'68 Camaro stock subframe mods......... - Lateral-g Forums

AWDPete · #1 05-28-2010, 10:24 PM

Hello all,

I just found this site about a week ago and have been looking for some info on modding the stock subframe on my '68 Camaro. Money is a big issue so I need to be frugal. It's not so much about appearance for me, it must work! I will be using the car for primarily autoX and big track venues, I want to be competitive! I gathered bits and pieces from different threads, and this is the conclusion I have arrived at - let me know if I am close?

Tall spindles or tall ball joints need to be used to correct geometry, are tall ball joints reliable?

Bumpsteer is an issue, can this be fixed with a power R&P?

I see coilover conversion kits, what will these do that a good shock and stock style spring can't do other then easily adjust ride height?

It looks like one of the bigger advantages of an aftermarket sub is the ability to run a wider wheel/more rubber. It's also probably stiffer and has better geometry.

Can I mod my stock sub geometry to be competitive with the aftermarket subs?

I've got tools and time, but not much money.

Tuske427 · #2 05-28-2010, 11:32 PM

Hi Pete:

Welcome to the site. There is a wealth of knowledge and knowledgeable folks here. I'm sure they can and will be able to help you out.

I'll try to offer what I can to help you out on your questions below. I'm sure there are others on there who can help you even better, but, since I'm first to reply, here it goes:

Suspension geometry isn't great on these cars as you know. One low cost fix is the "guildstrand mod". You can read more about it here:

https://lateral-g.net/forums/showthread.php4?t=20492

Bump steer, to my knowledge won't be fixed with a rack and pinion. I don't believe it has anything to do with it. Bump steer is the changing of your wheels direction as it travels through the suspension travel. Ideally, you want 0 bump steer, so your wheels stay pointed in the same direction no matter where they are in the suspension travel. Bump steer can change the direction of your car on you as you hit a bump, go around a curve, etc and can cause you to reduce/ lose control of your car. not good.

To fix it, you want to improve the suspension geometry. doing this optimizes the camber curve and eliminates bump steer. this is where I believe the correct length and located control arms come into play. the taller spindles help change the geometry of the stock suspension by altering the location of the pivoting points in your suspension.

The coil overs allow for quick ride height adjustment and may possibly reduce unsprung weight. Also, since they are a self contained unit you may not need a spring compressor for spring removal/ installation. then again, if you're careful (and I'm not advocating it) it is possible to remove and install the springs on the first gen f-body without a spring compressor.

I'd do more searches on the aftermarket subframes. It seems from my readings that many aftermarket frames are weaker than stock. You can weld up the factory subframe for increased stiffness. you can also do other things like use solid body mounts, subframe connectors, roll cage, etc. all these things in combination will substantially increase chassis stiffness. These are the types of things i plan do do to my car.

I think with the above mentioned stuff plus some research on this board you'll find all the tips/ tricks to do what you want. many of the aftermarket parts are for show and convenience as well. Like you said, you want function, not looks.

People raced these cars long before all these trick components came out and were successful. Hand built fabrication and ingenuity worked for them. I'm sure you can do it, too.

Of course, this is my opinion. Everyone has one. I hope this is helpful.

-Brendon

AWDPete · #3 05-29-2010, 07:57 AM

Thanks for the reply Brendon

That link is a GREAT find - Thanks for sharing!

You are the second person that has told me that "some" of the aftermarket subframes aren't that strong, must be some truth to it. While for me, finances determine I stick with the stock sub it's good to know it can be brought up to todays standards. The one limitation that still remains is tire size, correct? The aftermarket still holds an advantage.

I have already done some of the things you suggested: solid mounts, subframe connectors and a 6-point roll cage - these have really stiffened the car up! Some forward struts would really help alot. If you think about it the whole front subframe is held to the body with just 4 main bolts!

Vince@Meanstreets · #4 05-29-2010, 11:58 PM

weak aftermarket frames are still stronger than the stock ones.

I'd recommend getting your frame blasted and then weld all the seams. You will see why after you get it back from the blasters. We made a bunch of money fixin the stock frames.

They can be made to work very well.

