Transmission problem on a lifted F-150

[crandall]

My son has a lifted Ford F-150 (late 90s) and is experiencing the following problem: (His explanation follows from an email he sent me).

First of all the truck has to warm up a few minutes before it will even change gears at all. Warm up about ten minutes or so. There is no grinding put like a noticably jerk of the entire truck when it switches gears going up and shifting down. It goes in reverse without a problem. The truck switches to Drive Neutral and Reverse without a problem. I check the fluid this summer when it first started happening, it was red. I have been driving it to work and it has been doing ok once warmed up but still jerks when the gears change.

I would like to pull the tranny and look into the problem. Any thoughts on what might be wrong?

Topic

[Matt]

I don’t have a whole lot to offer on this, as automatic transmissions are extremely complex, especially the newer electronically controlled ones. If the fluid is bright red, was a fluid service done recently? If so, was the correct fluid put in it? I don’t know what Ford calls for, it might be a generic like Dexron. Is there a check engine light on? Was it overheated if it was taken mudding recently? These are things my dad might ask me if I was bringing him the truck, and I might not be super honest about it if I was embarrassed. Other than that, just make sure the fluid level is correct. I could dig out my text book and go over line pressure testing with you, but I doubt we’d get very far. Hopefully someone hops on with more insight.

[dreamer2355]

Is the CEL on and how many miles are on the vehicle?

I would first start with checking the transmission fluid and making sure it has the OEM type fluid.

Some vehicles will delay the transmission from shifting in cold weather until the engine has warmed up.

However, you still may have some internal problems such as pump issues and so forth. That would be diagnosed as Beefy stated by checking the fluid pressure.

Good luck and keep us posted.

[EricTheCarGuy]

The truck being lifted might be the most important clue. If the problem has occurred since the lift it could have something to do with the driveline angles meaning that if they are extreme it will put the U joints into a bind and make the rest of the driveline work harder. I don’t remember the exact number for the angle for optimum driveline angle but if he left it stock at straight ahead this could be the problem. Also since it’s a 90’s truck the transmission is most likely electronically shifted so be sure all the wires and connectors are intact if not they can cause shifting issues.

[crandall]

This is an update to the transmission problem.

I found a bad fuse that controlled the dome lights, speedometer, and the vehicle speed sensor. Not sure why it went out but it did. With the new fuse, the VSS was able to input to whatever module controls the tranny and it has been smooth shifting ever since.

[W00DBar0n]

[quote=”EricTheCarGuy” post=22709]The truck being lifted might be the most important clue. If the problem has occurred since the lift it could have something to do with the driveline angles meaning that if they are extreme it will put the U joints into a bind and make the rest of the driveline work harder. I don’t remember the exact number for the angle for optimum driveline angle but if he left it stock at straight ahead this could be the problem. Also since it’s a 90’s truck the transmission is most likely electronically shifted so be sure all the wires and connectors are intact if not they can cause shifting issues.[/quote]
+1
You beat me to it.

[moparfan]

normally with any lifted truck and adding bigger tires will make the tranny shift much softer because it is working harder to move them big tires plus the higher gear ratio you are going to get with bigger tires. its like hooking a trailer to a stock pickup but the load is always there! this will forever put extra stress on the tranny and will for sure wear it out much faster. this is why you build up trannys and add shift kits.

driveline angle will have nothing to do with how the tranny shifts. it will create vibrations and binding in the driveline but wont effect shifting in any way!!!

[college man]

Thanks for the update and the fix.

[Author]

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