C4 Transmission

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This topic contains 7 replies, has 4 voices, and was last updated by  Anonymous 5 years, 11 months ago.

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    I am about to change my 53 mercomatic to a C4. Can anyone tell me what pitfalls I may run into?

    I have a C4 and have bought all the necesary adapters from Flat-O-Matic.

    Stan Bishop


    I did that swap a few years ago in my ’53.  It is very straight forward.  We were even able to use the stock shift linkage.  As I recall the transmission mount was in the proper location and needed a new hole drilled to complete that part of the install.  Would suggest an auxiliary trans cooler be installed while you are doing all this.  Have fun!!


    You have to watch out for exactly which C-4 transmission your are getting.  There are a bunch of different ones.  They range from th light duty ones used in Mavericks and Fairmonts, through the mdeum duty ones in Grenadas through the ones used in LTD and Crown Victoria, through those used in light trucks.  I can not give you any pointers on how to tell the difference, but I can tell ou from bitter experience, that if you get one from anything less than a Crown Victoria, you will be sorry.  The bad part is that they will all bolt up just fine.



    The C4 conversion is complete and seems to be OK except that the shifting seems sort of abrupt. I have connecected a vacuum line from under the carburator to the modulator. I turned to modulator to see if it was tight but it continues to turn clockwise without tightening. I can’t see if there is a place to get a wrench on it.


    Any one have ex perience with this?



    This may never shift as smoothly as you want it to.  Remember you are dealing with gear ratios that are not necessarily the best for the particular set up you have so shifting can seem early or late depending on the circumstance.  I guess I would yank the modulator back out to make sure the threads are not stripped in the case or the modulator.



    All the modulators I’ve ever seen on a C4 are held in by a forked clamp like the speedo. The modulator has an O-ring to seal it held in by the plate or clamp.



    I started having starter problems and found that the original starter bracket pulls the starter towards the  engine leaving it at an angle to the flexplate. I  don’t  have  the equipment to    make one. Does any  one know where I can get one that can be adjusted?



    I found the problem.  The starter plate that came with the kit from FlatOMatic had the starter mounting hole off  slightly and the starter mounting threaded holes about 10 degrees counterclockwise.  I found a plate that I think came off a 49 Mercury that worked fine and the bracket that  secured the back of the starter to the engine worked fine.

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