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Discussion Starter #1
Here is a list of what I hope to accomplish with the tubular front control arm design... please reply if you have other issues that you think need to be addressed in the re-design.

Lower Arms:
Maintain stock geometry.
Maintain stock bushing size.
Beef up shock mount area for use with coil-overs.
2 ball joint options for use with 5/8 or 9/16.

Upper Arms:
Arm will be shortened 5/8" to improve geometry. Can be used with 2" spindle spacer.
3 degrees of toe-down to correct ball joint mounting location.
Will use factory size bushing.
Will fit in factory SS wheel.
0-6 deg camber adjustment feature available on either upper for $70 extra.

Price will be approx $525 for the set of 4.

As mentioned before they will be in ash gray/silver powder coat or $25 extra for your choice of color.
 
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Discussion Starter #3
1) What does it mean to design the lower arms for 5/8 inch ball joint?

2) How does the spindle spacer work?

Mike
 
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Discussion Starter #5
Mike : the 5/8" balljoints are the ones for the Cop Car application (late 95 and all 96 9C1). As it is now, to run them you need different lower A-arms (same exact geometry/size as our A-arms, but slightly different balljoint mounting) and spindles (with different taper for the larger lower balljoint).

It is possible to machine spindles that are currently setup for 9/16" balljoints to use the 5/8" balljoints (with the proper tapered machine bit). However once modified, the spindles can't "go back" to using 9/16" balljoints later.

Chris : since not everyone will want the mandatory swap over to 5/8" balljoints to do this, an option the vendor might wanna consider is either :</font>
  • Sell the upper and lower arms separately. This would enable those with 9/16" balljoints to keep their current lower arms, but get the benefits of the better upper arms without requiring a spindle swap/machining operation.</font>
  • Sell 2 versions of the lower arms, identical except for the lower balljoint mounting size (i.e. one set setup for 5/8" balljoints, other set setup for 9/16" balljoints).</font>
The spindle spacer mounts in sort of "series" with the upper balljoint, making the spindle/balljoint combo effectively taller.
 
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Discussion Starter #6
Ed, I didn't realize that the 5/8 inch ball joints mounted differently than the 9/16’s to the lower arms.

I like the idea of being able to purchase just the upper arms. It would be a disincentive to those already using custom spindles with 9/16 inch ball joints to have to also upgrade spindles to get the arms to work.

When I changed my ball joints recently, I wondered why you couldn't bolt the upper ball joints under the control arm instead of on top of the control arm. This would give you a little more height (maybe 1/4"?).

If the ball joint spacer works with the stock ball joint. Would the ball joint spacer work with the stock upper arms?

This sounds like a great project!

Mike
 
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Discussion Starter #7
Hey Ed... Thanks for responding to everyones questions.

I agree on the ball joint and will see if we can get 2 versions on the lower arm... one for 9/16 and one for 5/8. I've edited the first post to reflect this.

BadRod:
yes, the spindle spacer will work with the stock upper arm... but the geometry isn't very good. As the outboard end of the arm raises (which is the result of the spacer) the arm needs to get shorter.
 
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Discussion Starter #8
Ed, I didn't realize that the 5/8 inch ball joints mounted differently than the 9/16’s to the lower arms.
Actually the mounting "mechanism" is the same. However the hole that you press the balljoint into is a little bigger on the 5/8" balljoints compared to the 9/16" balljoints.

It is possible to modify a 9/16" arm (stock one) to use 5/8" balljoints....Bill Harper has offered this conversion service for a few years now.
 
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Discussion Starter #9
How are these spacers going to attach to the spindles?
I remember seeing some made for earlier "A" and "F" bodies that had a straight bolt going through the upper taper holding a spacer that the taper bolted into.
Looked a little scary.
BadRod questioned mounting the ball joint to the bottom of the upper arm.
While tilting the arm upward, it would have no effect on the roll center as the ball joint pivot and the inner pivot would still be the same height off the ground as stock.
If you are going to go to all the trouble of fabbing up new upper and lower arms I wonder if a guy could go the extra mile and adapt a completely different, taller spindle from something else.
How tall and tough is a C5? Granted the car is a lot lighter
Bill?
Regards, Gerry
 
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Discussion Starter #10
Ed, having just changed my lower ball joints, if we could adapt a "bolt on" lower ball joint I could REALLY be excited!

Chris, oh yeah....you can’t use a stock arm cause it needs to be shorter too. I'm finally catching on...


Gerry, ahhh I see...the spacer would effectively go between the ball joint and the knuckle, not between the control arm and the ball joint....still catching on...


Guess, I didn’t understand this as well as I thought I did! :D
 
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Discussion Starter #11
Here are the details on the spacer:
Spindle Spacer

I have signed up as a "dealer" with them so that I can get us a bit of a price break on the parts if I place a large enough order. For those of you that have been looking into this issue for a while may remember Bill Harper discussing this part in the past.
 
