Edmunds.com | Inside Line | Auto Observer Your Account | Help | Directory
You are here:
![[F]](http://a332.g.akamai.net/f/332/936/12h/www.edmunds.com/media/townhall/webxicons/site.gif){kind=small}
Forums
Hatchbacks Ford Focus Ford Focus Care & Maintenance
309 messages, Last post on Oct 18, 2009 at 1:19 PM
You are in the Ford Focus Forum. Your Host is pf_flyer
|
They'll probably have to use a different differential on the SVT.. I've read that Foci have anywhere from 100-115 hp at the wheels. Maybe I got one in the upper range. |
|
I'm pretty sure that mine is in the upper range too.....I get some good torque steer going at the slightest tap from a dead start. My ZX3 really hauls  ss from a dead stop, I was in such shock the first time I drove it. When I test drove the first Focus, it was Auto, and I was even impressed with that one. I really wish that all of the auto makers would take a tip from Subaru. Even if they can't get EXACTLY the same size axles, even if they get them closer to equal length, it would be better. The worst torque steering car I ever had was an old Rabbit GTI (the original GTI). I changed a CV joint on this car once, and it was hysterical to see the axles....one was about twice the length of the other. I'm not really sure on this, so don't quote me, but I think that a 'locking' differential will be an option on the SVT. If so, this would proably eliminate or at least, greatly lessen the torque steer effect. I'm not 100% sure on this, because I never had a FWD car with this feature. I did see that Ford Racing sells a differential kit for all FOCI, though from the picture, I can't really tell what exactly it is. If it involved opening the trans to install it, then that would certainly not be worth it. Anyone else have any experiance with FWD locking diffs? later V |
|
|
"I realy wish that all of the auto makers would take a tip from Subaru." What do you mean? Switching to the boxer engine layout? |
|
|
|
Just so you know, torque steer isn't related directly to half shaft length - it is more closely related to the mass of the drive axle. In the case of the VW you mentioned, the axles were of different length, but very similar mass - how? VW used a hollow shaft on the long side and a solid shaft on the short side. Very clever. Those early GTIs still suffered from some torque steer, though. Try driving a new SAAB Viggen if you want to experience serious torque steer 
|
|
|
I think modernperformance.com sells a differential for the ZX3 for $300. I've seen a Quaife differential but I think that was ALOT. I don't know what the difference is but I'm thinking I'm going to need one to lay the power down after I start modifying my Focus. For the time being I'm trying to put some easy miles on to break it in. I'm going to hit 1000 miles tomorrow. |
|
|
No, vadp, what I meant was that more effort should be put into trying to eliminate torque steer in mid to high power FWD cars. Obviously, other automakers are not going to switch to the boxster layout, but even with our 'regular' 4-bangers it is still possible position everything to get more even length axles. Maybe I'm ranting a little, but you would think after 20 years of mostly FWD cars be produced, more effort would go here. And Silver_bullet, just so YOU know, your completely wrong about mass. It is in no way MORE important than length. Anyone good at physics will confirm this. The physics equation for torque is 'torque=forceXdistance'. It has nothing to do with mass. You can have the same length axles with a DIFFERENT MASS on each one and it will have no effect. It may be true that VW and others MAY have tried to compensate by different mass axles (I can't confirm or deny that one), but it would have little effect. Think of this....have you ever tried to break a bolt free on say, a lugnut that was really stuck on? If you put a long pipe on the end of the the lug wrench then broke it free, it came right off right? Same principle for the longer axle. The mass of that pipe has nothing to do with it, it's the length. That's why the harder you step on the gas (more force), the more torque steer you get. It's a whole different ball game once the car is already moving, that's where a locking differential would help. That's a really complicated equation that you can't really apply without knowing the weight of the car, speed, length of the axles, etc... As far as driving a 'SAAB Viggen', my guess is that model SAAB is turbo right?....MORE FORCE, MORE TORQUE !!!! (see torque=forceXdistance above)...hehehe Please don't think I'm trying to flame you, cause I'm not. Just trying to point you towards the truth. Now, when some idiot tries to argue with you about this, grab the nearest physics book and bash him over the head with it. Even with our ultra-modern, technologically advanced, new millenium automobiles (yeah right), we STILL cannot defy the laws of physics or gravity....YET !!! later V |
|
|
|
|
Yes, 20 years as an ASE certified tech taught me a few things about stuck fasteners . And yes, I remember my college physics, too - but your lesson about force x distance has nothing to do with this drive axle discussion, because the drive torque is being applied along the axis of the shaft - not at some perpendicular distance from the center line of the shaft. If you assume that the differential is delivering equal torque to both drive axles, and the wheel/tire/brake assemblies are the same at the outboard ends of the shafts, the MASS of the shaft itself will affect how it responds - Isaac Newton taught us that objects at rest like to stay that way, so when you apply torque to a massive shaft and a less massive one simultaneously, the less massive one will spin up faster. It is the difference in how each side "spins up" that produces the phenomenon known as "torque steer". No flames meant from this end, either.
|
|
|
So torque = mass x acceleration x distance. Seems to me that torque is directly proportional to mass, n'est pas? |
|
|
Ok, I've considered BOTH of our equations here. Mine has everything to do with this, you just have to 'reverse' the process. As it turns out, we are BOTH right !!!! Here's something I found on another site: "There are two another torque steer problems unique to front-drive cars with transverse engines. typically, the engine is mounted on the right side of the chassis with the transaxle on the left. As a result of this configutration, the right halfshaft is usually much longer htan the left halfshaft. The first problem arises as, itf these were manufactured from iddentical materials, the longer right shaft would have a much greater torqe angle then the left for the application of an equal amout of torque. Step on the gas, and the car would veer immediately to the left then straighten. This is a fairly easy fix - change the Torque moment of the shafts to be equal. On VW products using trnasverse engines, the right halfshaft is usually a much larger diameter than the left and is hollow. The second problem arises as a result of the CV joints needed (two per side). Torqe si needed to drive CV joints unless they are running with zero deflection. The torque required is a function of the angle between the driving and driven halves. The more they are deflected, the more energy they consume. As a result, under acceleration, drive shafts on either side of a FWD will tend to adjust themselves to equalize torque. As the shafts are of unequal length, the CV joints on either side would run with unequal deflections. The geometry involved usually causes transverse FWD cars to pull slightly to the left under acceleratione. One FWD manufacturer (whose identity escapes me) used a layshaft on the right side of their vehicle so that both halfshafts were of equal length and torque steer was minimized. My bet would be Cadillac on the Northstar equipped vehicles, as that much power from a transverse engine could be a real wheel-ripper, and a rude surprise to your typical Cadillac owner." |
|
|
Sorry, had to do this in two posts because of the length....now, read this page:
http://www.motorage.com/edindex/0299032.htm Like I said, we ARE both right, but the LENGTH (or distance) of the axles is still more important. If adjusting the mass worked correclty, then my old GTI would nt have had ANY torque steer. If VW is still doing things this way, it's not working 100% because even the new cars (especially any with the 1.8T) still have very noticable torque steer. The Audi on the other hand has a similar front end, but the AWD models don't have the problem because of the AWD and traction control. There are OTHER ways to compensate, but the only MECHANICAL way that works 100% is having the same length axles. If you want proof, go drive any Subaru or Porsche Boxster for that matter....they both have equal length axles. |
|
You are here:
Forums
Hatchbacks Ford Focus Ford Focus Care & Maintenance
New? Join Now!
Forum Tools
Search Forums
Browse by Vehicle
2010 Ford Focus
Browse by Board
Browse by Topic
Today's Chats
