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Discussion in 'Autocross/Road Course' started by Turbo6inKY, May 8, 2016.
Do the Ridetech upper and lowers do the same ?
That last run was very smooth. And I didn't hear any tire squealing... Nice run!
After I put on some new tires and wheels, I notice my rear wheels appeared to be out of round. But it turned out that both my axle shafts were bent. Rebuilt my rear end...and no more wobbly wheels.
The SPC arms from SC&C allow for the most caster and camber adjustments that I am aware of.
Not only do the UCA and LCA SPC/SC&C arms relocate the pickup points to a more favorable position to help correct many of the front geometry issues, including bumpsteer, but the lowers have built-in caster that actually locate the wheel into a more central location in the wheel well, allowing you to run as wide of a tire as you can fit inside there without hindering the caster/camber or performance.
SC&C were the first guys to use the taller ball joints, then everyone copied them. The key is that they are not only taller ball joints, but the actual locations of the ball joint on the arms has been changed-these are a ground up design, not a tubular version of stock arms- and by doing so they were able to fix many of the inherent geometry issues in the g body.
You don't necessarily need the lowers if you get the Stage 2 Plus UCA kit, which gives you the taller ball joints for both the upper and lower arms. This helps address the majority of the geometry and bumpsteer issues. If you want the extra caster the lowers are needed. They locate the wheel into a more central location, and allow you to run more caster.
I would call SC&C and talk to Mark if you get a chance. The guy did write the book How To Make Your Muscle Car Handle, afterall...and he is a huge G-body fan! Wait until you see what they are coming out with in terms of high performance rear ends for these cars....
Great info. Thanks
The RideTech and SpeedTech arms provide similar amounts of additional caster, but nowhere near what the new UMI racing arms are supposed to provide. The OE arms gave you 2 degrees of caster, and you could maybe squeeze 3.5 out of them. With the SpeedTech arms I'm running 4.7. A friend of mine got nearly 9 out of the RideTech arms with really long UCA mount bolts and a ton of shims.
But the car wants 10 degrees of caster for autocross.
The problem with adding that much caster with shims in the upper arm is it moves the upper ball joint backwards, which moves the wheel backwards, and you end up with clearance issues in the back of the wheel well.
The new UMI arms are supposed to move the lower ball joint further forward so you don't need so many shims in the UCA to get the kind of caster we want and it keeps the wheel centered in the wheel well.
So you're saying UMI kinda copied what SPC did with the lowers?
Don't get me wrong, I run hella UMI pieces on my car, but I chose SPC because they spent the time to R&D it with Mark.
And I agree with everything you said about Caster.
On a related note- you guys really should pick up Jerry Bickels chassis book...friggin blew my.mind...
I didn't know SPC even had a lower arm. I used to run the adjustable uppers, got them through Mark Savitske years ago. They worked OK, but because they're flat, you lose suspension travel in droop. And they'll fatigue. I sold mine when I got my SpeedTechs, and one of them broke on the guy that bought them from me. The SPC arms are definitely a wear item. Also, having the adjustment in the arm can result in different camber curves on either side of the car and a wandering roll center that can make the car feel a little goofy, since you end up with essentially two different UCAs.
UMI has been working with Ron Sutton to fix the caster issue using a stock spindle. I don't think they're copying anything. Just different companies coming up with solutions for the same problem.
If you use the SPC uppers or lowers with different arms then you can run into issues where they break. This is not due to the product being inferior, but rather the arms being designed to work with only their SPC counterpart.
Because the pickup points are relocated on these arms, if you use the UCAs with a different companies LCAs (like Speedtech, or UMIs, etc) or vise-versa, you may run into issues where there is additional stress placed on the LCAs because of the distorted/incorrect angle the LCAs now sit at. This is because the SPC's were designed to work with each other, not other companies parts. I have seen where the SPC arms have bent when used with another companies UCAs, and Mark Savitske actually responded to the thread stating that due to the other companies UCAs locating the pickup points in different locations than what the SPC UCAs have, this puts the LCA ball joints/arms at a different angle than what they were designed to, and creates extra load at an unfavorable angle, which can lead to part failure.
Basically, the SPC arms were designed to work with each other, and not be used with another companies UCA or LCAs.
As for them being flat-if you used the Howe extra tall ball joints for both the UCA and LCA (the LCA ball joints come with the SPC Stage 2 Plus UCAs) it locates the arms higher, which gives you additional clearance from the frame. If you used those ball joints then you shouldn't have had issues with droop... and where did you run into issues of not having enough droop?
As for them fatiguing or having different camber curves...what bushings did you get? And any part that is adjustable will have to be set at the same points on either side.
It isn't the design of the arm that causes different camber curves on each side, it is how you aligned the car. If you didn't set things up correctly then yes, you would have different roll centers/instant centers per side. However that isn't a mechanical issue, that is a human issue.
I have seen UMI's UCAs and LCAs, and they look really nice. Their LCAs look like a very similar design as the SPCs, and even appear to have a shock mount that can be used with coilovers as well. At least it looks that way.
From what I've read, unless you build the caster/camber into the arms, and change the pickup points for the tie rods on the spindle, adding taller ball joints only helps with part of the issues.
