flash-o-matic problems

Hi all, I'm new to the AMC scene. I recently aquired a 1964 Rambler 770 classic 2dr hardtop 327 with the floor shifted flash-o-matic. Car has 48,000 original miles. Car is all original. The problem:   The transmission will not go into gear till you warm it up for at least 10 minutes. When going from park to reverse or drive, there is about a 6 second delay before it goes in. Seems to vibrate bad when going into reverse. Going down the road seems ok, till it goes up a hill, then it slips. The suspected culprit according to the previous owner is the adjustable vacuum modulator/solenoid. Upon inspection I noticed it has been siliconed where the wire goes into the can. It leaks tranny fluid. Tried adjusting it several times turning in and out but with no effect. Changed fluid/cleaned filter.The car shifted fine till the previous owner messed with this modulator. Have done hours of researching on this and stumbled upon this forum. I can't find a replacement. Found a rebuild kit for it, but the company wants $198 for it. What are my alteratives here. Does anyone know where I can find another without ripping my old one apart? Is there something else wrong with the transmission ? I am in Maine and there is little to no help with this problem here. Thanks in advance. Sorry for such a long post.

rdmsbm97 wrote: Hi all, I'm new to the AMC scene. I recently aquired a 1964 Rambler 770 classic 2dr hardtop 327 with the floor shifted flash-o-matic. Car has 48,000 original miles. Car is all original. The problem:   The transmission will not go into gear till you warm it up for at least 10 minutes. When going from park to reverse or drive, there is about a 6 second delay before it goes in. Seems to vibrate bad when going into reverse. Going down the road seems ok, till it goes up a hill, then it slips. The suspected culprit according to the previous owner is the adjustable vacuum modulator/solenoid. Upon inspection I noticed it has been siliconed where the wire goes into the can. It leaks tranny fluid. Tried adjusting it several times turning in and out but with no effect. Changed fluid/cleaned filter.The car shifted fine till the previous owner messed with this modulator. Have done hours of researching on this and stumbled upon this forum. I can't find a replacement. Found a rebuild kit for it, but the company wants $198 for it. What are my alteratives here. Does anyone know where I can find another without ripping my old one apart? Is there something else wrong with the transmission ? I am in Maine and there is little to no help with this problem here. Thanks in advance. Sorry for such a long post.

I recommend that you get a service manual for your car, commonly called a Technical Service Manual or TSM.   The transmission section has a pretty good list of the symptoms and causes for transmission problems. Your probably might only be worn bands which can somewhat be remedied by proper band adjustments.   Joe

The previous owner used Dextron 3. Always had. I used the same. Cleaned filter as I could not find a replacement, only the gasket. Filter was cleaned with brake clean and blown off with compressed air. I found another modulator/solenoid and will try that. I am also planning on using a type of transmission seal conditioner that softens seals. If that doesn't work I will pull the tranny and take it apart and see what's going on in there. I assume the transmission has never been cracked open and being 48 years old all the seals have probably dried out. The car has pretty much sat in a garage for most of its life.I have an original TSM and it seems very detailed. I will post my results so others can benefit from my findings. I'm sure it will be a long cold winter, and I will most likely have plenty of time to get the Rambler ready for next spring. Thanks in advance.

If its like the later M11/M12 then there is a pressure requirement that is adjusted via the vacuum modulator, it's reasonably sensitive so could be way out if someone has been playing, would probably also lead to failure if the pressure was set to low causing slippage. You need to buy a transmission pressure test gauge, they are reasonably inexpensive, maybe $30-40. Also go through the band adjustment procedure. If that doesn't work then it is probably rebuild time.

There is a post at the top of this thread advocating the use of Dex 3 in all AMC transmissions, remember these thing came out before the advent of Dex 1,2,3 or Type F, so they should run on either but don't mix them together.

If it is an true 1964 transmission it does not use a throttle cable but an 12v electric/vacuum modulator.