95 Jimmy reverse problem.

[Vacdaddyt]

I have scanned some of the posted transmission problems and one of the recommended fixes is oil additive or a boost valve upgrade.
My question is if putting the lucas additive in didn't work will changing the boost valve do it , or is mine too far gone?
When I put it in reverse it hesitates and if you step hard on the gas or are trying to push a trailer it acts like it is chattering or slipping, but if you go easy you don't notice anything wrong. This is a 5TBD model 4L60E in a two wheel drive that I used from an S10 Extreme. Forward it shifts a little hard but goes through all gears but the reverse is weird, note the old transmission was doing the same thing. The motor and transmission have been replaced. The motor is an early model with the upright plug towers and when the transmission was replaced I changed the oil and seals in it. The test port is where? I do not remember seeing one when I had it out.
Sorry for the long post.
If trying the boost valve is a good idea I'm game to do it but was wondering how it is done, the directions I viewed were a little scketchy.

 

[Molson02536]

I have scanned some of the posted transmission problems and one of the recommended fixes is oil additive or a boost valve upgrade.
My question is if putting the lucas additive in didn't work will changing the boost valve do it , or is mine too far gone?
When I put it in reverse it hesitates and if you step hard on the gas or are trying to push a trailer it acts like it is chattering or slipping, but if you go easy you don't notice anything wrong. This is a 5TBD model 4L60E in a two wheel drive that I used from an S10 Extreme. Forward it shifts a little hard but goes through all gears but the reverse is weird, note the old transmission was doing the same thing. The motor and transmission have been replaced. The motor is an early model with the upright plug towers and when the transmission was replaced I changed the oil and seals in it. The test port is where? I do not remember seeing one when I had it out.
Sorry for the long post.
If trying the boost valve is a good idea I'm game to do it but was wondering how it is done, the directions I viewed were a little scketchy.

Start with testing your transmission line pressure. Base pressure at idle in P,N,OD should be around 70psi and around 140psi in R. Max line pressure should be at least 190psi at WOT in 1st or 2nd, 225psi is optimum. If base pressure is low, trans or pump is worn out. If max pressure is low, check EPC solenoid. If reverse is slow to engage, and line pressure does not come up to at least 130psi in reverse, replace the boost valve with a Transgo 0.490" boost valve and takes 5 min to replace after the pan is dropped.

Here is link to where the pressure test ports is located, from what you have described, it's going to be a worn out clutches since you mentioned it shifts hard going forward. That indicates your EPC valve is maxed out from worn clutches or a weak boost valve, you may also have to replace the boost valve sleeve which could also be worn.

Good luck and keep us posted.
http://www.sonnax.com/instructions/HP-4L60E-01-IN.pdf