4R70W Hard 1st-2nd Shift

[RandomNerd2000]

I have a 99 5.0 drivetrain I'm going to be using, it shifts hard from 1st to 2nd and I want to fix it while the transmission is out the truck, what's the process for fixing that?

 

[96eb96]

Check your 1-2 accumulator and spring(it could be broken). Not really a pattern failure past 97, but who knows. You don't even have to drop the valve body.

 

[RandomNerd2000]

I think that's what it is to be honest, it's a early 99, it does it every single time without failure, throttle doesn't matter

 

[CDW6212R]

Ditto. With it out, that's an easy time to replace some common wear items. The control systems are the cause of 90% or more of issues, not the hard parts or clutches. So think about spending $150 or so on new solenoids, accumulators, and a couple of Sonnax upgrades. A VB kit is a good idea too if you are up to intricate(small parts) work in the VB. The J-Mod is kind of simple and easy if you know what size holes to drill, and where. Researching that is tough, so many people suggest different sizes for various vehicles. I didn't find anything about the Explorer versions, but lots for Thunderbirds, Mark VIII's, CV's and Mustangs.