WendellB

How can I tell if my 1978 Olds Toronado TH425 has a Swing Pitch torque converter?

joe_padavano

If you mean "switch pitch", it isn't. They were last built in 1967.

WendellB

Thanks Joe. However, what if the previous owner installed one, how could I tell?

oldcutlass

There would be some sort of a switching device on the linkage to make it work or a switch inside the car to work it manually.


Here's an article on a switch pitch T400:
http://www.hotrodhomepage.com/hrhp/2...the-overdrive/

Octania

That would be some trickery, what with the different mating part on the trans, the solenoid, the passages for the pressurized oil... in a TORO?! Not saying it could not be done, but it is so not just a matter of swapping torque converters. The RWD trans would be somewhat easier.

joe_padavano

Actually, not so much. The GMC motorhome folks have been doing this swap. It's not too different from converting to a switch pitch on a conventional TH400. Change the front pump, change the converter, and install the solenoid valve. Apparently all the TH400 valve bodies have the passageways in place, and apparently so do the TH425 valve bodies. I installed a switch pitch conversion on a TH400 years ago (actually, decades ago ) back when Kenne-Bell still sold the kits.

As for whether or not this particular TH425 has such a conversion, it's not impossible, but pretty unlikely unless you have first-hand knowledge otherwise. The first thing to look for is the electrical connector on the side of the trans. If it only has one terminal, game over. If it has two terminals it MAY have been converted (or it may just have the pressure switch for transmission controlled spark). If you do find two terminals, you need to drop the pan on the trans. If you find only on control solenoid bolted to the valve body, again game over. If two, then yes, it's a switch pitch.

rustyroger

I understood the switch pitch was dropped after GM stopped putting two speed transmissions in their cars.
That makes sense to me, it would reduce production costs and with three speeds would not be needed anyway.
Am I on the right lines here?.


Roger.

ostie13

I installed a switch pitch in my 71 Toronado.If you really want to talk to some one about it I recommend emailing Bruce Roe(bcroe@juno.com). He has made a converter box that make the system work better and do more..If you want to purchase a "Switch Pitch" Transmission Manny Travao (manny@travao.net) has them.Thats who I purchased mine from. Let me know if I can help you.

joe_padavano

Ah, no.

Switch Pitch transmissions were dropped after the 1967 model year, but the Jetaway was offered (without switch pitch) through the 1969 model year. Also, the three speed TH400 and TH425 came with switch pitch, so that argument doesn't apply either.

WendellB

Thanks Joe! Actually my '78 Toronodo is a GMC Royale that I recently bought with only 47,000 miles on it. But the 403 seems to work real hard at when starting out and the transmission cover had some yellow markings like it was from a junk yard. I changed the filter and trany fluid but did not know what to look for inintially. The previos owners where part of a GMC Motorhome club and had installed an Energizer ignition system and headers. My RV has a built in blender and vacuum cleaner. Perfect for taking a fine lady jet skiing in New Melones and afterwards start the margaritas while she cleans the sand off the carpet. LOL! If she wants to drive the she has to wear a fine bikini.

WendellB

Your link was very interesting and informative. Thanks