n4ggs

i have searched and i cant find a straight answer to the simple question, what is the rear end of the mustang gt? someone said something about the car applying brake to one wheel to transfer power to the other but that sounds like phooey. nothing in the mustang pamphlet i snaged at a dealership, nothing on the ford website...
does anyone know?

sam_abuelsamid

All 2005 mustangs come standard with a limited slip differential but the design that ford uses is next to useless. The GT also comes standard with traction control ( and abs, optional on the v6). The traction control does exactly what you mentioned. When excess wheel slip is detected the engine torque is reduced and brakes are applied to the rear wheels to bring them under control for optimal acceleration. Also if one wheel is slipping more than the other brakes will be applied to the lower traction wheel to transfer torque to the other rear wheel. The traction control is much more effective than the limited slip diff.

algregory

I don't know the name of it, Quaff, I think. But I have a really "brainy" friend, likes to spend money. Unlike me, I don't have money. []

However, he as had that differential installed on several cars. Instead of gears and clutches or what ever in the rear end, this rear end has conical type gears, so you have like three pryamids in there each with "ramps" running aroud their circumference. Strickly mecanical, and any slippage of one tire is immeadiatly giving the tire with traction the command. He lives in the mountains and corners, rain, whatever, he's got traction if there is traction surface to be had by either wheel. Instantly, seamlessly.

281GT

sam, You mentioned the stock limited slip diff is not a good design. I don't know much about it and now I'm curious, what are the problems with the stock LSD?

don_w

Check out this link... some decent info from the factory on all aspects of the car.

http://www.fast-autos.net/ford/05fordmustang.html

n4ggs

i know what traction control is and i know what a limited silp is. the "limited slip" that you just described is tracton control, nothing limited slip about it. a limited slip can transfer power from one wheel to another without scrubbing off speed with the brakes and without the computer taking power away.

n4ggs

nothing in there about the diff. what i am getting from all of this is that its a simple open diff...

sam_abuelsamid

I didn't want to get into a long winded description of tc works, but I will try to elaborate a little more on the some of the details. Just for reference I work for the company that produces the brakes and the abs/tc system for the new mustangs. I have been developing the control software for slip control systems including the new mustang for going on 15 years now and the stang includes some of my code. The tc system uses a combination of engine control and brake application in different amounts depending on the conditions that have been detected. If both drive wheels are spinning the engine torque will be reduced enough to reduce the amount of wheel slip to a point that will provide maximum acceleration and stability. On dry pavement it doesn't reduce slip to nothing because in that case the engine will just bog. The brakes may be applied if needed to reduce wheel slip but only in extreme conditions or on lower traction surfaces. The engine control definitely takes priority over brakes for this type of control. This is done to provide smoother control and not prematurely wear out the brakes.

In the event that one wheel is spinning significantly faster than the other, (this is known as split mu control) the brake on the lower traction wheel is applied in proportion to the speed difference. This has the effect of transfering torque to the higher traction (lower speed wheel. This is precisely waht an lsd is intended to to do. However, a tc system has much more information can make intelligent decisions about the control as well as adapting to changing conditions like patchy surfaces and transitions. These 2 control strategies work in combination to try and provide smooth control and achieve maximum acceleration and stability under all driving conditions.

There is also a vehicle speed component to all of this. As speed is increased, the brake application is gradually phased out. at higer speeds there is little or no brake application. The brakes do not really scrub off any speed nor does the engine control. The torque is reduced only enough to restore wheel stability. Vehicle stability control systems will actually reduce vehicle speed as well as do other things, to maintain vehicle stability. The mustang does not have vehicle stability control at this time though.

This is a very basic description, of how tc works but I can say without hesitation that I would rather tc than most of the mechanical limited slip diffs I have tried. It is more effective and adaptive. The diff that ford uses only does a very limited torque transfer. If you get on a slight incline with one wheel having less traction so that it slips the vehicle will not move. With the tc it will climb a hill with no problem. Some diffs are much more effective than the ford diff (such as the Quaiffe unit mentioned elsewhere in this thread) but they still cant help if both wheels are slipping.

n4ggs

thank you for sharing your expertise. if i understand you correctly, the mustang effectivly has a lsd while the traction control is on, the systems are integrated. Would this type of torque transfering work as well as a quaffie while putting power down exiting a corner (the inside wheel having a smalled distance to travel)? or is it most effective in a straight line?

sam_abuelsamid

The TC does provide lsd type functionality, however if I was not clear, there is also a mechanical lsd. The TC does work just as well in cornering as it does in a straight line. The Quaife http://www.quaifeamerica.com/differentials/diffs.htm operates on basically the same principal as a torsen diff. They work very well and in combination with tc, the tc would probably activate a lot less often in side to side torque transfer mode. Whether it would be better or not I couldn't tell you, since I haven't personally tested such a setup. Most likely it wouldn't be radically different in normal day to day driving. Where you might see a difference is if you are going to be drag racing and you turn off the tc (there is a tc disable switch on the dash). In this case the diff would still function, and much more effectively than the standard diff. The same also applies to a torsen or some of the other higher end limited slip or locking diffs.