anyone know the taper on C6 Vette ball joints?

[byndbad914]

thanks all Press fit is around .001" to .0015" - the holes were a bit out of round once I got the UBJs out so I measured with a bore mic until I found the min and max diams, took the average with the assumption the hole will become round again after I press in the parts, and shot for .001" minimum.

[MillerBuilt]

Originally Posted by byndbad914

Interesting that the taper reamed in the bottom of the Vette spindle didn't work with a 10 deg tapered Howe ball joint but the upper BJ works with a 10 deg ream... you sure about that? The stock upper and lower BJ seem to have the same taper to me.

Better late than never as I see you have chosen your path, but for others...

The C5/6 Upper and Lower are the exact same taper, AND when I was researching the same..... I was told by a Speedway tech that their "10 degree" reamer (as probably Coleman and others too) are not truly 10 degrees but slightly under, and ARE an exact fit ironically enough to the C5/6's slightly under 10 degree taper.... I was told by Speedway that they simply round up for advertisement simplicity, and call them "10 degree" but their techs will confirm differently if/when quized.

Cool Nova by the way!

[byndbad914]

thanks - I suspect it is all "close enough" as if I measure the reamer and the Howe joint they aren't quite the same. Frankly I hate the tapered crap altogether and have been only running heims for some time now but I thought I would try to go with more off the shelf stuff on this car.

One thing I wanted to do was move the UBJ as well so I was pretty much always on a path to dump the stock upper - here is a shot of my dual A assy as of today - all the numbers are exactly what I want in terms of roll center, camber gain, and overall adjustability. I now have to fully adjustable pivot points (top and bottom) that I can mess with ride height and roll center pretty much at will.

For the Nova I am starting with a 13.5" lower arm length, 10.5" nominal upper length, and what both calculated in my computer and was verified with my angle finder in the attached image is a parallel lower arm nets me an 11 deg upper angle for a static RC of ~2.5" which is what I was shooting for. The lower pivot is not a ball joint but monoball from Coleman and they make a set of spacers that come with it. I can swap those around to vary the upper A angle and therefore static RC but comes with a 1:1 change in ride height (move the pin up 1/4" and the car drops 1/4") so if I need to make a big change I can then just buy a longer or shorter upper ball joint insert.

[phantomjock]

Originally Posted by byndbad914

Here are the uprights with the plugs I made to replace the factory UBJ with a tapered, press-fit bushing.

Long-time lurker here - Jim (aka phantomjock).
AWESOME SOLUTION to the C5/6 UCA! That is exactly where I was "stumped" - just today, in fact. My Howe gm K6141s were about to get sent back - but not now.

I've pressed (not Pounded) the Uppers out and cleaned up the uprights. My plan for lowers is straight forward - but that damn upper ball joint was the bugger! You've done the deed!

Coleman Racing makes a steel/weldable Spindle Eye/Taper, but mixed metals might not be as sweet as using aluminum. Have you considered making a small run of those in aluminum? I'd be in for a pair. There would be a nice niche market I'd think.

Again - Nice solution. Thanks for sharing that.

Cheers - Jim

BTW that is a BAAD 914!

[byndbad914]

thanks for the kudos Jim Unfortunately I am not going to do a run of those inserts - at work I am pretty limited as to how much personal use I get on the machines, and if I were to make parts for anyone else it can all go bad. I probably should have made some spares for myself and I didn't do that. Unfortunately it is the one bad apple sort of deal - a guy was doing some "personal" work and selling parts and that lead to him being let go and a serious clamping down on the shop usage. I am already about at my limit so I have, for example, stayed out of the shop for the past few weeks and let it die down a bit.

That said, if you can find a shop with a lathe (which is pretty much any shop) and buy a taper reamer (Speedway has about the cheapest one I found and that is what I used), it is really easy to make these parts. It is all a matter of how much press fit you feel comfortable with. Dissimilar metals of course have a different thermal expansion so on parts that can get hot, like heat transferred from the brakes and so forth into the spindle, you could get a loosening of the parts, specifically steel into aluminum. The other way around, aluminum into steel, would get tighter as it got hotter and that would be fine, but I would be careful if you fall back on the steel insert idea. Make sure to get a good press fit, maybe go .002" press, freeze the steel part overnight, in the AM plop the spindles in the oven at 350 deg, make sure your press is set up and ready to roll, then with some good welding gloves and moving pretty fast, do one at a time to get the parts together and that should be pretty solid I would think.

