Well i'm giving up on my th400 switch pitch. I've replaced the wiring, servos, and related hardware several times over the past 3-5 years and it keeps shorting the servo behind the pump. I'm basically fed up with pulling the trans every year to mess with it.
What do you all think is a good option for a new trans? I have the stock 2.93 rear end. Should i get a regular th400 with what stall? Or is there a better option that would require some mods?

Thanks

 

Is the transmission/converter stuck in high or low stall? If it is in low stall would you need to do anything? Run what you have until it quits, I would.
I know many switch pitch cars that have had the switches disabled/broken/disconnected and ran fine. Many owners do not even know their car has the switch pitch. Both 2 speed and the 400 turbo.

 

Stuck in low stall. Makes it a dog off the line and passing gear. Especially since i live @ 9,000' above sea level. Makes a built 425 feel like a stock 350

 

I personally like the SP400's, I would spend the money to fix it and troubleshoot why it keeps giving you trouble.

 

They are in low stall by default. In other words, without 12v energizing the solenoid they start in low stall.
Sounds like you have something stuck inside. The solenoid just opens a fluid passage. So unless you're running it (energizing it with 12v) constantly I don't understand how they are going bad. Do you have a short to ground somewhere in the line from case plug to solenoid?
Only other thing I can think of is you're running it through a toggle switch of some kind and it's on constantly, even when the car is off unless it's going through a switched contact. Get yourself a momentary switch to control it. On when you want it and off at other times when not engaged.

 

Thanks for the advice and link to the momentary switch. I guess i'll give it one last try.
I've replaced all wiring inside trans and outside twice to be sure. As well as the pass through terminals on the trans. 12v is not on constantly either. The linkage switch supplies power at the correct time when actuated, but is short lived... It starts blowing the trans fuse shortly after a new solenoid is put in. Maybe your right and there is a piece of trash in the fluid passage. I'll take a closer look. Do you have a link to someone who has the solenoid i need? I have ordered through my trans guy before, but i'd like to know too.
Are you wiring the switch off the "trans" fuse on the fuse block or running a seperate 12v supply with an inline fuse? And i'm assuming you're leaving the kickdown wire on the throttle linkage?p

 

My TH400 S/P wasn't originally offered in my 66 or 70 Cutlass so I initially used a simple toggle switch directly to a 12v and later used the momentary on switch. It's on when held down then off once pressure is removed. (Cheap thing from Summit)

More recently I purchased a controller from Bruce Roe that is fine tunable and might be just what you need for your altitude and problems. I haven't installed it yet because my car is in a restoration process but I think it works through existing linkage or can stand alone. It's quite nice.

http://s93.photobucket.com/user/bcro...tml?sort=6&o=0

bcroe@juno.com

Here is Bruce's email if you want to get in touch with him. He has no website and does it all through the mail.

 

Thanks for the info. I just emailed him. Sounds like a more user friendly option instead of pushing a button all the time.

 

Well i ordered a new detent solenoid, kickdown switch, and Bruce's standalone controller. I hope it works, i will keep you all posted when i get the time to put it all in. Thanks for the friendly advice!

 

Let us know how it all works

 

These are the questions I would ask:


Have you confirmed yourself, that the coil is open on the suspected failed solenoid?


Are you certain that it is the correct solenoid being installed?


If it's burning a fuse, the coil in the solenoid is not open. If you pull the connector off of the trans and it doesn't burn the fuse then everything upstream of the connector is good in terms of short circuit.


If the coil is not open, then it is either still good or has an internal short. If you keep replacing them and the coil keeps shorting internally, then probably is not the correct solenoid.

 

You can actually hear the solenoid click when 12v is supplied to it. If you can't hear it the plunger isn't actuating.
The S/P solenoid is only on at two points, just off idle for about 20% throttle opening and WOT (along with the kick down solenoid). At the most it is probably on at a minute at a time but no more and this only at low speeds. Unless you're running the salt flats at WOT.
By turning the key to the 'run' position and moving the throttle linkage you should be able to hear both points happen and possibly two at WOT, kick down and S/P. This is assuming the throttle linkage switch is working correctly and isn't all dicked up inside. I'm assuming the 65 is similar to my 66 but I may be wrong there.

 

Something else I thought of. Is the original plug being used to the pass through connector? Having them reversed either inside or outside could cause a problem I'd imagine.
The top connector pin, horizontal one, is for the S/P solenoid which is the forward of the two inside since they look identical.

 

Thanks for the input on troubleshooting. The fuse only blows when 12 v is applied to the sp solenoid. If its unplugged from the linkage it wont blow and i get power to the spade. It's definetely the sp solenoid(either the short is in the wire from the pass through plug to the solenoid, or the solenoid itself). I had my trans guy install a new pass through plug and the NOS solenoid last time i had the trans out. I got both of those parts from my local switch pitch guru here in colorado.

This time i will just take the pump cover off myself and do some bench testing with the culprit solenoid and see what i can find. I've got another NOS solenoid in case it is the culprit.

Either way, bruce's control box and a b&m kickdown switch should be more reliable and efficient than my old linkage.... I hope!

 

Just for reference my throttle switch on the inside was worn out through years of use but I took it apart and rebuilt it. I could see where it could draw extra amperage to work properly if in need of repair. I have pics if you want to see.

I added the pics. On the 2nd pic at the two o'clock position you can see where the brass contact wore through and I repaired it with hard solder that has a higher melting point than the old school stuff. It had worn completely through the brass contact at that point after 50 years of use. I'm sure that didn't help things electricity wise. Everything under here was corroded to some degree or another so I cleaned it all up and lubricated it with the correct electrical contact lube.

 

Update: pulled trans out this morning. Removed pump cover and vp solenoid. The wire inside the solenoid came off the spool and was shorting it out. Stripped some copper wire and wire tied it back on the spool. No more short! There was a kind of paper tape around the wire spool I had to remove. I am wondering what kind of tape I can use to re-insulate the wire spool? Good ole electrical tape? Not sure if it will hold up to hot trans fluid? Any suggestions?
Tonight I can start putting everything back together and install Bruce's controller. Can't wait for a test drive.

 

Glad you found the short to ground. I should have guessed that right off the bat when you said the fuse kept blowing.
I doubt any kind or electrical tape will withstand the temps without the glue melting away. I would just put it back without anything on the coil and solder that wire back to it's contact point for a clean worry free installation.