Our 94 Ford -full size- van shifts quite harshly in all four gears. No slippage -I supose clutches are good- just allmost bangs into each gear most of the time. It will do it in auto mode or if you shift youreself. It does not seem to be shifting late -high rpm- either. We're going to change the trany filter and flush it, though I suspect that wont help.
Posts: 3307 From: LaSalle, Michigan Registered: Jun 2008
Its almost always a bad idea to drain and flush an older auto trans. If its just shifting firm and not slamming into gear, your usually better off than soft shifts. Thats why people put shift kits in...to firm up shifts. The firm shifts eliminates a lot of slipping changing between gears and thats the biggest cause of failures.
Hulki U. My-BFF Member
Posts: 5949 From: Back home in East Berlin, PA Registered: Apr 2008
I know most people say not to flush old trannies, but my '97 Silverado I had did the same thing, banged from 1st to 2nd gear. I had the tranny flushed and new filter/fluid, and never had a problem again.
Jun 4th, 2010
Francis T Member
Posts: 6620 From: spotsylvania va. usa Registered: Oct 2003
It's almost always a bad idea to drain and flush an older auto trans. If its just shifting firm and not slamming into gear, your usually better off than soft shifts. Thats why people put shift kits in...to firm up shifts. The firm shifts eliminates a lot of slipping changing between gears and thats the biggest cause of failures.
Well when it does do -was fine all day yesterday?- it's more on the banging into gear than shifting firm side. I'm not sure about the ABS, how would that paly into things?
Posts: 482 From: Morrisdale, PA Registered: Jun 2009
The reason I asked about the abs is because there might be a speed sensor in the rear axle. This speed sensor might be for ABS, shift timing and harshness, and possibly speedo. That is one thing that sucks about Fords, they do such different things on similar set ups. My friends Bronco was shifting extremely hard due to that sensor going bad.
Posts: 258 From: Portland, Oregon USA Registered: Jan 2008
Understand that I am NOT a transmission guy, but I have rebuilt my own 4R100, which is the uprgraded version of the transmission you should have.
All of the shifts are made by adding friction elements - there is no release of any clutch on any upshift. So to my mind there are only a couple of possibilities. One is high line pressure - easy to check, there should be an 1/8" pipe plug on the driver's side of the tranny, above the pan rail, toward the front. Check a manual for the correct pressure - I am not sure if yours is old style or EPC. The later EPC units (Electronic pressure control) should show a DTC if the pressure is not in spec. The actual pressure valve is part of the front pump, transmission needs to come out, pull the converter, pull the pan, remove the fiilter - it plugs directly into the pump, then pull the pump. No need to go any deeper into the transmission if the pump is all you are after. Line pressure is likely to affect ALL of the shifts. Otherwise, inside the pan is an accumulator body, with accumulator valves that affect the harshness of each shift. It would be POSSIBLE that they all gummed up at once, but not likely. Still, it is easy to remove with the transmission in the van.
First for me would be to pull the pan, change the filter, get a good idea of how much junk is in the pan. Maybe a flush with cheap fluid, then switch to Mercon V?
Again this is all for what it's worth, my experience is a sum total of one transmission in my '99 Navigator.
Best of luck,
Jun 5th, 2010
Posts: 49601 From: A Western Caribbean Island/ Columbus, Ohio Registered: Apr 99
Im just getting my Coronet back together after some yokels screwed it up. Its got a 727 auto. Since engines been out 4 times now in 4 months (long story), and 6 quarts of new fluid replaced each time, Im fully expecting to have transmission issues soon. It was a perfectly fine working one that had been untouched since 1970. If it has problems, Jegs sells a built up one for $1,000 that Ill prob put in. I dont know anything about fixing them past putting in new rear shaft seal.
Posts: 656 From: West/Central Texas Registered: Oct 2008