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  #1  
Old 03-21-2007, 03:40 PM
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nextse7en nextse7en is offline
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Binding

Tell me if I have this right.

My 4.44s are binding a bit, quite noticeable in reverse when turning. Power light flashes, but I can't pull codes, so I don't know what the problem is. I would assume that duty sol C is the problem, but FWD engages just fine when the fuse is put in, and the binding goes away. What else should I be looking for?


Thanks.
Patrick.
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  #2  
Old 03-21-2007, 05:08 PM
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You are on the ball with your FWD fuse test, which should indicate that the centre clutch assembly is not at fault.

Think about what could have been altered during the ratio changes. Limited slip differential issue.
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Old 03-21-2007, 05:24 PM
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I really hope they didn't install a 4.11 rear diff. I really took safeguards to make sure that was not the case..

Duty sol C seems to be working just fine.

I would assume that if there were some kind of mechanical problem in the diff that it would bind regardless of the driveshaft being engaged.


Wish I could pull codes.


Could someone explain to me what duty sols A and B are responsible for, I know one maintains line pressure, but I'm not sure which. And while I don't know what the heck that would have to do with binding, the line pressure feels wonkey as well, almost feels as if the resistor is unplugged.
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  #4  
Old 03-21-2007, 05:51 PM
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Quote:
Originally Posted by nextse7en
----------

Could someone explain to me what duty sols A and B are responsible for, I know one maintains line pressure, but I'm not sure which. And while I don't know what the heck that would have to do with binding, the line pressure feels wonkey as well, almost feels as if the resistor is unplugged.
Some will be getting bored reading this, but as you have asked specifically, here it all is :-

DUTY SOLENOID VALVE "A".

This is a pulse width modulated duty solenoid valve, ( Sometimes known as a pulsoid). The device is incorporated in the SVX transmission control system in order to adjust line pressure in the following manner :- The fluid line is provided with a bleed or bypass via an on/off device, in the form of an electrically operated valve.

This solenoid valve is opened and closed repeatedly, in a rhythmical manner by a control current which is turned on and off by the transmission control unit (TCU) at a very fast rate. The valve is a normally closed device, and remains closed in the event of the loss off a control current.

After passing through this modulated solenoid valve, the continually interrupted pressure is in the form of a pulsed flow. When the peaks level off with the troughs, there is a resulting overall steady reduced pressure. The level of this pressure is adjusted by varying the on/off intervals. Most often the length of the on time is adjusted and the number of on/off pulses per second is kept constant. The usual rate is around 50 cycles per second.

The resulting adjusted output pressure is therefore delivered as a rapidly fluctuating stream. The system incorporates an expansion chamber as a smoothing element, which works as a sort of cushion. This device is usually in the form of a cylinder and piston or diaphragm, backed by a coil spring. In the SVX system the component is described as a Pressure Modifier Accumulator. The high pressure peaks in the stream press the piston outwards and become rounded off, while the low pressure troughs are filled in as a result of the piston moving inwards under spring pressure. The end result is a smoother level of pressure, such that controlled devices are not materially affected. An increase in the volume of fluid controlled, is achieved by transferring the solenoid regulated pressure, to a pressure modifier valve and a regulator valve.

It should be clear that by “chopping” the fluid supply in an adjustable way, pressure control is achieved economically using a simple poppet type solenoid valve, with few mechanical or electrical complications. However the valve remains in a continuous cycling mode, which imposes rather arduous mechanical stresses.

THE DROPPING RESISTOR CIRCUIT.

It will be immediately apparent that a sudden on off cycle tends to cause what could be called a hammering of the valve seat, even though this is largely checked by the viscosity of controlled fluid flow. The dropping resistor introduces a second series of current pulses applied in parallel with the control signal.

These shorter pulses are applied during the off cycles and timed to check the travel of the armature as it reaches the closed position, thus reducing both shock and noise. These secondary parallel signals in effect, “round off” the closing period and reduce the closing shock. This arrangement can be made even more sophisticated and configured so as to soften the opening cycle, as well as the closing of the valve.

It will be appreciated that increasing the resistance in the circuit, or opening the circuit by omitting the dropping resistor, has two outcomes. Firstly the relative electrical off time is increased, thus increasing the line pressure and therefore makes shifts more abrupt. Importantly as a second issue, increased shock loads are applied to the valve. The resistor should measure between 9 and 15 ohms to be within specifications. The usual is about 12 ohms.

It is a documented fact that the line pressure control solenoid is the first to fail due to having by far the most arduous duty to fulfill. Failure is usually mechanical resulting in the valve seat not closing properly and as a result line pressure is markedly reduced. The end results are drastic, especially in respect of transmission friction surfaces. The fault will not necessarily be registered as a fault code, as the armature of the valve can be in the fully closed position with the problem confined to a worn or obstructed valve seat. In the event of an electrical fault, which should register, the valve being normally closed, will fail safe and result in maximum line pressure.

SOLENOID "C".

Also a pulse width modulated solenoid valve this device is arranged to adjust control pressure to the centre differential, or alternatively clutch actuating mechanism, according to model. Solenoid C operates along the same lines as solenoid A and cycles continuously. However the duty is in no way as arduous as that involving constant control of line pressure and no parallel secondary circuit is incorporated.
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  #5  
Old 03-21-2007, 06:08 PM
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lol, I read some sections of that 3 times before I got the idea. With that in mind, not wanting to drop my pan if I can at all help it (I get squemish under cars as low as the svx without a lift) I'll check the resistor first, if it has failed, that may be the reason for my abrupt shift; that could also be the reason for the TCU throwing a code.

It is also becoming clear to me the sol. c is working properly, as evidenced by the FWD fuse working as intended.

I'll assume that my rear diff isn't 4.11, as a 20% difference in wheel rotation would cause binding on even the most gradual of turns, I also believe I would be feeling some form of braking on straight stretches.

This trans and rear were not from the same car, the frictions may just need to "adapt" to this rear.

In the mean time, I'll run some LSD fluid in that transmission, to prevent torsional forces from hurting the frictions as they "set in"

Life would be eaiser if I could pull codes.


-Patrick
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  #6  
Old 03-21-2007, 11:51 PM
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Good one Patrick,

It is obvious that you know what you are about and will be sure to sort things out. I think I recall someone else having a problem due confusion with diff ratios. If relying on heresay, one can come unstuck without being personally at fault.

Best of luck. No, the application of your ability. Trevor.
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