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94 Chevy 1500 no reverse

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Old Jun 22, 2015 | 09:30 PM
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Default 94 Chevy 1500 no reverse

I just bought a 1994 Chevy 1500 4wd v6 4.3l and it goes forward and all the gears shifts fine but it will absolutely not go into reverse and I have a 4l60e automatic transmission ik that I need to check the pan for debris incase the clutch spring broke or the valve body gasket is warped but I do know that I need a reverse boost valve can some one please tell me on where it's located and how hard is it to replace cause I went on rock auto and I can get the valve body gasket and reverse boost valve and filter n gasket for 70 dollars I just need some advice on how to fix it
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Old Jun 22, 2015 | 10:45 PM
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If all the other gears work fine and you only have no reverse, your lo-reverse clutches might be worn. Unfortunately, that would require the transmission to be dropped IF that's the problem. As you said, checking the fluid for clutch material and the pan for debris is a good idea.

The boost valve does not require a transmission drop. It's located in the pump and is accessible with only a pan drop. It's easy to replace and the only slightly special tool you'll need is snap ring pliers.

Here's a diagram of the pump internals. It's not quite the same as the '94, but the boost valve location is the same.


The pump is on the front/engine side of the transmission. You can tell the difference between the bore with the boost valve and the bore with the converter clutch valve by the little coin-like circle of metal that is on the outside of the converter clutch valve bore. Be absolutely sure to install the boost valve in the correct orientation in the boost valve sleeve.


And I'm not nearly as experienced as some of the guys on here, so give them a chance to post too. They might have a better idea of your problem and also some advice while you've got the pan off.
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Old Jun 23, 2015 | 04:08 PM
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Why do you think you need a reverse boost valve? If you feel you must replace the reverse boost valve use a Sonnax valve with the two o-rings that fit your year trans. For a 4L60E to work in reverse the reverse input clutches and low/reverse clutches must be applied. Most likly one of these clutch packs has worn out. You can check the low/reverse clutches by pulling the shifter into manual low at around 15 to 20 mph, if you have engine breaking then the low/reverse clutches are working.
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Old Jun 25, 2015 | 09:30 AM
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I also highly recommend the Sonnax Boost valve over the stock one; its o-rings seal even a worn bore and thereby eliminate some low pressure problems.
A very worn boost valve might cause Reverse to be lost, but kinda unlikely.
As mentioned, the reverse clutch pack might be worn out.
In my (limited) experience, it is more likely that the teflon rings on the stator shaft are worn out.
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Old Jun 25, 2015 | 10:10 AM
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Cause I been looking online about what it could be and everything is coming up bad reverse boost valve it won't be hard for me to fix cause I done it before but the last one I did need a whole new valve body everything works fine it goes in and park and it drives just won't go in reverse
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Old Jun 28, 2015 | 11:06 AM
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Originally Posted by bbond105
Why do you think you need a reverse boost valve? If you feel you must replace the reverse boost valve use a Sonnax valve with the two o-rings that fit your year trans. For a 4L60E to work in reverse the reverse input clutches and low/reverse clutches must be applied. Most likly one of these clutch packs has worn out. You can check the low/reverse clutches by pulling the shifter into manual low at around 15 to 20 mph, if you have engine breaking then the low/reverse clutches are working.
Often when I'm riding with friends in automatics, they shift into drive while the car is still moving backwards.they never go into complete stop then shift. Do you think that bad habit contributes to worn out reverse clutches?
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Old Jun 28, 2015 | 02:08 PM
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Originally Posted by warriorpluto
Often when I'm riding with friends in automatics, they shift into drive while the car is still moving backwards.they never go into complete stop then shift. Do you think that bad habit contributes to worn out reverse clutches?
I don't know about the clutches, but shifting to forward while the car is moving in reverse is really hard on the sun shell.
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Old Jun 28, 2015 | 02:28 PM
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Going from reverse to drive does not apply the low/reverse clutches, so no I don’t think it would lead to worn low/reverse clutches. It does put an unnecessary strain on the low roller clutch, forward clutches and the whole drive train.
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Old Jun 28, 2015 | 04:29 PM
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I took the transmission pan off and found no debris and the valve body gasket is good but when I checked the pan I found a fitting its about 1 inch long and it has two flat bars attached to it can some one tell me what that's for
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Old Jun 28, 2015 | 06:36 PM
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Can you post a picture of it?
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Old Jul 2, 2015 | 08:43 PM
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He is what I found in the pan
Attached Thumbnails 94 Chevy 1500 no reverse-0628151941.jpg  
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Old Jul 2, 2015 | 10:39 PM
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That looks like a power resistor; it is not part of the transmission. Perhaps someone before you disconnected the 3-2 downshift solenoid and hooked in the resistor to fool the PCM into thinking the solenoid was still there.
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Old Jul 3, 2015 | 08:08 AM
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Not anything you would normally expect to find in a trans. Does the wiring harness look like it has been modified?
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Old Jul 16, 2015 | 09:16 AM
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I just got a 2wd transmission from my boss but the things is it won't work in my truck how will I be able to change the input shaft that runs thru the trans and take the 2wd out n put my 4wd into the new trans
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Old Jul 16, 2015 | 04:10 PM
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Sorry to be so blunt, but how about getting the correct trans that fits your vehicle. There are various incompatible types of 4L60E starting with LT style and LS style. And not all LT style are even compatible....

Not sure about a Chevy 1500 truck, but a '94 F-body trans is an odd-ball year and only another '94 trans will work with the '94 PCM.
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Old Jul 16, 2015 | 05:30 PM
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I checked everything and it matches up together n my boss said he took it out of his 1994 Chevy 1500 but his was 2wd and the trans was just rebuilt And that's why I'm asking how can I change the input shaft they both are 4L60e trans but one is 2wd and the other is 4wd
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Old Jul 16, 2015 | 06:35 PM
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You do a complete teardown and replace the output shaft with the 4WD output shaft.
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Old Jul 16, 2015 | 06:38 PM
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To change the input and output shafts you will have to disassemble both transmissions and remove the output shaft and reassemble. I don’t understand why you would need to change out the input shaft if both transmissions came out of the same year and engine type truck. The input shafts should be the same. If not the input drum and clutch assemblies would have to be swapped over and possibly the pump.

To make a 2wd drive trans a 4wd all that has to be changed is the output shaft, but like I said is the whole trans has to be disassembled.
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Old Jul 17, 2015 | 06:00 PM
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When you mentioned swapping the input shaft I thought you had an incompatible trans.
As mentioned, you have to disassemble a lot to swap output shafts. Considering the age, opening the trans will probably tear some of the teflon seals and expose other problems. You really should get the entire trans rebuilt.
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