IRS and drag racing

[scottpe]

For all I know, Ford went with line lock because they figured it could help burnouts and thus, reduce wheel hop... :shrug:

My point was, as a manufacturer you don't put a feature like that (clearly a drag specific feature) on a production vehicle -- for the first time ever -- unless you have some confidence in its ability to perform the task at hand.

IRS was implemented for comfort and(and some think, safety to a degree) not by any means for drag racing.

Oh, there's no doubt you're right about it not being implemented for drag racing. But just because it's not 'designed for' drag racing, that obviously that doesn't mean it can't launch as well or better than an SRA. I believe the latter is very possible if it's designed right. Drag racing or not, putting power to the ground from a standstill is an important priority for any performance car...

In fact, I think comfort was the only original intent and that it seems to offer better grip by keeping more tires planted over bumps was simply a bonus we learned along the way.

I think that might be a stretch. I think the engineers knew exactly what the benefits would be if they got it right.

Bottom line is, odds are that hard core drag racers will want to consider an SRA swap for durability and simplicity. For casual racers, especially those that do not plan to run slicks, the IRS may hold up just fine and also perform very well at putting the power down... Possibly better.

But at any rate it appears Ford is still at least somewhat in tune with the drag racing part of the Mustang's heritage, as evidenced by the drag-friendly features the car offers. Thus I have some confidence that they factored drag performance into their design of this suspension, at least to some degree. Time will tell how well they did.

Sponsored

 

[thePill]

IRS is bad for drag racing, it's all kinds of bad. Axle wrap/Pinion Angle, parasitic loss, half-shalf's w/U's... Camber gain on squat... Whole different ball game now.

Another thing fella's, according to the early rear frame section shots, the S550 has NO REAR KICKUP. That means, major structure changes need to be made to accommodate a 3 inch tube. Don't expect a bolt in solid axle kit.

 

[EXP Jawa]

Somebody will do something. I'd be willing to bet that if Ford Racing continues to offer Cobra Jet models, they (and Strange Engineering) will find a way.

 

[scottpe]

IRS is bad for drag racing, it's all kinds of bad. Axle wrap/Pinion Angle, parasitic loss, half-shalf's w/U's... Camber gain on squat... Whole different ball game now.

Again, while I completely agree that SRA is overall better suited for it, the IRS is not the end of the world. There are some INCREDIBLY fast cars racing on IRS.

Bottom line is, it's a compromise that needed to be made, given the direction Ford needed to take the car, and people will adapt to the change one way or another as they always have.

Another thing fella's, according to the early rear frame section shots, the S550 has NO REAR KICKUP. That means, major structure changes need to be made to accommodate a 3 inch tube. Don't expect a bolt in solid axle kit.

I agree with EXP Jawa... they will find a way. ;)

 

[Rob WH]

My point was, as a manufacturer you don't put a feature like that (clearly a drag specific feature) on a production vehicle -- for the first time ever -- unless you have some confidence in its ability to perform the task at hand.

Oh, there's no doubt you're right about it not being implemented for drag racing. But just because it's not 'designed for' drag racing, that obviously that doesn't mean it can't launch as well or better than an SRA. I believe the latter is very possible if it's designed right. Drag racing or not, putting power to the ground from a standstill is an important priority for any performance car...

I concede it would be hilarious to see this causing failure and therefore, Ford must have confidence. I also know that with better traction, there is less wheel hop... unless you have leaf spring suspension. Also, it's typical to not have the forward traction with IRS because of all the movement it allows. Even if it doesn't spin, it's spreading out the load and that means power is spread out rather than centered.

My point is, IRS simply hasn't ever been made to do this job as well as SLA can and I don't see any way to make that happen because any time we move along to add comfort or safety or maneuverability or to reduce harshness... anything to make the ride better... we have to take away something else and in the case of IRS, that something else is basically... squat. That means the vehicle in question simply cannot hit the launch as hard. Conversely, a 6-link system can be very well tuned and might, depending on weight and power, truly help with straight launches. Such a setup would surely make regular driving less than desirable.

You could point to the Corvette, which has a very different IRS, and say even that has been seen pulling the front wheels. Of course, the weight bias is 50/50 from the factory and people are moving more toward the rear in those cases... however, the car is quite light from the factory and lighter still in many cases if it's pulling wheels. It's also highly modified in the already comfort lacking IRS. Many times it's a modified 6 link.

I think that might be a stretch. I think the engineers knew exactly what the benefits would be if they got it right.

There's a trade off, no matter what they know or learn... they already know that. ;)

Bottom line is, odds are that hard core drag racers will want to consider an SRA swap for durability and simplicity. For casual racers, especially those that do not plan to run slicks, the IRS may hold up just fine and also perform very well at putting the power down... Possibly better.

