anyone know the taper on C6 Vette ball joints?

[byndbad914]

as the titles states, I am hoping someone knows the taper on the ball joints for C6s...

I have uppers in the used spindles I got but they don't measure to what I consider a "normal" GM taper. The lower reamed taper in the spindle measures out the same but I am hoping to confirm the angle since, again, it is not what I expected.

[bdahlg68]

Normally a 1:6 taper

[byndbad914]

I guess I need to verify what you mean by "normally" - normally for GM or normally for a C6 Corvette?

From my days working with circle track stuff, GM is normally 10 deg, or as you note, a 1 in 6 ream. However, the upper I have is measuring out around a "normal" Chrysler at roughly 7 deg.

[bdahlg68]

Normal for the OEM's (almost all of them). Nearly all ball joint tapers are 1:6 nowadays unless there is a taper washer. Looking online, I see people say both about the C6 tapers. I will see if I can dig something more definitive up.

This is interesting..... http://www.fastcar.co.uk/forum/showp...9&postcount=50

[mfain]

Originally Posted by byndbad914

as the titles states, I am hoping someone knows the taper on the ball joints for C6s...

I have uppers in the used spindles I got but they don't measure to what I consider a "normal" GM taper. The lower reamed taper in the spindle measures out the same but I am hoping to confirm the angle since, again, it is not what I expected.

I just went to the shop and picked up a new C6 spindle and a low friction ball joint that Howe provided to me for the lower end. The factory ball joint is installed in the upper end. I measured them with a digital caliper (not a micrometer which would probably be more accurate). The upper comes out 2 inch. per foot taper consistently, a number I've heard several times on another forum. The Howe technician provided me with a lower ball joint stud that fits correctly -- part number 224240 which shows to have a 2 inch. per foot taper. I just called the Howe tech and he confirmed that (by the way, he said "Corvette" as the application without me mentioning it, so it kind-of sounded Corvette specific). Measuring the tapered hole in the spindle I get 1.92 inch. per foot taper, but my caliper may not be that accurate on inside diameters. As a side note, I was originally told by a manufacturer that the GM C6 taper was "proprietary". When I measure the Howe stud I actually get 1.84 Inch per foot. Hope this helps. By the way, Howe has an excellent stud taper/fitment chart.

Pappy

[byndbad914]

Thanks to both for the info. 2 inch per foot = 1:6 so that all lines up. Interesting I spoke to a guy at Speedway and he thought all the late-model metric stuff was 7 deg taper, which is closer to what I measured... but I will take Howe's word over it any day as they make 'em

I am already looking at Howe adjustable ball joints so I can vary the roll center and didn't even think to talk to them directly about Corvette stuff so I will contact them.

I think what I am going to do at this point is machine up an insert to replace the ball joint in the spindle with the taper, then use a ball joint in the upper arm which is more of a "normal" setup, simply flipping the joint over and have it point up into the spindle v. down like say an old Camaro/Chevelle setup. Having the joint in the spindle is odd so I was going to have to make a thread-in tapered item to screw into the IMCA uppers I am looking to use anyway. This way I get the exact ball joint I want in the IMCA uppers and the exact reamer dimensions for the top side of the spindle.

The joys of trying to do custom stuff but maintain as much "off the shelf" stuff as possible for ease of maintenance - I end up with two ball joint holes at the top and no tapered side to bolt into

edit - sorry, forgot this part from the link above
"One unique feature of theGMR uprights is they have matched the stock lower ball joint taper perfectly using a custom built reamer. They will not disclose the exact taper but we can assure it is not either of the standard 7 or 10 degree tapers.Their uprights matches the stock taper perfectly to ensure quality fitment with the stock GMR components"

I can say that the math on my upper didn't seem to match either exactly so maybe that is what they have found as well, but maybe Howe determined it to be "close enough" to 10deg that is works? This is why I am thinking I will just make a plug for the upper side of the spindle and ream it to an exact known 1:6 Howe ball joint for the IMCA upper.

[bdahlg68]

Well 1:6 is actually like 9.xx degrees or something, so technically they are right, it isn't EXACTLY a 10 degree taper...

Originally Posted by byndbad914

Thanks to both for the info. 2 inch per foot = 1:6 so that all lines up. Interesting I spoke to a guy at Speedway and he thought all the late-model metric stuff was 7 deg taper, which is closer to what I measured... but I will take Howe's word over it any day as they make 'em

I am already looking at Howe adjustable ball joints so I can vary the roll center and didn't even think to talk to them directly about Corvette stuff so I will contact them.

I think what I am going to do at this point is machine up an insert to replace the ball joint in the spindle with the taper, then use a ball joint in the upper arm which is more of a "normal" setup, simply flipping the joint over and have it point up into the spindle v. down like say an old Camaro/Chevelle setup. Having the joint in the spindle is odd so I was going to have to make a thread-in tapered item to screw into the IMCA uppers I am looking to use anyway. This way I get the exact ball joint I want in the IMCA uppers and the exact reamer dimensions for the top side of the spindle.

