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4/22/2013 3:54 pm  #1


PhantomJock's IRS Build Thread

Back i the early 1980s, John Giovanni - patented a design to improve the C3 Corvette IRS. Mine was just a few years old then - but unaffordable (to me) at the time. 
Here are some images from his Patent, a few words from Corvette Fever at the time, and my efforts on it.  Hope you find some interesting information here:


http://i36.tinypic.com/10z4too.jpg



The upper control rods were atttached to the rear Differential with this bracket:

http://i37.tinypic.com/15nmwee.jpg



His effort was to remove this camber change from the C3 Rear Suspension:

http://i37.tinypic.com/epmyj5.jpg


Here is a Hardware View of his implementation:

http://i35.tinypic.com/2qb4qas.jpg



I was reluctant to mount directly to the diff - so welded brackets - and tabs to the rear diff carrier that is mounted to the chassis:

http://i33.tinypic.com/2h4hveg.jpg



The installed pics of my implementation:

http://i37.tinypic.com/3311yza.jpg



I did some "bench testing" measured camber change and plotted against the Patent Claims (His are black - extended in BLUE - mine observed in RED):



http://i34.tinypic.com/15cdjz5.jpg


ANd here is a comparison (graphic representation ) of my implementation and the "original C-3" Camber Curves:

http://i36.tinypic.com/21oxxlv.jpg


That green curve is hastily drawn - but you'll ghet the idea  - MAJOR improvements.  And while I was pleased with those results - the toe change is still governed (over-ridden) by the rear trailing arms of the C3. Thats why these occurr:

http://i35.tinypic.com/1hbbya.jpg


Now a few words from... (Corvette Fever)




http://i34.tinypic.com/2z4fo91.jpg



Next I'll start you on the journey investigating a bit of C5/6 implementation on my C3 Corvette.

Hope you enjoy the trip!

Cheers - Jim

Last edited by phantomjock (4/22/2013 3:57 pm)


UNDERCONSTRUCTION! Highly Modified C3 Corvette
         Dual Wishbone IRS w Subframe + Custom Uprights
 

4/22/2013 4:18 pm  #2


Re: PhantomJock's IRS Build Thread

So, having been down the investigation and "practice build" of "Jim's Giovanni" I searched out the C5/6 option.

C5/6 IRS is fairly available (as are Vipers) on eBay and through  Craigslist, etc.  They offer a dual wishbone and if you go Hub to hub a full set at often "reasonable" prices - frequently well under $2K.

http://www.vettemod.com/forum/imagehosting/12694ec7f8de1ed3d.jpg


Had I staretd down this pathe - Before the Diff build and the investement in the slip join half shaft - I'd be miles ahead - not learned as much!

My planning for the C3 mod for the C5 was like this:

http://www.vettemod.com/forum/imagehosting/12694ec7f8e1ecd8a.jpg


Do a lot of cutting and welding - try and figure out how to mod the chassis;
http://www.vettemod.com/forum/imagehosting/12694ec7f8e320bb2.jpg


reattching per teh earlier diagram,

http://www.vettemod.com/forum/imagehosting/12694ec7f8e4013af.jpg


and hopefully winding up with something like this:

http://www.vettemod.com/forum/imagehosting/12694eff04f6c31b8.jpg


but on a fairly "stock" C3 Chassis. 

Naturally, nothing is easy like this details;
http://www.vettemod.com/forum/imagehosting/12694ef8b21405684.jpg


NOPE!


http://www.vettemod.com/forum/imagehosting/12694ec7f8e4db7c8.jpg



See, my plan was to cut off both rear subframes - swap sides and then have the deal done!  Oh, yeah - but I can really "over think" a project if I have a little time... You'll see as the thread continues.

More to come!

Cheers - Jim









 


UNDERCONSTRUCTION! Highly Modified C3 Corvette
         Dual Wishbone IRS w Subframe + Custom Uprights
     Thread Starter
 

4/22/2013 5:06 pm  #3


Re: PhantomJock's IRS Build Thread

Pick up any reputable text on suspension design and I'll bet you it starts with the Tires/Tyres.
Why? Clearly, that is the interface we all operate with.  So, you can spend a lot of time working that - or pass it by (I did) because I am not funded as F-1 teams are to invest a lot in that (albeit) improtant design attribute. 
So, What is next?
Suspension Upright.  This is where Tire transfers load to the chassis.  The design and lay out of the upright is as critical as the mounting location of the wishbones. 

I did a bit of sleuthing for various upright designs and some are chronicled here on the forum, as are Bits and Pieces.

I spend a lot of time poking around teh Locost Forums - folks that do it all DIY - and came on a few neat approaches.  Here are a few:

http://i35.tinypic.com/qs8sxy.jpg


and this one:

http://i34.tinypic.com/f9ktvd.jpg


That one I call "Inspiration."  It made me realize if one guy could do that - so could I.  I wanted to keep my C-3 bearings - remember the slip jointed half shafts - so if I kept the bearing mount I could factor those in.  

