So I was thinking about the controversy between the Crown vic, Taurus, RWD FWD etc... And I thought of something. I know there are alot of old school guys on here, and I was wondering what you thought of the IRS/IFS vs Live Axle. At this point I'll simply say that unless it is a truck, Independent suspension does darn near everything better than a solid axle.
IRS vs Live Axle
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On a car a live axle is still more robust and probably longer lasting than independent stuff. Parts are bigger, simpler, and the lifetime cost is less. Performance is not as good.
Although some VERY powerful muscle/sports cars (Vipers/Vettes/03-04 Cobras, etc.) have gone pretty durned fast in the quarter mile with IRS (albeit beefed up in some cases), solid axles still rule in drag racing.
Also, even though it was/is required by the rules, the Trans Am/GT-1 racing series, and Aussie Supercar series seem to do OK turning left and right with solid axles.
That being said, I would prefer my next RWD car to have an IRS, despite the weight/straight line, and strength/longevity penalties.
Also, even though it was/is required by the rules, the Trans Am/GT-1 racing series, and Aussie Supercar series seem to do OK turning left and right with solid axles.
That being said, I would prefer my next RWD car to have an IRS, despite the weight/straight line, and strength/longevity penalties.
the only real advantage of a solid axle is you can launch them harder at a drag strip. If i was building a road racer i woudl only keep a live axle if it was required by the regulations or budget constraints. Its not hard to make a live axle handle, I had a nice setup on my mustang.
I've got independent under my car and a 9" under my truck.
Depends how much horsepower I was putting down, if I was planning on modifying it highly, budget, etc.
I could probably have several 9" rearends built to hold more power than you can produce for the cost it might take for you to get a stock IRS unit up to part, short of buying a high performance vehicle's unit (which would likely still be quite expensive).
Albeit, I can see how handling the curves easier could be expected from an IRS unit, while a straight line would be a cake walk for a solid axle, but I think the differences could be made nearly negligible.
Depends how much horsepower I was putting down, if I was planning on modifying it highly, budget, etc.
I could probably have several 9" rearends built to hold more power than you can produce for the cost it might take for you to get a stock IRS unit up to part, short of buying a high performance vehicle's unit (which would likely still be quite expensive).
Albeit, I can see how handling the curves easier could be expected from an IRS unit, while a straight line would be a cake walk for a solid axle, but I think the differences could be made nearly negligible.
Originally Posted By: BeanCounter
I've got independent under my car and a 9" under my truck.
Depends how much horsepower I was putting down, if I was planning on modifying it highly, budget, etc.
I could probably have several 9" rearends built to hold more power than you can produce for the cost it might take for you to get a stock IRS unit up to part, short of buying a high performance vehicle's unit (which would likely still be quite expensive).
Albeit, I can see how handling the curves easier could be expected from an IRS unit, while a straight line would be a cake walk for a solid axle, but I think the differences could be made nearly negligible.
Yes, it takes similar amounts of money/effort to get a solid axle to handle very well (Watts links/decoupled torque arms, rod ended control arms, full floaters, etc.), as it does to get an IRS to handle massive power and tractive drag strip launches (300M material & larger axles/half shafts, beefier U/CV joints, stronger centers, braces, anti wheelhop devices, etc.).
I've got independent under my car and a 9" under my truck.
Depends how much horsepower I was putting down, if I was planning on modifying it highly, budget, etc.
I could probably have several 9" rearends built to hold more power than you can produce for the cost it might take for you to get a stock IRS unit up to part, short of buying a high performance vehicle's unit (which would likely still be quite expensive).
Albeit, I can see how handling the curves easier could be expected from an IRS unit, while a straight line would be a cake walk for a solid axle, but I think the differences could be made nearly negligible.
Yes, it takes similar amounts of money/effort to get a solid axle to handle very well (Watts links/decoupled torque arms, rod ended control arms, full floaters, etc.), as it does to get an IRS to handle massive power and tractive drag strip launches (300M material & larger axles/half shafts, beefier U/CV joints, stronger centers, braces, anti wheelhop devices, etc.).
I personally prefer independent for road vehicles, and solid axles for like, jeeps. As some have pointed out, the mustang does just fine with a solid axle. But in not a straight line, it seems that fully independent multi links suspension with all the fancy stuff is usually alot better when it comes to going round bends and stuff.
IS is great for smooth and controlled ride, and solid axle is the only real thing you can have it you offroad.