I did not do any math on the spindle stress since the stock ball joint was already .005" (I literally measured this multiple times, then asked the lead machinist to measure it as I couldn't believe it, that is an insanely high press fit but I believe it is because the walls of the UBJ are rather thin compared to a plug like I pressed in), so I figure being around the press I used should be fine without generating too much "hoop stress". I would think .002 would be okay with steel...

edit - did some math. I will start off by saying this is for your reference, I can't guarantee anything... trust me, I will be watching these press in slugs like a hawk once I am using this car on the track... but I found a hoop stress calculator and messed around with it. At .005" press fit using an alum piece like mine, the stress is around 26.5 ksi, which is within yield on pretty much any decent aluminum. Using a steel slug would be just over .004" press for the same stress. Reality is the engineers didn't design to 26.5 ksi as the UBJ has a "thin wall" and the slugs I pressed in are more like a solid plug, so the stress would be much lower pressing in the UBJ. I guessed a .125" wall thickness for the UBJ and worked with that and got about 10.5 ksi, which would equate to a .002" press on my part. Gut feel was to shoot for .0015" so I wasn't too far off If you go with .002" on steel the stress will be more due to the steel material but I think that would work. Just get the temps very different and the press in won't be too bad.

[phantomjock]

Tim -
thanks for doing those "maths."
I've got a line on a machinist locally that "does" ball joint re-tapering as a part of his business. I'll be heading over there tomorrow - numbers in hand with my steel slugs, uprights, reamer (mine from Coleman Racing), and 2 of my Coleman Universal Ball Joints. I can do a weld up fixture like the unit you got from Southwest Speed.

Wish me luck!
Pappy - looks like I've nearly got it sorted!

Cheers - Jim

[phantomjock]

Well, I'm back from South East Asia and working this suspension mod.
Getting close - but have a question maybe Tim or someone else can help with.
Does anyone know the taper on the Rear Toe Control on the upright? I'm looking to use tapered bolts with heims rather than ball joints. Unfortunately I don't have the toe control rods to measure.

These tapered bolts are widely used on circle track front suspensions. Speedway Motors has them in 2 version, GM and Pinto.


GM:
Stud is 5-1/8" long
Steering arm end has 7/16" thread
Tie rod end has 5/8" thread and is 3" long with 2-5/8" of thread
10 degree taper = 2" per foot
Pinto:
Stud is 4-13/16" long
Steering arm end has 1/2" thread
Tie rod end has 5/8" thread and is 3" long with 2-5/8" of thread
7 degree taper = 1.5" per foot

I'm hoping the C5 Rear Toe Control is either 7 or 10 degrees taper...
TIA - and Cheers - Jim

[phantomjock]

Well, thought I'd do a bit of measuring and see what shakes out.
The top (small end) of the location point measures 53/64" on my analog caliper. The large (lower) is 66/64" and over 116/64s and using the calculator I found here: http://www.magafor.com/841/uk.htm
I get pretty close to a 7 degree taper. [6.93 degrees]

Guess I'll be buying the Pinto shafts!

Cheers - Jim

[Vince@Meanstreets]

I have this tracker kit and im getting a different measure than you are.

http://www.summitracing.com/parts/bae-3302001/overview/

[byndbad914]

Vince - thanks for posting that. I was unaware of those custom made parts for the Vettes and am down a different path on my Nova, but had I known about those, I likely would have bought them and just used the pins or tried to find those tapered adjustable pins separately, then made my own custom length tube to fit the Nova dimensions...

BTW Vince, have you noticed horrible bumpsteer in your experiences with using these spindles?

To me it apprears bumpsteer is HORRIBLE and it can't be fixed, just minimized. I pretty much gave up on setting up a dial indicator to measure it and have just used a tape measure while I roughed in the tie rod angle on the Nova. The first 1" of bump is okay, worse than any suspension system I have designed or set up on circle track cars, but can be tolerated. Beyond 1.5" of bump it goes to heck very quickly. Looking at my own Vette it appears they set the ride height such that the lower arms aren't parallel to ground, but angle down a bit so the car goes from toe in to zero at parallel then start toeing in again on bump - something I do NOT want at all on a track car. I want one direction of motion during bump. Anyway, setting the car up as they did gets some more motion without huge toe change, but still, not great.

The rears are oriented with the toe arm back which actually means the rear toes OUT on bump. I can't imagine how that bad idea got incorporated. Nonetheless, I am now working out swapping the rears on the Nova and figuring out how to put the toe link to the front.

I have been super tempted to take a torch to the toe arm on the struts but have no idea how that would hold up with the aluminum material on the track. If it was a forged steel spindle I would be bending that puppy to fix this. For now I intend to see how it works out. I will be limiting suspension motion anyway with stiff springs and bump rubbers.