Ralphy wrote:

It occurred to me recently that most modern high performance manufacture IRS suspensions have a common trait. Which is a single mounted upright at the LCA and the UCA and they all use a separate toe rod behind the halfshaft. Cars included are the Corvette, Cobra Mustang and Dodge Viper. Reasoning may be to remove any twisting of the upright with higher powered motors. Corvette has been using this type of toe control since the C4.  Just thought I would throw that out there.

Ralphy

The C-4 Corvette used an adjustable toe rod, but it did not use an upper/lower control arm setup. Instead it used a double trailing arm setup similar to 4-link.

C-5 was the fist year for the upper/lower control arms.

Shiny Side Up!
Bill

Ralphy wrote:

ProTouring442,

Yes I understand that, however it still used a separate toe rod behind the HS. I just became aware of the fact most of the higher output OEM cars use this design controlling toe directly behind the HS. This position would seem to me the best in controlling any flexing in the upright. The  C4 I guess under hard acceleration would want to draw the HS's inward.

If you mark the positions of the uprights pivot points say Jag Vs. C5, the triangle has a horizontal base with the Jag. The C5's points are rotated 90 degrees and of course the HS is no longer a stressed point. Ive always noticed this fact but however again I never really noticed this design in parallel to power.

Got ya...

I'm not sure it's really all about power, or if packaging and cost aren't in there somewhere. The ability to make the more complex systems work, coupled with the customer's demands perhaps? I say this because the C-2/C-3 sure had some high HP models (L-88 for example) in conjunction with the same old C-2 design. There are also NVH issues that the newer design alleviates. High HP or no, the modern consumer will not tolerate the same NVH the buyer of a C-3 or older Corvette found to be perfectly acceptable.

As far as packaging for a retrofit, I don't think you can beat the C-4 trailing arm design. Since it still uses the halfshaft as the upper control arm, you don't have the frame clearance issues you would have with a more "modern" design.

Shiny Side Up!
Bill

phantomjock wrote:

ProTouring442 wrote:

As far as packaging for a retrofit, I don't think you can beat the C-4 trailing arm design. Since it still uses the halfshaft as the upper control arm, you don't have the frame clearance issues you would have with a more "modern" design.

Not really a fan of that myself - but to each his own.
The shortcoming in the C3 is the toe variation.  That can be overcome by modifying to a 4 link and more than a few do.
But the half shaft as a loaded member is just asking for trouble - if you max perform the vehicle.  Sooner or later - you'll loose it.

C5 or C6 would be a better  Corvette choice for an IRS  - IMHO,   But I'm on my own design/build and trying to take even those "One Step Beyond." And you are entirely correct - the frame does make a real clearance problem.  I've solved that with a hacksaw.  As the build progresses - I'll start loading pics in a separate thread.

Cheers-Jim

Of course, altering the C-3 to a 4-lonk design is, in effect, making it a C-4.

I don't think I agree that the using the halfshaft as a loaded member is such a bad idea. From the L-88 to the '90-'95 ZR1, Chevrolet used such a setup with no difficulty. True, I wouldn't throw 1,000hp at it, but I think anything 600hp or less (at the crank) should be OK for a "hotrodded" IRS.

As for the hacksaw, I am going IRS in a '72 Olds 442. I think I would need to basically "back half" the car to go with a C-5/C-6 style setup. If I were going to do that, I would have gone with a custom frame... first I would need the bucks to spring for that 20K frame though! :D

Shiny Side Up!
Bill

phantomjock wrote:

"Pro-touring", and this is only my second IRS mod, I'm taking a bit of a "use what I have," and mod what I need. And, I can do for a significantly less value than the $20K.  If you wanted to, I bet you could do a Team321IRS install  for 5-10% of that!  And they did all the work but the cut and install!

Cheers - Jim

20K was a full Roadster Shop frame with C-5/C-6 front and rear suspension. And believe me, if I ever have the money (got to get those books finished!), I will be contacting them. Probably for the whole build!

I'm going to use a Jag center with C-4 halfshafts, uprights, trailing arms, etc. C-6 Z06 brakes. It's more of a Pro-"Grand Touring" car really. 6-way power seats, tilt/tele, custom console, nice stereo, etc. A bit of American Muscle Car meets BMW M6 I guess.

I'm looking forward to seeing what you come up with!

Shiny Side Up!
Bill

Ralphy wrote:

Bill different but mechanically similar, the C2/C3 does control toe from a horizontal plain as the C4. Except from the front of the trailing arm. Which has two, no at least three shortfalls. The wheels toe outward with travel and the rubber bushings allow the arm mounts to move under loading and last, any suspension motion shortens the wheelbase. I've read enough posts where knowledgeable guys have drove both versions and they say the C4 is vastly superior.

