Many years ago I had experienced climbing vertical rocks out in the Capitan Mountains of Tinnie New Mexico. After doing my first top rope climb, I had to rappel down. Well, if you can imagine, as you stand on the edge of a three-story high cliff with rock ledges on the way down and a pile of jagged boulders waiting for you at the bottom, stepping off didn’t seem to be the right thing to do. As I was frozen, standing there on the edge about to make that one large leap for this mankind, I experienced another first. Have you ever heard the expression “knees knocking?” What can I say, at least I didn’t %#@* my pants! As I was standing there, I looked up at my partner who would rappel me down. He was just a few yards in front of me secured to a tree. He saw my legs shaking and I said to him, “Is this normal?” He laughed and said, “Well, it’s not abnormal.” This couldn’t have been a better humorous response and off I went…..literally.
|Want more ? Enjoy a free subscription to Motor Age magazine to get the latest news in service repair. Click here to start you subscription today.|
ENTER CODE : ART30 AT CHECKOUT
|Figure 1||Figure 2|
|Figure 3||Figure 4|
“It is not abnormal” to experience trucks using the 5R110W transmission such as Super Duty and Excursion vehicles to develop a delayed engagement into drive. This delay may also be accompanied with a shudder on take off. This obviously is “not normal” driving conditions but it is a common problem. It occurred enough times that ATSG produced a bulletin about this concern in 2008. The bulletin recommended using solid endless style Teflon rings used on 4L60-E pump stator support on the forward clutch drum instead of the step cut rings this drum uses (figure 1).
The bulletin does say to check and verify line pressure first. Line pressure and line rise problems may indicate a faulty pressure control solenoid, sticking PR valve, boost valve, bad filter (aftermarket?), or faulty oil pump.
Carefully inspect the forward clutch housing (figure 2), molded piston (figure 3) and the seal ring area in the center support is also recommended.
Should all these possibilities be ruled out, putting those solid rings on could remedy the problem. Checking the clutch with compressed air while the drum is on the center support can confirm the need for these rings when it reveals excessive leaking in this area.
Buddy Lee from Lee’s Transmissions in Shreveport Louisiana had experienced a similar problem with a 2008 F450 Power stroke Diesel. It would engage Drive without a delay but would slip on take off just above idle and get worse with heavier throttle. Even though it slipped a little on light throttle, it pulled well enough for the owner to drive it in for repairs.
He pulled the unit expecting to find the forward clutches roasted but they were not all that bad. He cleaned everything up, put in new parts; air checked the drum and all seemed well. Once in the vehicle the problem was still there. Line pressure was checked and verified to be working properly. He then pulled the unit and put Teflon rings on the forward drum. The air check was much better so he thought the problem was resolved. In the transmission went and back out it came. Upon closer inspection of the drum, a crack was noticed just below the direct clutch hub area of the forward drum (figure 4). The crack opened when under a load only dropping forward clutch apply pressure. On the bench, it checked nicely with compressed air. The drum cracking the way it did would be considered “abnormal” as this is not a “common” failure. So it could catch you off guard making you want to drive this vehicle off a 3 story high cliff.