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11/14/2011 8:28 am  #1


IRS in 67 mustang

Daze,
First off, I love your site.  I also voted for you for sema.  I'm In A tough spot , I want to get a rear setup for my car and I want something trick.  I've thought about solid, 03/04 cobra  conversion, jag setup. And now I see the new heidts setup.  I like the inboard brakes and the complete setup built ready to bolt in part.  I'm just stuck because everytime I price out each type, they are all with in a few dollars of each other.  What do you think of the heidts pro-G setup?

http://www.heidts.com/6769_camaro_rear_independent_suspension.html

Last edited by Daze (11/14/2011 8:47 am)

 

11/14/2011 8:53 am  #2


Re: IRS in 67 mustang

well that is an interesting suspension
http://www.heidts.com/_uploaded_files/high_horsepower_irs.jpg

http://www.heidts.com/_uploaded_files/high_horsepower_irs_front.jpg


That is the most beautiful "Frankenstein" of parts I have ever seen:
ford 9"
Jag stile inboard rear discs
Jag stile tubular LCAs
custom hubs
UCAs like a modern Musting IRS

I am impressed.

My question to you is what are your plans for the car?  road corse? drag strip? street only?  also you had said on the other forum that you were worried about breaking a Jag set up what kind of HP are you putting down at the rear wheels???


If it isn't broken..... modify it anyway!!!!
http://dazecars.com/dazed/JagArmssignature.jpg
 

11/14/2011 9:21 am  #3


Re: IRS in 67 mustang

Well, I have a built 351 W. with Alum CHI heads and a big vortech Ysi.  I'm looking at 550+ to the rear tires.  It is mostly a street car, and future road corse  track time car.  Never a drag car.  Im looking for a great handling, trick looking, comfortable car.  I'd like to do the occasional burnout and power slide.

     Thread Starter
 

11/14/2011 9:32 am  #4


Re: IRS in 67 mustang

So what am I missing? Is this trailing arm a special alloy that expands when in motion or what. When I look at the product pics, I see two arc's that don't match and cause a bind during suspension travel. Is this a rear toe-in that uses the chemical give of the lower control arm?

I am sure that I'm missing something but don't know what it is.

Heidt's advertises them for 65-70 Mustang's too.

Mustsed

Last edited by Mustsed (11/14/2011 11:41 am)


Nothing is impossible, some just cost more!
 

11/14/2011 9:38 am  #5


Re: IRS in 67 mustang

Yes, that is what sparked my interest is that it is a bolt in unit.  Comes completely assembled to your door free shipping.  With subframe connectors included.

     Thread Starter
 

11/14/2011 9:51 am  #6


Re: IRS in 67 mustang

Mustsed wrote:

So what are we missing? Is this trailing arm a special alloy that expands when in motion or what. When I look at the product pics, I see two arc's that don't match and cause a bind during suspension travel. Is this a rear toe-in that uses the chemical give of the lower control arm?

I am sure that I'm missing something but don't know what it is.

Heidt's advertises them for 65-70 Mustang's to.

Mustsed

Oh I missed that, I don't like the trailing arm design either.  I am sure the arms are so long because that will reduce the for and aft movement as the arm goes through its arc but the bushings on both end would have to be rubber to take up the rest of the change.


If it isn't broken..... modify it anyway!!!!
http://dazecars.com/dazed/JagArmssignature.jpg
 

11/14/2011 9:54 am  #7


Re: IRS in 67 mustang

Could u break that down for me? I don't exactly know what you guys are talking about

     Thread Starter
 

11/14/2011 10:03 am  #8


Re: IRS in 67 mustang

The lower control arm has no forward motion built the way it is. The trailing link going forward about 3 feet arcs forward thru travel up and down. This would want to pull the lower control arm forward when it's not built to go forward. BIND!


A few Cobra guys have been doing this for some time now. without the trailing link.
http://www.primequip.net/products/Project_427/rear_end.htm

Last edited by Ralphy (11/14/2011 10:43 am)

 

11/14/2011 10:36 am  #9


Re: IRS in 67 mustang

Gee! This is what I have been hinting around to Day about. A UCA, then add a upper watts link and throw out the trailing link. Or just add a two point mounted UCA.