The joys of trying to do custom stuff but maintain as much "off the shelf" stuff as possible for ease of maintenance - I end up with two ball joint holes at the top and no tapered side to bolt into

edit - sorry, forgot this part from the link above
"One unique feature of theGMR uprights is they have matched the stock lower ball joint taper perfectly using a custom built reamer. They will not disclose the exact taper but we can assure it is not either of the standard 7 or 10 degree tapers.Their uprights matches the stock taper perfectly to ensure quality fitment with the stock GMR components"

I can say that the math on my upper didn't seem to match either exactly so maybe that is what they have found as well, but maybe Howe determined it to be "close enough" to 10deg that is works? This is why I am thinking I will just make a plug for the upper side of the spindle and ream it to an exact known 1:6 Howe ball joint for the IMCA upper.

[byndbad914]

Originally Posted by bdahlg68

Well 1:6 is actually like 9.xx degrees or something, so technically they are right, it isn't EXACTLY a 10 degree taper...

yeah, it is like the roof on our houses, they're called out in pitch, not angles, but in the case of ball joints everyone talks angles.

and the thot plickens... I found some Viper stuff on the Howe site that is 1.69"/ft taper which is almost exactly 8 deg - which is also exactly the angle I calculated my upper ball joint on the Vette spindle to be. Not 7, not 10, but 8 degrees.

So maybe the Vette and Viper are both running this funky taper. WTF? Being a mech engineer I deal with stupid crap like this on a regular basis - someone reinventing the wheel - I would love to hear the excuse why the standard 7 or 10 degrees is not quite right but 8 is perfect Apparently I missed the class at school that discussed the finer points found in children's books such as porridge temps and mattress firmness. Must have to have a PhD to get exposure to that kind of knowledge.

Chevy Corvette - built in America... using metric fasteners and other nonstandard items. Wouldn't surprise me one bit if taper was based on millimeters; man enters store, walks up to counter, 14mm over 100mm reamer prease!

edit - took a break, stepped back from the tree to see the forest, and thought this thru a bit here. I think I have a simple plan to circumvent the funky taper stuff for my project. I can run a Coleman lower control arm with a monoball lower and standard Chrysler K727 1.5"/ft taper, ream the spindle lower to this taper (as this will not open up the bottom diameter which is good), then press out the C6 upper and make an adapter to fit in it for the same 1.5/ft taper, run a Speedway upper A arm assy which takes a standard K772 ball joint which I can get variations from Howe and others. The only "custom" part is the adapter for the spindle upper and reaming which is all pretty cake to redo if I mess up a corner. Whacka$$ taper should then be circumvented. Now to let this simmer a bit and make sure I didn't miss something

[JasonElvisHeard]

It is a little different, I actually had a custom reamer made for the fabricated uprights we make.



lower BJ on C6 upright.

[mfain]

edit - took a break, stepped back from the tree to see the forest, and thought this thru a bit here. I think I have a simple plan to circumvent the funky taper stuff for my project. I can run a Coleman lower control arm with a monoball lower and standard Chrysler K727 1.5"/ft taper, ream the spindle lower to this taper (as this will not open up the bottom diameter which is good), then press out the C6 upper and make an adapter to fit in it for the same 1.5/ft taper, run a Speedway upper A arm assy which takes a standard K772 ball joint which I can get variations from Howe and others. The only "custom" part is the adapter for the spindle upper and reaming which is all pretty cake to redo if I mess up a corner. Whacka$$ taper should then be circumvented. Now to let this simmer a bit and make sure I didn't miss something."


Tim,

I am heading in kind-of the same direction. I tried the Howe stud they sent me for the C6 lower (part number 224240) in a Coleman spindle eye (part number 808-700, Chevrolet lower taper K-6141 (10 degrees)) and it fit perfectly. That means the stud IS 2 in./ft. taper. When I try the same stud in the spindle, it is slightly loose at the small end (which was indicated by my 1.84 in./ft. hole taper measurement earlier). I tried the Howe-recommended "magic marker" test and that also showed the stud to be tight at the big end and loose at the small end. The fix I am going to use is to run a 10 degree taper tool through the aluminum spindle taper to make it the same as the stud. It will take very little material removal, and the stud is long enough to pull that off without running out of stud and pushing the threads out the top of the hole. For the top end, I will use a Coleman CM-12-2 heavy duty rod end which is 3/4 in. thick and has a 1/2 in. hole. I will run the 2 in./ft. taper reamer through it to create a taper. I will then check that taper against the taper of the C6 upper ball joint. I have measured that stud a dozen times and I still get right at 2 in./ft. taper, but who knows? Anyway, if that taper works, all is good for what I have planned. If that doesn't work out, I will go the same approach as you -- ditch the C6 top ball joint and build a sleeve to accept a more conventional ball joint. What a PITA.

Pappy