So I replaced my transmission in my 68 Riviera and now it won't shift, this was a used transmission that I got from a guy who said it was sitting around for about ten years waiting to go back in his car but it never happened he also said it worked fine and had no reason to lie since he was cleaning out his garage from a rental property he had up here in NY and he lived in Maryland so he was selling a completely rebuilt Buick 430 motor and used th400 tranny for $150 bucks to get it sold that day (I was Lucky). So I bought this so that I could build up a nice drivetrain to go in my Riv but my transmission went out so I replaced it with the tranny that I had, I only reused my original torque converter and vacuum modulator and my transmission I used before was working fine but the clutches wore out. I don't have the cash to rebuild this one right now and I am wondering why it won't shift, it go's into gear fine and I have driven it around the block a couple of times but no matter what speed I go it will not shift into second, I also replaced the filter in the tranny and I didn't see any abnormal material in it, PLEASE HELP.
Dude, its prolly your vacuum line that goes to the modulator is either not hooked up right or has a split in it. -Shiny
Pull of the modulator hose at the carb and hook up a mitey vac vacuum pump , pump and see if it holds vacuum this tests the line and the modulator. The governor could be stuck from sitting or the gear on the governor is stripped.It is located on the rs of the trans with 4 bolts holding the cover on, governor is under this and should come out with little effort.
Did you flush out the clutch debris from the cooler and lines? If not the governor is probably full of debris and need to be cleaned out.
I guess I will check the vacuum line again, that was the first thing I looked at but maybe I should test it like stated above.
One more thing to check is the drive gear on the governor. That just happened on my rig. It is plastic and strips/breaks easily if the governor binds up a bit. Also how many quarts of fluid have you put in it. If the converter was dry it will take quite a bit of fluid before it works right. And lastly, each one of us who has posted an answer here has assumed that you changed the filter.
vacum is not the problem. The govener will overide the vac modulator it will just shift later and harder.Like other's have said pull the govener out it's very easy . Just remove the 4 bolt's and pull out.There are two things to look for the first will be obvious as soon as you pull it out,the gear might be stripped.Second thing is the valve inside the govener. Hold the gov up and look through slot's in the shaft and work the weight's up and down .The valve should move freely.If not just drive the roll pin holding the gear on and pull gear off and remove and clean valve and reassemble.If your unsure stick the govener from old trans in and try it. Hope this help's .Let us know
Start with the obvious and work your way to the least obvious... I'd check your transmission fluid level first, then vacum... With the vacum off it will shift, but you'll have to rev it up pretty high and it'll shift really hard.
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