 

11/14/2011 10:55 am  #10


Re: IRS in 67 mustang

So all this means?  Is it a poor design, seems to do well at the good guys track events.

     Thread Starter
 

11/14/2011 10:59 am  #11


Re: IRS in 67 mustang

I think I get it, the Uca will move but the bottom won't due to the connection to the subframe. Connectors.

     Thread Starter
 

11/14/2011 11:12 am  #12


Re: IRS in 67 mustang

Yes!
Look up Heidt's vids and you will see some running without the trailing link.

http://www.youtube.com/watch?v=1cHrmZ8ufco

Last edited by Ralphy (11/14/2011 11:15 am)

 

11/14/2011 1:04 pm  #13


Re: IRS in 67 mustang

Suicide67 wrote:

So all this means?  Is it a poor design, seems to do well at the good guys track events.

Jag-ish with CVs and an upper lateral link.

Thoughts:

1) It looks like the diff is rigidly mounted to the upper crossmember, and the lower crossmember below the nose, and that whole assembly rigidly mounts to the rear subframe rails, which is going to pass a whole lot of gear noise into the car.  Is there any rubber in there that I'm missing?     I'd have thought that if they were going to go to that much work they'd have gotten the suspension links completely off the diff carrier.

2) Others have noted that that trailing arm is going to try to pull the lower arm forward with bump travel; the question is where do they get enough compliance in the whole thing to permit it to do so without bind?

3) Inboard brakes are a PITA to work on and if they get hot they're going to put more heat into the side bearing seals (the Jag bugbear.)  Not an issue in street use or the little Good Guys autocrosses but may bite you in real track-day use.

4) Looks like the upper arms and maybe a few other places use rod ends, not fond of that for a road car, fair bit of NVH and they don't last if not sealed.

Last edited by JEM (11/14/2011 1:05 pm)

 

11/14/2011 1:09 pm  #14


Re: IRS in 67 mustang

Thanks for that reply. It made sense to me giving thoughts on problem issues.  Thanks JEM.  Maybe I'll just stay solid axle then

     Thread Starter
 

11/14/2011 4:16 pm  #15


Re: IRS in 67 mustang

Suicide67 wrote:

So all this means?  Is it a poor design, seems to do well at the good guys track events.

I don't think it is a poor design.  I am sure there are rubber bushings in those trailing arms absorb any deflection, I just don't like it because I think there is a better way to do it.  It is an easy enough fix if you get that system just make your own trailing arms and set them up correctly.

Suicide67 wrote:

I think I get it, the Uca will move but the bottom won't due to the connection to the subframe. Connectors.

it has nothing to do with the UCA  picture the trailing arm as if you were looking at it from the side.  now picture that same arm being used to draw a circle with the front mount being the center pivot and the other end of the arm creating the arch.  At ride height if the trailing arm is parallel with the road any movement up or down is going to be in an arch which will pull the LCA where it's mounted forward.  The LCs is rigidly mounted for and aft so the two forces will pull against each other and cause a bind.  however if the trailing arm bushings have enough give than that movement can be absorbed by the bushing and eliminate the bind.  make sense???

Suicide67 wrote:

Thanks for that reply. It made sense to me giving thoughts on problem issues.  Thanks JEM.  Maybe I'll just stay solid axle then

I agree there is going to be some road noise and drivetrain vibration transmitted in to the chassis.  But the inboard disc are not necessarily a problem. yes they are a little harder to work on and can be prone to heat issues however  it would not be that hard to run some cooling ducts to the brakes and any issues that may arise due slightly harder maintenance is well worth it due to the unsprung weight.  I mean how often are you going to need to do brake work on the rear???  As far as HP goes it is my opinion that you could go either way.  a live axle will be easier to channel all that power through but I think an IRS can still be set up to handle it with minimal wheel hop.


If it isn't broken..... modify it anyway!!!!
http://dazecars.com/dazed/JagArmssignature.jpg
 

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