I was considering a different approach. Rather than a total swap, build around what's there and give it basically ... stop points... to make it have no side to side give using adjustable heim joint links. With the twist of a wrench, it could be made stiffer or even be disconnected, bringing back stock ride or something close... it all depends on space available.

But at any rate it appears Ford is still at least somewhat in tune with the drag racing part of the Mustang's heritage, as evidenced by the drag-friendly features the car offers. Thus I have some confidence that they factored drag performance into their design of this suspension, at least to some degree. Time will tell how well they did.

There's been talk about Ford actually offering a solid rear over the counter... that would be cool, but expensive.

 

[DHG1078]

The 2015 Mustang GT will most likely perform better in a straight line drag than the 2014. Ford is not dumb and they know how to design cars. Yes, SRA is imho a better design strictly for drag racing, but an IRS can hold its own at reasonable power levels. When we start talking about modifying cars, we aren't really comparing apples to apples here. Stock for stock, the 2015 mustang gt will be faster in a straight line at the drag strip. It will be dependable.

Side note: can we please stop calling a Solid Rear Axle a SLA? never heard anyone call it an SLA since that stands for Short-Long Arm.

 

[JimmyTwoTimes]

DHG: Stands for Solid Live Axle.

Honestly, the IRS is the reason I'm trading in my old Mustang for a 2015. It's my daily driver, and the solid axle causes me problems every single day. I've gotten used to it at this point, but cornering on a pot-holed road (and all of the roads I drive on are pot-holed like they've been shelled by artillery) with a solid axle means the back end is stepping out of place three times a second, and the looseness you feel in the back end bouncing over pot holes can get downright dangerous sometimes. A car that can at least keep one drive wheel on the ground at all times is something that will make my life a whole lot easier.

 

[DHG1078]

DHG: Stands for Solid Live Axle.

OMG I can't believe that didn't click!!!

lol every time i saw SLA i just thought short-long arm.

I retract my previous statement.

 

[Rob WH]

The 2015 Mustang GT will most likely perform better in a straight line drag than the 2014. Ford is not dumb and they know how to design cars. Yes, SRA is imho a better design strictly for drag racing, but an IRS can hold its own at reasonable power levels. When we start talking about modifying cars, we aren't really comparing apples to apples here. Stock for stock, the 2015 mustang gt will be faster in a straight line at the drag strip. It will be dependable.

Side note: can we please stop calling a Solid Rear Axle a SLA? never heard anyone call it an SLA since that stands for Short-Long Arm.

Of course Ford isn't stupid. That doesn't mean IRS is better than SLA/SRA for drag racing. Give and take, friend... That's what engineering is all about.

How many people who care about how well their Mustang performs are truly likely to leave it 100% stock... About 3%... So it's apples to apples without question.

I want it to be quicker on any track... faster doesn't mean jack squat to me. That said, I think it's utterly foolish to simply believe it's going to be quicker on the drag strip while also being more efficient and more powerful and having a better ride quality... That's like asking for a motor home to get Prius economy with the road grabbing qualities of a GT-R... It's just expecting too much impo. Either way, racers don't typically leave their cars altogether stock.

DHG: Stands for Solid Live Axle.

Honestly, the IRS is the reason I'm trading in my old Mustang for a 2015. It's my daily driver, and the solid axle causes me problems every single day. I've gotten used to it at this point, but cornering on a pot-holed road (and all of the roads I drive on are pot-holed like they've been shelled by artillery) with a solid axle means the back end is stepping out of place three times a second, and the looseness you feel in the back end bouncing over pot holes can get downright dangerous sometimes. A car that can at least keep one drive wheel on the ground at all times is something that will make my life a whole lot easier.

What did you own before the Mustang?

Potholes can be a problem. I used to live in Cleveland, Ohio and it's been called the pothole capital of the world... it's bad. I lost a hubcap there one day and not only never found it, but when I went back for it, what I did find was probably 30 or more... just not mine! It was hilarious! That said, have you seen artillery damage? Way worse...

Not that you wanna hear it, but if the roads are that bad and not being repaired, you may wanna consider a larger vehicle, like an SUV. I miss my Explorer in that regard. It had a full frame and after the thud, just kept moving. It still bounced and lost footing here and there... nothing's perfect. For about the price of the high end Mustang, you could have an Explorer Sport... so sweet... I just didn't wanna spend 50 g's.

OMG I can't believe that didn't click!!!

lol every time i saw SLA i just thought short-long arm.

I retract my previous statement.

I've specifically labeled it both ways because I know some people aren't totally aware of the acronyms.

 

[scottpe]

Potholes can be a problem. I used to live in Cleveland, Ohio and it's been called the pothole capital of the world... it's bad. I lost a hubcap there one day and not only never found it, but when I went back for it, what I did find was probably 30 or more... just not mine! It was hilarious!

