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Old 09-19-2017, 11:03 AM
  #16  
951and944S
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To any CNC guys peeping in...., what is the file type I need to create to supply to the CNC operator for these arms...?

Will Autodesk AutoCad Mechanical output a usable file...?

T
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Old 09-19-2017, 11:14 AM
  #17  
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Originally Posted by 951and944S View Post
my son pops his 87 NA in the second row of a 50 car field with 25 E and D 911 "real race cars"...., or his qualy time would put him 6th in a 20 car Boxster only group.....

T
+1 All is right with the world then.
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Old 09-19-2017, 01:34 PM
  #18  
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Originally Posted by curtisr View Post
+1 All is right with the world then.
Yup...., would be, except for the $600 race entry, 2-12 hour travel and expenses, 2-5 day hotel expense and $1200 worth of tires it takes (not counting other consumables) to run at top level.

Not to mention the time it takes to keep a car prepped all to have your victory snatched away by a $10 ball joint pin that nothing short of scheduled x-ray would find in a maintenance routine.

I'm going to solve it though.

T
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Old 09-19-2017, 02:03 PM
  #19  
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Originally Posted by V2Rocket View Post
ahem..
wonder if subaru arms might work...i recall years ago somebody was fitting RX7 arms to a 944 too.

if you want i can go measure...

Not allowed/approved by PCA. Fabcar, Charlie, Racer's Edge, and High Strung/Custom Fabr, and modified factory steel arms are approved.
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Old 09-19-2017, 02:05 PM
  #20  
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Originally Posted by 951and944S View Post
LOL, are you really tight with him but taking a friendly jab...?
Friendly jab. Know him from when he used to live up in MN.
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Old 09-19-2017, 02:11 PM
  #21  
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Factory alum late offset arms on the '87, with the original balljoints, not using a rebuild joint kit (?).

What was the pin failure - did the ball pop out of the socket, did the pin break at the base of the ball, or did the pin break at the pinch bolt notch, or other?

What was the age/mileage on the arms?
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Old 09-19-2017, 02:19 PM
  #22  
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Originally Posted by 951and944S View Post
Yeah, I was in that thread, it was probably me with the tie down through the wheels theory because it seemed to happen mostly right off the trailer.

All previous failures were with 17mm pins and the spindle bore is usually worn which allows less than 100% clamping...., pin moves, more wear in spindle, domino effect, then..., snap.

Like I said, at least for what I'm doing, the stock arms are great and I have plenty of them.

I want to either bore and and modify the stockers to accept a thread in like I linked or have billet stock copies that have a similar feature designed in.

The arms are 12 1/4" wide so would take an 18" x 18" x 2" billet each, so $500 material plus hardware.

I'll buy the equipment to make them myself before I pay $1700 for a pair.

You in....?



T
hmmm I have a Friend who has a business that makes air cyl's. He has all sorts of CNC/Mazak Okuma ECT If I had the CAD File I could just hand it to him and load the Alu... I Definitely want to make my own as well before I shell out that kind of cash.. (Yea we all know racing isn't cheap, but being bent over for $1700 is a whole different level)

I will have to do some asking around, I buy allot of parts from Troyer Eng in Rochester.. I know for the Modified series they make their own A Arms Lowers with Thread in Ball Joints.. I was Crew Chief for a Modified to 10 years and won allot of championships.. They Do Really Nice Work..

I have A Arms from High Strung hanging in my shop that I wanted to copy..But they are the Heim Joint Type.. but Maybe we should find the Ball Joint First then make the arm to accept it..?

As an Aside, With the "off the Trailer" Failures.. Next time your done Racing, As FAST as you can.. Take a temp reading of the steel on the ball joint or outer portion of the spindle.. Im wondering if heat Cycling might have something to do with your issue.. Just a Thought..

Between us we should be able to come up with a Reasonable solution..

Glen.
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Old 09-19-2017, 03:07 PM
  #23  
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Originally Posted by Oddjob View Post
Friendly jab. Know him from when he used to live up in MN.
That's what I figured.

I PM pinged him to this thread.

T
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Old 09-19-2017, 03:12 PM
  #24  
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Originally Posted by Oddjob View Post
Factory alum late offset arms on the '87, with the original balljoints, not using a rebuild joint kit (?).

What was the pin failure - did the ball pop out of the socket, did the pin break at the base of the ball, or did the pin break at the pinch bolt notch, or other?

What was the age/mileage on the arms?
Factory aluminum arms, bead blasted, acid washed, high temp clearcoated, rebuilt with metallic pivot cup insert and longer geometry correcting 19mm pin.

This may be the first 19mm pin though.

Symptoms, barely noticeable steering wheel offset to the left going straight on track where it was previously perfectly centered, seconds later...whammo.

T
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Old 09-19-2017, 03:22 PM
  #25  
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Originally Posted by GPA951s View Post
hmmm I have a Friend who has a business that makes air cyl's. He has all sorts of CNC/Mazak Okuma ECT If I had the CAD File I could just hand it to him and load the Alu... I Definitely want to make my own as well before I shell out that kind of cash.. (Yea we all know racing isn't cheap, but being bent over for $1700 is a whole different level)

I will have to do some asking around, I buy allot of parts from Troyer Eng in Rochester.. I know for the Modified series they make their own A Arms Lowers with Thread in Ball Joints.. I was Crew Chief for a Modified to 10 years and won allot of championships.. They Do Really Nice Work..

I have A Arms from High Strung hanging in my shop that I wanted to copy..But they are the Heim Joint Type.. but Maybe we should find the Ball Joint First then make the arm to accept it..?

