727 at idle pretty rough in gear

[ToddMcF2002]

Rough, noisy and vibrations in gear at idle (stop signs, lights scenario). To the point I'm inclided to put it in neutral but going back into first can create a thunk due to an inconsistent delay going into gear.

What to look at first? Fluids look good. Shifts pretty decently. This is my first 727 so please assume I know nothing since that is the case when it comes to automatics.

 

[Rockland71GTX]

What's your idle speed?

 

[Don Frelier]

Could be lots of things:
1. Big cam and too low of a stall speed
2. Running poorly (and someone turned up the idle speed to compensate)
3. Broken or bad mounts
4. Exhaust hitting somewhere
1st thing is to make sure it's tuned properly and slow it down if you can.
Then see what happens.
You may end up needing a torque converter with a higher stall speed.

 

[ToddMcF2002]

I'll check the timing and RPM's but its not over 1000. Everything is new, cam appears to be stock base on the lope - certainly not a big cam.

 

[BeatersRus]

sounds like the trans is on its way out.
the inconsistent delay is what catches my eye.
these trans dont pump fluid till they are put into gear or neutral.
over time,so many people just yank them into park and go,that it wears them down.
that being said,you also said your fluid looks clean and doesnt smell.
at the very least id check the transmission filter for sludge,and change if found.
also look for Materials in that filter and in pan/band material and sludge.

the thunk could be many things,driveshaft/u-joints worn,bad rear trans mount,rear end wear.
theres also the pump bushing,and the lovely flex plate bolts/working themselves loose/or/even cracking the flexplate ears where those bolts fasten thru and then having a vibration.
can you tell where the thunk noise is coming from ?
and do you have a Kickdown linkage or cable setup?

 

[MoparLeo]

So more backround please. Did you just get this car ?
What just happened to prompt this question ?

 

[ToddMcF2002]

Yes just got the car. Previous owner took stuff off that I’ve confirmed. Looks like he pulled a carb and gave me an old Holley and probably took the original throttle linkage because the Kickdown is bypassed with a cable. Is this a contributor? The linkage appears to be all there down to the transmission at least.

 

[Ron H]

All great tips posted, just adding in is your ignition stock or electronic? You’ve already thought about timing, also check dwell if it is a stock setup, want to make sure your carb is adjusted right. Assume your ride is in ‘tune’. Didn’t indicate your idle speed; but if it’s too high, you may get a thunk putting it in gear and RPM might be too low when dropping it in gear..

 

[Dave6T4]

Get the proper carb and kick down linkage. I have used the cables where there was no other option, but I do not like them. They are too hard to set up to work properly. That being said, it sounds like your problem could be torque converter or drive plate related.

 

[BeatersRus]

Yes just got the car. Previous owner took stuff off that I’ve confirmed. Looks like he pulled a carb and gave me an old Holley and probably took the original throttle linkage because the Kickdown is bypassed with a cable. Is this a contributor? The linkage appears to be all there down to the transmission at least.

View attachment 1194554

that kickdown linkage doesnt appear to be hooked to anything and will deffo cause major problems.
the lone cable shown isnt that the gas pedal?
you are gonna need either the missing carb to pivot linkage arm and adjusted properly,or a cable setup that does the samer thing.
this is exactly how they get messed up = no kickdown.

 

[Ron H]

Not sure how kick down would be ‘bypassed’ with a cable – would mean IMO it’s not or is goofed up. Throttle and kick down linkage are two things. And “old” Holley...could be in need of rebuilding/replacing who knows what shape it is in and setting it up properly – fast and slow idle, float adjustment, jets good, etc. Maybe post another photo showing the carb linkage

 

[ToddMcF2002]

OK taking a step back. Yes I'm missing ALL the topside linkage for the kickdown. The lower linkage to the transmission appears to be intact and connected. Here are more pics and the diagram from the 69 manual. Love to hear more about the kickdown function? Also note the angle of my throttle cable because of the manifold height

 

[Ron H]

Don’t see any kick down linkage. It attaches to the rod sticking out from the carb linkage. Rear vac hose shouldn’t be impeding movement of the linkage (once it is put on). The throttle cable is cocked upward creating a bend…it should be setup in a straight run from the bracket to prevent possible bending or binding…

 

[ToddMcF2002]

Right I pointed out the bent cable. The kickdown throttle lever and the linkage to the transmission is there. I'm missing everything by the manifold

 

[Ron H]

My goof, as ya know you have no linkage. Kick down function mates with the trans shifting points, upshift/downshift. Improperly set it may not drop into 1st or 2nd gear when giving it gas, or may start out from a stop in 2nd gear…the lack of the connection to the VB lever means the trans doesn’t know where the eff it is, lol.

 

[ToddMcF2002]

My goof, as ya know you have no linkage. Kick down function mates with the trans shifting points, upshift/downshift. Improperly set it may not drop into 1st or 2nd gear when giving it gas, or may start out from a stop in 2nd gear…the lack of the connection to the VB lever means the trans doesn’t know where the eff it is, lol.

Yeah it seems to hunt alot and never quite shifts where I expect it to so that makes perfect sense. So I'll source all this stuff and I don't think I can really use this intake manifold? Or at least the linkage will be aimed upward at an angle? Maybe that doesn't matter

 

[Ron H]

You may be able to take the slack off some by moving the throttle cable back a bit. On mine I drilled another hole in the bracket to set the cable more in-line. Shift points are pre-set such as factory, or guys have altered them nicely. There are a few good utube vidoes I’ve seen that walk you through setting up the kick down – old school (with the linkage installed) is open the throttle full and identify the position of the VB lever. It should be pert near to its full travel, not beyond, meaning the linkage has bound up stopping travel. That’s the adjustment.

 

[BeatersRus]

everything in that pic is urghly.
throttle cable is way too slack,theres no kickdown lever at all connecting,and tbh why use that carb when there are so many better options out there?
may i suggest a holley speed demon 1904 ??
thats the new version of the old thermoquad carb,and its Very good and itll use all your factory linkages,once you actually find them.

as far as the intake goes,well,you can get as creative as you like..if it was mine,id swap it out.
and that arm thats holding your throttle cable right now,that also holds your kickdown linkage,has been bent vigorously by some cretin....that will require some adjustment Back.

 

[ToddMcF2002]

someone bent the cable holder upwards apparently - easy to fix. Yes the carb is going but I'm focusing on the kickdown first.

 

[AR67GTX]

Unless someone has already mentioned it - it’s always been my understanding that it’s dangerous to the well-being of an A727 to drive it without the kick down linkage installed as it regulates fluid pressure in conjunction with the valve body. You can damage the transmission (as I understand).