Here are a couple of CAD files I created in developing my uprights:
http://i35.tinypic.com/2zzqq1h.jpg



That design seemed to carry a lot of ""weight - all unsprung"  so I skinneyed it down a bit to look a bit like this:
http://i36.tinypic.com/33ww0gm.jpg


More modeling and anayysis -- did I say "Over Think" again?

More coming.

Cheers - Jim.

Last edited by phantomjock (4/22/2013 5:07 pm)


UNDERCONSTRUCTION! Highly Modified C3 Corvette
         Dual Wishbone IRS w Subframe + Custom Uprights
     Thread Starter
 

4/22/2013 6:24 pm  #4


Re: PhantomJock's IRS Build Thread

Ok-
So I was designing uprights.
A major concern I was busy "O-T-ing" was regarded load transfer from Tire to Rim to Upright to UCA/LCA to Chassis.  Seem to make sense, that if the Upright most closely matched the rim diameter - there will be less torque to transfer to the chassis.  In other words, the loads at the rim from tire to road surface (while turning/sliding/under load) would not be causing the upright to rotate about its longitudnal axis.
Such an alignment should minimize jacking forces.

I used a few of teh available online and download-able resources - chron'ed elsewhere to help locate the outter and inner suspensiojn points. 

By this point I was firmly committed to design/engineer.build my own IRS.

I wanted to:
1. Minimize Roll Center movement (left right) under roll/bounce/jounce.
2. Minimize Jacking forces.
3. Acheive a Low rear Roll Center.

At this point I must give credit to my Team Manager - "She who Must be Obeyed - gave me full support (and tacitly permission) as I - once again - morphed the project/design from a Daily Driver to Track Car/street Legal DD.  That opened a lot of options like:
Limiting the shock travel
Stiffer springs (if you don't let it work - any suspension  will do)
Lower road height clearence.

So, I reattacked the CAD.  Here is a drawing from earlier on in the effort. (some parts not shown for clarity)

http://i36.tinypic.com/66yteo.jpg

PURPLE - Original Frame pieces
GREEN  - New sub-frame I'd build,
BLUE     - New IRS components designed and built by me
RED       - Bellcranks TBD/Bought/Buil
BLACK   - QA-1 Dual Adjust/Coil Overs

With a few ideas in hand - time to tackle the frame and do some damage!


More to come!

Cheers - Jim

Last edited by phantomjock (4/22/2013 6:28 pm)


UNDERCONSTRUCTION! Highly Modified C3 Corvette
         Dual Wishbone IRS w Subframe + Custom Uprights
     Thread Starter
 

4/23/2013 6:04 pm  #5


Re: PhantomJock's IRS Build Thread

Very col stuff.  i like a couple of the uprights.  The one's you've designed appear tall and wide at the top.  What size wheels are you planning for?  Could be an illusion but looks like you'd need some pretty big spacers if your wheels aren't pretty big.

 

4/23/2013 6:35 pm  #6


Re: PhantomJock's IRS Build Thread

rficalora wrote:

Very col stuff.  i like a couple of the uprights.  The one's you've designed appear tall and wide at the top.  What size wheels are you planning for?  Could be an illusion but looks like you'd need some pretty big spacers if your wheels aren't pretty big.

Ahh yes - thanks for asking -- I have migrated from 15x9.5 wheels  -- Western Wheel Vectors (love the look - also called Turbine) to 17x11 rear and 17x9,5 front ZR1s from a C5/6.  In designing the uprights - (pics to follow ... still organizing) I purposely designed/built the uprights to:
1. Be adjustable - I have 3  upper and 3 lower mount options for the control arms, and
2. Fit inside the wheels I have with their backspace, and
3. have the lower control arm mount  (wheel transmit of force point) as close to the horizonal plane of the wheel lower tire/lip bead -- is that confusing?  I'll have to draw a picture I'm sure.


BTW i I do have 2 and 4 inch spacers - the 2 are all that is needed for the ZR1s - because of the stud length,.  On the ZR1s the pocket accomodates the  LONG 1/2 studs,  but the vectors need 4 inch spacers.  I could cut back the studs  - BUT man, have I got Track width! PICs will follow!

Cheers - Jim

Last edited by phantomjock (4/23/2013 6:37 pm)


UNDERCONSTRUCTION! Highly Modified C3 Corvette
         Dual Wishbone IRS w Subframe + Custom Uprights
     Thread Starter
 

4/23/2013 6:47 pm  #7


Re: PhantomJock's IRS Build Thread

OK - Because you asked - but I'm getting ahead of myself...


http://i36.tinypic.com/1zc3l8y.jpg


Here you can see the upright and the opportunity for the wheel depth to nest around it -- but I  have the wide (4 inch) spacers in on this fitment - to trial for max Track.
You'll also note teh "substitute: for my coil over shocks and the belcrank install in this shot too. 
Also the infinately adjustable inboard mounts for UCA/LCA, The fuel tank - now replaced with a proper fuel cell, The mounting of the "new" rear sub-frame brackets, the hose for the diff catch can...
DIY adjusters (left/right threaded - by hand) on the UCA/LCA with SPHON spherical joints. 
Not so easy to see - the diff is raised nearly 2 inches! (or the chassis lowered).


Wow  - seems like we snuck past a few chapters!  

