Problems with my 2001 F250 4r100 transmission. Transmission will only shift to 2nd gear when throttle is feathered at @2500 rpm. All other gears shift perfectly. This problem is consistent.

Any help will be appreciated.

Thanks.

 

It's time for a rebuild.

The 2001 4R100 behind the 7.3L had a new type of one way clutch called a mechanical diode. When (not if) it fails you will get the exact symptom you have described. The only solution is to rebuild the trans and replace it. There are kits available to replace the mechanical diode with the older (and newer) sprag type one way clutch.

 

Is this something that we can do ourselves? Would you recommend replacing/or upgrading any other components after we tear down the trans?
thanks, Deb

 

You probably shouldn't attempt to rebuild a 4R100 if you've never done any transmission work before. There are a whole host of upgrades that should be included in the rebuild.

The quality of rebuilds on this transmission vary widely. If you take it to your local aamco or random transmission shop, you may or may not have a lot of problems with it.

I do almost all of my own work and I wouldn't rebuild mine. It's going to John Wood later this year.

 

Like Andy said, John Wood on the West side of the country or BTS if on the East side.

 

Mark,

Does that shop in Joliet IL know how to build a high quality 4R100 ? I have a little over 282,000 on the truck and my trans seems like it is slipping some times.

Thank you,

BBD

 

Yes, I believe they do. They don't do a lot of modifications like the high dollar shops, but I'm sure they can get you a high quality trans.

 

Some people can, some cannot. I really don't know your skill level. I don't mean anything derogatory by that, I just don't know if you can or cannot do this. It's not a simple job, but it isn't rocket science, either. It requires a really good shop manual. Automatic Transmissions Service Group has a good manual.

All the friction material should be changed. There is one band and several clutches. All seals should also be changed. A master rebuild kit will have everything that needs to be changed. You'll also need the kit to replace the mechanical diode with a sprag clutch.

 

Mark,

Thank you again for all of your help and the lead in Joliet.

In the transmission world, I have heard the "updates and modifications" terms used.

BBD

 

The 4R100 transmission is pretty stout in its own right, but there are parts upgrades and other steps that can increase reliability and longevity. The ATSG manual doesn't touch on this or the ability to recognize current, or potential,, failure points.
The retrofit of parts, for the mechanical diode replacement, is fairly simple and is not too costly to do. It does require you to change the proper clutch pack that companions it. Most kits only include these frictions nowadays, as it is no longer serviced.

 

Its diode season!

Here is my diode fun thread I just started. My first ever auto trans attempt. Only thing I can say about it so far, ALLOT of reading!

https://www.ford-trucks.com/forums/1...diode-fun.html

 

I apologize if this is the not the best thread to ask this question on, I am new here. I have an 02 F250 with the 7.3 and 4R100 combo and I have the exact same symptom in my transmission except it is with 3rd gear. I am guessing I will probably need to rebuild it or replace it after reading this and some other threads.

 

Welcome to FTE, Winston. It would be best if you started your own thread and outline what your symptoms are. Older threads get passed over a lot of times.

 

There is also a spring on the 1-2 upshift valve in the main valve body that is known to break that will cause an upshift issue and is completely repairable with trans still in vehicle. https://m.youtube.com/watch?v=S5a0BkRkUrI