I think in the case of trucks Its because w front steer the same basic ch***is works w 4wd (4wd needs it all out front) P*** cars …. front steer frees up a lot of space for exhaust - oil pans …………………..
Stupid answer: because they can. Longer answer: if every engineer got to start from scratch and design the Perfect Package then everything would probably be front-steer at least in cars because it permits a progressive deflection understeer. With rear-steer any slop or flexible bushings in the steering linkage tend to create a deflection-oversteer (less predictable and less comfortable for the driver) condition. But...very rarely does an engineer get that level of control. Front-steer is almost impossible with FWD, which is 85% of p***enger-car production these days (unfortunately.) If you're fortunate enough to be working on a RWD design, you've got to have an engine that isn't going to force you to put the sump where the steering should be (this is why, for instance, in the E39 BMW 5-series the 6-cyl cars are front-steer rack-and-pinion, while the V8 cars are rear-steer recirculating ball - BMW's then-new V8 design still had the pump down in the front of the pan - pan-mounted oil pumps in general could reasonably have been considered obsolete in new engine designs since the mid '80s. Ford dealt with the situation creatively in the Fox cars with the double-sump pan on the Windsor, but then the Fox platform had the front wheels unusually far back for a RWD design anyway.) So...if you want front-steer, and you're dealing with a front-engine rear-drive ch***is, you've got to have an engine package that'll permit it.
Doesn't rear-steer work better for getting the Ackerman angles right? My Jeep is front-steer and makes a hell of a noise making tight turns in multi-level car parks. I'm at crawling speed but sounds like someone doing a wheel spin!
"My Jeep is front-steer and makes a hell of a noise making tight turns in multi-level car parks. I'm at crawling speed but sounds like someone doing a wheel spin! " Ackerman is usually a compromise on front steer cars. The steering arms have to be very close to the tires for it to be correct. I had an '80 Malibu that made lots of noise on those circular parking ramps. I think the engineers get the steering arms out as far as they can and let us suffer the noise on tight turns.
Expressed differently, with front steer Ackermann and scrub radius tend to militate against one another.
The wifes '05 Chevy squeals the tires in parking lots as most Chevy trucks do. My old Willys does OK, it is rear steer with front mount tie rod, unless you put it in 4WD, then it is clawing and scratching at everythig that it can. I believe that is because of the quad track and not because the it rods are out front. I think that front steer cars as has been mentioned has a lot to do with packaging. Something to bear in mind is that a design engineer more often than not is given a box and all the components that are required to fit into that box. Sometimes the designer has to think out side of the box to make everything fit into the box. Now I have a question, when we say front steer v rear steer front steer is when the steering box is in front of the the axle center correct? or do we mean a frint end with the tie rod out front and the steering box can be anywhere?
Front steer means the tie rods and center link are in front of the axle. The steering box is usually out front, too, for simplicity.
I'd have to think that the outside of the obvious like 4x4 axles that have the tie rod in front of the axle because the pinion gear and differential case would be in the way on the back side most of the front steer rigs came about because of clearance issues with rear mounted steering on previous models The 67/69 Camaro/Nova /Firebird rear steer setups work (ed) great but with many engine combinations there were big clearance issues with the steering linkage and box right where the exhaust and or oil pans wanted to go. Look at some of the first generation Novas with engine swaps that had oil pans with tubes through them so the tie rod could p*** through the pan. Guys on here with shoebox Fords with stock suspension and steering fight tie rod clearance on almost any engine swap. From a production engineering standpoint it makes sense in most cases to move things out front out of the way so other things will clear and in a lot of cases you might be able to set the engine lower in the ch***is to get the car's profile lower. When I was doing front end work daily in the 70's I didn't see any real differences in similar body styles handling with front or rear steering if everything was in top shape and the alignment was set to specs with adjustment for local conditions. That usually meant setting the alignment so that the car would track straight on local roads depending on how much crown the road surface had. Some things that did make a difference in handling were the durometer or density of the rubber in the A frame bushiings between models, the rate of the springs and the sway bars and shocks that were used. Even though they were the same dimensions mid 70 Trans AM control arm bushings had a different part number than six cylinder Firebird bushings when you got them over the dealer's parts counter. When you went to the local parts house there was only one number that fit everything.
I'm hoping ElPolacko jumps in on this later when he hits his shop for the day. He and I sat and discussed this a few months ago over lunch, and although I can't remember his exlpanation entirely, other than scrub radius and Ackerman, there are other forces in the form of side loading that makes one of the other superior.
