get some of these IRS cars on the track, just for the sake of argument.

Pappy

Vince@Meanstreets · #5 09-24-2010, 09:38 PM

hey Pap, you have any build threads of your camaro project, love to see it.

Vince

Silver69Camaro · #6 10-08-2010, 10:00 AM

It's been said over and over that IRS cars typically only show a benefit over solid axles on bumpy surfaces, and ride quality is noticable on the street. IRS also allows you to adjust camber and toe, both of which are great things to have. But if you know what you are doing, you can do that on a solid axle as well. IRS setups typically wont have pad knockback issues either.

But, our cars just aren't packaged for IRS systems. If you want to chop the rear tin, go for it. Be prepared to run flat-faced wheels and narrow the IRS enough for the correct hub track.

If you want a all-out race car like Tyler, then I think IRS is worth considering. If it's a track day car, I wouldn't bother. But that's just my opinion.

Teetoe_Jones · #7 10-08-2010, 02:25 PM

Quote:

Originally Posted by Vince@MSperfab

hey Pap, you have any build threads of your camaro project, love to see it.

Vince

Quote:

Originally Posted by CamaroAJ

what has two thumbs and wants to see more pictures? this guy.

Here ya go you lazy bastards. It's a Corvette though, not a Camaro.

https://lateral-g.net/forums/showthread.php4?t=21031
https://lateral-g.net/forums/showthread.php4?t=20865

Tyler

Vegas69 · #8 10-08-2010, 11:35 PM

That's the problem with this whole PT boom and all the talk about what car or set up is faster. It's all about the DRIVER. This isn't the sprint cup series where it's less than a second from first to last. There are very few that are capable of setting there car up, wheeling it, and beating on it at the same time. I respect these high end IRS builds but having a functional car would be my first choice.

Gaetano, you talk a big game and may very well be the best road racer around these two sites. Practice makes perfect. Show up to RTTC next year and prove it. I seriously doubt you are 8 seconds faster than bad penny on a road course with an even playing field. That's a HUGE difference.

Vegas69 · #9 10-09-2010, 08:01 AM

I have no problem with an ego, I've got a fairly large one myself. I just want to see you show up to one of these major events and back it up. I'll be the first to congratulate you.

mfain · #10 10-09-2010, 08:48 AM

Thanks guys, I am enjoying the dialog. My primary focus regarding suspension configurations was to try to lower the rear roll center in a way that would force the rear of the car to do more work without making the car unusable on the street. NASCAR did it by putting the outboard panhard bar mount VERY low and close to the ground -- probably wouldn't work well on the street. With a Watts linkage, the moment center is at the pivot point of the link, so it is hard to move that down and keep reasonable geometry or to not get it too close to the ground. The roll (moment) center is very easy to control/change with an IRS. An "old style" set-up with a low front roll center and high rear, with stiffer roll resistance in front, can be set up well for specific dynamic conditions (lateral g, basically), but is not necessarily perfect for slinging the car back and forth in various turn radius turns at varying speeds (road course). There are lots of drawbacks to various IRS systems, and many can be outperformed by a well set-up 3-link; however, a properly designed, well sorted (not necessarily a bolt in deal) IRS should give the results I want (to answer Greg's question). Like most of you, I've had many early Chevy hot rods - 55-57s, Camaros, Chevelles - but as you know I'm also kind of a Corvette guy. I've had a couple of Vipers and I'm on my second C-6 Z-06 (a 2011 Z07 big brake car), and I see the geometry and tire changes they have made and the handling is beyond excellent. I am, by choice, stuck in the 60's, but I still want the cornering and braking ability of the new stuff. There is a lot of bantering about the IRS in a PT car, and its not for everybody, but I think you will find that a large percentage of the good handling first and second gen Camaros already have C5/C6 based front suspensions. Since I'm so slow at getting things finished (ackowledged,Todd), I am looking for IRS PT cars that are a little further down the road in making the handling improvements that I believe are possible.

Pappy