IS is great for smooth and controlled ride, and solid axle is the only real thing you can have it you offroad.
Originally Posted By: dailydriver
Yes, it takes similar amounts of money/effort to get a solid axle to handle very well (Watts links/decoupled torque arms, rod ended control arms, full floaters, etc.), as it does to get an IRS to handle massive power and tractive drag strip launches (300M material & larger axles/half shafts, beefier U/CV joints, stronger centers, braces, anti wheelhop devices, etc.).
I'd gladly welcome you to break that down for me.
I have $80 and $250 in polished Strange racing gears and a full Detroit. I can get chromo shafts for under $200. Throw in a Daytona support and a nodular case for relatively inexpensive and you can pump some serious power with ease.
A decent IRS unit would likely be pricey in its stock form, so I'm not buying until I see some reasonable pricing info here. It appears most the items you mentioned for a solid axle have nothing to do with the unit but rather the suspension. That was never part of the comparison as far as I was aware. And a full float setup is needed to get as strong as an independent setup? Reality must be severely skewed...
Yes, it takes similar amounts of money/effort to get a solid axle to handle very well (Watts links/decoupled torque arms, rod ended control arms, full floaters, etc.), as it does to get an IRS to handle massive power and tractive drag strip launches (300M material & larger axles/half shafts, beefier U/CV joints, stronger centers, braces, anti wheelhop devices, etc.).
I'd gladly welcome you to break that down for me.
I have $80 and $250 in polished Strange racing gears and a full Detroit. I can get chromo shafts for under $200. Throw in a Daytona support and a nodular case for relatively inexpensive and you can pump some serious power with ease.
A decent IRS unit would likely be pricey in its stock form, so I'm not buying until I see some reasonable pricing info here. It appears most the items you mentioned for a solid axle have nothing to do with the unit but rather the suspension. That was never part of the comparison as far as I was aware. And a full float setup is needed to get as strong as an independent setup? Reality must be severely skewed...
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Quote:
It appears most the items you mentioned for a solid axle have nothing to do with the unit but rather the suspension.
Which handling, if I read the original post correctly and mind read for intent, would be the only thing that one could adapt. The axle itself is a fixed object.
I saw no reference to "putting blown out ultra tweaked hp to the ground that was never offered off of the show room floor" in the original post.
It appears most the items you mentioned for a solid axle have nothing to do with the unit but rather the suspension.
Which handling, if I read the original post correctly and mind read for intent, would be the only thing that one could adapt. The axle itself is a fixed object.
I saw no reference to "putting blown out ultra tweaked hp to the ground that was never offered off of the show room floor" in the original post.
Originally Posted By: rudolphna
So I was thinking about the controversy between the Crown vic, Taurus, RWD FWD etc... And I thought of something. I know there are alot of old school guys on here, and I was wondering what you thought of the IRS/IFS vs Live Axle. At this point I'll simply say that unless it is a truck, Independent suspension does darn near everything better than a solid axle.
There's no clear answer. There was a period of time when advertisers could brag about a new car having IRS and people would call live axle cars "stone age." But that was all marketing [censored], not truth.
Live axles actually have some handling ADVANTAGES over IRS, believe it or not. In general, there's a more favorable roll center, meaning that less sway bar is needed for the same amount of body roll.
Also, as any drag racer knows, solid axles do a better job of sheer straight-line acceleration without wheel hop (unless its an old GM A-body rear suspension, anyway).
Solid axles maintain perfect camber control through all maneuvers and throughout the full range of suspension travel, too.
And as others have said, solid axles are FAR more rugged and reliable- which is why my favorite 4x4s all have solid axles at BOTH ends, not just in the back. But IRS and REAR drive (so the CV joints don't have to go through huge angles like they do with FWD) is about 90% as rugged as a live axle and rear drive. So if the controversy is about copcars to replace the CVPI, then really the question should be whether they're rear drive or FWD. FWD has no business under a copcar, or ANY performance car for that matter.
Really the only significant drawbacks to a solid axle are more unsprung weight, and the fact that when cornering on rough pavement, the bouncing and hopping of one wheel disrupts the traction of the wheel on the other side too.
The last one is actually fairly significant, and why IRS does so well in the real world. But really... the differences are WAY overblown. Pick on other features of the car, not on how the rear suspension works. Most of the time if you were blindfolded and led to a car and asked to drive it, you'd have a hard time figuring out what it had from the way it drives.