I'd better get writing!

Cheers - Jim


UNDERCONSTRUCTION! Highly Modified C3 Corvette
         Dual Wishbone IRS w Subframe + Custom Uprights
     Thread Starter
 

4/24/2013 7:27 pm  #8


Re: PhantomJock's IRS Build Thread

OK, now there's a lot going on in that one photo; cant wait to see more.  Is the LCA adjustable in both vertical and orizontal planes?  

Think you said it's a track car, is your plan to leave it infinitely adjustable?

Also, what will keep the LCA's from twisting under torque?  They look lighter/smaller than mine and i'm  only running 225's with a mild small block Ford 302.  Don't know how much motor you have, but tires that fill up the rest of the space you have should hook up pretty well.

 

4/25/2013 2:48 am  #9


Re: PhantomJock's IRS Build Thread

rficalora -
Great questions. There is some adjustment on the inner mounts
http://i36.tinypic.com/23tfoe0.jpg


The bracket is same for upper and lower. They are mounted in different orientations to match the rear subframe members.  (Naturally welded and boxed to the rear subframe!)

My plan is to sort it out, then weld washers to the bracket for the (near) final locations.  Track Car - and sometimes DD.
The control arms are 1x1 and stouter than many of the Aluminum hex ones  I''ve seen on other setups.  Pushing 450/450 HP/Tq with the 383 going in the front.  I'll get some more posted in a bit.

Cheers - Jim


UNDERCONSTRUCTION! Highly Modified C3 Corvette
         Dual Wishbone IRS w Subframe + Custom Uprights
     Thread Starter
 

5/09/2013 10:24 am  #10


Re: PhantomJock's IRS Build Thread

HOLY COW ! ! ! ! ! ! ! ! 

 

5/09/2013 2:00 pm  #11


Re: PhantomJock's IRS Build Thread

http://i40.tinypic.com/2ryn0jn.gif
MOOO!
Cheers - Jim

PS MORE Pics this weekend -- when its raining!


UNDERCONSTRUCTION! Highly Modified C3 Corvette
         Dual Wishbone IRS w Subframe + Custom Uprights
     Thread Starter
 

5/11/2013 3:15 am  #12


Re: PhantomJock's IRS Build Thread

Udderly Funny!

http://t2.gstatic.com/images?q=tbn:ANd9GcR-mWiM94ENKZXZWn27OVaWRemPYUxO-MoJ6t5o-kSjJ-Qnvw7AWg


Ralphy

Last edited by Ralphy (5/11/2013 3:18 am)

 

10/21/2013 4:28 pm  #13


Re: PhantomJock's IRS Build Thread

Well - its been since MAY and now October!  I'd better post some progress - or be accused of slacking -off!
So What is new?
I build a set of UCAs & LCAs - Upright and mounted to chassis with the Tabs shown in teh previous post.

Seemed effective, but HEAVY!  I was willing to sacrifice that bit of weight gain - thinking good for balance - it is in the REAR - but after adding the Roll Cage and more bits - thought I'd better do something else.

I was fiddling about with a few ideas - back to the C5 Corvett bit - and after I "graduated" from my final tour of Active Duty - said; "Screw It, i'll do it the way I should have from the start!"  So I got a pair of C5 Uprights and started cleaning them up - no A-Arms - just the uprights. 
They are just about polished - and I'll post the bling when they are, but spent some time on CAD today, and ordered a heap of bits from Coleman Racing to fab the IRS - finally!

http://i41.tinypic.com/2qcdsma.jpg


UNDERCONSTRUCTION! Highly Modified C3 Corvette
         Dual Wishbone IRS w Subframe + Custom Uprights
     Thread Starter
 

10/21/2013 4:42 pm  #14


Re: PhantomJock's IRS Build Thread

CONTINUED...

My overall plan is to fab the ball joint holder for the upper using the cool "Spindle eye/Taper" Coleman Racing sells:
http://i40.tinypic.com/x2324g.jpg


I'll warn you now -- these were cheaper this morning when I placed the order - so watch the price of "precious metals!"

Another cool part they have is teh Integral Ball Joint.  It is a weld-able piec and pball joint in one. Saves about 1/2 pound per side:
http://i44.tinypic.com/2s0ijdg.jpg

The plates I'll have fabricated by a "net buddy in Iowa - unless I find someone closer -- hint hint Ralphy!  ;D

The overall aopproach is like this shamelssly swiped pic form somewhere on the 'net:

http://i43.tinypic.com/jrql34.jpg



While that may be a FRS - it is close enough to what I'm up to.  Next - I'll need to source a pair of C5 Corvete CV half Shafts and have the Differential ENd modified to fit my stock C3 4.11 rear end!

AND - I'm planning on a Pushrod to Rockers Still for the Dampers.  Those are installed and I gotta take those pics soon too.

NO SLEPING GUYS!  Lets get to work before the snow falls --oops sorry Daze...That shovel get a work out yet?

Cheers - Jim


UNDERCONSTRUCTION! Highly Modified C3 Corvette
         Dual Wishbone IRS w Subframe + Custom Uprights
     Thread Starter
 

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