Ok, I popped over here from bp, hoping to maybe find an answer to an issue I've got with a 727 in my '79 Scout II (345). I'm about to swap a good used 727 into my rig, but noticed the throttle pressure shaft seemed to be freefloating. It turns a full 360 degrees. I don't think that is right, and wondered if anyone had any thoughts as to what might have come loose.
727 Throttle Pressure Shaft
- Thread starter Rob Moore
- Start date
Michael Mayben
IHPA Tech Moderator - Retired & No Longer Online
Do you mean the throttle pressure control shaft to which the lever is connected simply swivels back and forth and stays in any position you place it?
If so...then it's most likely that the spool valve is stuck in it's bore...that creates a "max" line pressure situation which is not good for the trans and of course inhibits normal shifting. If the valve is stuck, then the internals of the valve body are trashy, it will need to be dismantled and completely serviced/cleaned.
Second most likely, the actuator for the spool valve has broken loose from the pivot rod, it's a welded assembly.
Either way...simply drop the pan and take a look! It's about the simplest thing you can do.
This pic is a closeup of the area of concern. On the right side is the manual shift valve which connects to the shift selector. The throttle pressure valve can be seen to the left of the manual shift valve. In that shot it is in the "minimum" position (throttle closed). As the throttle opens, that valve is depressed against it's internal spring in a linear fashion.
Disregard the tie wrap...I place a tie wrap over the throttle pressure control/shift control before removing a valve body from a trans so that the control does not "jump" out allowing the detent spring and ball for the manual shift assembly (rooster comb) to fly across the shop.
If so...then it's most likely that the spool valve is stuck in it's bore...that creates a "max" line pressure situation which is not good for the trans and of course inhibits normal shifting. If the valve is stuck, then the internals of the valve body are trashy, it will need to be dismantled and completely serviced/cleaned.
Second most likely, the actuator for the spool valve has broken loose from the pivot rod, it's a welded assembly.
Either way...simply drop the pan and take a look! It's about the simplest thing you can do.
This pic is a closeup of the area of concern. On the right side is the manual shift valve which connects to the shift selector. The throttle pressure valve can be seen to the left of the manual shift valve. In that shot it is in the "minimum" position (throttle closed). As the throttle opens, that valve is depressed against it's internal spring in a linear fashion.
Disregard the tie wrap...I place a tie wrap over the throttle pressure control/shift control before removing a valve body from a trans so that the control does not "jump" out allowing the detent spring and ball for the manual shift assembly (rooster comb) to fly across the shop.
Attachments
Thanks for the quick response Mike.
The shaft itself, and therefore the arm if it is attached swivel and remain anywhere I put it. There is absolutely no friction, or resistance whatsoever.
Ok, I'll drop the pan and have a look see. Thanks for the pictures that is a huge help. I figger I best get a hold of the munroe book. Damn, I was hoping this would be an easy swap.
The shaft itself, and therefore the arm if it is attached swivel and remain anywhere I put it. There is absolutely no friction, or resistance whatsoever.
Ok, I'll drop the pan and have a look see. Thanks for the pictures that is a huge help. I figger I best get a hold of the munroe book. Damn, I was hoping this would be an easy swap.
Michael Mayben
IHPA Tech Moderator - Retired & No Longer Online
Your welcome rob!
Once ya git inside, if ya need anymore help just post to this thread. I've got several "training aids" such as this on hand along with a couplea 727 builds in process now.
Once ya git inside, if ya need anymore help just post to this thread. I've got several "training aids" such as this on hand along with a couplea 727 builds in process now.
Much obliged. Once I get the trans issues sorted out, I get to finagle the lokar throttle and kickdown cable and linkages out for my new jet performance rochester qjet.
Its a guarantee I'll be back to read and pick some brains.
Michael Mayben
IHPA Tech Moderator - Retired & No Longer Online
That lokar cable set is one fine piece of work!
It corrects all the deficiencies (and rot) of the oem throttle cable and kickdown lashup.
I just finished up a build of a "late" quadra yesterday...454 gmc motorhome chassis (1989 production, last of the carbed units). This one was really grunged internally due to the fact it's spent most of the past year sitting with 80 gallons of e10 on board.
