Mustang II SLA
12-02-2016, 08:34 AM
#1
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Join Date: Oct 2007
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Mustang II SLA
I was just browsing a catalog from racecar engineering and while looking through it I saw all those packages they sell for hot rods using the basic design of the Mustang II front suspension. It's a shame Ford went backwards with the Fox Body and latter mustangs. I know those bloody accountants have a lot to do with it but Goddamnit it would have been nice to have an SLA without forking 8k on a Griggs or Cortex setup. Even the S550 doesn't have an SLA in the front.
But being the curious type I wonder if one of those heidts or similar setups would fit the S197. God knows they are cheaper than the Griggs and Cortex, but the real question is, does the SLA offer such a greater advantage over the McPherson to justify the cost?
Off topic: i also looked into the heidts and similar rear irs for 60's Mustangs. I hope in 40 years we can get an affordable irs and sla for our cars
NOTE: Before I get chewed up about how the McPherson and solid axle can be made to handle just as wel as a full independent suspension, I know that' Mine has almost everything installed already except coilovers and a watts link, I just thought it would make an interesting topic considering this section is mostly dead. Apparently people still cling to the idea that Mustangs can't handle and are made to go in a straight line only.
But being the curious type I wonder if one of those heidts or similar setups would fit the S197. God knows they are cheaper than the Griggs and Cortex, but the real question is, does the SLA offer such a greater advantage over the McPherson to justify the cost?
Off topic: i also looked into the heidts and similar rear irs for 60's Mustangs. I hope in 40 years we can get an affordable irs and sla for our cars
NOTE: Before I get chewed up about how the McPherson and solid axle can be made to handle just as wel as a full independent suspension, I know that' Mine has almost everything installed already except coilovers and a watts link, I just thought it would make an interesting topic considering this section is mostly dead. Apparently people still cling to the idea that Mustangs can't handle and are made to go in a straight line only.
12-03-2016, 09:29 AM
#2
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Join Date: Feb 2007
Location: state of confusion
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Front suspension:
Making it all fit without compromising the geometry (too much)?
Weight?
Crash performance? (different load paths mean different structure)
Strut suspensions are probably more likely to guarantee limit understeer, which might be better compatible with stability control techniques.
In the end, it's a case of the devil being in the details whether it's a strut or SLA up front, or a stick-axle or IRS in the rear. As a front suspension example, some regular production SLA cars have actually had the front geometric roll center located below the ground (worse geometry than a strut in some respects).
My recollection of the Mustang II SLA was that the links were pretty short, making things like front view instant centers and geo roll centers migrate more rapidly with suspension movement than desirable. Whether the aftermarket has corrected that in their versions, I don't know.
Norm
Making it all fit without compromising the geometry (too much)?
Weight?
Crash performance? (different load paths mean different structure)
Strut suspensions are probably more likely to guarantee limit understeer, which might be better compatible with stability control techniques.
In the end, it's a case of the devil being in the details whether it's a strut or SLA up front, or a stick-axle or IRS in the rear. As a front suspension example, some regular production SLA cars have actually had the front geometric roll center located below the ground (worse geometry than a strut in some respects).
My recollection of the Mustang II SLA was that the links were pretty short, making things like front view instant centers and geo roll centers migrate more rapidly with suspension movement than desirable. Whether the aftermarket has corrected that in their versions, I don't know.
Norm
Last edited by Norm Peterson; 12-03-2016 at 09:32 AM.
12-11-2016, 09:23 PM
#3
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Join Date: Oct 2007
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You're probably right. The only advantage I see in an SLA setup is that since the strut isn't there you can fit a bigger tire. Although I think you can go up to 315 up front with Vorshlag.
Have you seen the IRS they sell at mustangirs.com? Looks well made but getting it properly tuned must be a nightmare, since nobody uses it. I mean spring rate and such. For the street the ride must be nice though. I wonder if they've actually sold any? I don't think anyone in any of the forums I visit has it.
Have you seen the IRS they sell at mustangirs.com? Looks well made but getting it properly tuned must be a nightmare, since nobody uses it. I mean spring rate and such. For the street the ride must be nice though. I wonder if they've actually sold any? I don't think anyone in any of the forums I visit has it.
12-12-2016, 07:09 AM
#4
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Join Date: Feb 2007
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I've heard of at least one Mustang IRS conversion before, but I don't know if it was this one or not. On a quick glance at their assembly drawing, I think I'd rather have the suspension feature real upper links separate from the half-shafts. I realize that Jaguars and Corvettes both used half-shafts as UCAs, but that was strictly 1950's IRS technology. Corvette got completely away from it by (I think) the 5th gen in 1997.
Norm
Norm
Last edited by Norm Peterson; 12-12-2016 at 07:18 AM.
12-28-2016, 04:30 PM
#5
Join Date: Jun 2015
Location: Florida
Posts: 18
An IFS gets you the ability to reduce brake dive and add in camber gain in roll. Strut cars are really limited in what you can get in both areas. You can lower the car without the same disadvantages in geometry a strut car has. It puts the load path higher so its easier to control forces AND its easier to "net-build" the alignment because small errors in the strut mount holes don't give large caster and camber errors, as well. IFS' usually have some alignment method.
With a stick axle, Norm's right, it gives limit understeer as the negative camber goes away. The Gen 4 Camaros screwed up by adding an IFS rather than an IRS - IMHO - all to get better impact harshness over bumps and then had to live with the torque-arm stick axle. The S197 Mustangs made a better choice, again, IMHO.
The aftermarket hasn't really fixed the Mustang II geometry but it packages well in a street rod and it is better than a beam axle!
With a stick axle, Norm's right, it gives limit understeer as the negative camber goes away. The Gen 4 Camaros screwed up by adding an IFS rather than an IRS - IMHO - all to get better impact harshness over bumps and then had to live with the torque-arm stick axle. The S197 Mustangs made a better choice, again, IMHO.
The aftermarket hasn't really fixed the Mustang II geometry but it packages well in a street rod and it is better than a beam axle!