Trans Oil for lightning 4R100

[wsa111]

What trans fluid do you recommend for the lightning 4R100 trans???

Dextron III or mercon V??? Thanks Bill

[gearmesh, inc.]

Dexron III or regular Mercon is the factory recommended fluid in any year 4R100.

Mercon-5 is more expensive due to it being semi-synthetic and it has one hell of a friction modifier package to keep torque converter clutch shudder at bay. Mercon-5 was originally invented to deal with TCC shudder in the AOD-E and 4R70W transmissions. It also has one hell of an anti-oxidant and anti-foaming additive package in it.

Due to Mercon-5 being a little bit more "slippery" than regular Dexron III/regular Mercon, you may notice a slight decrease in shift firmness when running it in your Dexron/Mercon spec trans without a shift kit in place. It will also make your torque converter clutch slide/slip a little more during its engagement, but this strategy of slipperier fluid keeps the TCC shudder at bay in these factory calibrated transmissions. Decent shift kits on the market address the slow factory application rate of the TCC in order to bring the TCC engagement on more abruptly to avoid the shudder in the first place. TCC apply will feel like another gearshift instead of the factory slide engagement since it would be applied quicker.

The only time I recommend Mercon-5 is in high rpm / high hp applications that throw a lot of fluid up out of the pan and into the tailhousing on hard launches. In instances like this, a lot of fluid is exposed to the rotating assembly at high rpm and the anti-foaming properties of the Mercon-5 are desirable. Mercon-5 helps noticeably in C-4s which historically have a problem of foaming trans fluid up out the vent in high hp applications.

Since the Lightning isn't normally a high rpm candidate, save your money and just run Dexron III/regular Mercon. Change it every 20-30k miles and keep it cool and you won't have any fluid related failures.

[wsa111]

Thanks for the quick response.

I just found out ford has a TSB that says use mercon V in place of the dextron III on many applications.

Any idea what brand shift kit speeds up the converter lockup? Transgo??

Thanks again Bill

[DolSVT00]

There's only a few out there to choose from anymore that are just Mercon, I've been using Valvoline Max Life Dex/Merc

[gearmesh, inc.]

Any idea what brand shift kit speeds up the converter lockup? Transgo??

Thanks again Bill



The Transgo shift kit for the 4R100 by itself doesn't do it, but a special separate Transgo valve can be purchased that turns the modulated TCC into an ON/OFF function. The only drawback is that this valve only works in conjuction with a Transgo shift kit. I am not too fond of the Transgo kit for the 4R100 as there are too many calibration options to choose from that have undetermined results concerning shift feel until you road test the truck. Then if your shifts aren't firm enough for your liking, you have to drop the pan and accumulator body and drill some holes out bigger and road test again. If you get ambitious and shoot for one of the firmer calibrations to start with and your shifts end up too firm, you can't go back because you have holes that are already drilled too big.

For the 4R100, I prefer to use the Sonnax shift kit as it has better engineered valves for the accumulator body. It also doesn't cost as much as the Transgo kit. Though this Sonnax kit doesn't address the modulated TCC, you can have your electronic tune modified to ramp up the apply rate of the TCC and achieve pretty much the same affect. The Sonnax kit also has a special main regulator pump valve that ensures that converter charge flow is not compromised during high line pressure requests like can happen with the stock valve. This converter charge flow/pressure is also your TCC apply fluid.

To start off with, all TCC clutches in transmissions such equiped apply and release the TCC clutch by changing the direction that fluid flows into and out of the converter. All fluid that leaves the converter is sent to the cooler for cooling, and then back to the transmission to feed the lube circuits. The 4R100 has a unique TCC and cooler flow arrangement. It is basically a series circuit. The fluid that feeds the converter is under control by the MCC (modulated converter clutch) solenoid. The fluid that leaves the converter has to go through an orfice before it can go to the cooler. If this orfice is made bigger, you will have more cooler flow, but at the expense of dropping apply pressure feed to apply the TCC to hold it with enough force. Make this orfice smaller, and cooler flow is reduced, but your TCC has more "back pressure" to hold the TCC tighter but with a reduced apply rate, as fluid has to leave the release side of the TCC piston to go through this orfice. Kind of damn if you do, damn if you don't kind of situation if you try to re-engineer it. Best to leave this orfice alone and address the supply side by getting the MCC solenoid to ramp up pressure/flow quicker to get the TCC gripping at a faster rate.

Another thing to do with the 4R100 is to do away with the external cooler bypass that goes between the cooler fittings at the transmission. There is a relief valve inside that lifts in case of a restricted/plugged cooler so that the cooler loop can be bypassed around. Yeah, your lube circuits keep their flow, but your fluid overheats as a result of bypassing the cooler anyway. These relief valves are famous with age to crack open too soon, even when your cooler isn't restricted, leading to overheated fluid. If you have a plugged factory cooler, it probably got plugged by internal damage in the trans to begin with.

[DolSVT00]

Most just buy a Gregg evans Valve body (AKA FTVB) drop the old one and put the new one in (the whole valve body) I just baught the accumulator valve (aka Line mod Valve) the rest can be adjusted in the tune like gearmesh said.

Depending on how hard you hit the pedal and how much spinning you do, what I have is enough to make you swallow your dentures. Normal driving its almost unnoticeable, part throttle it has a nice crisp snap, WOT feels like someone smacking you in the back of your head.

[chrisheltra]

Any idea what brand shift kit speeds up the converter lockup? Transgo??

Thanks again Bill

Call Tim at Chickenears he can hook you up with a street VB or a race version VB.

Oh just incase VB = valve body (AKA shift kit)