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Anyone ever replace the detent (kickdown) solenoid on the THM425? Rockauto shows the one I have attached to this message but to my eye that one looks like it will have a wire on it that's going to be too short. I'm guessing it's incorrectly listed for the THM425 and more likely for the THM400.
Any other options out there?
Cheers! That wire looks too short This is the THM425 solenoid (detent, or kickdown). The wire looks much longer.
RockAuto also lists manual transmission parts for a 1966 Toro, which should be your first clue that their on-line catalog isn't trustworthy...
More to the point, the catalog shows that this "shift solenoid" is only used on Toronados with the rare RWD TH400, which should be your second clue that the info isn't correct.
Now, if you look in the factory parts book, you will find that the detent solenoid for the TH400 is P/N 1993620. The solenoid for the TH425 is P/N 1993319, so clearly if a solenoid is listed as fitting the TH400, it won't fit the TH425. Unfortunately, no one makes a replacement solenoid for the TH425 anymore, so either find a good used one, an N.O.S. one, or get the TH400 one and lengthen the wire.
Are you satisfied with your troubleshooting that it's the internal solenoid that has failed? Only reason I ask is the solenoid is 3 or 4th down the factor tree if it's not down-shifting properly.
Mine isn't upshifting into 3rd until very late. I was going to change the fluid and filter out anyway so I thought I would have a look at the solenoid while I'm there to make sure it wasn't stuck open.
RockAuto also lists manual transmission parts for a 1966 Toro, which should be your first clue that their on-line catalog isn't trustworthy...
More to the point, the catalog shows that this "shift solenoid" is only used on Toronados with the rare RWD TH400, which should be your second clue that the info isn't correct.
Now, if you look in the factory parts book, you will find that the detent solenoid for the TH400 is P/N 1993620. The solenoid for the TH425 is P/N 1993319, so clearly if a solenoid is listed as fitting the TH400, it won't fit the TH425. Unfortunately, no one makes a replacement solenoid for the TH425 anymore, so either find a good used one, an N.O.S. one, or get the TH400 one and lengthen the wire.
Yeah, I'm aware of everything you mention there. I guess I figured that many parts might interchange between the 400 and the 425 as they're basically the same transmission. I can easily lengthen the wire so maybe I'll try it.
Verify the vacuum line to the modulator is in tact AND not obstructed.
Does the modulator and its vacuum line hold a vacuum?
Look at the detent switch above the gas pedal for integrity. Did it move out of position?
Verify the vacuum line to the modulator is in tact AND not obstructed.
Does the modulator and its vacuum line hold a vacuum?
Look at the detent switch above the gas pedal for integrity. Did it move out of position?
On the 66', the detent switch is mounted aft of the carburator, in the engine compartment, not at the pedal like later Toronados. The detent switch on mine is rigged right on the money.
I will definitely double check the vacuum lines to the modulator though.
Just familiar enough to be dangerous on the 66s. Theory is the same part location is not. Thanks for clarifying this.
Dad had a U paint code Dubonnet Deluxe with the same color interior. When space permits I will add one to the barn along with a 66 Riviera same color. U code Riviera Plum.
Please report back if the modulator assembly was the prob.
I do have a TH400/TH425 motors manual. Cant get to it at the moment. If you need more specs shout.
Just familiar enough to be dangerous on the 66s. Theory is the same part location is not. Thanks for clarifying this.
Dad had a U paint code Dubonnet Deluxe with the same color interior. When space permits I will add one to the barn along with a 66 Riviera same color. U code Riviera Plum.
Please report back if the modulator assembly was the prob.
I do have a TH400/TH425 motors manual. Cant get to it at the moment. If you need more specs shout.
I swapped in a replacement modulator last year. It really didn't make much difference.
Mine isn't upshifting into 3rd until very late. I was going to change the fluid and filter out anyway so I thought I would have a look at the solenoid while I'm there to make sure it wasn't stuck open.
A bad solenoid would also cause a problem with the 1-2 shift.
My question was already answered. For the most part, your first reply was enough for me. I haven't continued the thread, but if you absolutely must know, I'm having late shifts. 1-2, 2-3, and all feel too late in the RPM range. The 2-3 shift stands out worse than the 1-2. No other issues, goes into reverse fine and shifts smoothly but in the wrong spots.
I have replaced the modulator with an original I had from the stores department (trunk). I have given the vacuum line a cleaning, a couple of quick inspections, and plan to do a little more. Other than that, I'll be popping the pan off and changing the fluid and filter. While I'm in there, I'll be looking at that detent solenoid and wanted to have a spare on hand if possible, thus the reason for my post.
Before you pull the pan and drop the fluid, plug into the test port with a high PSI trans pressure gauge and see what each circuit is doing, Its the easiest way to check the trans health. At minimum now you have baseline data.
May 3rd, 2023, 03:59 PM
