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9/15/2015 2:35 pm  #1


2005 GTO IRS

Hi guys.  I'm new here, but have been winding up here almost consistently with various searches on IRS questions.
Great forum!  Anyway, I'm curious if anyone has or has attempted to narrow this semi-trailing arm suspension.  And if they did, how did it work out?  It is going in a '33 Victoria replica.  I found out that the Driveshaft Shop can make me custom half shafts narrowed 6" each, for about what a good pair of 8.8 Mustang axles would cost, about $400.00.  As I look at the stock setup, it looks like I could cut and move the inner pivot on the arm, making sure to keep the same geometry.  Second, since that would put the arm right in the way of the toe link, I would lose that and go with a camber / toe bushing setup from one of the manufacturers out there.  Any input would be greatly appreciated.

 

9/20/2015 8:16 pm  #2


Re: 2005 GTO IRS

Ok, so after MUCH searching on the web, it looks like the effort to narrow the semi-trailing design is far more work than the performance this design is worth. So, it looks like I'll be using the Dana 44 as a center section, Thunderbird knuckles, spindles, and brakes,  modified for a 4-1/2" bolt pattern, and custom half shafts from the Drifeshaft Shop.  I may or may not be able to use the factory control arms, if not I'll fab them from 1-1/2" dom tubing and spherical rod ends.  Any comments would be appreciated!
 

     Thread Starter
 

9/21/2015 2:24 am  #3


Re: 2005 GTO IRS

Welcome Aboard! 
I note the forum has been kinda' slow form some of the frenzy pitch we had a while back.  http://cdn.boardhost.com/emoticons/grin.png


There is a great deal of info here and folks that have built their IRS like you're planning. 
There are a number of other options to using DOM and welding bungs to make your corntol arms - but those will certainly work! 
You'll be at the threshold of submitting pics - be sure and post some.  [I am overdue on my project - and better do some too.]

Cheers - Jim
 


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

9/21/2015 3:43 am  #4


Re: 2005 GTO IRS

phantomjock wrote:

Welcome Aboard! 
I note the forum has been kinda' slow form some of the frenzy pitch we had a while back.  http://cdn.boardhost.com/emoticons/grin.png


There is a great deal of info here and folks that have built their IRS like you're planning. 
There are a number of other options to using DOM and welding bungs to make your corntol arms - but those will certainly work! 
You'll be at the threshold of submitting pics - be sure and post some.  [I am overdue on my project - and better do some too.]

Cheers - Jim
 

I'm just getting to setting the center section this week.  I'm going to pick up the rest of the hardware at the bone yard during the week.  Once I have everything mocked up, I'll be sure to post pics. 
I'm curious, besides the oem arms or fabricating from tubing, what other options were you thinking of.  I'm always open to suggestions / learning new stuff!

     Thread Starter
 

9/21/2015 3:32 pm  #5


Re: 2005 GTO IRS

A while back I posted a thread that was on the "bits and Pieces" - or something like that.  There are a number of hex tube and swedged tube manufacturers that might be enough for your MOD.  The dirt track and circle track folks use a lot of that and really put it to the test.

Here is that link:
http://irsforum.boardhost.com/viewtopic.php?id=260

The total project is here:
http://vettemod.com/forum/showthread.php?t=10667
I started with some rightous - I mean LARGE DOM and threaded it rather than do the weld in bungs.  MAN what weight.  I've since gone to oversize AL hex Tubes. Haven't run it yet.

RE:  Halfshafts.  will you have enough end-play to accomodate any  suspension movement (in and out)? 
I had some slip shafts built for my Corvette project - much doccumented here - and on Vettemod.com   Have since gone to CV axles - less weight and rotational mass.
Here's the 'vette link :
http://irsforum.boardhost.com/viewtopic.php?id=490



Cheers - Jim

Last edited by phantomjock (9/21/2015 3:36 pm)


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

9/21/2015 4:37 pm  #6


Re: 2005 GTO IRS

Thanks for the extra info.  I plan on using the Dana 44 center section from the GTO rear, as the 'Bird units available around my area all seem to have the 7.5" rear. The GTO  used cv joints, so since the T-Birds did too, its only a matter of having the shafts made, one end with the GTO cv joints, and the other with the 'Bird joints.  The Driveshaft Shop quoted me $400 for two standard half shafts, and $1,300 for two half shafts with a plunging joint at one end.  I'll have to see how much travel there is once I have it mocked up and go from there.

     Thread Starter
 

9/24/2015 3:59 am  #7


Re: 2005 GTO IRS

Ok, so a quick update.  Sometimes you have to step back, have a cup of coffee, and look at something with a fresh perspective.  I may not be able to use the control arms from the GTO, but if I cut the forged bearing carrier off of the stamped portion of the arm, trim the "fat" from the side the stamped portion was attached, I can fabricate my own uprights, and use the forged bearing carrier as a more traditional hub.  Keeps the rear all GTO for future parts consideration.  All I need are shortened half shafts.  The added benefit is that I also get to keep the rear disk brakes, which are in perfect shape, so another couple of hundred dollars saved!  I'm going to set the center section over this weekend and then start mocking up for the control arms.  Wish me luck!
 

     Thread Starter
 

9/25/2015 1:43 pm  #8


Re: 2005 GTO IRS

Good Luck on that!  I tend to take my pause with a beer in the afternoon and refocus...http://cdn.boardhost.com/emoticons/grin.png

I bet downstream you'll end up using the couple 100 bucks you saved!  Ain't "hot-rodding" FUN?

Cheers - Jim


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

9/25/2015 3:57 pm  #9


Re: 2005 GTO IRS

phantomjock wrote:

Good Luck on that!  I tend to take my pause with a beer in the afternoon and refocus...http://cdn.boardhost.com/emoticons/grin.png

I bet downstream you'll end up using the couple 100 bucks you saved!  Ain't "hot-rodding" FUN?

Cheers - Jim

I don't think there is any question that that $500 or $700 that the additional brake kit wold have cost will be used on something else ( ain't that the point of saving on something, more to spend elsewhere? http://cdn.boardhost.com/emoticons/happy.png
)   
 

     Thread Starter
 

10/04/2015 12:35 pm  #10


Re: 2005 GTO IRS

Got the center section mocked up.  Hopefully get final bracketry made up for next weekend.  I plan on making it a complete bolt in.  Then I can start making up the lower control arms and the uprights.  Modifying the trailing arms by cutting the bearing hub off and having it machined flat to use as a hub looks like it will work just fine.

     Thread Starter
 

10/04/2015 12:58 pm  #11


Re: 2005 GTO IRS

I got a couple of shots of the rear mocked in position.  Hopefully much more progress by next weekend!http://i57.tinypic.com/34ep1g3.jpg
http://i58.tinypic.com/2m2fl7s.jpg

     Thread Starter
 

10/05/2015 4:24 pm  #12


Re: 2005 GTO IRS

The GTO bearing carrier / brakes, less all that nasty trailing arm baggage.  http://i59.tinypic.com/2zy8u9d.jpg
 Now to fabricate the actual uprights.

     Thread Starter
 

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