As an Aside, With the "off the Trailer" Failures.. Next time your done Racing, As FAST as you can.. Take a temp reading of the steel on the ball joint or outer portion of the spindle.. Im wondering if heat Cycling might have something to do with your issue.. Just a Thought..

Between us we should be able to come up with a Reasonable solution..

Glen.
You pretty much hit the nail on the head.....as somebody else put it perfectly on here once, some of these parts are like a cartel.

I'll buy a 3 axis mill or a cnc machine before I pay $1700 for a set of a arms.

I am making progress.

I can ship an arm off and have it 3d laser scanned into both a 3d image and an autocad file. Est $100-$300.

Right and left is just mirrored.

I have some local CNC guys (I am on the Mississippi River in the most industrial part of the country) that will make me a set or two but if people are interested, we can just submit the file to emachineshop.com, pay a setup fee (maybe waived if enough qnty) and have them spit out as many as we want.

I want to modify the factory pin socket in AutoCad (I already have software) to accept a generically available spherical and non bottom bolt in tapered pin.

Let's get going on this and we can both benefit.

I'm not doing it to make money and don't care if 50 RL community members are involved.

T
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Old 09-19-2017, 03:30 PM
  #26  
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Originally Posted by GPA951s View Post
hmmm I have a Friend who has a business that makes air cyl's. He has all sorts of CNC/Mazak Okuma ECT If I had the CAD File I could just hand it to him and load the Alu... I Definitely want to make my own as well before I shell out that kind of cash.. (Yea we all know racing isn't cheap, but being bent over for $1700 is a whole different level)

I will have to do some asking around, I buy allot of parts from Troyer Eng in Rochester.. I know for the Modified series they make their own A Arms Lowers with Thread in Ball Joints.. I was Crew Chief for a Modified to 10 years and won allot of championships.. They Do Really Nice Work..

I have A Arms from High Strung hanging in my shop that I wanted to copy..But they are the Heim Joint Type.. but Maybe we should find the Ball Joint First then make the arm to accept it..?

As an Aside, With the "off the Trailer" Failures.. Next time your done Racing, As FAST as you can.. Take a temp reading of the steel on the ball joint or outer portion of the spindle.. Im wondering if heat Cycling might have something to do with your issue.. Just a Thought..

Between us we should be able to come up with a Reasonable solution..

Glen.
BTW - also, spot on.

I want to solve this myself and/or with help of forum members who want the same thing.

I build my entire cars from a primed tub. Suspension, roll cage, engine, transmission, custom fabrications, cooling, body and paint.
No other hands touch anything from the tires on up except for me and my son.

T
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Old 09-19-2017, 04:35 PM
  #27  
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Glen, one of my buddies with CNC has a friend flying in to visit from Nicaragua for three days.

Ace wizard in SolidWorks.

Says he can draw these in SW without a scan in 20 minutes.

I am going to do the late offset 968 arm with the brake cooling scoop mount tabs.

All I need to do is solidify a selection for the spherical and pin to be able to give him od and depth of spherical for lock ring locations.

Can you be researching best options on that....17mm non tapered pin will be fine because I am going to sleeve and weld my pins to the spindle anyway and this will leave more meat on the spindle pin bore.

T
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Old 09-20-2017, 09:49 AM
  #28  
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Originally Posted by 951and944S View Post
Factory aluminum arms, bead blasted, acid washed, high temp clearcoated, rebuilt with metallic pivot cup insert and longer geometry correcting 19mm pin.

This may be the first 19mm pin though.

Symptoms, barely noticeable steering wheel offset to the left going straight on track where it was previously perfectly centered, seconds later...whammo.

T

What rebuild kit was it, or where did you get the cups and 19mm long pins?
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Old 09-20-2017, 11:16 AM
  #29  
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Originally Posted by Oddjob View Post
What rebuild kit was it, or where did you get the cups and 19mm long pins?
Hmm, don't recall.

You know...., we bought enough to do 6 arms maybe and still have 2-4 pins, so probably two untouched kits.

It's not something you put your hands on a lot like replenishing supplies of brake fluid, oil, etc.

I would have to say either SSI or Rennbay.

They have the metallic lower (not nylon/plastic) cup so that might narrow it down...?

It's not a fault of the kits, it's that with extended pin length you have 1.5-2.0" of exposed length between the top of the ball and the bottom of the spindle pinch bore.
There's a lot of leverage on that pin.
The long pin on the RE tubular arm, the Charley, etc use extended pins of end user choice...., and while I'd say that they don't have this problem, there was a guy on here the other day looking for just a pin for one of those arms because he had snapped one.
My pins have just a notch for pinch bolt, not circumferential groove.

Either way, pin strength is not going to be as important, as I am either sleeving the pin all the way to the spindle, or I am going to use the large taper pins mentioned above and tig without a sleeve.

We don't have a race soon coming up, so it's not priority for me but I am in high gear on this.

I want to be able to spit out quantities because I am building the 944S SP2 car I PM'd you about.

With Hoosier R7 grip, a car setup to be able to do it and a driver that can take it to the limit, it's bound to happen.

These (or the stock) pins may last a slow driver his entire lifetime....

T

Last edited by 951and944S; 09-20-2017 at 11:31 AM.
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Old 09-20-2017, 12:43 PM
  #30  
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Umh, ok, so I drop off two 968 arms to machinist.

Right off the bat, his 1st suggestion is that because I am making these from a billet anyway, I can solve the spacing issue of extending the pin to correct the position of the a arm at rest by just building up the pedestal height where the ball joint is, closing the distance between the spindle pinch bolt bore and the top of the a arm.

Jim...., Glen, what do you guys think about this alternative...?

I drew something quick up in emachine just to display what I'm talking about -



T
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