Hi,
First I would like to say Great Site! Lots of information help me understand and become more prepared on doing the work myself.
With that said, I have a 2 speed PowerGlide in my '68 and the Transmission wont down shift. I'll have the car in drive and it wont downshift to first, it just stays in 2nd gear the whole time... I have to manually downshift it everytime I stop the car(unless I want to go like a slug until 2nd gear reaches its RPM range). I dont even know where to start. Is this a problem that I could do in a day? (I have access to a lift and air tools. I've heard it was the governer and then I've heard that it's some kind of vacum problem

Thank you for input
Mike, Stockton, Ca

Welcome to the Club!!!

I assume the trans works good, as in no slippage. Depending upon mileage, oil pump could be worn out. You can have the trans shop do a pressure check to verify.

Lift hood, at the rear of the engine on the intake, you will find a vacuum hose, approx 1/8 inch inside diameter, going to the rear of the car disappearing below. This hose connects to the vacuum modulator on the trans.

Pull the hose off from the intake, and either manually suck on it or apply a vacuum hand pump to see if it holds a vacuum. If it does not, then either the hose/tubing is faulty or the vacuum modulator needs replacing.

If the above doesn't fix the problem, then I would suggest a removal of the pan and valve body for a cleaning. Maybe even remove the valves from the valve body, one by one, and lightly sand them with emery paper. BrakeKleen works great for cleaning.

Upon installation, be sure manual valve is hooked into the shift lever. Clean the pan, install a clean filter and gasket, and fill with fresh fluid, DEXRON III.

Checking & repairing the governor requires removing the rear extension housing, after unbolting and removing the trans cross member. BE SURE TO SUPPORT THE ENGINE/TRANS FROM FALLING. Could really make for a bad day. Then, remove the speedometer driving gear with a long jaw (15 inches) gear puller. Then, remove a lock bolt and pull off the governor assembly and clean it or replace with a known good unit if worn parts are found. Replace in reverse order.

If you would like, remove the bottom cooling oil line from the radiator, attach a length of hose to the cooling line, direct this hose into a drain pan, and have an assistant start the engine. The pump will pump clean fluid from the pan thru the torque convertor out the cooling tube. When bubbles appear, turn off engine, add a few more quarts of ATF, repeat again. When fresh fluid comes out, stop engine, re-attach cooling tube to radiator, top off the trans fluid. And keep fingers crossed....

Others here may have some suggestions.

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Everett "OBJECTS IN THE MIRROR DISAPPEAR UPON RAPID ACCELERATION"

is your kickdown linkeage hooked up to the carb?

I would suspect kickdown linkage as well since the problem is with downshift. A problem with the vacuum modulator usually seems to effect upshift.

edit: Seems like it should go back to 1st when the car stopped regardless of kickdown linkage.
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Robert Johnson

'69 getting better every day... (every pay day) (http://www.angelfire.com/ab7/tempcarpage)
350ci 700r4 3.55 posi A/C PS PDB

[This message has been edited by rojo (edited 11-05-2002).]

I've looked at the engine and transmission with no luck I havent found a vacuum line/modulator, Maybe it would help to tell you that the engine is a 6 cylinder... Is there anything else that it could be... without me taking out the whole transmission?

Thanks again
Mike

The vacuum modulator would be on the passenger side correct? Also, did some powerglides not come with a vacuum modulator?

The modulator is at the rear pass side of trans. Every P/G has one, regardless whether a 6-cyl or 8-cyl engine.

Since its a 6-cylinder, it will still have a line going from the intake manifold to the modulator. If the car is equipped with power brakes, the line would come off the same fitting. Otherwise, it might be connected to the bottom of the carburetor.

Throttle linkage is only for downshift, as in passing gear.

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Everett "OBJECTS IN THE MIRROR DISAPPEAR UPON RAPID ACCELERATION"

Do you guys have any pictures. I cant seem to find one(even with the help of my father). There is no line visible nor is there any vacuum modulator. There is a bolt in the transmission where it might go, but I dont know, So I would like to see if any of you have any pictures of the powerglide modulator position, or a picture of the underside of the car where I can see where it is. My car is a 68 by the way.

Thanks
Mike, Ca.

The modulator is on the drivers side on a power glide, right above the rear corner of the transmission oil pan. It is above the cross member and hard to see. The vacuum line is a steel line (originally) that runs along the drivers side of the transmission case at about the mid line of the transmission body, then up over the bell housing at about the 10 oclock (looking towards the front of the car) position, over the rear corner of the 6 cyl exhaust manifold, along the left side of the valve cover, then it turns 90 degrees and connects to the bottom center of the carb flange. Modulator controls up shifts, if the vacuum line is off the carb will upshift at a high rpm (like under hard acceleration). The shift linkage on a 6 cyl is a long straight rod that runs from the same linkage that the accelerator cable is attached to. This controls the downshift RPM of the transmission.

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Mark Canning
1969 Indy Pace Car
350/300HP RPO Z11
My 69 L48 - 350/300HP Engine (http://www.townisp.com/~markcanning/camaro/transparent%20air%20cleaner3.jpg)