All the "epoxied" plug-offs in that one were rotted through/shrunk also, had to remove all old sealant and re-plug.
Next up is building the carb on the onan apu, it's grunged also, raw fuel runs right into the crankcase on that one, but we caught it in time before the engine internals were washed down.
Been over 20 years since I quit scruuin' with quadras...now I remember why I quit scruuin' with 'em! Good luck with the jet!
It corrects all the deficiencies (and rot) of the oem throttle cable and kickdown lashup.
I just finished up a build of a "late" quadra yesterday...454 gmc motorhome chassis (1989 production, last of the carbed units). This one was really grunged internally due to the fact it's spent most of the past year sitting with 80 gallons of e10 on board.
All the "epoxied" plug-offs in that one were rotted through/shrunk also, had to remove all old sealant and re-plug.
Next up is building the carb on the onan apu, it's grunged also, raw fuel runs right into the crankcase on that one, but we caught it in time before the engine internals were washed down.
Been over 20 years since I quit scruuin' with quadras...now I remember why I quit scruuin' with 'em! Good luck with the jet!
Alright, I finally got back to that 727 I was talking about. Got it up off the floor and threw it on an engine stand to make it easier on me. Dropped the pan and found the problem. The bottom of that shaft has an arm on it that actuates the actual throttle pressure valve. Well, the arm on the end of that shaft was sheared off, also, the long black adjuster bolt was also bent. Looks an awful lot like the top of that shaft took a hit from something hard enough to drive it down into that adjuster, bend it, and shear the arm off. I grabbed the valve body out of the other trans and swapped it, plus the shaft and arm. Adjust the bands and closed it up. The other thing I noticed is this trans must be from an older model than my '79 as it has the bigger torque converter, since I ain't got the matching flex plate, I'll swap the converter from a donor. I snapped some pics but forgot to download them. Hopefully my saga with this trans has come to an end. Thanks for all the help Mike.
Michael Mayben
IHPA Tech Moderator - Retired & No Longer Online
That tranny was badly abused at some point! As in beat ta shit with a hammer or in a totaled crash????
The '79 trans should be a "part throttle kickdown" valve body if it's original to the trans and vehicle. But no telling. You can go here and review some info about that in post #38. The valve body ya swapped in May not be a part throttle unit. If it's not, then no problema...just adjust the throttle pressure control (kickdown linkage) up on the carb/manifold combo and get used to the fact that it's "different" from how it acted before!
The production line "cut" for the changes regarding the tf 727 (t-407) is only given in a parts list as "8/30/77 and later". But I would not trust that for shit. Only thang that matters is what ya got yore hands on! Same "production date" deal holds for the flex plate/torque converter, but again who knows if that was "clean" or not.
I spent years as an oem field service engineer dealing with vehicle production/parts "change control" on oem assembly lines throughout north america and argentina, I know how fucked up all this stuff gets even today with all the 'bots and pooters drivin' 'em!!! Sum dumshit production engineer "forgets" to write down a simple vin "cut" or an assembly monkey pulls the wrong part off the staging rack and the entire system goes to hell forever, the trickledown behind that is enormous in years to come regarding service parts replacement, recalls/campaigns, etc.
The '79 trans should be a "part throttle kickdown" valve body if it's original to the trans and vehicle. But no telling. You can go here and review some info about that in post #38. The valve body ya swapped in May not be a part throttle unit. If it's not, then no problema...just adjust the throttle pressure control (kickdown linkage) up on the carb/manifold combo and get used to the fact that it's "different" from how it acted before!
The production line "cut" for the changes regarding the tf 727 (t-407) is only given in a parts list as "8/30/77 and later". But I would not trust that for shit. Only thang that matters is what ya got yore hands on! Same "production date" deal holds for the flex plate/torque converter, but again who knows if that was "clean" or not.
I spent years as an oem field service engineer dealing with vehicle production/parts "change control" on oem assembly lines throughout north america and argentina, I know how fucked up all this stuff gets even today with all the 'bots and pooters drivin' 'em!!! Sum dumshit production engineer "forgets" to write down a simple vin "cut" or an assembly monkey pulls the wrong part off the staging rack and the entire system goes to hell forever, the trickledown behind that is enormous in years to come regarding service parts replacement, recalls/campaigns, etc.