I realy don,t know if one is better then another,but for swapping a front steer in say a 36 chevy It could have the box sticking out the front fender.
i bet some one with nascar connections can answer this. if i remember a few years back this was a big deal and everyone had different opinions.
Intended purposes and desired outcomes. Beam axle and other non compliant suspension structures, front or rear is practically irrelevant. It becomes a matter of packaging and convenience. When it comes to more compliant structures, such as rubber bushed double wishbones, there are advantages and disadvantages to both. To those comparing late model trucks and such and squealing tires in the parking garages, to things are contributing to this. Low Ackerman values (nearer to 0 toe change with steering input for highway stability) and possibly positraction rear differentials. In the case of an IFS with compliant rubber bushes, front steer systems when compressed will require further steering input angle to maintain the same line whereas rear steer will require less steering angle to maintain. To put it in more layman's terms, you are making a hard right hand turn and to continue on the same arc, a front steer system will feel like it is understeering and you will have to turn the steering wheel in more to compensate. Rear steer cars will have the opposite effect, it will give you the feeling of oversteer. I suspect that these are the same reasons that NASCAR and other racing series prefer rear steer for short track work and front steer for speedway and road co****.
To answer your thread question directly, as it differs from how your ***le reads (meaning what's better) Mr48chevy said it best. It just boils down to clearance issue's.
Don, still front steer. Steering arm and tie rod end is ahead of the King Pin Centerline. Want to really blow your brains out. Some FWD cars like Audi will have the rack mounted on the firewall well behind the king pin center and still have the steering arms ahead of the KPC, and it's front steer Check the picture, you can clearly see the rack behind the strut towers and the tie rods in front of them.
Oh, my, first the 'rat rod' build and now Audi pictures...the HAMB Purity Police should be knocking on your door any minute... For what it's worth, the Chrysler LH cars used the same configuration, and I believe the Renault 20/30 design (built here, badly, for a little while as the Eagle Premier and Dodge Monaco) they're derived from did also. Those center-takeoff racks might be useful to someone in some kind of build somewhere... There might be other examples of this as recent practice but I can't think of any, GM did lots and lots of FWD platforms with firewall-mounted racks but they were all rear-steer.
That's why I said "Front Steer" As for the Audi, I drove one of the Audi Quattro Sport Rally cars, back when I was actively racing in pro Rally and I looked at that steering and thought are they kidding? But it did work well
Well I was thinking about saying something ugly my self. But I think Steve is mad at me already, I mean hell he never writes or calls. Steve, How much of that engine is in front of the axle center? is that one you have in the shop or have had in the shop? its a little hard to tell from the pic.
Stole picture from the interwebs... just familiar with the platform. Still have a soft spot for those boxy little cars. The entire engine is ahead of the axle CL. Those crazy Germans have been putting the engines on the opposite side of where they should be for quite some time now.
Nascar stock cars are all front steer, have been for years. Short track cars such as late models and modifieds are also front steer.
Not only have they been putting the engine in the wrong place but they do it and make it work. It all comes back to thinking outside of the box to make everything fit in the box. I was just curious abut it.
Yup, and we made your old FOX do things "Zee Germans" would have never thought of... And did them quite well too! Speaking of engines hanging where they don't belong, I mean.
In Audis prior to the current A4 platform the whole engine and most of the bellhousing are forward of the wheel CL.
Maybe, I'm no fan who follows the details. When I was involved in working with a company that built simulators for NASCAR, I had to understand the charicteristics of both short and long track cars and feed that information to the game programmers. All I now is what I can still get front or rear steer setups through the suppliers, and there are still plenty of guys doing rear steer. Click link and scroll down. http://www.laughlin-racing.com/productlist.asp?cid=17
Steve, i think what DoubleJ meant was that all NASCAR CUP cars are now front steer - lower cl***es and dirt cars are different There is an old racing saying that "the simplest adjustment to a race car is the forceful application of a very large wrench to the northern most point of a driver's body."
Some of those center-takeoff racks have been known to fail. Apparently, the bolts connecting the tie rods to the rack are mounted in single-shear and may not be properly designed. The government has failed to conclude that there is a defect, and has not forced Chrysler to do anything about it ... but the auto and airline industries and the government are very cozy, and most investigations seem to go nowhere, even when they have merit. http://www.dontbuydodgechryslervehicles.com/dodge_chrysler_steering_problems.htm I am just saying I would probably use a more proven design in my own vehicle.
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