So I was thinking about the controversy between the Crown vic, Taurus, RWD FWD etc... And I thought of something. I know there are alot of old school guys on here, and I was wondering what you thought of the IRS/IFS vs Live Axle. At this point I'll simply say that unless it is a truck, Independent suspension does darn near everything better than a solid axle.
There's no clear answer. There was a period of time when advertisers could brag about a new car having IRS and people would call live axle cars "stone age." But that was all marketing [censored], not truth.
Live axles actually have some handling ADVANTAGES over IRS, believe it or not. In general, there's a more favorable roll center, meaning that less sway bar is needed for the same amount of body roll.
Also, as any drag racer knows, solid axles do a better job of sheer straight-line acceleration without wheel hop (unless its an old GM A-body rear suspension, anyway).
Solid axles maintain perfect camber control through all maneuvers and throughout the full range of suspension travel, too.
And as others have said, solid axles are FAR more rugged and reliable- which is why my favorite 4x4s all have solid axles at BOTH ends, not just in the back. But IRS and REAR drive (so the CV joints don't have to go through huge angles like they do with FWD) is about 90% as rugged as a live axle and rear drive. So if the controversy is about copcars to replace the CVPI, then really the question should be whether they're rear drive or FWD. FWD has no business under a copcar, or ANY performance car for that matter.
Really the only significant drawbacks to a solid axle are more unsprung weight, and the fact that when cornering on rough pavement, the bouncing and hopping of one wheel disrupts the traction of the wheel on the other side too.
The last one is actually fairly significant, and why IRS does so well in the real world. But really... the differences are WAY overblown. Pick on other features of the car, not on how the rear suspension works. Most of the time if you were blindfolded and led to a car and asked to drive it, you'd have a hard time figuring out what it had from the way it drives.
Originally Posted By: Gary Allan
Quote:
It appears most the items you mentioned for a solid axle have nothing to do with the unit but rather the suspension.
Which handling, if I read the original post correctly and mind read for intent, would be the only thing that one could adapt. The axle itself is a fixed object.
I saw no reference to "putting blown out ultra tweaked hp to the ground that was never offered off of the show room floor" in the original post.
Read my comment that he responded to, Gary.
Quote:
It appears most the items you mentioned for a solid axle have nothing to do with the unit but rather the suspension.
Which handling, if I read the original post correctly and mind read for intent, would be the only thing that one could adapt. The axle itself is a fixed object.
I saw no reference to "putting blown out ultra tweaked hp to the ground that was never offered off of the show room floor" in the original post.
Read my comment that he responded to, Gary.
Originally Posted By: BeanCounter
Originally Posted By: dailydriver
Yes, it takes similar amounts of money/effort to get a solid axle to handle very well (Watts links/decoupled torque arms, rod ended control arms, full floaters, etc.), as it does to get an IRS to handle massive power and tractive drag strip launches (300M material & larger axles/half shafts, beefier U/CV joints, stronger centers, braces, anti wheelhop devices, etc.).
I'd gladly welcome you to break that down for me.
I have $80 and $250 in polished Strange racing gears and a full Detroit. I can get chromo shafts for under $200. Throw in a Daytona support and a nodular case for relatively inexpensive and you can pump some serious power with ease.
A decent IRS unit would likely be pricey in its stock form, so I'm not buying until I see some reasonable pricing info here. It appears most the items you mentioned for a solid axle have nothing to do with the unit but rather the suspension. That was never part of the comparison as far as I was aware. And a full float setup is needed to get as strong as an independent setup? Reality must be severely skewed...
Well, a beefy solid axle won't break but if the suspension components controlling its motion aren't up to the task, what good is it? You just break other stuff up the line...
The axle is a component of a suspension system.
On rough road racing courses I don't think the unsprung weight penalty of a solid axle can really be made up given all else equal, suspension tuning can only do so much.
I
Originally Posted By: dailydriver
Yes, it takes similar amounts of money/effort to get a solid axle to handle very well (Watts links/decoupled torque arms, rod ended control arms, full floaters, etc.), as it does to get an IRS to handle massive power and tractive drag strip launches (300M material & larger axles/half shafts, beefier U/CV joints, stronger centers, braces, anti wheelhop devices, etc.).
I'd gladly welcome you to break that down for me.
I have $80 and $250 in polished Strange racing gears and a full Detroit. I can get chromo shafts for under $200. Throw in a Daytona support and a nodular case for relatively inexpensive and you can pump some serious power with ease.
