- Sep 5, 2000
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I was reading something on the new mustang mach 1 and it mentioned it had a live rear axle. What does that mean, what are the downsides/upsides and what are the alternatives?
What does live rear axle mean?
- Thread starter Bignate603
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Zenmervolt
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- Oct 22, 2000
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There are two kinds of axles, "live" and "dead". In both cases there is an actual physical connection between the wheels on opposite sides. A "live" axle is one where the connection between the sides is powered (ie, the wheels on the ends of a "live" axle are the drive wheels). A "dead" axle has no provision to drive the wheels. An example of a "dead" axle is the second set of rear wheels on a bus or some semi tractors.
ZV
ZV
- Oct 28, 1999
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Basically one rod running the width of the car that the wheels are connected to. Hitting a bump with the left wheel will transfer some motion/energy to the right wheel.
In a nutshell. |------|
[Edit] I'm kinda confusing "live rear axle" with the differening implementations between FWD and RWD cars.
In a nutshell. |------|
[Edit] I'm kinda confusing "live rear axle" with the differening implementations between FWD and RWD cars.
Evadman
Administrator Emeritus<br>Elite Member
- Feb 18, 2001
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The wheels verticle motion he means. Not rotation. Basicly the entire axle is unsprung weight, with the whole axle from centersection to lugs being one piece that does not move indepentantly. but inside the axle the axle shafts can roate at different speeds assuming they are not locked together in some way with a "locker" or "spool".
Live axles are also used in Go carts and shifter carts where they have a slightly different meaning. in go cart nomenclature a live axle means there is one axle shaft. The wheels are each bolted to each side of the axle, and it is not inside a tube like in a car. The spinning shaft itself supports the weight of the cart through roller bearings or a bronze bushing.
I should probably point out that some axle designs on cars have the axle supporting some of the weight of the vehicle. these are called "semi-floating". A "full floating" axle would have no weight of the car on the axle.
That is basically the same drive setup used in 1964 Mustangs. This type of rear wheel drive is cheaper to build and consumes less space. It does not provide the performance you get with an independent rear axle.
Evadman
Administrator Emeritus<br>Elite Member
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Independant axle The center section is fixed to the vehicle.
Live axle on a truck the entire axle is free to move. (front and rear are both live axles.)
live axle gocart exploded view Notice the one piece axle from wheel to wheel.
Live axle on a truck the entire axle is free to move. (front and rear are both live axles.)
live axle gocart exploded view Notice the one piece axle from wheel to wheel.
I think the current platform is a 1979 Falcon. Ford calls it a FOX platform and used it for many models besides the Mustang.
Actually don't all current gen Mustangs have live axle rears? I know the Roush 380R (2002) and SVT Cobra both do as well as the GT and prementioned Mach1.
Babbles
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- Jan 4, 2001
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I believe you can put a whole lot more power onto that type of axel though the problem is that the steering goes all to hell.
If you make a turn, the inner wheel only has to turn a fraction of the outer wheel and that works out fine on independent axels. In fact you should be able to hold one rear wheel and apply the gas and only the other wheel will rotate.
If you make a turn, the inner wheel only has to turn a fraction of the outer wheel and that works out fine on independent axels. In fact you should be able to hold one rear wheel and apply the gas and only the other wheel will rotate.
In the past few years there were a few (very few) high performance (SVT?) models that did have an independent rear end. Mostly though, you are right.
Evadman
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I am not exactly sure what you are saying, but here goes anyway:
In general terms a live axle or beam axle is stronger than a IRS or IFS (indepentand rear and independant front). This is because on a live axle the axle shafts do not have a hinge to allow wheel movement. They are one solid piece from the differential to the flange (where the wheel and brakes bolt on). This hinge is usually called a CV joint (or contant velocity joint) This is a weekspot.
Of course things get complicated if the live axle is a front axle, because now the wheels have to turn. generaly a solid piece of steel does not want to bend repeadly. So what is done is a joint called a U joint is put in. On one side of the axle are splines (or groves) that mate the axle to the center differential. ont he other end is a U shaped recepticale that accepts a X shaped piece of steel with 4 bearings. then another piece of axle (usually called a stub shaft) attaches to the other 2 bearings on that X. This makes it so the stub shaft (and wheel) can turn upt o about 70 degrees from the plane that the axle is in. Again, this is the weak spot. That X piece likes to break and when it does it usually takes the stub axle with it.
Steering is not a problem with either type. a solid front axle (live axle, beam axle, whatever) wil lhave a total of 2 joints that allow movement out of the plane of rotation. A IFS will have 2 per side for a total of 4. Since the wheel has to move up and down and then turn for steering you need both. For the most part, the outboard (one closest to the wheel) does all the work and is the first to fail.
You are correct about the inner wheel on a turn spinning less than the outside wheel. This is whatt he differential is for. it allows the wheels to turn at different speeds while still applying force. But if you give to much power, then one of the wheels is overpowered and will spin while the other just sits there. This is where a "locker" comes in. A locker will make a conenction between the 2 axles while the vehicle is going straight. If you turn, the lcoker will disengage (through a clutch pack, gears, pring loaded systems, etc) and allow the inner wheel to turn slower. A POSI is a version of a locker, but is not really called a locker since it relies on a clutch pack. Most lockers use big ass teeth that forcefully lock the axles together. A POSI is not perfect and will allow slippage.
Also, just FYI some go carts are one wheel drive only ( the really cheap ones) these, if you stomp on the gas will usually do a nice sharp turn for ya.
No - the Cobra has had IRS since 99, including the current 2003 Cobra. The Cobra hasn't had a live axle since 98.
Evadman
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Originally posted by: iamwiz82
lol, feeling like your efforts were wasted?I like my solid front and rear axles. Sure, they can have adverse handling effects(mine bump steer like mad) but they are loads tougher and more desirable offroad.
Bump steer can usually be aleviated with a drop pitman arm or a crossover steering system. For those that do not know, bump steer is when you hit a bump and the steering wheel moves in yoru hand as the suspension travels. This is caused by the steering linkage not being parallel. ( or close to it.)
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