Sounds like road conditions may be a bit more extreme in his area, but I think the general situation applies in a lot of places. Where I live the roads are overall pretty good from a maintenance perspective, however, there are always bumps, irregularities, seams, etc. that unsettle my Mustang's rear, especially around corners. Not very confidence inspiring. I'm not expecting miracles, but I'm quite confident that if the 2015 IRS is well engineered, that will situation will be significantly diminished, which is a big plus in my book.

That said, have you seen artillery damage? Way worse...

Whoa, you must really live in a rough part of town!! :lol:

But seriously, ex-military I presume? If so, thank you for your service... :clap2:

 

[Rob WH]

Sounds like road conditions may be a bit more extreme in his area, but I think the general situation applies in a lot of places. Where I live the roads are overall pretty good from a maintenance perspective, however, there are always bumps, irregularities, seams, etc. that unsettle my Mustang's rear, especially around corners. Not very confidence inspiring. I'm not expecting miracles, but I'm quite confident that if the 2015 IRS is well engineered, that will situation will be significantly diminished, which is a big plus in my book.

I lived in Dallas(Addison mostly) for quite awhile.... Idonno about his specific area, but the midwest and east in general are likely to have bad spots all over due to harsh winters. Dallas was awesome in comparison... like Florida, really. PS... I miss Dallas! If not for a solid reason to stay in Florida, I'd be there instead.

Whoa, you must really live in a rough part of town!! :lol:

Heh... I've seen the results of mortars... and such. ;) It's not one of these... [ame]http://www.dailymotion.com/video/x4pbux_daisy-cutter-in-vietnam_news[/ame] ... :shocked: but...

But seriously, ex-military I presume? If so, thank you for your service... :clap2:

Yes and thank you. I got retired because I was hurt... still pisses me off, frankly. My weapons systems actually made a mortar round blast zone resemble a common pothole... 1 was made to sink ships, 1 to sink subs and 2 to take out missiles and/or aircraft. It was cool stuff and I never even got to fire it... all I ever got to do is track the targets... that too, used to piss me off. Looking back, everyone was needed to ensure the job was done right.

 

[Norm Peterson]

DHG: Stands for Solid Live Axle.

Alphabetically correct but logically confusing at best, given that the acronym "SLA" has been in general use for the written-out term "Short-Long Arm" . . . for decades.

What I have heard of before is "SRA", for Solid REAR Axle. Isn't that a whole lot clearer, even though neither you nor I made it up?


Norm

 

[TungstenGT]

Here's what I don't get: If you're serious about drag racing, why would you start with a $40,000, brand-new, heavy IRS Mustang? Why not just get a '79 Mustang, stuff a big block in it and squirt nitrous? You'll consistently run 8s for a lot less money and effort. If you're not serious about it, and you just want to have fun, then what difference does it make if you lose or gain a 10th of a second due to IRS? It will still be fun, right? :shrug:

 

[Rob WH]

Here's what I don't get: If you're serious about drag racing, why would you start with a $40,000, brand-new, heavy IRS Mustang? Why not just get a '79 Mustang, stuff a big block in it and squirt nitrous? You'll consistently run 8s for a lot less money and effort. If you're not serious about it, and you just want to have fun, then what difference does it make if you lose or gain a 10th of a second due to IRS? It will still be fun, right? :shrug:

What if ... you only wanna run 10's in your daily driver? How about if you also want navigation or A/C or to be able to tune it for the drag strip, road course or street on the same day ... w/o visiting a shop? There are many reasons to want your daily driver to be very quick rather than to go home to get your quick car for a trip to the track. Besides, a 10 second DD with A/C etc. is way more cool than an old FOX body lacking all creature comforts and not street acceptable.

Sure, if you want a drag only set up, an old FOX body is great(I like the Futura). I got rid of an 82 a few yrs ago... Once upon a time, it had a 460 in it and was street driven. I didn't like it much since the front was so heavy. Besides, the 460 isn't cheap and my 351W build was much better for street use. Anyway... I no longer want a race only car. The one I do have sits... and sits.... and sits.

 

[Norm Peterson]

I type too slow.

Here's what I don't get: If you're serious about drag racing, why would you start with a $40,000, brand-new, heavy IRS Mustang? Why not just get a '79 Mustang, stuff a big block in it and squirt nitrous? You'll consistently run 8s for a lot less money and effort. If you're not serious about it, and you just want to have fun, then what difference does it make if you lose or gain a 10th of a second due to IRS? It will still be fun, right? :shrug:

Makes sense. Maybe even too much sense for people looking to buy a new car for whatever reason. I hear what Rob is trying to say, but I think he's describing people who aren't quite serious enough.

The catch comes when you consider the (overly) strong general public association linking U.S. domestic ponycars and muscle cars with the dragstrip and "street challenges". And the perceived need to always beat the other guy by that tenth rather than lose by the same amount.

It will get interesting for the drag race fans and wanna-be's once all three ponycars are running IRS.


Norm

Sponsored