Resistor mod ver2.0

[Bonestock]

So after a bit of trouble trying to source a "dropping" resistor for my 92 LS-L I figured I just fab one up myself. I looked online at digi-key and selected a variable resistance resistor. Its adjustable from 0-50ohms. I currently have it set at 28.5ohms. Works GREAT!!!

http://search.digikey.com/scripts/Dk...-50-nd&x=0&y=0

P/N AVT25-50-ND Shipped came out to (IIRC) $8.50





Hope this helps those looking to do the same thing! Enjoy!!!!

[Sean486]

What is it for?

[Bonestock]

Originally Posted by Sean486

What is it for?

longassname's

Re: Transmission resistor mods - differences?
Resistor mods increase the line pressure during times that the tcu is trying to reduce the line pressure. People have been using them to try to defeat the slow, sloppy shifts that SVXs came with from the factory. While it is possible to get at the sloppy shifts that way it's better to do it through the hydraulics because then you can increase line pressure when the tcu isn't trying to reduce the line pressure. Increasing the maximum line pressure increases torque holding capacity. Increasing torque holding capacity so that the brake band and high clutch do not slip prevents your transmission from burning up. Changes can also be made to increase lubrication of the planetary sets and bearings. The most common failure in SVX transmissions after high clutch and brake band burn out is failure of the thrust bearing on the rear support.

Resistor mods also mainly firm up shifts and don't dramatically speed up the shifts. They will speed the shift up a little because anything that reduces slippage during the engagement time will make the clutch pack or band being activated grab quicker. Valve body mods can speed up the shifts dramatically because there are modifactions made specifically and seperately to the fluid circuits that are slowing the shifts--not just line pressure. I have the valve body modifications for the SVX dialed in now. Shifts in transmissions with my modified valve bodies are instantaneous, firm, and smooth.

The short of it is that a good valve body not only shifts better than a resistor mod--it makes your transmission last much longer.


And from Trevor
The dropping resistor circuit.

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

The dropping resistor 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 moves, thus reducing both shock and noise. These secondary parallel signals mean that in effect, during the closing/closed period, the voltage does not fall completely to zero.

This second series of pulses must be at a lesser level than the control signal, hence the dropping resistor. A resistor with a high current rating is required, which can 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 PWM voltage during closed periods falls to zero, resulting an increase in its effect, thus increasing the line pressure and making shifts more abrupt. Secondly, as an undesirable issue, shock loads applied to solenoid valve “A” are increased.

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

[Sean486]

Ok, I have seen modified ones, but never quite like that.

[Bonestock]

This method I have the ability to change the shift firmness to my personal taste. Quite easily at that.

[svxfiles]

Originally Posted by Bonestock

This method I have the ability to change the shift firmness to my personal taste. Quite easily at that.

Yea, I made an adjustable one about five years ago.
It was a simple thing, using a variable resistor.
But I could not tell the differance between the low setting and the high setting...
That is why I settled on the 20.6 OHM resistor that just works.
(With out tripping the Power Light.)
I am glad that you used my research to come up with this.

[Bonestock]

Coming up with my own method enabled me to actually GET what I wanted.

I'd leave it at that.

[NiftySVX]

Ok so what exactly are you trying to do with this mod?