gyromatic problem

[jrb182]

I have tried to do my research before I posted this since there is already so much info on the m6 and fluid drive but, I need some advice. My 49 Coronet had been sitting for many years (maybe decades).Finally I have the fuel system ,front end and brakes completely finished and took it for its first road test this past weekend..To my disappointment the gyromatic tranny slipped so bad that I barely made it home .Now,I do not have the correct carburetor yet, so the wiring is not complete, but from what I understand I should still be able to drive in low range (1st) and high range (3rd) without it automatically shifting to 2nd or 4th because of the wiring. The car shifts perfectly into reverse and between the two ranges. I don't smell clutch or see smoke but it feels like the clutch is slipping. The other issue is that when I come to a stop I have to use the clutch or it will stall which makes me wonder if the fluid drive is bad.  My question are: Bad Fluid?      Should I drain all fluids and replace them since I really don't know whats in there  ? Would a bad fluid drive unit cause slipping ?  Should I just bite the bullet and replace the clutch. My last option is to install a manual 3 spd with the proper input shaft which I have. Any advice or knowledge will be greatly appreciated. Thanks

 

 

[Los_Control]

YES! You would need to get rid of the old fluid, I would really wish to have done it before driving it. But that is how life goes.

Get out all of the old fluid as much as possible. Add new and then run it a bit, maybe just on jackstands with the rear wheels off the ground, then flush it again.

Old oil turns to gunk, You should drop your oil pan and clean out all the sludge in it. I have seen cars that have sat for years, pull the pan and is like 3" of sludge on the bottom.

Just the old oil turning into a solid from the years. As you run the engine, this semi solid will soften and plug up oil passages and eventually your engine will starve from lack of lubrication and blow up. The sludge I have seen, You need a putty knife to scrape it out of the bottom of the pan.

And this would be my thoughts on your transmission as well. You want to try and get as much as the old stuff out that you can. Give it at least 1/2 a chance to work for you.

 

I bet many have gotten by without dropping the pan, But if you saw what is lying in the bottom, you would take the extra time to clean it out.

Who knows, maybe 20 years and it does not turn into a solid, but 30 years it will? But those chunks floating in your transmission will not help it.

[_shel_ny]

Stalling may be carb adjustment, or vacuum leak. My D24 did that until I replaced the defective(torn diaphragm) vacuum advance, and got the carb adjusted right.

A low on fluid coupling can act like a slipping clutch, but if it were low and slipping it does not seem that it would cause you to stall without using the clutch.

Fluid drive coupling.  Check the fluid level. If OK, put the plug back in, and leave it alone.

Correct oil, and oil level in the M6 is also important.

[rb1949]

At least change the tranny fluid, it's only 3 pints. With incorrect components it should still work with electrics disconnected. No paper manual? Hit the Imperial Club website for 2 good manuals on the M6. Print them if you want. How to test the governor & solenoid. Process of elimination one step at a time.

[greg g]

I would look at the dry clutch part of the system.  It may be the source of the slippage.  Shorten up the linkage a bit and see if it has any effect on feeling of operation.  The fluid drive component is usually bullet proof and maintenance free except for proper fluid level.  The modern equivalent for the fluid drive unit is universal tractor hydraulic fluid.  The lube for the transmission is SAE 10 motor oil. The idle should be at 500 rpm.  If too high it may be causing the need for declutching at stops.  

[Dodgeb4ya]

It's slipping upon acceleration because of low Fluid Drive coupling oil or a oil soaked clutch. The FD coupling access hole and 2 plugs are located on the rt side of the floor on the side of the floor hump. Onr on the floor pan hump the other one on  the bell housing . Then you can remove the 3/4" FD coupling plug after using the key to turn the engine over slowly to see the 3/4" hex plug line up with the access hole. DO NOT DROP the 3/4" hex plug down into the bell housing!!!!!! You fill the FD coupling up to the bottom of the threaded plug hole with universal tractor fluid. 

The literature I have seen from Chrysler does not recommend ever changing the Fluid Drive oil, just topping it up annually. Maybe this is why they never mention how much oil it takes.

A lot of us use TDH tractor oil, ISO 22 or ISO 32 grade. TDH stands for Transmission, Differential and Hydraulic oil. It is supposed to be good for the transmission as well as the Fluid Drive.

The trans will upshift with out the wiring hooked up but will not down shift normally..... very slow to shift down. Hold the clutch in and wait a couple seconds at a complete stop.

[dpollo]

It sounds like your fluid drive unit is low on oil.   Raise the mat on the right hand side of the transmission hump and remove the cover and the rubber plug in the bell housing.  Have someone turn the engine with the fan blades until the fill plug for the fluid drive is exposed.

A special non foaming oil was used in these units but I know of no reason why ATF will not work. See oil recommendations from Dodge b4ya. 

The transmission itself has no parts which can slip and uses SAE 10 motor oil.  The foot clutch need only be used when starting the engine and to move the gear lever.  They rarely wear out.   The trans will shift without the electrics as they only control the kick down.

  Take a few deep breaths, I doubt that anything is seriously wrong. 

Edited November 17, 2016 by dpollo
to refer reader to prior post

[Tom Skinner]

Usually an Oil Soaked Clutch Judders. Especially at acceleration between 15-20 mph, and again at 30-35 mph.

All m6 Transmissions that are low on 10wt will seem worse or not upshift properly (they need about 40lbs/psi) to work smooth.

The Fluid Drive Coupler takes the ISO22 and should only be topped off if necessary. All m6 tranny's are dogs off the line. I would bet your Vacumn Advance is the culprit if its a dog off the line, using allot of gas, and stalling at stops. If It needs replacing you will know by taking it off the Distributor and sucking and or blowing it opened and closed, if it doesn't have Vacumn its because the diaphram is shot. Andy Bernbaum sold me a good one about a year ago. No more worries. 

Tom

[jrb182]

THANKS to all for the advise. I will work on it this weekend. Thank goodness for all of you and this site ! The mechanics in my area don't have clue what I'm talking about which is completely understandable !

[James_Douglas]

I wish that people would stop tossing around the recommendation that ISO-22 should be used in the fluid couplings without informing people of the issues.

The fluid needs to be matched to the perceived state of the roller bearing in the coupling. Also, NOT ANY ISO-22 fluid will do.  It MUST have anti-foaming agents in it.  Most NAPA ISO tractor fluid does not.

 

Read my old post in its entirety to understand the fluid that one should consider using in a fluid coupling.

Best, James

 

[Tom Skinner]

James,

I have owned 1948 Chryslers since 1973, and never had to top off a Coupler yet. I am of the opinion if it ain't broke don't fix it. I never changed the fluid out either.

But I always do see fellows stating use the ISO 22 so I mentioned it. I certainly didn't mean to ruin your Holiday with that comment. Happy Thanksgiving.

Tom

[Dodgeb4ya]

I totally agree with Tom as I too own several chryslers and dodges with FD and the M5/6 transmissions and have for over 40 years.

Just check the fluid levels... that's it.

I have run 10/30 in the M6 transmissions on flipper cars.. what a nice fast upshift!

Also 20 weight engine oil in the FD coupling... no issues either. I don't recommend these fluids though.

No matter what fluid you use it really wont make the car perform much better... top em off that's enough.

If it ain't broke don't do it a favor and change the FD fluid!!!!

Transmission top it off. Done.

Edited November 24, 2016 by Dodgeb4ya