on April 30, 2010, 6:55 pm, Daze wrote:

Thanks for posting the pix!!! It is nice to get a little diversity, and see....
   the differences between the Mark VIII unit and the JAg unit. How wide is the Mark VIII unit hub to hub??

on May 5, 2010, 3:19 pm, farna wrote:

That type IRS (along with many other fairly new ones) has one big problem -- the spring seats (in this case air bag seats) are made onto the unit body it came from. So you'll have to devise a support for the bags on the body, and the shock crossmember right above it isn't designed to carry the weight of the car in most cases. I'd replace the bags with aftermarket ones if you plan on keeping them. The old Mark VIII and other Lincoln bags are known for leaks. Of course they are around 10 years old by the time the system develops leaks, and it might be in the plumbing and not the bags themselves. Spring kits to replace the bags are, however, popular for a reason! I bet Ford used plastic (actually nylon) lines and they give out.

The old 280Z/280ZX IRS might be a better choice. It is narrower and uses struts. Coil-over shocks could be substituted without too much trouble.

on May 6, 2010, 6:18 pm, HoosierMike wrote:

Sorry it took so long to get back, I've been pretty busy lately. Backing to backing is right at 63". If I use the IRS it will be on a 66 TBird. I bought a 95 Mark 8 that was slightly wrecked to get the motor and tranny to use in my 66 Mustang. (I've already put the Heidt's MII suspension in the Stang.) I pretty much stripped everything off of the Mark before I junked it. Since I have the TBird I thought one day I might be able to put the IRS under it. I haven't done any measuring or figuring yet. May be completely
impossible, I honestly don't know. I've got so much work to do on the Stang that I need to keep my mind on it. But with a site like this I'm sure to get plenty of ideas once I do start on it. I will say the Jag IRS looks like it would be much easier to modify. Looks like a real nice unit.

on May 8, 2010, 7:34 am, Joe wrote:

How do you like the Mustang II suspension? Did you do the install yourself? Anything that you would do different?

on May 9, 2010, 8:32 am, Joe wrote:

Thanks Mike, sounds like we are on similiar paths. I have my motor being built right now. When the old motor comes out I am going to put in the new MustangII front suspension, new motor and then the Jag IRS. My thinking here is that I need all of the new stuff in the front so that I can position the Jag rear end for the proper ride heigth.

on May 10, 2010, 8:21 am, Daze wrote:

Here is my over all opinion on a MII kit.
There is a time and a place for a Mustang II kit. Mike wants to put a 4.6 in his car so it makes sense to remove the shock towers. Nolan 62 is putting a Mustang II kit in his falcon because he had shock tower damage. Both of those instances are good reasons to go Mustang II, however a Mustang II front suspension is by no means the best suspension you can put in to a classic Mustang IMHO.

I have spent the last 10 years learning everything I can about mustang suspension, including leverage angles, suspension geometry, camber curves, ackerman angle and much much more. From that I have come to the conclushion that a Mustang II suspension is better than a bone stock classic Mustang suspension , but is not as good as a performance front suspension based on the original Mustang suspension.

There are some aspects of the Mustang II suspension such as ackerman angle that are completely incorrect for the track width and wheel base for a classic Mustang.

A classic Mustang with the following list of improvements to the original suspension configuration will out perform a classic Mustang outfitted with a Mustang II front suspension:
performance alignment
1" sway bar
adjustable strut rods
roller spring perches
slightly stiffer than stock coil springs
performance shocks such as kyb

I know you said you wanted the adjust-ability and with that in mind there is an even better option. One of the reason a Mustang II kit is an improvement over the stock components is the spring and shock connect directly to the LCA which in turn improves the leverage angle of the suspension. A Mustang II kit also often times comes with adjustable coil over shocks which can help in dialing in the suspension. Both of these improvements can be had by going to a coil over front suspension designed for the classic Mustang. They are made by global west, ron morris, and TCP. Like the Mustang II kit the coil over shock connects directly to the LCA, but still maintains the over all original suspension design and it works with stock spindles which maintain the correct steering geometry including ackerman angle. 

For may Mustang I am building my own coil over front suspension because it is the most superior option currently available for a classic Mustang and will be a nice compliment to my IRS.

on May 10, 2010, 7:39 pm, Daze wrote:

here is the basics of ackerman angle Ackerman angle is the angle that the steering arm has in relation to the rest of the car and controls the arch of the spindles when turning. If you think about it, when cornering, the inside wheel of the turn needs to turn sharper than the outside wheel. To accomplish this the difference between the inside and outside arc is determined by the angle of the steering arm, which in turn is calculated based on both the track width and the wheel base. Proper arm angle is created by angling the steering arms along a line drawn between both the LCA ball joint bisecting the steering arm pivot points and ending with the center line of the rear axle.   

The length of the arm creates the steering ratio where longer arms take less effort to turn the wheels but do not turn the wheels as sharply. In contrast shorter arms have a sharper turning ratio but require more effort to turn the wheel. Ackerman angle is the main reason why you can’t just take a spindle from one car and throw it on another unless there is a similar wheelbase and track width. Incorrect Ackerman angle and steering arm length will result in tire scrubbing during cornering, less front traction during cornering and reduced or over exaggerated turning radius.
On a classic Mustang running a Mustang II kit these effects are minimal but still there. the biggest problem you may notice is reduced turning radius. Don't be alarmed however you car should still handle and drive well.

on May 11, 2010, 6:35 pm, Daze wrote:

Joe, I think I may have given you the wrong idea   In my Passion for suspension... I know its an illness... and my own pursuit for the best possible suspension combination, I may have given you the idea that a Mustang II kit in a classic Mustang was a bad idea, and that is simply not the case. The effects of incorrect ackerman angle and reduced spring shock leverage are not so drastic that by installing the Mustang II kit you are going to be downgrading your suspension. There are lots of classic Mustangs, Falcons, and Cougars running around with Mustang II suspension, not to mention the countless street rods that use this system.

What I was trying to convey is that there are better options than the Mustang II kit. I am not to be argumentative, but rather just curious, why do you want to do a Mustang II kit rather than a full coil over kit?

on May 12, 2010, 10:47 am, Daze wrote:

If you are wanting to eliminate the shock towers than the Mustang II kit  makes total sens. I think you will be happy with that set up. Of all the research I have done on steering and suspension the most informative page on ackerman angle was this one http://www.rc-truckncar-tuning.com/ackerman.html Its is a page dedicated ackerman angle on remote control cars, but the principal is no different on our full size cars. It will give you a really good education on Ackerman, and should clear up any questions you may have. As always if I can help further please don't hesitate to ask.

on May 15, 2010, 5:01 pm,HoosierMike wrote:

Joe  Here's some pics 






The arm is 5" from center of spindle pivot to center of hole on steering arm.

Hope this helps.

A question for anyone that reads this, the sway bar on the Mark 8 IRS is hollow. I assumed they were solid, aren't most sway bars solid?
Thanks HoosierMike

Last edited by Daze (10/08/2011 7:18 pm)