- Joined
- Oct 31, 2025
- Messages
- 138
I am planning to perform a transmission service on my 1993 K1500, 5.7TBI, which has 110,000 on odometer, and 60,000 miles since last transmission service.
She will be getting a OEM deep pan, and 2 of the round pan magnets. Additionally, I will also be performing a pressure test due to the fact that I have noticed the shifts are getting softer (a fair less “crisp”) as the transmission starts to warm up. This being the case, I have been limiting throttle input during shifting at operating temperature. She is most definitely beginning to develop the dreaded “Pressure Loss Syndrome”. I had noticed (via tachometer) an occasional, slight flare during shifts into 4th gear when at operating temp, however there is no noticeable “flare” during any forward shifts at operating temperature, and shifts when cold are excellent.
I am, by nature, a “conservative driver” (OK, I will admit, that I was once, way, waaaaay back in the mists of time, a tad “exuberant” in my driving “style”. In my defense though, Sabertooth Tigers were a hoot to drive. They had phenomenal short distance acceleration, a very sharp cornering ability, and could stop on a dime and give back change. They were however, just a “TAD” temperamental, and performance would quickly fade during longer distance pursuits. I was quite saddened when they finally went out of production)
So, my “Plan” is to drop the pan, inspect for debris, then address the items that are known to be “problematic pressure loss areas” with this “family” of transmission, items that do not require dropping the transmission. The parts and modifications I am planning to implement are as follows:
PUMP:
VALVE BODY:
SERVO:
NOTE: The following might raise an eyebrow (or 2)
I am not planning to upgrade to a larger diameter Servo assembly for the following reasons:
I have to admit that even though I have some experience in this area, it took forever to:
Well, I think it is time that I bring this post to a end. I wanted to “throw out my reasoning” for others to examine and comment upon. I am genuinely interested in other peoples thoughts, and hope that my thoughts might be of aid to others. I am also thinking about starting a thread involving the transmission rebuilding tools that I made for my own use, way back when I first started playing with the earlier 3-speed automatics. (I used to work as a welder/fabricator and had to have something to do during the “slow” days) I will probably name it something like “Home Made Transmission Tools”
A last opinion concerning the older transmissions. I do miss the old style of sintered iron sealing rings. I may be a “Tad” strange for feeling that, but the old iron rings always seemed to seal well for quite a long time IF you performed regular transmission services, thus preventing the transmission fluid from becoming an abrasive slurry.
Sir Barger, I am quite certain that I speak for everyone at BITOG when I say thank you for all of the information you have taken the time to impart to others. It is sincerely appreciated! (I am also quite sure that there are many transmissions that are living healthier and happier lives entirely due to your efforts)
To Sir Barger, and everyone at BITOG, I hope that have a great year!
Patrick.
She will be getting a OEM deep pan, and 2 of the round pan magnets. Additionally, I will also be performing a pressure test due to the fact that I have noticed the shifts are getting softer (a fair less “crisp”) as the transmission starts to warm up. This being the case, I have been limiting throttle input during shifting at operating temperature. She is most definitely beginning to develop the dreaded “Pressure Loss Syndrome”. I had noticed (via tachometer) an occasional, slight flare during shifts into 4th gear when at operating temp, however there is no noticeable “flare” during any forward shifts at operating temperature, and shifts when cold are excellent.
I am, by nature, a “conservative driver” (OK, I will admit, that I was once, way, waaaaay back in the mists of time, a tad “exuberant” in my driving “style”. In my defense though, Sabertooth Tigers were a hoot to drive. They had phenomenal short distance acceleration, a very sharp cornering ability, and could stop on a dime and give back change. They were however, just a “TAD” temperamental, and performance would quickly fade during longer distance pursuits. I was quite saddened when they finally went out of production)
So, my “Plan” is to drop the pan, inspect for debris, then address the items that are known to be “problematic pressure loss areas” with this “family” of transmission, items that do not require dropping the transmission. The parts and modifications I am planning to implement are as follows:
PUMP:
- Sonnax O-Ringed Line Pressure Boost Valve (.470")
- Transgo 4l60E-PR (Drop-In Pressure Regulator Valve)
VALVE BODY:
- Transgo 4L60E-ABUSE-BP (Abuse Plugs)
- Transgo 4L60E-VBPLUGS (Valve Body Plugs)
- GM 24209145 EPC FILTER
- Transgo 46-PLT-94 (Separator Plate)
- Sonnax 77987-01K (Pinless Forward Accumulator Kit)
- Sonnax 10000-08 (Torlon Check Balls)
- 2 GM 29535617 (or equivalent) Pan Magnets.