Have you seen Pier's C3 conversion?

By the way your ride is awesome, stealth NOT! LOL!

Ralphy

Thanks for the compliment!

I haven't seen (or maybe haven't seen) Pier's conversion... is it on this board?

I pick up my Jag center on Thursday, and my 'Vette halfshafts/uprights/etc are on their way! Woohoo! LOL

Shiny Side Up!
Bill

Its hot outside - and I bet everyone is having a great time enjoying the summer with their IRS builds!
I'm working on the Garage remodel - and while taking an Air Conditioned break from the heat, I came across a couple of interesting suspension ideas for your consideration:




That is a great pic of the front suspension for the Dodge Tomahawk - an 8 cylinder 4 - wheeled "scooter." 
The rear  (IRS) information is a bit spotty but came across this:


And the "Type 1" has an interesting camber approach to consider:



Enjoy - I gotta get back to the ceiling!

Cheers - Jim

How much did the reamer cost?

Ralphy

Ouch!
But I figured as much, yeah, consider that cheap. That's a rare animal, even in a machine shop. I'm guessing it's made of HSS/High Speed Steel. Charish it like a child always use a cutting oil and spin it slow maybe 50 RPM. I may need to rent it someday!

Ralphy

Last edited by Ralphy (10/24/2013 6:29 am)

Hey Ralphy - Wanna cut some steelplate (3/16 or 1/4) for those 8 pieces I'll need to make the upper and lower ball jint attachments?  The RED plates in the diagram.  I can provide pdf, stl, stp, gcode (but out of practice).  My drawing is Rhino - but can export. 

Interested in making some pocket money over lunch?

Cheers - Jim

Cool - We can take this off line to PM.  I  need to get the Ball Joints (Coleman Wed-In place)  in to spec the holes for the lowers and the ""weld-In" "SLUGS" for the ppers.  Shortly -- I hope - shipping says tomorrow.  Then we can look at the drawings and see if do-able. 

Cheers - Jim.
 

But guys, if you take this discussion to a PM, we won't have nail biting updates
Just kidding.
Post pics when you're done, this should look great!

Ralphy pointed out - I didn't show the shock/spring mount -- here is an update for that:


BTW - there are some great discussions over on the Lateral-G.net regarding suspensions too.  Ken sutton knows his stuff!  Here are the three key stickies if you are interested:

1.  Overview of handling and his background  -- http://www.lateral-g.net/forums/showthread.php4?t=42423

2.  IRS - very key for this forum -- http://www.lateral-g.net/forums/showthread.php4?t=42568

3. for the front end -- http://www.lateral-g.net/forums/showthread.php4?t=42467

Cheers - Jim

Last edited by phantomjock (10/25/2013 2:27 pm)

phantomjock wrote:

There is a SIGNIFICANT challenge with using C5 - or C6 uprights.  They are meant to be replaced if/when the ball joint goes bad.  And there are NO replacement Ball Joints to be had - buy a new UPRIGHT!  What Idiot thought that up?!!

Much of this has to do with pressing the ball joint in and out of aluminum. Many auto manufacturers who use aluminum arms or uprights do not sell the joints as serviceable parts. My BMW M5 (E34) has aluminum control arms in the front suspension and the ball joints are not replaceable for that reason.

I would think, to properly replace them, you would have to do as I must when replacing the bearings in my Triumph Bonneville's engine cases, heat up the aluminum until the bearing (or in the case of the control arm or upright, the ball joint) nearly falls out or drops in. Otherwise, pressing them in may gall the aluminum to the point where the interference fit is of too little tension.

Just my .02... take it for what it is worth.

Bill
 

SO that may well explain the number of C5 uprights that are routinely for sale on eBay.  Not all from wreckers - just left overs following replacement for a bad ball joint.  Also, I  suppose the system doesn't encourage ball joint replacement (using heat as you have suggested - for liability reasons - and so no replacement ball joint is made available.  It has been declared Non-Servicible and the lawyers would love to sue  if some shop did replacements!

That TR-Bonneville wouldn't be the same as Steve McQueen's ride in the Great Escape, would it Bill?

Cheers - Jim

Over the past few years there has been a minor movement to DIY/CNC manufacturing of Alumiinum Billet Uprights.  The nice part about some of the designs, they can be modular and assebled rather than welded saving on fabrication, and easing manufacturing complexity.  This is a set built by a fellow who is building a Formula 1000.  Ok it weighs between 1000-1400 pounds wet, but the DIY work was done without a CNC as I understand.

Cheers - Jim