[HWYSTR455]

The gain is well worth it, and it's a heck of a lot less than a full frame/suspension kit.

At some point, you would want to do a brake upgrade, and the AFX spindle is one of the best ways to get it, most cost effective too.

Control arms you would want too, if you're goal were to improve handling/performance.

The only real issue is that a lot depends on going with the AFX setup, which is a little steep for a one-time shot in the wallet. But down the road, you could very well save by skipping the 'intermediate' setups.

Would you balk if your daily driver needed $1500 in struts or cats/exhaust to pass inspection (example)? You would look at the cost differently, wouldn't you?

Have you ever said "I should have done xyz from the start, would have saved alotta trouble". This is one of those things.



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[Scarebird]

SC&C had a nice affordable setup consisting of 4 tall ball joints and upper control arms. It placed the steering arm in the right spot height-wise.

HWYSTR455 may have better knowledge of recreating this setup.

[HWYSTR455]

The SPC/SC&C stuff is good, but can be confusing to choose/config. I did the homework on it a while back, will give my 'opinion', but it may be a little dated.

You can choose a lower tall BJ up to a 1/2" without having to change out the lower control arm.

To get max benefit, you should use both the upper & lower BJs with the upper & lower control arm.

The setup uses stock spindles and steering arms, and the control arms are @ $1200 for uppers, $1700 for lowers:

https://www.spcalignment.com/compone...tion&pid=97110

https://www.spcalignment.com/compone...tion&pid=94344

They might be available from others for less, but those are the prices SPC lists.

You can use a tall spindle upper control arm from other vendors, but at your own risk.

The gain, when measured by amount of additional caster, is nominal (@ 3 degrees).

The original spindles may be a weak point under hard use, 'seasoned' spindles can be compromised (bearing & seal area wear, structural integrity)

In order to do some types of big brake kits, you have to mod the spindles. Also, going to big brakes can push the wheel out making it more difficult to source wheels. (You may even have to change existing wheels, depending on the brake kit, but usually almost all kits require larger diameter wheels)

The bump steer is still archaic and could be improved with a bump steer kit from other vendors.

There is no to little ackerman gains.

The end results is still nowhere near as good as the AFX setups.

You still have to pack wheel bearings, and still have the maintenance, more so in hard use.

My opinion is the GW spindle would be a better option, but it still uses legacy wheel bearings:

https://www.globalwest.net/kit423-ne...1-spindle.html

Not to mention, it's $6500-$7700.

When you look at all the options available, the AFX setup is the most cost effective, and has the best performance gains, without going to a full frame kit. Full frame kits are $12-$15k+.

All new AFX uprights come with the upgraded 'vette bearing, and those are race-ready.



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[chiphead]

Looking into the same thing, and I'm trying to find the gotchas in the SPC/AFX setup.

What steering arms should be used with the AFX spindle? In doing research, several posters on GM websites (mostly camaro/Nova builds) struggle to find steering arms that clear 17 or 18" wheels, 5-5.5" backspace and the AFX spindle.

What about wheel selection for the AFX spindle? Does the AFX spindle/vette rotor push the wheel mounting flange inward? What backspace is typically required to properly locate a 17 or 18" wheel in the wheelhouse?

What springs should be used with the SPC/AFX? By the time you add the .5 ball joint drop, the 2" A-arm drop, the 1" AFX spindle drop, the 1" SPC spring drop, the headers will drag the street. The SPC spacers aren't going to offset all the drops. Can you use other brands of spring with the SPC arms? The SPC lower doesn't require a special spring purchased from them, does it?

Is it necessary to use the SPC uppers and lowers together? Is there a downside to using less expensive LCAs? Other than how the SPC lowers allow the use of spring spacers?

Do the SPC lower control arms have the travel stops for the steering in A-bodies?

Does the corvette brakes require any changes to the brake hydraulic system? Will the 71-style GTO power disc brake setup work? (I've got later style combo valve below the master)

What steering box? I've got a borgenson 12.7:1 box coming for this build, seems to be well recommended.

[JLMounce]

On an A-body with the AFX spindle, you want to use SpeedTech's steering arm. It corrects bumpsteer and adds a good amount of akerman. You "can" use a factory arm, but you end up with some wonky bump steer on the A-body platform.

The AFX spindle has about 1" of drop built in to it, so if you're targeting a 2" drop, you want to go after springs that are a 1" lower drop. You can use any conventional spring here, it doesn't have to be the SPC spring.