The real fix comes from relocating the tie rod pickups and the ball joint pickups. Addressing the arcs that the ball joints move along on the spindle and the tie rods move along will have the greatest effect on curing bumpsteer issues. If the spindle and tie rod pickup points on the LCA are not parallel, the sweep arcs on the arms as they travel through rebound((extension of the shock) cause the tie rods to push outward, causing Toe Out to occur, and on extension (down travel) the tie rods pull the steering arms to Toe In. This is where the bump steer comes from....or at least part of it. If you do not change the tie rod length and height relative to the LCA ball joint pickup point on the spindle, you will have varying arcs as the suspension goes through its sweep/movement. This is why a ground-up design like the SPC arms and the AFX spindle, where you start with a clean sheet and can design the pickup points to the correct/optimal locations, is the only real answer to fixing our bumpsteer. Simply adding taller ball joints does not remedy these issues if you are not mechanically/by-design changing the locations that the pickup points actually travel along and locate the tie rods/spindle at.
This doesn't take into account things like the Steering Axis Inclination (SAI) either. If you do not have the streering axis located centrally to the tire's contact patch, you will run into issues with tire travel (scrub radius) and directional stability....if the SAI is determined on one side by drawing a vertical line down from the upper and lower ball joints down to the ground, and drawing another line down the axis the spindle turns the tires on (the tie rod location on the spindle) and these lines do not intersect, we experience tire scrub and less-than-favorable stability in the steering as we drive the car. This is why having a re-designed spindle (like the AFX) or fundamentally changing the pickup points to also change/relocate the spindle's tie rod pickup points is the real answer to solving our bumpsteer issues. This goes for any companies CAs. Yes, I like SPC's products, and I also run a ton of UMI's stuff on my car, so I am not saying one is better than the other. I am saying that Mark Savitske and ATS did create a brand new spindle for the G-body called the AFX spindle, which all the issues that I just wrote about. To my knowledge, SC&C/ATS is the only company to do this. The SPC/SC&C UCA/LCAs with the Howe extra tall ball joints also help accomplish close to what the AFX spindle does, without having to shell out the money for the AFX spindles. I am not that intimately familiar with UMI/Ridetech/Speedtech LCA/UCAs, but if they do the same thing, then they would be perfect for addressing bumpsteer.
...and for what it is worth, Speedtech uses the ATS spindles in their performance handling packages...the same spindle that Mark Savtiske from SC&C helped design... juss' sayin'....
Sorry for the rant, but I hope some of what I wrote makes people think about what exactly they are buying before blindly purchasing a product without knowing what exactly it may fix...if it fixes anything at all...
EDIT: The more I look at Speedtech's parts they offer, the more it seems like they just copied and pasted, with a few words changed, the descriptions for the same parts that SC&C has...
For example, the front swaybar that Mark Savitske helped design in partnership with Hellwig, has this description at SC&C's website:
"`78-`88 GM A/G body Monte Carlo, Grand National, etc. 1 5/16" tubular front bar, with all hardware included. Hellwig Motorsports tubular Sway Bars feature our latest designs and utilize high strength tubular DOM steel to maximize performance but with up to half the weight of a solid bar. Hellwig quality shows in the details such as end treatments where the sway bar is tapered from round to flat to eliminate stress risers. Also, the ends are radiused for better clearance and a clean appearance. all bends are done on computer-controlled benders to provide consistent bends in a sway bar that fits right every time."
Now, here is the description from Speedtech's website on "their" front swaybar...
"....Engineered specifically to fit the '78-'88 G body GM frame, Speedtech front sway bars utilize high strength tubular DOM steel to maximize performance at up to half the weight of a solid bar. All bends are performed on computer-controlled tubing benders to provide consistent bends in a sway bar that fits right every time. Quality shows in the details such as end treatments that taper smoothly from round to flat to eliminate stress risers. The ends are radiused for a clean appearance and better clearance. All sway bars come powder coated Gloss Black and include all new mounting hardware and bushings."
Also found it kinda weird that Speedtech's description for the AFX spindle says the "Speedtech/ ATS Tall Spindles..." when they had NOTHING to do with designing them...
Maybe I am old fashioned, but I am a bit leery of trusting a company that appears to be blatantly copying another's products and inadvertently wording their descriptions for parts to appear as if they had input or aiding in designing it...
You lack proper frame of reference.
I bought those arms from Mark in 2003 after running across him in the bumpsteer thread at Montecarloss.com. They were still called Pole Position back then, and the formula was truck UBJs with the adjustable arms and the stock lowers. They were steel bushed and aligned correctly. The combo just didn't fit as well as the newer stuff. Mark didn't even know what he didn't know back then, but he was the only person at the time actually measuring the car and putting the numbers into a piece of suspension software and coming up with stuff other than stupid thick swaybars and cut springs.
I hear ya, but frame of reference doesn't change the geometry issues I was discussing. Although I do lack many things, including a properly-functioning brain hahah!
And yea, they are still coming out with new pieces for the UCAs, like the newer chrome moly cross-shafts and HD adjuster sleeves. I bought mine about 7 or 8 years ago and there wasn't even the option for those at the time.