Help w/ set up. 68 Camaro still pushes a lot (understeer)

[Chad-1stGen]

Hey guys,

You would think that with two hits off the crack pipe (aka track days) in as many weekends I'd be sated. But like any true addiction I want MORE!

My car still probably has a lot left in it as far as differential between my car's ability and my own as a driver, but I'd really like to try and make some tuning adjustments to reduce the amount of under steer. I need your guys help.

Current set up:
68 Camaro at or near stock weight (have done nothing really to lighten weight and if anything have added sound deadening and a decent stereo, etc).

Front suspension:
Hotchkis springs PN 1907F 2" drop rate: 600 lbs
Hotchkis valved bilstein shocks
Hotchkis front sway bar, PN 2207F 1 1/8" hollow bar, not sure of anything like rate
SPC adjustable upper control arms
SPC lower control arms
AFX tall spindle (with arms fully shimmed still another 1" or so drop)

Rear suspension:
Hotchkis leafs PN 2407 (no rate listed on Hotchkis site that I could find)
Hotchkis valved Bilstein shocks

Tires:
Nitto NT-05 (get more than twice the life out of the rear tires than the front currently)

Alignment:
Caster: 5.5* /6* (road crown)
Camber ~-2.5*
Toe 1/16" in

I have a fair amount of pics and video up of recent track days.

Here is a pic from a recent track day of the front suspension under load:





Halp! I want to go faster and I want my front tires to last a little longer...

Time for rear sway bar? Time for different suspension components? Tempted to sell these parts and get a subframe that I can run wider front tires on and is all matched components.

Also, about ready to measure my AFX spindles and make sure I didn't get shipped short spindles by mistake...

[Matt@BOS]

Chad, have you talked to Carl to see what he is running? Since he is running Hotchkis parts, I was wondering if you're setups might be similar.

In any case, it might not be a bad idea to run a rear bar. These cars love to understeer, and as it is, you might be asking the front to do too much work in the turns, which would (I believe) end up with you overloading the front tires.

This site is great because it has a wealth of knowledgeable people, who I'm sure will chime in, and be able to provide better insight than myself, especially in regard to technical advice.

That said, the one bit of advice I feel confident in offering is to tell you to come out to an event where a suspension guru like David Pozzi or John Hotchkis, etc. is on hand to drive your car and get some first hand impressions. A car can push for a number of reasons, so while having a knowledgeable person tell you over the internet to add a rear bar is one thing, having them behind the driver's seat is invaluable.

I'm glad to see you've been out having fun with the car recently, and I hope you get something figured out,

Matt

[CarlC]

What are the tire sizes Chad?

[David Pozzi]

Looks like you have a good setup, I don't see anything wrong with it. Is the front end pretty light? What size tires & wheels?

[Gitter Dun]

First thing, how much time did you spend monitoring tire temps and air pressure? Are your tires wearing more on the inside or out? Secondly, these cars are known to be nose heavy. Have you corner weighted the car? I'm not going to get into tires yet because I think there is about a 1/2" in width difference between 255's and 275's.

I didn't see a rear bar listed in your rear suspension set up so I would say thats an easy way to get started. Another thing I didn't see was adjustable shocks.

I would start from there.

[zbugger]

I'd also like to know what the tire sizes are. Also, go ahead and try an adjustable rear bar. If you don't like it, take it off. But you may see a benefit in your case. Running wider front tires I doubt would help you any right now. Adjustable shocks are also worth looking into, especially since you do track the car.

Oh, and how do you like that tow hook? Any input on it? Any good pictures of it?

[MrQuick]

I agree, rear bar may help......Chad are you sure about that camber?

what is the height on the springs you are running? Maybe more travel?

[Gitter Dun]

I agree, rear bar may help......Chad are you sure about that camber?

what springs are you running? Maybe more travel?

I agree. That camber doesn't look like -2.5. Also, tire looked like it was rolling over.

[monteboy84]

A laser temp gun for the tires would help a bunch on checking to see if your camber and pressures are correct, but just looking at how much more rear tire you have than front, I'd throw a rear bar at it to try and strike a balance with that. If your car is pretty well stock in terms of weight and front/rear percentages, the high front percentage will give you understeer on entry.