In regards to using both the upper and lowers, you don't absolutely need the lower control arm, however it's beneficial to have. The SPC lower has about 2* of positive caster built into it. This does two things. It first allows you to run more positive caster without setting the adjustable uppers at a point where you're starting to lose threads in the adjusters. The second thing it does is recenters the wheel in the wheel well. By moving the ball joint position forward, you are counteracting the rearward movement of the wheel by adding positive caster in the upper control arm.

It's still possible to achieve about 5* of positive caster with just the SPC upper, but depending on the wheel and tire size, this may create rub as the tire is moved towards the rear of the car.

The lowers on my car do have a travel stop integrated into the lower arms.

Your steering box choice is fine and the corvette brakes if you go with an AFX spindle would need a 15/16" master for manual or a 1" master for power assist brakes. The disc/disc combination valve is fine for most instances.

[HWYSTR455]

What he said! Heheh! Didn't get a notification for the other post, but was going to respond.

What I will add is this, that the SPC uppers do not have a cross brace, and there can be deflection in them. You get the same benefits from the GW 42A or the Speedtech upper, both are less than the SPC offerings.

I suggested the knock-off lowers over using the factory one, deflection on the factory arms are ridiculous. You don't get as much camber advantage, but in most cases you may not notice anyway. I believe the GWs and the knock-offs have 1 degree built into them, but I would have to go back and look to be sure of that.

There's no significant advantage to running tall ball joints with the AFX spindles, just to say it out loud. Never thought of doing that, but if you have questions, call Speedtech and ask. It may not even be supported.

With the GW uppers and lowers, AFX spindle, at 4-4.5 degrees caster, the wheel is not noticeably not-centered in the wheel opening in my config.

Another thing, I have no issues with the steering arm (contact) with 18x9s and 5.31 backspacing. There's even room for more when it comes to the steering arm.


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[HWYSTR455]

Oh, on the drop, the control arms don't provide any drop that I'm aware of.


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[JLMounce]

Originally Posted by HWYSTR455

Oh, on the drop, the control arms don't provide any drop that I'm aware of.


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The SPC lower arms have a dropped spring base. Without the use of their shim kit, the lower arm will drop a stock car roughly 1". If you are going to some sort of coil-over where the mount would exist on the flat of the spring base, this would drop the car about 2" as the spiral spring perch is removed completely.

The standard shim kit comes with 2, 1/4" spacers that will adjust ride height up to the factory ride height. You can add additional spacers to the lower or upper pocket if you need, or run a combination to dial in ride height to .5" increments.

This is one area of the SPC arms, that can be a bit challenging. You have a lot of options to dial the ride height, but when dealing with conventional springs, it does add time in labor and guessing to get it right. Especially when taking a car from an antiquated and likely sagging suspension system, to new and modernized.

I don't really like to spend other people's money, but if the budget could handle it, I'd spec a true coil-over from SpeedTech as well, using their Chicane mount.

https://speedtechperformance.com/pro...arrior-shocks/

The Chicane brackets tie directly to the upper control arm mount and adds strength there while providing a double sheer mount for a control arm that is actually stronger than the factory upper spring perch. This is unlike the RideTech and other coilover conversions that use the factory shock mount to hold the weight of the car. That piece is fairly robust on GM cars but it wasn't really designed to hold the weight of the car itself as a stamped steel piece.

[HWYSTR455]

Oh, I get it now. Well, all the tubular lowers have that, even the knock-offs, and accept the 'shims' for adjustment. Pirate Jack has a set that some of the most affordable I have found:

https://piratejack.net/1964-1972-che...-shim-spacers/

Keep in mind that the amount of height increase is double the thickness of the shim/spacer.


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[JLMounce]

Correct, the motion ratio of the factory GM short/long arm suspension is just about 2:1. It's not quite, but near as makes no difference. 1" of motion at the spring is equal to 2" of motion at the wheel.

And yes, even the china copies typically have the lowered spring pocket. The ones we used on my wife's chevelle did.

[chiphead]

Thanks for the explanation. So I'm pricing it out.

When I add up what a SPC/AFX/18" wheel conversion will cost, it adds up to about $5500.

I can do UMI/AFX/18 wheels for roughly $4700. So the price difference is roughly 700-1100. I can put that toward the springs/swaybars.

Will I notice the difference between UMI and SPC? My application is spirited street driving and backwoods carving but no auto x. What combo provides the best ROI for a street car?

[HWYSTR455]

Like I said, the knock-off tubular lower arms are fine, I run them in the 442, held them right next to a set of GWs and measured roughly without seeing any diff. Again, just change the ball joint.

The uppers is where certain arms come into play, there are differences, especially for an AFX spindle. You can save money on the lowers, but recommend getting an upper specific to the AFX spindle.

