Ford FMX trans

Ok, my '78 LTD has got a FMX trans being pushed by a 400 cid engine. The question I have is kinda weird. When I step on the gas hard, the trans seems to "lag" and slip just a bit when shifting, like its having a hard time getting there. When I feather the gas, it seems just fine, also when I manualy shift from 1st, 2nd, and 3rd, it seems VERY strong when shifting, no shudders and/or slipping.

Shes got 143k miles, as far as I know, its all orginal. The fluid dose NOT smell or look burnt, just used a bit. When I worked on Swedens finest, it was known as the "kiss of death" when you changed the trans fluid when the car was over 100k miles. Would this be the same on the FMX?

I'm still new to the FMX, ALL of my Fords/Lincolns had the C-6 and I sware they where damn near bullet proof......

Thanks,

Jonny

 

Are you saying "all original" as in it still has the factory transmission fluid?
Like it's never been changed?

 

I'd check the vacuum reservoir and the vacuum line to the tranny modulator valve, and the valve, of course.

Never heard you couldn't change tranny fluid and lose the trans. :confused:

But if the valve bodies are clogged up, maybe you could change the filter. But I'd check the reservoir and vac. line first. Happened to me on 1963 Olds. Almost got suckered into a full rebuild. The tank had a small pin hole of rust. BTW, because they're usually made of tin, you can solder them back up, until you get a replacement. Epoxy might work too.

If its just surface rust, put it in a bucket of white vinegar and 2 table spoons of table salt for a couple days, rinse off, and use something like Por 15's Metal Ready to etch it before soldering. Those cannisters get pricey after all this time.

 

The fluid has been changed, but the trans have never been rebuilt.

 

Checking the vac line and valve sounds like a good idea. Um, when I was at the dealer, people would have the trans fluid changed on 850s or S70s at some quick lube place. Or they would want us to do it. About a few months later, the trans would go out......I really don't know if its a Volvo thing or what.

 

The theory is that if you change the fluid in an old, high mile, automatic it will "clean" it and thus allow it to fail. It is said that the new fluid will clean varnish and any subtle clogs that may be protecting some valves and moving parts thus promoting the wear to be exposed and failure to occur. I too, like Jonny above, have seen many old trannies fail after changing the fluid and filter. I'm not sure that the fluid change was the reason for failure but....I'm also not a believer in that much coincidence.
MY theory is that if you change the fluid at recommended intervals you'll be fine. But when forcing sandy, dirty fluid through the tranny it will undoubtedly become damaged. At the same time....it is rather counterintuitive.... but, that same dirt will cause a certain sealing and lubrication ability.

 

what about that vacumm line or maybe the tranny filter? or maybe the vacumm modulator? you never know?

 

Here I am trying to find new ways to get gross, down and dirty, to beat the 'language' filter, and you go and raise the bar. How am I ever gonna succeed?

 

Thank you, could NOT have said it better my self......

 

When I have a nice long and warm day here in Chicago, I'm going to spend some nice quality time looking everything over.....vac lines, modulator, all that....

I had a vac mod go bad on my '77 LTD, had the C-6. It did some funky stuff....

 

x2
good luck!

 

Sarge hit it!!
1st...replace the vacuum line to the 'modulator'
if that doesnt cure it ....then change the modulator
if that doesnt change it......then take that FMX and use it as a planter!!!!!!
Ford should be bitch slapped for the FMX....yank it and put in a C6

 

Another hotbutton, Rev. Crappy intro's and Ford's slush-o-matics.

 

What the Rev said. I used to buy and sell cars off a little lot I had after I retired...when at the auctions we would look under the Fords...if it had the FMX we just walked away. Same applied to the Ford 3.8 V6.

 

mmmmmm, the plot thickens.....

This is my 1st FMX, ALL of my other Fords had the C-6....never had a problem with them.

So here is my next question. If this FMX trans turns out to be a pile of rubbish, how much work would be involved to change my '78 wagon to a C-6? I have a '9 inch rear axle, would I have to change the drive line over? What about the speedo cable?.......

I'm pretty sure I can find a donor car if it comes to that.....

Again, thanks for ALL your input guys!