Hard Shift into Reverse

[SR77]

Little backround first. The trans problem is on my 1996 Explorer 5.0 V8 AWD with the 4r70w trans. The Explorer has 92,000 miles on it and this is the second trans that was installed around 55,000 miles. I bought this truck off my parents around 6 months ago and it has had this problem since then, but not sure how long ago it started before that. The problem is that when the trans is cold it shifts into reverse hard, hard enough to jolt the truck, and the bang into gear is loud too. It does it everytime i shift into reverse when it is cold. If i have been driving for a while and the trans is warmed up it will not slam into reverse. Also it shifts fine into drive or and other gear even when cold, it is only revese while cold that it shifts hard into. What could be causing this and how do i go about fixing it? I am worried that everythime i shift into revese that it is putting a beating on the trans and that it is shortening the life of the trans. Don't want to have to put a 3rd trans in this truck, so thats why i want to get this fixed soon, so this second trans last the rest of the life of the truck. Thanks for the help

 

[Glacier991]

I am not familiar with the 4R70W (yet) but your problem COULD also be U joint related. We often are quick to blame the trannie for other drivetrain issues.... just a thought. I do have the 3 ring factory manual for that trannie and can look up possibles on harsh reverse engagement if you are sure it's not U joint.

 

[Bronco638]

My best friend's mother used to have the same issue with her Buick. She'd start the car, put it into reverse without stepping on the brakes and BANG!, chirp the rear tires. This would only happen when the car was cold (as you stated) and the engine on HIGH idle.

Try this, let your Ex warm up a few minutes (so the idle comes down below 1000 rpm). Then try to shift into reverse. I'm willing to bet it will work a little more smoothly.

However, if anyone will be able to help, it's Glacier991 (and Brain, too).

 

[SR77]

thanks for the replys. I don't think it is the U-joints because I would think the problem would occur in other gears too and while warm also. I do use the brake when shifting into gears and it doesn't matter how warmed up the engine is or at what RPM idle it is at. If the trans is cold, no matter what the engine temp or idle is, it will shift hard when i go into reverse. It will go into drive ok when cold, but not reverse. Once the trans in warmed up though it will shift more smoothly into reversed.

 

[Glacier991]

Well, mind you I know little about the 4R70W, specifically.... but here is what the Factory manual on this trannie says (and it is 2 large thick 3 ring binders of material...very interesting)..

Harsh Reverse Engagement

Possibles: 1. Powertrain COntrol System - Electrical inputs/outputs, vehicle wiring harnesses, PCM, TFT sensor, EPC solenoid. [My comment, TFT = Transmission Fluid Temp sensor - a possible there based on your description]

Action: Run self test, Perform engagement test. EPC Test and Pinpoint Tests B and E, as outlined.

2. Fluid. Improper level, condition.

Action: adjust or change.


3. Shift linkage - damaged or out of adjustment.

Action: Verify that the TR or DTR sensor is properly adjusted. Inspect and service as required, adjust linkage as outlined.


4. Improper Pressures - High line pressure or high EPC pressure.

Action: Check pressure at line tap and EPC tap. If high check main controls and fluid filter and seal assembly.


5. Fluid Filter and Seal assembly - plugged or damaged, filter seal damaged.

Action: Replace filter and seal assembly.

Hope this gives you some ideas... things you might easily do yourself... replace filter and seal, and flush tranny. Then we can go from there. You able to do this yourself?

 

[SR77]

Glacier991, thanks for that info and your time. The trans was completely drained including the torque converter, filter changed and fluid changed to Mercon V when i first got the truck. I also check the level monthly so I know it is not the fluid level. I will have to check into a sensor or line pressure as the problem. Don't know much about trannys so i am going to have to figure out how to go about checking these areas. If not I guess i could go to an AAMCO or something, I was just hoping it was something simple that i could fix. I would think that if it was the TFT sensor that is would shift hard into all the gears too right? Does Reverse have its own line seperate from the rest of the gears that maybe just that line pressure is off causing only reverse to shift hard. I just don't understand how it is only reverse shifting hard and only when cold, not warmed up.

 

[Glacier991]

Well, to start reverse enjoys a higher control pressure by allowing the boost valve to kick in. TFT is used to control a "cold start shift schedule" which might account for the 'only when cold' problem.

Of our list above, I'm more of the mind your problem lies somewhere in number 1. Unfortunately the only way to really test as set forth is to use the Rotunda Automatic transmission tester, something your dealer ought to be able to do, as well as read transmission codes, if there are any. They can also quickly verify that the transmission range sensor is correctly positioned. As for the pressures, I did a post on using a Transmission Pressure Gauge in this forum and posted in it a few days ago so it should be on page 4 or so by now. I found it interesting the 4R70W has both a line pressure tap AND an EPC pressure tap. [edit: and 2 more, one of which is forward clutch, the other I do not know yet...4..count em FOUR taps!] More info can be gleaned as a result.

I think if you are inclined to have it looked at somewhere, the dealer may be your best bet... take along that list - it's right out of the FORD factory manual for the 4r70W. Ask them to perform the tests in part 1 above. Also make sure they test the TFT sensor.

 

[SR77]

Glacier991, again, thank you for posting that info from your manual and your time. I appreciate it. I hate going to the dealer without any backround knowledge of the problem. I guess then this is a job for the dealer since they have all the testing equipment. I will print out the manual info to take to them. I just hate dealer prices, but at the same time want this problem fixed. thanks again

 

[Gatekeeper]

I have this similar problem! Fluid is full, u-joints are solid but she kicks into first and reverse. Also she vibrates badly at 50mph+ Any ideas?

 

[machineguns]

same here

150+K miles and all of the sudden hard shifting into reverse only when cold start up, letting truck warm up doesn't change a thing.

Does not shift hard into reverse if its been driven for a bit.

I will post what I find out later for others..........

2002 ford ranger 4.0 automatic here


May try a TPS throttle position sensor if I get no answers before I get into the transmission.....under 30 dollar gamble is cheaper than tranny work for sure

 

[Pumfe]

@ machineguns

I have a 2002 4.0L Vin E with the same problem. Had the tranny rebuilt as it was slipping other gears. I advised the shop of the reverse problem, but when i got the tranny back and re-installed, the reverse issue was still there.

Very curious to find out what may be causing it. I'm sure it's something electrical...