WTB Dropping Resistor

[IsaiahEyre]

So here's the deal... I've been having issues with my 4.44 tranny ever since day 1, and I recently took it to a tranny shop and we discussed the possibility of electrical problems. I called my local Subaru dealership and they told me that the SVX and the Legacy dropping resistors are different... only trouble is, they can't order the part unless they have the VIN from the donor car. To simplify things, I thought I'd just ask if anyone has a dropping resistor from a pre - 9/97 legacy that I could buy and see what difference it makes? If not, I'm going to have to go junkyard hunting.

Thanks,
Isaiah

[processengr]

http://www.svxfiles.com/custom.html#resistor Go here!

[Trevor]

Originally Posted by processengr

http://www.svxfiles.com/custom.html#resistor Go here!

The advertisement states:-

Custom Dropping Resistor Mod
The Solenoid A (dropping) resistor controls the line pressure in the transmission.* By adjusting the resistance, we can "firm up" your shifts.* NOTE:* Core charge applies.

The actual and proper function of the resistor is as Follows:-

THE SVX DROPPING RESISTOR CIRCUIT.

It will be apparent that the sudden on off pulse width modulated duty to which solenoid valve “A” is subject, tends to cause what could be called a hammering of the valve seat, even though this is largely reduced/damped by the controlled fluid flow.

The dropping resistor circuit introduces a second series of current pulses, applied in parallel with the control signal. These pulses are applied across the off cycles, so as 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, mean that during the closing period the voltage does not fall completely to zero, so as to reduce a closing shock.

This second series of pulses must be at a lower level than the control signal, hence the dropping resistor. A resistor with a high current rating is required, which could not be mounted within the TCU enclosure.

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 voltage during the closed time becomes zero, thus increasing the line pressure and making shifts more abrupt. Secondly, as an undesirable issue, shock loads applied to the valve are increased.

The SVX resistor should measure between 9 and 15 ohms to be within specifications, and is usually very close to 12 ohms.

N.B. Some time ago a member posted a very good set of instructions covering the repair of the resistor module, but I can not find this within the how too section. You may be lucky with a search.

[SVXRide]

Radio Shack FTW!
-Bill

[wtdash]

Originally Posted by IsaiahEyre

So here's the deal... I've been having issues with my 4.44 tranny ever since day 1, and I recently took it to a tranny shop and we discussed the possibility of electrical problems. I called my local Subaru dealership and they told me that the SVX and the Legacy dropping resistors are different... only trouble is, they can't order the part unless they have the VIN from the donor car. To simplify things, I thought I'd just ask if anyone has a dropping resistor from a pre - 9/97 legacy that I could buy and see what difference it makes? If not, I'm going to have to go junkyard hunting.

Thanks,
Isaiah

HI,
I may have one from a '91 or '93 Legacy, if it'll work, and I'm 'just up the road' in CDA.

I've been looking @ getting that 'custom resistor' but if they're different between the SVX and Legacy I may wait for your results.

Let me know if you're interested.

thanks,
TD