Join Date: Nov 2001
Location: Clifton Park, NY
Feedback Score: 0 reviews
Re: Effects of Mercon V in the 4R100?
Ford tech was replying to a question about a dealer putting Mercon V in a vehicle that was Mercon only.
It depends on which trans you have. If you have the 4R70W, they did the right thing. If, on the other hand, you have the 4R100, GET IT OUT!
The difference between the two fluids is in the additives, and that "V" is at least partially synthetic. The synth is NOT the reason you CANNOT use it in a 4R100, but the additives are.
Let me explain as best I can.....
The 4R70W/AODE/AX4N/S etc. suffer from "shudder" which is caused by the T/C clutch not slipping smoothly under steady state cruise conditions. So, FMC re-engieers the ATF to make them less prone to oxidation and burning, this also makes the fluid slightly LESS grippy. This is ok, because the trans controls and the clutches are aggressive engough to handle the Tq, and they DO NOT typically perform full throttle upshifts into OD (you'd be going faster than the speed limiter is set for).
Now, with the 4R100, it's Tq capacity is 1000 ft-lbs, and that's A LOT. When you take peak engine Tq and multiply it by the T/C ratio, you can get pretty close to that (especially with a 7.3L DIT). You NEED all the grip you can get to clamp the friction elements. If you put the "slippier" Mercon V fluid in, the T/C clutch and other friction elements will be BELOW the required Tq limit, even if only slightly. Also, the 4R100 and the "Tq Shift" are the two ONLY FMC transmission that are DESIGNED and programmed to allow and handle full power upshifts in EVERY gear. Again, you need all the grip you can get for this to not totally burn up the clutches.
There are also differences in the clutch materials, but I don't recall the specifics. Suffice it to say that because of the lower absolute tq capacity requirement of the "smaller" ATs, they can get away with a slight loss of element Tq capacity.
Believe it or not, the T/C clutches are DESIGNED to slip at a constant rate to absorb driveline harmonics which could confuse the cam sensors on the engines. It truely is NOT needed, but they do it anyway. If not for that, Mercon V would not be required at all.
2001 F-250 (pcm PMT2) ISS Pro EV tranny, boost, pyro gauges. TS Performance flip chip. Banks MONSTER exhaust, Maghytec rear diff cover, ITP H/X kit, Whelan 52" Strobe Bar, Fisher 8.5' Snow Plow, 3 Weatherguard tool boxes. HUTCH fuel tank mods, REMANFACTURED Ford transmission.