A decent IRS unit would likely be pricey in its stock form, so I'm not buying until I see some reasonable pricing info here. It appears most the items you mentioned for a solid axle have nothing to do with the unit but rather the suspension. That was never part of the comparison as far as I was aware. And a full float setup is needed to get as strong as an independent setup? Reality must be severely skewed...
Well, a beefy solid axle won't break but if the suspension components controlling its motion aren't up to the task, what good is it? You just break other stuff up the line...
The axle is a component of a suspension system.
On rough road racing courses I don't think the unsprung weight penalty of a solid axle can really be made up given all else equal, suspension tuning can only do so much.
I
Originally Posted By: IndyIan
Well, a beefy solid axle won't break but if the suspension components controlling its motion aren't up to the task, what good is it? You just break other stuff up the line...
The axle is a component of a suspension system.
On rough road racing courses I don't think the unsprung weight penalty of a solid axle can really be made up given all else equal, suspension tuning can only do so much.
I
And components down the line of a strong IRS driveline are immune? Not to mention u-joints and such are meant to wear so other parts don't.
I mentioned curves in my prior comments, but this was never directed strictly towards road racing, which I still don't know if I would say a solid axle couldn't hack it.
FWIW, there are some very light solid units out there. Shoot, the one under my truck out of '78
Bronco I could almost pick up in the curl position and move by myself and that was bone stock 65" in width with a locker.
Well, a beefy solid axle won't break but if the suspension components controlling its motion aren't up to the task, what good is it? You just break other stuff up the line...
The axle is a component of a suspension system.
On rough road racing courses I don't think the unsprung weight penalty of a solid axle can really be made up given all else equal, suspension tuning can only do so much.
I
And components down the line of a strong IRS driveline are immune? Not to mention u-joints and such are meant to wear so other parts don't.
I mentioned curves in my prior comments, but this was never directed strictly towards road racing, which I still don't know if I would say a solid axle couldn't hack it.
FWIW, there are some very light solid units out there. Shoot, the one under my truck out of '78
Bronco I could almost pick up in the curl position and move by myself and that was bone stock 65" in width with a locker.
Originally Posted By: rudolphna
I personally prefer independent for road vehicles, and solid axles for like, jeeps. As some have pointed out, the mustang does just fine with a solid axle. But in not a straight line, it seems that fully independent multi links suspension with all the fancy stuff is usually alot better when it comes to going round bends and stuff.
The solid axle Mustang out handles the new Camaro and Challenger, both IRS equipped. The solid axle has proven its worth in various racing series as well, including Grand Am Cup.
IRSs, in general, are better for both handling and ride, but generalizations rarely tell the whole story.
I personally prefer independent for road vehicles, and solid axles for like, jeeps. As some have pointed out, the mustang does just fine with a solid axle. But in not a straight line, it seems that fully independent multi links suspension with all the fancy stuff is usually alot better when it comes to going round bends and stuff.
The solid axle Mustang out handles the new Camaro and Challenger, both IRS equipped. The solid axle has proven its worth in various racing series as well, including Grand Am Cup.
IRSs, in general, are better for both handling and ride, but generalizations rarely tell the whole story.
Originally Posted By: Ben99GT
Originally Posted By: rudolphna
I personally prefer independent for road vehicles, and solid axles for like, jeeps. As some have pointed out, the mustang does just fine with a solid axle. But in not a straight line, it seems that fully independent multi links suspension with all the fancy stuff is usually alot better when it comes to going round bends and stuff.
The solid axle Mustang out handles the new Camaro and Challenger, both IRS equipped. The solid axle has proven its worth in various racing series as well, including Grand Am Cup.
IRSs, in general, are better for both handling and ride, but generalizations rarely tell the whole story.
I would agree that the mustang beats them, but it is a lot lighter too. And if that was the case, why do nearly all the high end european, and japanese, use Independent suspension? The Nissan GT-R, the Mitsubishi Lancer Evo, Porsche, Lambo, Ferrari, Aston Martin.... The list goes on forever. IS does work, and when done well, it works well, but I don't think even the most sophisticated live axle would compare to a high end IS setup.
Originally Posted By: rudolphna
I personally prefer independent for road vehicles, and solid axles for like, jeeps. As some have pointed out, the mustang does just fine with a solid axle. But in not a straight line, it seems that fully independent multi links suspension with all the fancy stuff is usually alot better when it comes to going round bends and stuff.
