Does anyone of you have any idea why my 69 FMX transmission is slipping while cold.
When starting cold (even in warn garage) start engine and select D, 2, 1 or R, the tranny hooks up but then after few secs let go the gear.
More revs hooks it again but then let go the gear when revs go low. After 10 mins of warming up before cruising fix the problem but this is embarrassing.
The problem started gradually last summer and during the winter I overhauled the tranny strictly according Ken Collins video (it was very good).
However, the problems stays eventhough I took special care while adjusting the bands and other adjustments. Of course did the job with new seals etc.
Both my 70’s had/have this issue. Both have FMX trans also. not sure of the fix and havent really messed with it simply because the car works when I need it to and I will eventually be going O/D or 4 spd standard!
Check the fluid level. the symptom sounds like it could be caused by low fluid. The engine needs to be idling with the shifter in Park to get the correct reading.
Not to tell the master his business, but how about hard clutch piston seals Mark? I don’t know the internals of the FMX but have had this problem on other transmissions and the culprit was the rubber seals were hard. Summer, fine. Winter, no good! In fact it is how I got into fixing auto’s to begin with. A '68 Toyota Corona 2-speed (a cast iron powerglide knock-off) back in the day, my first car.
Thanks for your hints!
I have checked the fluid level as instructed; warm, idling and in park-positition. During the overhaul I replaced the all the seals including the servo/piston seals.
I will think this further and report here if any breakthrough…
Hey Bob, that is definitely a cause for that type of symptom.
Sounds like what should be done next is to put a gauge on the trans to see what kind of pressure there is. Then, drop the pan to look at the pressure regulator body. Also, pull the valve body to use some compressed air to air check the clutch packs. As I remember the compensator valve is known for hanging up, but I am not sure if that could be the cause of this type of symptom. If you have to remove the valve body and finder everything else is o-k as far as air checking, I’d recommend installing a Trans Go shift kit…Trans Go SK3-67 if the trans is the correct year. Or, if the trans is 73 and up use the SK3-73.
Yep, when I was troubleshooting the direct clutch on the Toyota (those many years ago), that is exactly what I did. I connected a gauge on a plug on the side of the trans for the direct clutch and was able to tell for sure that the clutch piston was bypassing fluid when cold.
Hi,
i just wanted to share you what was the corrective action to my slipping problem - more driving!
Yes, nothing else. I was alarmed too early just after couple of test drives.
Now FMX works very well.