The UMI uppers I think come with tall ball joints, but can't remember.

The Speedtech uppers are $40 more than the UMI. Save the money on the lower, get the knock-offs, and spend an extra $40 for the Speedtech uppers. You might even get a deal from Speedtech if you're buying the spindles.


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[HWYSTR455]

The Global West ones are right inbetween those two in price:

https://www.globalwest.net/cta-42a.html


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[JLMounce]

Originally Posted by chiphead

Thanks for the explanation. So I'm pricing it out.

When I add up what a SPC/AFX/18" wheel conversion will cost, it adds up to about $5500.

I can do UMI/AFX/18 wheels for roughly $4700. So the price difference is roughly 700-1100. I can put that toward the springs/swaybars.

Will I notice the difference between UMI and SPC? My application is spirited street driving and backwoods carving but no auto x. What combo provides the best ROI for a street car?

How would you grade yourself as a performance driver? If you're a fairly average driver, on the street with a typical street tire, you're probably not going to notice a difference. If however you've spent a bit of time in real high perfomance driving events, racing schools etc. and you're running something like an Falken Azenis, R888 etc, you're probably going to come up against the car's limit.

These cars plow by nature, especially when you give them grip in the rear. That's going to be what you end up fighting as you get comfortable with the car. It's just the nature of how these things are built with tons of weight forward of the front wheels.

You counter this by adding a lot of negative camber gain, a lot of positive caster, and as much of the stickiest rubber you can fit in the front. This is where the SPC items will have an edge, with the ability to run quite a bit more positive caster.

So I think answering this question really is posing another question. How serious are you about how the car needs to perform? If this is a weekend toy that you can take through the hills and have some fun, I'd save the 1000-1500 and put it elsewhere. If you're trying to keep up with the modern stuff at Deals Gap, you're going to want to spend the extra.

[rohrt]

Did anyone happen to see this yet?

https://ridetech.com/product/gm-afx-hub-spindles/


I went with both upper and lower SPC arms on my 68 FB and just upper SPC arms on my 64 Tempest. I can't really say I love them. They have their pros and cons.

The SPC lower BJ is 1 deg forward to allow more caster. I use to have some tire rub on one fender. Now I have no rub and 5 deg caster dialed in. MY 68 is a mis-match of parts but it handles pretty good now considering its on 235/60/15 tires.

When SC&C was still around Marcus always suggested going with the SPC upper arms and keep the stock lower arms. The upper arms have the tall BJ and the adjustability to increase caster, so this makes sense for a mostly street driven car.
The SPC lower arms have a lowered spring pocket. I had to use several shims to make them work with my 2" lower Ridetech springs.

[HWYSTR455]

Yes, I've seen the Ridetech ones, and the CPP ones. I have firsthand experience with the CPP ones, pretty sure I posted that info here, originally bought them for the 442, and they were near unusable. It would have been better if I kept the original suspension on that car. And to fix it, I went to the ATS/Speedtech AFX spindles and arm.

After looking at the SPC lowers, and the Ridetech ones, it appears the pocket is dropped lower than others (drops 1" off ride height). I guess they did that to better accommodate coilover conversions, but just guessing.

You start stacking 1" here, 1" there, and drop spindles, it adds up. Keep in mind that the optimum location for a lower control arm puts it parallel to the ground. That puts it in the starting position where it's in the range of motion that the suspension was designed around.

Ridetech spindles are too much drop (2"), like many of their' products, and much like the CPP ones (I think they drop 1"). You have to add the $150 for 'standard' brake caliper brackets, $450 for the wheel bearings (and that's just for the regular vette bearings not the upgraded ones), then you need to figure out which steering arm to use. So your very close to spend as much for the ATS/Speedtech stuff, or more.

SC&C/SPC took the F/B-body spindle swap and did it with the tall ball joint approach, using the original A body spindle. Since the uppers have adjustable rods, you avoid having to stack shims in some cases. But like I said, there's deflection in that.

I still don't think it's a supported config to run tall ball joints with ATS/Speedtech AFX spindles, and there's no need to. The more drop built into the spindle will tilt the wheel back more as caster increases, and adding a tall lower BJ will make it worse.

The ATS spindles have a 'street performance' alignment that is 4-4.5 caster, which is plenty. You can go 5+ but will depend on the uppers you use. I'm at 4.25 on both the GTO & 442 and it's great, plenty good for aggressive street and some autocross.

There's no caster 'improvements' in the arms like Speedtech & GW (just checked), and they are specifically designed around the ATS AFX spindle. All the 'magic' is in the design of the spindle and steering arm.