Def recommend the guldstrand mod, and maybe a relocated lower arm to increase room for more caster ability. Get a good box, a 2nd gen fast ratio is a cheap and easy add on.

If you can weld make your own coil over mounts and subframe connecters.

Vince

AWDPete · #5 05-30-2010, 07:51 AM

Thanks for the advice Vince!

Welding the stock sub makes good sense - GM was a little stingy on the welds!

Tell me a little more about relocating the lower arms, haven't heard about doing this before? I planned on getting tubular upper/lower arms and tall spindles (haven't decided whose yet) - will these accomplish the same thing?

I already have a 6-point cage and solid subframe mounts. I installed some bolt-in Moroso subframe connectors many moons ago which I need to replace with some weld-ins.

I was thinking about welding up some forward struts as they seem to add quite a bit of stiffness right where it needs it most.

At first I wasn't considering coilovers for the front but the more I think about how the car will be used it's beginning to make more sense. Making mounts to accept a "standard" coilover also makes more sense $$wise then using one of those conversion kits, especially when it limits me to using a custom shock.

I like the idea of the 2nd gen box because it's inexpensive - it's just so darn big and heavy! Not sure if it will fit with the big-block?

coolwelder62 · #6 05-30-2010, 01:58 PM

The 2 gen steering box is no bigger in size than the 1st gen box. And if you really want the car drive it's best dont put a big block in it unless the block &heads are alum. or you're willing to move the motor back about 5-6 inches.You will have to much wt.# hanging over the axle centerline.Most of the after market subframes are built & engineered really well.And most of them work very well also.I have bought others sub frames & built my own from scratch. And been very happy w/ both.Scott

AWDPete · #7 05-30-2010, 06:39 PM

Hi Scott, thanks for setting me straight on the 2nd gen box. So the power box will slot right in?

The BB has been in there for quite some time and will likely stay there until I win the lottery! I know it's heavy but it's what I have to work with for now. It does have aluminum heads and I've got an aluminum rad, glass hood and inners and the bat is in the trunk, about as good as it's gonna get for now.

It's not that I don't 'want' one of the aftermarket subs, it's just not in the budget.

Vegas69 · #8 05-30-2010, 06:41 PM

You can hang with the LSX guys all day long with that big block. Concentrate on getting a well balanced chassis and the driver.

AWDPete · #9 05-30-2010, 06:51 PM

Thanks for the input Todd, wasn't sure if I was

or not!

I agree with you about the 'balance' - just not sure how to get there other than trial and error. That's why I'm asking for some advice from the people who have 'been there, done that'.

Maybe I should have asked this question: How do I get my BB '68 to run with the LS boys on a budget

Thanks for the insight

Vince@Meanstreets · #10 05-31-2010, 07:04 PM

Quote:

Originally Posted by AWDPete

Thanks for the advice Vince!

Welding the stock sub makes good sense - GM was a little stingy on the welds!

Tell me a little more about relocating the lower arms, haven't heard about doing this before? I planned on getting tubular upper/lower arms and tall spindles (haven't decided whose yet) - will these accomplish the same thing?

I already have a 6-point cage and solid subframe mounts. I installed some bolt-in Moroso subframe connectors many moons ago which I need to replace with some weld-ins.

I was thinking about welding up some forward struts as they seem to add quite a bit of stiffness right where it needs it most.

At first I wasn't considering coilovers for the front but the more I think about how the car will be used it's beginning to make more sense. Making mounts to accept a "standard" coilover also makes more sense $$wise then using one of those conversion kits, especially when it limits me to using a custom shock.

I like the idea of the 2nd gen box because it's inexpensive - it's just so darn big and heavy! Not sure if it will fit with the big-block?

Hi Pete,

The coil over part should be easy as you are starting from scratch. Find your desired stroke and build around it.

On the lower control arm you can either repocket or buy a tubular arm. We used to repocket before the arms were available. Most add caster and are available for coil over mounting. I'd say put your money there.

Also try to find a cheap LSX engine. They are popping up everywhere. Take a visit to your local engine machine shop. You'd be surprised on what you'd find poking around. Big blocks are great but if you can find weight loss without loss of power go for it. I found an LQ9 core for $400 and it would make a nice track motor.

Vince