-matt

[Chad-1stGen]

What are the tire sizes Chad?

Looks like you have a good setup, I don't see anything wrong with it. Is the front end pretty light? What size tires & wheels?

Tire sizes are:
245/40/18 on an 8" rim with 4 7/8" BS
275/40/18 on a 9" rim with 5.5" BS

First thing, how much time did you spend monitoring tire temps and air pressure? Are your tires wearing more on the inside or out? Secondly, these cars are known to be nose heavy. Have you corner weighted the car? I'm not going to get into tires yet because I think there is about a 1/2" in width difference between 255's and 275's.

I didn't see a rear bar listed in your rear suspension set up so I would say thats an easy way to get started. Another thing I didn't see was adjustable shocks.

I would start from there.

Not a lot of time on air pressure. I'm not sure what to do exactly. I've played around more in the past and the last two track days not at all. The fronts are rolling over slightly as can be seen in the pics at 35-37 PSI so going lower didn't seem like a good idea.

No rear bar currently.

I'd also like to know what the tire sizes are. Also, go ahead and try an adjustable rear bar. If you don't like it, take it off. But you may see a benefit in your case. Running wider front tires I doubt would help you any right now. Adjustable shocks are also worth looking into, especially since you do track the car.

Oh, and how do you like that tow hook? Any input on it? Any good pictures of it?

I like the tow hook a lot. Knock on wood, i have not needed it but it's a little more peace of mind out on the track. Install is easy and the bar is a spring loaded removable deal which is nice though I tend to leave it on full time. I will look for some pics I took of it and post them later.

I agree, rear bar may help......Chad are you sure about that camber?

what is the height on the springs you are running? Maybe more travel?

Well the front springs are rated at a 2" drop, arms 1" drop and spindle 7/8" drop however, I've added 2" worth of height increase to the arms so total it's supposed to be about 2" drop but I believe the arms are mislabeled and advertised and that they still are contributing about 1" to the drop for a total drop of about 3". The ride height is slightly too low. Though I rarely am bottoming out, I can tell when I do in my quarter panel vids because I also have slight rubbing and will see a puff of blue smoke off the tire when I do. I'm thinking about getting new lower arms to correct the ride height.

Also, I'm not 100% sure on the camber. I had the alignment shop set up my street camber at -0.75* and added two 1/8" shims for a total of .25" in equal amounts front and rear to the upper arm. Using a digital level i'm getting readings of between -2.5* and 2.75* static. Its quite a bit of camber to the naked eye sitting there, however this is also what makes me want to measure the spindle to make sure I didn't get ripped. In the pics my camber at compression should of gone up but it doesn't look that way. Would love to work with someone in the area with a home alignment to help me learn the ropes

A laser temp gun for the tires would help a bunch on checking to see if your camber and pressures are correct, but just looking at how much more rear tire you have than front, I'd throw a rear bar at it to try and strike a balance with that. If your car is pretty well stock in terms of weight and front/rear percentages, the high front percentage will give you understeer on entry.

-matt

Funny you mention the laser temp. I FINALLY remembered to bring mine last Sunday. But of course I only remembered to use it once and that was after the car had too long to cool (several minutes after parking in the pitts). I had readings of 119* pretty evenly across the front tire (inner, outer, center) but of course only measured the front right like a noob and on the clockwise track the front left is getting more work.

Thank you all for the help so far!

[killer69]

the tall spindles are 8 5/8 over all height.
your car dosen't look like it has anywhere near 4" of drop. i'm just sayin.
i would double check your camber 2.5 deg is a TON i only run 1.5 on my nova

what model of tire are you using

[Mkelcy]

Chad: I'm not seeing the camber gain I'd expect. Remember this thread? https://www.pro-touring.com/showthre...928#post597928

IIRC, the OLC uses the ATS tall spindles for camber correction, but shows a lot more camber gain than your picture does. I'd look at alignment and check the spindles. I have a set of the tall ATS spindles here if you need a reference for what they should be.

[Chad-1stGen]

the tall spindles are 8 5/8 over all height.
your car dosen't look like it has anywhere near 4" of drop. i'm just sayin.
i would double check your camber 2.5 deg is a TON i only run 1.5 on my nova

what model of tire are you using

Thanks Blake. Total drop is closer to between 2.5" - 3" not 4". The lower arms allow you to add spacers of 1" for a ride height change of 2" but I think they start off 2" lower not the 1" advertised.

