Hello all. I own a 2003 7.3 with auto trans 37k on the truck is as ford delivered it bone stock. This summer I had a transmission shift improvement kit installed trying to correct a less than crisp shift that has existed since new. The truck went on a family vacation to colorado and performed well with only one noticed glich. While using the engine as a brake, locked in 1st if you were going to slow and used throttle then the brakes the lock up torque converter would really lock up and unlock hard. Well this weekend while trying to back my camper in to its spot at the lake another glich appeared, it would not push the camper uphill, it slipped with no movement, 2500 rpm worth of rev, no tire slip. I used 4 low to get the camper set and it pulls fin in forwward gear but reverse pushing a load is all but gone. What went wrong and where do I go from here. Sorry for the long post but I wanted to cover the entire story. So do I trade it off while it still moves, fix it, will this problem come back again, and why did it break to begin with. My trailer only weighs 7k and its been well cared for. I'm lost and really pissed about this as I planned on keeping the truck as a puller for 10 years then maybe a daily driver beyond that. Help?

 

I'm trying to figure out whether or not you actually have a problem. Basically, you are experiencing what some small circles of people call "too high of a gear ratio in reverse". There is not enough torque multiplication through the reverse gear ratio and torque converter to get any power to the ground. I really feel that there's nothing wrong with the truck.....it's just that you don't have either enough gear or enough power. You found out that low range is a godsend with the 4R100 transmission and most folks will recommend that you use that whenever you plan on backing a heavy load.

 

I have backed my camper or loaded trailer before and not had the problem you describe. The trip before this I noted it shuddering if you back up using a fair amount of fuel, like a hurried three point turn around. I would be well pleased if its fine but it sure never acted this way before. What if anything would you do at this point. I showed a mechanic friend at the lake by power braking it in reverse it spun up to 2500 with no real desire to slip a tire but would pull instantly in foreward. Does 1st and reverse share the same clutch pack. Is reverse a higher han 1st. I would not argue with anyone as I don't know. I do know I cant afford to travel with it and have a roadside break down, but that said dont have 5k to fork over for a bts trans.

 

Oh.

The infamous torque converter semi-lockup in reverse caused by low transmission pressure either from an internal leak, worn pump, or aerated fluid.

Easy: Loose transmission filter allowing air intrusion around seal in pump.
Not as easy: Pump replacement or sealing ring replacement.
Hardest to swallow: Transmission

First is 2.71:1
Second is 1.54:1
Reverse is 2.18:1 (ridiculously high)

As for apply/holding components:

First gear in "D" range
Forward clutch applied
OD one way clutch holding
Low/Reverse one way clutch holding

Reverse gear
Coast clutch applied
Direct clutch applied
Low/Reverse clutch applied
OD one way clutch holding


If you have engine braking in 3rd gear, the coast clutch is working
If you have no issues in 3rd or 4th, the direct clutch is working
The Low/Reverse one way clutch has to work if you have 1st gear as does the OD one way clutch.

 

Wow cletus you seem to really know your transmissions. Your last post got me to thinking and reading. I looked up the stall specs on my tranny and will start with that and your information on engine braking. With any luck that will catch it if not I guess we go deeper. The leaking at the filter would seem possible since it would have been out at shiftkit install. Thanks for the heads up and the info. SN

 

What ended up being the fix for your reverse slipping?

 

With only 66 post and this being back in 2009 I doubt you're gonna get a response from this guy.....

 

Surprise a 66 post lurker will respond. I had recently had the trans serviced a and a shift improvement kit installed. I returned the truck to the shop and he dropped the valved body. It had blown the valved body gasket. The installer apologized and fixed the issue at no cost despite having done the work 3 months prior.
That firmed up my shifts and eliminated the slipping in reverse and I have been very happy with the truck. Purchased may of 03 with 49 miles on it. It has been garage kept and only used for pulling our 30 ft rv and heavier farm pulling duties. It now has 62k on the clock most all pulling and has only been pulled with the od on once. That trip made the od light go blinky bliny in limp mode. That was at 30k I since stuck with the idea the od is the weak link and have always pulled at 2500 rpm od off. The truck has remained trouble free. I planned on trading it off at 10 years but given the cost of new one's and as dependable as it seems that date has been pushed back to an unknown date. Last summer's vacation racked up 5500 miles of hard mountain pulling and it happily chummed along like it did in 03. Color me a very happy 7.3 psd owner. Sorry for the long reply SN

 

I stand corrected... Thanks for getting an answer for the guy asking you 67 post lurker

 

It's a good forum with a good group of folks willing share their knowledge. I just have been lucky enough to be able lurk and learn. Hope he can get his issues fixed w/o spending 5k on a high quality trans rebuild. The lurker, aka SN

 

I know this is an old thread but are you saying you put a new valve body in it and the shifts were better and the reverse stop slipping I just installed a transmission from a buddy and it's doing the same thing shifts real slow and soft into all forward gears and reverse shutters and slips

 

My transmission from new was never very crisp in the shifting. Not sloppy but just not crisp. That equals slipping and the death of a trans. So after the warranty was up I paid a reputable shop to install a shift improvement kit. All was fine with the install until I went to back my camper up a hill and reverse failed to hold. I took it back and he removed the valve body found the gasket blown. He fixed it and the transmission has been flawless since. Major point the transmission had no issues until I paid to have it improved. I just hoped firming the shift would prolong the transmission life. The truck now has 82,000 miles and I still trust it to go on family vacations pulling our fifth wheel that weighs 10k. My kids have gotten older and we do not do long trips as much due to their activities. That said we took it on a trip last summer it was about 2500 miles total. So it is still asked to do more than a trip to the lake. . Service should be mentioned. It was drained and filter changed at 20-30 k. Same treatment at 50k and repeated last year only on a flush machine at 76k. So it has been well cared for. Good luck with your truck. SN

 

Mr.71postlurker now. Mine also failed in reverse and I basically lost my forward gears, I was 2 miles from home and figured the trans was junk but wanted to get home. By manually putting it in 1st and second gear I was able to get home, it wouldn't go to 3rd without falling on its face.

It turns out there are 2 bolts that have something to do with line pressure (topside of the valve body) that had backed out causing next to 0 line pressure. It may be something to look into. By the way my fluid wasn't burnt or anything. It's a fairly common problem with the 4R100

 

Nice thread. Good to see both of you (John and SN) still posting.

 

Yeah I just put a trans in my truck and I have 70 PSI at idle and it does not raise or lower switching it through the gears so it slips in reverse and all forward gears so I just ordered a Tugger kit going to pull the trans tomorrow night and installed a Tugger kit and make sure everything is as good as can be and hope for the best I'm hoping maybe the pressure regulator valve is stuck or something