SERVO:
- SONNAX 77787-02K (Servo pin)
NOTE: The following might raise an eyebrow (or 2)
I am not planning to upgrade to a larger diameter Servo assembly for the following reasons:
- Transmission shifts are quite “crisp” when the transmission fluid is cold, only to “soften and drag out” as the fluid begins to approach operating temperature. This indicates to me that for my particular vehicle, and MY style of driving, that the OEM servo is not performing in a “less than optimum” manner. (at least I “think” the servo is OEM) The previous owners service information written in the operators manual does not have any mention of a transmission rebuild, just a service at 40,000, but as I DO plan to remove and inspect said servo for wear, replace the servo seals, and install the Sonnax servo pin with seals, I will look to see if the servo is OEM or not.
- I would be, in NO way, comfortable in hitting the “problematic” OEM Sun Shell (that has been taking hits from the smaller OEM Servo for 110,000 miles) even harder with an even larger diameter servo. My luck in rolling dice has always sucked, and true to form, if I installed a larger servo, I would roll “snake eyes” and frag the original Sun Shell.
- I noted, (and after thinking about sealing methods) your tip to avoid using D-Ring seals on the servo assembly, and will stay with scarf-cut rings.
- Can the appropriate OEM Servo seals (scarf cut) be purchased by themselves? Or will I have to purchase a complete paper and seal kit?
- What is your recommendation for servo pin to band clearance? I am sure you have posted it and I saw it, but that brain cell is refusing to fire for some reason…...
- I am greatly concerned about wear in the 4th gear servo, which is one of the reasons for installing the Sonnax Servo pin with sealing rings. However, the Sonnax Pin would NOT address any wear at the servo pin to 4th gear apply piston interface with the old 4th gear servo piston, and this concerns me. Additionally, there may be some wear at the 4th apply piston to cover interfaces. I believe that it was you that posted that you install a new, OEM, 4th gear servo piston and cover in your builds? I am attempting to locate both of these items, but I have had no luck in finding a part number or supplier for them. Where do you find these lil buggers? I have no desire to install a larger, aftermarket, 4th gear servo piston and cover (refer to Servo Notes listed above) and also due to the fact that I do not carry heavy loads, and absolutely never tow in 4th gear.
- In regards to your modifications to the 4th gear accumulator circuit (delete the 4th gear accumulator piston, pin, and spring and block the 4th gear accumulator feed passage with a ¼” allen plug) I totally agree with this for new builds, but I am very interested in your thoughts on doing this modification to a transmission with a OEM 4th gear servo piston and a Sunshell that has already seen 110,000 miles?
- I had noted your post on orifice sizing, (which I assumed was for a freshly re-manufactured transmission of this family), but I am unable to locate the sizes in my notes. My question is if you would make any changes to the current orifice sizes, again considering the particulars of my old girl, mileage, driving style, and her cold fluid shifting qualities, and if so, what sizes you feel would be of benefit.
I have to admit that even though I have some experience in this area, it took forever to:
- Gather as much information that I could.
- Decide on the most critical things that should be addressed in my specific case.
- Avoid any “bright and shiny solutions in search of a problem.
Well, I think it is time that I bring this post to a end. I wanted to “throw out my reasoning” for others to examine and comment upon. I am genuinely interested in other peoples thoughts, and hope that my thoughts might be of aid to others. I am also thinking about starting a thread involving the transmission rebuilding tools that I made for my own use, way back when I first started playing with the earlier 3-speed automatics. (I used to work as a welder/fabricator and had to have something to do during the “slow” days)
I will probably name it something like “Home Made Transmission Tools”A last opinion concerning the older transmissions. I do miss the old style of sintered iron sealing rings. I may be a “Tad” strange for feeling that, but the old iron rings always seemed to seal well for quite a long time IF you performed regular transmission services, thus preventing the transmission fluid from becoming an abrasive slurry.
Sir Barger, I am quite certain that I speak for everyone at BITOG when I say thank you for all of the information you have taken the time to impart to others. It is sincerely appreciated! (I am also quite sure that there are many transmissions that are living healthier and happier lives entirely due to your efforts)
To Sir Barger, and everyone at BITOG, I hope that have a great year!
Patrick.