Torqueflite 999 downshift housing

[mmt]

I am rebuilding a TF999 from an 84 CJ7 258 I6. I noticed that the valve body does not have the 3-2 downshift housing that is shown on some of the diagrams in the service manual. Searching through a 727 book I see that the housing is for "some V8 models". I have a spare valve body that does have this housing. What is its function? Part-throttle shifts?

I assume I still have some sort of 3-2 downshift without it ? Full-throttle downshift perhaps? Anyway I have the option of using the spare one, or should I keep the valve body as it was? By the way I am adding a Transgo TF-SC shift kit, if that relates to this at all.

[passing you]

either, if I'm not misstaken, yer talkin part throttle which came out in 71' or your talkin lock up valve on the valve body itself?

John's pretty good with auto's maybe he can chime in/help you.

[mmt]

here's a pic of what I am describing, I can't post a link

jeepforum.com/forum/showthread.php?t=748468

[John Kunkel]

The housing and cover plate are the Part Throttle Kickdown (PTK) module, simply remove the existing cover plate and replace it with the PTK module and plate. All TF's will kickdown 3-2 at near WOT but the PTK will allow kickdown at less throttle.

Some Transgo kits have a spring that can be used to replace the limit valve spring in the PTK module, this will limit the PTK to 40 mph or so, I like to leave it as is.

[mmt]

Thank you John, so do you recommend I add the PTK module to my valve body? Do you know why it was omitted from the CJ7 setup, and will it work ok for the 6 cylinder?

[John Kunkel]

I like PTK and always add it to VB's that don't have it, no idea why they omitted it from the 6 cyl. since that's what PTK was originally used on.

[Tarrbabe]

downshift housing? This just another name for partial throttle kickdown? Maybe a marketing thing? TF's are so simple when you look at them that you wonder why everything isn't that simple. But then there are still parts of the valve bodies that I still don't understand.

[mmt]

I used the term "downshift housing" because that's what it's called in the Jeep service manual. This is my first auto rebuild so I came into it knowing absolutely nothing. Now John has pointed me in the right direction, I have searched and learned a lot about PTK. I am going to install the extra PTK I have onto my valve body . No idea why it didn't have one originally; and, I'm not sure if any CJ7's had it. One last thing is I wonder if they made a decision to not include it or if it was accidental. I have seen pictures of later year Wrangler Tf999s that show the PTK present.

[John Kunkel]

I long ago gave up trying to figure why the factory does what it does, the PTK was first introduced in late '66 for use with the /6, probably due to their poor lugging power. In '71 they added it to the V8 on some models but not others and it's use was kind of sporadic after that.