anyone know the taper on C6 Vette ball joints?

[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]

Originally Posted by The GMR

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



lower BJ on C6 upright.

Nice piece! Do you ream the uppers too, or just the lowers? Edit: Jason, after looking at your website, I see you have provision for a press-in upper ball joint -- do you stay with the C6 piece, or are you set up for a different upper ball joint? Thanks

Pappy

[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

[byndbad914]

thanks GMR and Pappy - further confirmation the angle is off from "normal" racer stuff. If I were doing a bunch I can certainly see the value in a custom reamer. Since I am doing one car, 4 spindles, I will go down the path of picking a "standard" and just getting that reamer.

Pappy - furthermore, imagine if you didn't really know what you are doing and just bought that ball joint on their recommendation and bolted it in! You wouldn't make it far before wallowing out the spindle and bending the castle nut threads and then just having it tear apart. Maybe they should read their own tech guide about misfit at the taper BTW, you are right, I went out and yanked the boot off of one of the joints so I could really get a good measurement and it looks to be about 9.9 degrees (I got .155" of total taper over a length of about .900"). 2"/ft = 9.6 deg. Doesn't seem like a lot but there is a difference, enough that you can see the slop of course once you tried to fit it in the spindle.

So far I am still thinking I will go down the ~7deg 1.5"/ft taper route but seeing now how close to 2"/ft it is I am going to go back and look at some stuff. After my post above I realized that Coleman offers a lower control arm with the smaller, upper ball joint thread and that Howe has a hybrid lower joint with the smaller, upper body but large diam lower stud so that will buy me a little more clearance to rotors. Another option v. the monoball item that has a Coleman pin in it, but that only comes in 1.5 taper from what I can tell, not 2. I can easily go to 1.5" without opening the bottom up (that is always the case as long as I am less angle than what is in the spindle now) and clearly going to the 2" reamer will be of little consequence if I choose to go that route as the angle change is slight. Howe offers a quite a few "hybrid" joints so I suspect they have the Chrysler housing with the 10 deg stud in some form that I could use.

[Ron in SoCal]

Originally Posted by byndbad914

Pappy - furthermore, imagine if you didn't really know what you are doing and just bought that ball joint on their recommendation and bolted it in! You wouldn't make it far before wallowing out the spindle and bending the castle nut threads and then just having it tear apart. Maybe they should read their own tech guide about misfit at the taper .

For whatever reason, this has happened before within our little community. BJ taper documented as different than spec and ripped the BJ's out. Could have been disasterous! Matter of fact a whole batch.

Make sure you check this every time...

[mfain]

Tim,

Howe offers a quite a few "hybrid" joints so I suspect they have the Chrysler housing with the 10 deg stud in some form that I could use.

I don't think the Chrysler housing is available with the 224240 stud (2 in./ft. taper), but Howe fixed me up with a heavy duty, screw in housing -P/N 22329X - that screws into a 22340 weld-in ring. I talked to a Howe technician this morning and he said he would investigate the C6 lower taper issue.

Pappy

[byndbad914]

thanks for the info. I spoke to Coleman today about their lower control arms with the monoballs and I believe this is my best bet. I can get either 10deg or 7deg pins - I think I am just going to go Chrysler and 7 deg. I can ream the bottom to fit the 7 deg pin, it is fully adjustable for roll center height, and if I need more I can swap the pins in the uppers as well for roll center variance. Then the angle matches the upper so I only have one ream to keep track of and a standard K772 upper will work.

On a good note, I got my Forgelines today built to fit my 2011 Z06 with the 395mm rotors and these are what I am using on the Nova (295 fronts/335 rears). I had already built the suspension up from my custom stuff I had in the Porsche then ended up finding a buyer for the roller so took it all back out of the Nova - turns out I could literally have reused everything from the Porsche with the Vette spindles and stock Vette wheel offsets. I had designed that suspension for the Porsche without much info on a Vette and decent info on a modern Porsche... but just having an idea of how suspension works... turns out the A arm ratios match the Vette, caster within a degree, kingpin inclination the same as a C6 Vette. Guess that explains why the car picked up nearly 10 seconds on the track when I put the new suspension in! Good news is this means the Nova should be impressive for cornering This time I am hoping to make inboard shock mounting work out as well, already designed the rockers.

also good to hear the Howe is going to reconsider the taper on the BJs they are selling for Vettes - they will have a problem some day if they keep up with what they have now. They just need to carefully measure the taper and make their pin match - just not that big of a deal for a mfr IMO.

[mfain]

Originally Posted by mfain

Tim,

Howe offers a quite a few "hybrid" joints so I suspect they have the Chrysler housing with the 10 deg stud in some form that I could use.

I don't think the Chrysler housing is available with the 224240 stud (2 in./ft. taper), but Howe fixed me up with a heavy duty, screw in housing -P/N 22329X - that screws into a 22340 weld-in ring. I talked to a Howe technician this morning and he said he would investigate the C6 lower taper issue.

Pappy

For those still following this issue, I completed my "fixes" and here is what worked for me. I used a quality 2 in./ft. taper reamer on the lower tapered hole in the C6 spindle. I had to remove only a slight amount of material, after which the Howe 224240 stud fit perfectly. I then used the 22329X screw-in ball joint housing to capture the stud. For the upper ball joint, I used the 2 in./ft. reamer to enlarge the 1/2 in. hole in a heavy duty (3/4 in. threaded shank) solid rod end. The factory upper ball joint in the C6 spindle fit the now-tapered rod end hole perfectly. The rod end then screws into a threaded insert welded into 1 1/4 in., .095 wall chrome-moly tude that is part of my upper suspension link. Taper problem solved -- moving on.

Pappy