I still believe the Speedtech ATS/AFX spindle and either the Speedtech or GW arms are the best bang for the buck without going to a full (or partial) aftermarket frame.


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[chiphead]

So far, the biggest "gotcha" with the AFX spindle is the need to run large wheels. I looked on their website, and on the steering arm page, it says their steering arms will not fit with 17" or smaller wheels.

https://speedtechperformance.com/pro...mp-steer-kits/

As far as my driving skill, I'd guess I'm slightly above average (who doesn't?) but I've got no track time. I've got no frame of reference other than my '15 Charger RT, which I think is amazing other than the stock 20/45/245s are a little undersized for the power. I understand how a good suspension should handle, in theory. All my other vehicles have been trucks or stock classics. My first car was a '54 Bel Air, which makes a dump truck seem like a Porsche. Steering on one of those has got to be 7 turns lock to lock. I also had a '73 International Scout II, which rode like a stagecoach, minus the horse.

The current LeMans has a worn out front suspension, drag springs, CE drag shocks and 215/70 tires on 4" Prostars. 275DR out back. (PO setup). Anything over 70 feels like I could die at any moment. I'll still throw it into a curve at high speed and hacksaw it through, but I can tell it's not right. That's the whole reason I'm not setting this car up for drag racing, because street handling sucks so bad. I'd rather drive it on the street and enjoy than suffer 90% of the time for 10% drag use.

Any long-term reliability concerns with the SPC uppers or AFX spindles?

[HWYSTR455]

I purchased the ATS spindles when ATS was still holder of the patent, and actually talked Tyler into making a steering arm for the A bodies. Pretty sure that thread is here, but may be on Pro-Touring.com. Tyler's main interest was for his 67-69 F body. At that time, he worked directly with Doug at GW to design and make the tubular control arms, lots of R&D went into those, not just a copy of the OE arm in tubular form.

Originally, the ATS AFX spindles used F body ball joints, but when Speedtech picked the rights up, they modded them to accept A body ball joints.

Anyway, I can say that with the ATS spindles and GW arms, the suspension rivals C5/C6 vettes. It brings the car(s) into modern territory, and along with an OD trans, is better than a lot of later model performance cars.

Having to upgrade brakes is not a 'gotcha', it's a blessing. Many wanted big brakes before any suspension enhancements kicked off with what is now called 'pro-touring'. Once your car has more power and better handling, you pretty much NEED big brakes. Once you reach that realization, looking at big brake kits will make your head swim and your wallet sweat, especially if you have to go back and replace stuff you recently upgraded.

I can say hands-down, the AFX setup is the one 'best' upgrade I've ever done, even more than adding more power.

Aftermarket control arms are way more reliable than OE, no worry of stress fractures, ball joints getting loose in the hole, and no/little deflection. I daily drove my LeMans for many years (@ 1991-2014), and beat it in the worst conditions imaginable. I've tried many different parts, most documented here, and yes, the AFX setup is the 'best' upgrade I've ever done.


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[JLMounce]

To piggy back on that, you also want the large wheels. The added hoop diameter starts putting suspension components of these cars inside the wheel, which gives you more clearance to run wider wheels and more rubber. Options for performance tires for 15" wheels are basically non-existent, except for drag race stuff.

If your goal is handling and all you ever want to run on these cars is a typical 235/55/15, there's no reason to spend thousands on suspension at all. Put a half inch tall ball joint in the stock upper control arm, add a sway bar and some decent shocks and call it good. The tire's limitation makes going any further than that a bad ROI. Once you get into 17" plus wheel sizing the tires you have available to you become worlds better. I know that not eveyone likes the look of big wheels on these classics, but it really is a case of form following function.

[1968GTO421]

Originally Posted by JLMounce

To piggy back on that, you also want the large wheels. The added hoop diameter starts putting suspension components of these cars inside the wheel, which gives you more clearance to run wider wheels and more rubber. Options for performance tires for 15" wheels are basically non-existent, except for drag race stuff.

If your goal is handling and all you ever want to run on these cars is a typical 235/55/15, there's no reason to spend thousands on suspension at all. Put a half inch tall ball joint in the stock upper control arm, add a sway bar and some decent shocks and call it good. The tire's limitation makes going any further than that a bad ROI. Once you get into 17" plus wheel sizing the tires you have available to you become worlds better. I know that not everyone likes the look of big wheels on these classics, but it really is a case of form following function.

Assessing my actual real needs (and my age over 60) I believe this is the best advice for my GTO. The only question would be who is a good source for the 1/2" taller ball joint? Or would I do better to just get a new upper arm with the taller ball joint (Global West)? Thanks.