I have a PSD tranny from a 90 in my 85. It as the flare/slip when shifting from 2nd to 3rd on hard acceleration. I believe the K1 kit will fix this. I have ordered the kit, drain plug seals, transmission filter and pan gasket. Do I need anything else?

This is my first auto tranny after 2 manuals. I want to make sure I do this right.

Will I need to touch the differential fluid, or can I drain the converter and transmission by themselves to do this procedure?

What is the 90 PSD fluid capacity and what is the recommended fluid?

Anything I'm missing or should do while I am fixing this?

 

If the tranny is kept hrizontal you should not have to drain diff but if you stand it up by the diff it will drain from the top vent. PSD uses the same DOT 4 as brakes. If it needs bleeding you need about a quart to do it well. If not, I'd venture to say 8-10 oz. Do a search on PSD flush and you should find a post I think by Arnould that will give you great info. Not really sure how you'd get the PSD to work on a non-PSD car!

 

Brett, I'm guessing you are doing this in situ?

If so, the diff and PSD will not be touched. Drain the Transmission and remove the pan. You will want to change the tranny filter and pan seal.

This thread by Tony is very informative and will guide you: https://rennlist.com/forums/928-foru...rt-number.html

One thing: when you are removing the screws that hold the plate behind which you replace the springs; remove only 3 screws and loosen the last screw so the plate can be rotated out of the way. It's not so helpful when removing the existing springs et al, but it is very helpful when installing the new more powerful spring assembly into the proper place. You will see what I'm talking about when you do the replacement.

Good Luck!

 

Only that a 1990 transmission had the updated K1 kit installed from new.....

And the "flare" that people talk about only happens at light throttle.

 

PSD fluid is brake fluid. But, it's not relevant in your case; you're not going to get PSD working in an '85 unless you spend zillions of dollars: Most of the PSD system is not in the transaxle. Only the PSD slave cylinder and clutch pack are in the transaxle. The pump, accumulator, locking solenoid, ECU, accelerometer, associated harnesses, relays, check valve, hard lines, reservoir, etc., are missing.

You do, perhaps, want to change the gear oil in the differential case though. 3-ish quarts of 75w-90 GL5 gear oil.

 

I bought the car from Klaus in Escondido. He said you had been maintaining the car for him, but to what degree I do not know. He mentioned that you told him the 2nd to 3rd issue was a solenoid or something, so I'm not sure what it actually needs, then. Do you recall?

 

I was told that the PSD was manually set @ 30%, whatever that means.

 

Likely not your problem, but I put in a shift kit ('86.5) to fix a 3-4 shift issue which turned out to be caused by a broken spring.

FWIW, once I got used to it, I really liked a normal firm 1-2 (softer than stock), an extra firm 2-3 (later shifting), and a normal firm 3-4 (firmer than stock).

https://rennlist.com/forums/928-foru...l#post11536836

 

The PSD system was designed to have a variable amount of lock up dependent on the need as calculated by some algorithm that took various parameters into consideration to determine the amount to apply. Thus in theory by constantly applying a certain signal it is possible to permanantly apply such amount of lock.

Whether or not that simulates the way a limited slip diff works I would defer to others but having the diff locked all the time to a fixed percentage of 30% irrespective of whether it is needed or not does not sound right to me.

 

PSD retrofits into earlier non-PSD cars seem to be done with a bolt and locknut through a plate where the PSD slave cylinder normally attaches. You can adjust the position of that bolt to apply pressure to the clutch pack, but the pressure changes as the case heats up or shrinks. The service really deserves a spring, maybe a "die spring" (flat ground ends) or a stack of Belleville washers to kep a somewhat consistent preload on the clutch pack as the temperatures change.

 

I worked on it once, to try to make it run better. Other than that, I did not have much to do with the car.

I never understood how an automatic transmission with a vacuum shift modulator works when exposed to boost. You might want to talk with the other supercharger people...definitely not my thing.

 

Correct. The PSD "bolt" instead of the brain, pump, slave cylinder, sensors, etc. absolutely doesn't work. Tiny amount of movement on the PSD actuation arm make huge changes in pressure, resulting in huge changes in lock percentage. And the changes in temperature of the case and actuation arm are enough to make these huge changes.

It's a useless, very dangerous (*) set-up.

(*) Minor changes in rear lock percentage influence oversteer and understeer. Huge changes (as the PSD adjusted with a bolt will do) will make huge/dangerous changes in oversteer and understeer characteristics of the vehicle.