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Discussion Starter #13
Originally posted by 95wagon:
[QBIf you are going to go to all the trouble of fabbing up new upper and lower arms I wonder if a guy could go the extra mile and adapt a completely different, taller spindle from something else. [/QB]
That'd be cool, but pretty darn expensive (spindles, hubs, rotors, calipers, control arms, etc). Plus any steering and ABS snags. :(
 
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Discussion Starter #14
Why not integrate or move the mount for the ball joint 2" down on the upper a-arm? That way you don't have to use a spacer. I don't like the idea of a spacer. Just design the drop into the a-arm. I am game for a set of both upper and lower a-arms when the design is finalized. I especially like the adjustability aspect.
 
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Discussion Starter #15
Why not integrate or move the mount for the ball joint 2" down on the upper a-arm? That way you don't have to use a spacer.
Don2:
I agree with you... maybe. The spacer is being sent with the stock arms for the prototype fabrication. We weren't sure if the arm could be made with an built in "spacer."

The problem is that when the angle of the upper arm changes the spacer would deflect also if it were part of the arm instead of part of the spindle. Also... your ball joint pivot would remain in the same spot geometrically... we need the spindle taller and the ball joint higher. I need to think on this issue a little more.
 
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Discussion Starter #16
Also... your ball joint pivot would remain in the same spot geometrically... we need the spindle taller and the ball joint higher. I need to think on this issue a little more
This last part nails it, and why attaching the spacer to the arm instead of the spindle won't do the job properly. You're looking to move apart the distance between the lower and upper balljoints.

Gerry : any idea on donor spindles that could work? Since most other GM cars goto OUR spindles as donors, that sorta rules out that "common" route for us
.

Mike : there are other balljoints that attach easier. One "option" that Bill offers on his current arms is to goto 11/16" screw-in balljoints. Obviously this requires work on the lower arms and machining the taper in the bottom of the spindle to match up, but it sure simplifies balljoint changes down the road
 
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Discussion Starter #17
Ahh! I get it. I was assuming the spacer was fixed to the a-arm. So we need the taller spindle as was mentioned. I went and re-read the spacer specs that you mentioned. I guess that would be the best option at this point if there is not another GM spindle we can use. Never mind my comment about lowering the a-arm end
. Just a thought, Early Classic Enterprises produces their own high quality reproduction and lowering spindles. I wonder how difficult it would be to get a B-body spindle reproduced with the added height needed.
 
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Discussion Starter #18
OK,

Elsewhere in Forum you'll find my "promise" that Global West will build front control arms--someday in the future....I'm so good at making these statements and then having to eat the words. I tried not to promise anything, but no matter, Chris, Doug (Wood) and others have pushed this ahead and it will be interesting to see what happens, whoever the source(s) may be.

As far as taller spindles, the only way to get there is with a spacer (cheap), such as the Dr Gas kit, or with a new casting (expensive). There does not appear to be anything that can be adapted from a production vehicle. For racing, I don't know if any of the sanctioning organizations will have a problem with the spacer setup.....

Gerry:

There are probably lots of issues with a C4 or C5 front suspension--height of the knuckle being the least of my concerns. The C4 stuff is probably stronger (than C5), since alot of work was done on the C5 to reduce mass--read the book "All Corvettes Are Red" to learn about how the knuckles were tested. The cartridge style wheel bearings may not have the necessary load capacity for the front weight of the B-body.

I've looked at the straight bolt issue with the extender--it would be nice to have it fit "correctly" into the tapered hole, but the upper arms don't see a huge load anyway, and the 1/2" (or 9/16") Grade 8 bolt is going to hold things together at the knuckle just fine. Some whittling of a concentric spacer setup might make you more comfortable, or check out the tapered studs in the Coleman catalog for another way to mount the spacer.

As I understand what happens with the spacer setup, the upper control arm needs to be shorter in order to create a camber curve that pulls the wheel in at the top on the outside wheel when in a turn (left turn/RH wheel, right turn/LH wheel). This does not happen now with the design of the stock suspension, and the outside wheel actually goes to positive camber, meaning the tire is "unloading" during turns. With shorter (inner pivot to ball joint center distance) upper control arms, the result is a greater amount of negative camber gain, which means the outer tire is working at an angle to better plant the tread flat on the surface, thus developing more cornering force. It doesn't mean you will have the tops of the tires leaning "in" with the wheels straight ahead, but that just depends on how agressive you setup up the car, alignment-wise. The spacer and arm setup, done properly, will actually let you run less "static" negative camber than the optimum setup with standard upper arms.

The desired negative camber curve can only be created if the knuckle is taller than what the B-body has stock--the spacer is about 2"
 
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Discussion Starter #19
Thanks for chiming in Bill. I was hoping you would see this and have some input.

On the lower ball joint issue.... do you know of a "bolt on" ball joint to use instead of the press fit unit. This would allow a single design of the lower arm and the ball joint size of choice could then be added by the owner.

I had planed to have two prototypes made... 2 lowers with each ball joint size and 2 uppers, one stock and one race... but it looks like this may be cost prohibitive for me. So i'm trying to come up with one set that will be good for most applications.
 
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Discussion Starter #20
Chris,
I don't think you should bother with the stock replacement. What would be the advantage of a stock geometry arm? Weight? I think that most people are going to want the performance advantage of the corrected geometry. Thanks for spear-heading this, by the way.
 
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