The solid axle Mustang out handles the new Camaro and Challenger, both IRS equipped. The solid axle has proven its worth in various racing series as well, including Grand Am Cup.
IRSs, in general, are better for both handling and ride, but generalizations rarely tell the whole story.
I would agree that the mustang beats them, but it is a lot lighter too. And if that was the case, why do nearly all the high end european, and japanese, use Independent suspension? The Nissan GT-R, the Mitsubishi Lancer Evo, Porsche, Lambo, Ferrari, Aston Martin.... The list goes on forever. IS does work, and when done well, it works well, but I don't think even the most sophisticated live axle would compare to a high end IS setup.
I'd think it's cheaper to stamp/cast a million control arms and other bits that can be sourced from almost anywhere vs. investing in a plant to cast solid axle castings. Unless you already invested in the plant, that is.
Originally Posted By: 440Magnum
The last one is actually fairly significant, and why IRS does so well in the real world. But really... the differences are WAY overblown. Pick on other features of the car, not on how the rear suspension works. Most of the time if you were blindfolded and led to a car and asked to drive it, you'd have a hard time figuring out what it had from the way it drives.
I dunno, I always feel the second vibration when a solid axle thumps a bump. I don't find it annoying most of the time but we have one very bad highway near us that has enough bumps that the extra movement at the back of my Tracker gets annoying after a while. Thankfully there are no real curves in the road either as I don't want to chase the back end on pavement at highway speeds.
The last one is actually fairly significant, and why IRS does so well in the real world. But really... the differences are WAY overblown. Pick on other features of the car, not on how the rear suspension works. Most of the time if you were blindfolded and led to a car and asked to drive it, you'd have a hard time figuring out what it had from the way it drives.
I dunno, I always feel the second vibration when a solid axle thumps a bump. I don't find it annoying most of the time but we have one very bad highway near us that has enough bumps that the extra movement at the back of my Tracker gets annoying after a while. Thankfully there are no real curves in the road either as I don't want to chase the back end on pavement at highway speeds.
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Originally Posted By: BeanCounter
Originally Posted By: Gary Allan
Quote:
It appears most the items you mentioned for a solid axle have nothing to do with the unit but rather the suspension.
Which handling, if I read the original post correctly and mind read for intent, would be the only thing that one could adapt. The axle itself is a fixed object.
I saw no reference to "putting blown out ultra tweaked hp to the ground that was never offered off of the show room floor" in the original post.
Read my comment that he responded to, Gary.
Quote:
. That was never part of the comparison as far as I was aware. And a full float setup is needed to get as strong as an independent setup? Reality must be severely skewed...
I didn't see that said anywhere. I saw (essentially) that you would have to tweak the suspension on a solid axle to get it to handle. You would have to tweak IRS to give it comparative strength.
..but I may not be reading enough into it..
Originally Posted By: Gary Allan
Quote:
It appears most the items you mentioned for a solid axle have nothing to do with the unit but rather the suspension.
Which handling, if I read the original post correctly and mind read for intent, would be the only thing that one could adapt. The axle itself is a fixed object.
I saw no reference to "putting blown out ultra tweaked hp to the ground that was never offered off of the show room floor" in the original post.
Read my comment that he responded to, Gary.
Quote:
. That was never part of the comparison as far as I was aware. And a full float setup is needed to get as strong as an independent setup? Reality must be severely skewed...
..but I may not be reading enough into it..
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Ford used IRS on the Cobra, including the '03/'04 "Termi", and it could be setup to handle some decent drag strip launched with the poly bushing upgrade; Essentially the centre section out of an 8.8" solid diff, but from cast aluminum w/31-spline axles, the Termi setup wasn't bad.
I have the 28-spline setup (Pre-termi Cobra) for my Capri. Lots of parts.
That being said, lots of drag-strip Termi's are swapped to an 8.8" solid diff. It is a "known quantity" performer at the strip when upgraded.
Parts for either are relatively inexpensive.
Of course Ford went BACK to live axle for the Shelby cars....... What that says, I'm not sure.
I have the 28-spline setup (Pre-termi Cobra) for my Capri. Lots of parts.
That being said, lots of drag-strip Termi's are swapped to an 8.8" solid diff. It is a "known quantity" performer at the strip when upgraded.
Parts for either are relatively inexpensive.
Of course Ford went BACK to live axle for the Shelby cars....... What that says, I'm not sure.
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