I will measure the spindles when I get home tonight.

Tires are Nitto NT-05

Thank you

[Chad-1stGen]

Oh I remember that thread all to well Mike. In fact I didn't click the link cause I'm 99.9% sure of which one you refer to

I was wondering on camber gain too. Gonna measure the spindles tonight.

[MrQuick]

I agree with Blake.

To be honest, most of the cars we have set up in the past run 1 to 1.5 degrees. They tend to react differently with anything over 1.9.
We like to use the suspension components to increase camber during compression. You can have too much camber that the tire will loose contact patch and skid across the track. Exagerated a bit, yes but its a tunable problem. Since you do have SC&C arms you can play with adjustments.

Please, lets see some pictures of the tow hook. ; )

[Nessumsar]

By just looking at your picture it seems that the rear is unloading a lot of weight in the inside tire. To me that screams that you could use a rear bar; as it would help in to ways, keep more weight on the inside rear, and transfer less weight to the front left.

Would still have to figure out what is up with the front end geometry. I hope your measurements go well.

[parsonsj]

Rear sway to start. Change one thing at a time. Many have reported that a rear sway bar leads to a loose (oversteer) setup, but that means you need a smaller rear sway or a bigger front sway bar.

Leaf springs are tricky since they have a high roll center, which is why many claim you don't need a rear sway bar.

jp

[David Pozzi]

When checking camber referencing off the tire, avoid placing the level on the tire bulge at the bottom.
Most first gens with larger tires on the rear need a rear bar. This need is more pronounced with sticky tires..If you have adjustable shocks, you can stiffen the rears & sometimes do without a rear bar.

[Gitter Dun]

So all things mentioned here it's all going to be about how deep you want to get into it and I think everything mentioned keeps you from going over the edge for now with rear sway bar and adjustable shocks. I've been using the Hotchkis rear sway bar for years now and have no complaints. For the money, the QA-1 single adjustable shocks can't be beat IMO.

The only reason I would go with 275's up front is for tire rotation. It helps keep the costs down. If you do go to other wheels, research for the lightest wheels. Another reason I stick with 17's is for the weight of the rims and tires. rotational weight savings is huge.

Pick up an air tank and a good air pressure gauge. If you cant tell where to go with air pressure by feel pick up a chalk stick and chalk the entire edge of your tires before each sesson and monitor the wear pattern. The chalk wear will help you see if you are over or under inflated. You want you tires to wear evenly across the face of the contact patch. It looked like you could have used about 3 more lbs in that picture. I've never used the NT05's so I dont know much about them but this is what I do with the Toyos.......Max air pressure rating is 40 lbs so I shoot for 38 lbs hot. The tires usually grow 6-7 lbs when hot so I will put 31-32 lbs cold.

Are you going to make it out to Buttonwillow July 30th?

[Chad-1stGen]

I'm seeing a trend here with the rear bar comments. Now I just need to find someone with a Hotchkis TVS kit who will sell me the rear bar since most don't run them with just TVS parts. I've seen em on here from time to time.

Gaetano. I have same/simliar thoughts on 275's up front so I can begin rotating my tires between front and rear. I let Marcus at SC&C talk me out of trying this and getting the speedtech lower arms that I called up to order from him. He pushed me over the edge in choosing the SPC lowers over speedtech because they are supposed to actually have geomtry changes to them to keep the tire centered in the wheel well with high caster set ups which helps looks and rubbing. However, with the drop / ride height / rubbing problems I'm having and with the idea of running a wider front I'm for sure leaning towards finding me some lower speedtech arms (or TCI subframe if I go crazy :p).

Chalk idea sounds good. Will have to try that. Once I eliminate the potential for having received the wrong spindles I will pursue the rear bar as step number 1 I think before moving on to shocks. This is because I would think shocks help most with bump and transition but longer sweeping turns like Buttonwillow's riverside the shocks are not going to contribute as much right? Or am I off base here?

Thanks again to everyone for taking time to provide me valuable feedback/input.