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Looking into this modification in general. You said GM added it to all production 400 pump bodies. I only remember that being in some pump bodies and not others. I was in a production facility rebuilding stock replacements. The only lube experiment we tried was full time feed. We scrapped the modification when we saw cooler pressure rise from 60psi to over 100psi at idle on a dyno. We made an assumption that it would add to thrust issues in the 400 and we didn't need more of that. Is that maybe why TransGo and others say to only drill full time feed to .055? Performance always takes everything to another level.
As long it is on the suction side of the outer pump gear. Do you as an engineer think the placement of this groove is critical? I noticed that the groove in the 400 pump body in the picture does not go to the bottom of the pump gear pocket. I remember that they did. Maybe my memory isn't very good. Do you think it should or is it not critical to the actual function. Why not use it in all performance units?
I remember cutting the crescent on the pressure side of 350/400 pump for pump whine. If you cut it to shallow or narrow, the modification did not have any effect on the whine.
I am sorry for any posted information that was unclear.
I am going to quote myself and trim down the entire quotation to the relevant information, per your questions.
Originally Posted by vorteciroc
I consider this a more significant Lube Modification!
This is something that I consider to be Mandatory for any 4L80E with Fixed High Line-pressure or a Trans-Brake.
Very briefly I wish to mention a design improvement that GM/ Hydra-Matic Engineers made to the Late design THM400 Pump.
Here is an image of the Late design THM400 Front half (Casting number ending in: 895) of the Pump:
The Blue Circle on the image above shows a small gap between the Outer Pump-Gear and the Pump Casting.
This small gap is referred to as a "Pocket" and it is for Oil to collect and help prevent excessive Pump Gear wear and tear.
Both the Early design THM400 Pumps and all of the 4L80E Pumps lack this "Pocket" that is shown in the Blue Circle.
So, we modify the 4L80E Pumps (and Early THM400 Pumps) to have this pocket made via a simple milling process.
The next image shows the same pocket, but with the Pump Gears removed.
Shown below inside the Red square:
This Modification should be performed on all 4L80E units that have Fixed Line-Pressure or a Trans-Brake.
Please follow the text that I have high-lighted in RED text.
-Looking into this modification in general. You said GM added it to all production 400 pump bodies. No. Only the Late design front Pump half (with the casting number ending in "895") had this modification.
I only remember that being in some pump bodies and not others. I was in a production facility rebuilding stock replacements.
-The only lube experiment we tried was full time feed. We scrapped the modification when we saw cooler pressure rise from 60psi to over 100psi at idle on a dyno. Indeed it can. We would need to discuss "Pressure Regulator Valve Balance" and go over what the Bleed-Hole or "Balance-Hole" that is drilled as part of the "Line to Lube Modification" is actually doing.
Here is a HyperLink to a Sonnax article that discusses some of this: Sonnax Article Link If you wish you discuss this more or have questions... Start a Thread, it would be cool!
-We made an assumption that it would add to thrust issues in the 400 and we didn't need more of that. Is that maybe why TransGo and others say to only drill full time feed to .055? Essentially yes on both counts... although with a THM400 unit the the Converter Charge Pressure should be regulated down. At least with a restriction orifice (like commonly seen in books and On-Line everywhere) or with a Pressure-Regulator on the Cooler-Line; that would dump excessive pressure back into the pan.
Please look at these two images below:
Performance always takes everything to another level.
-As long it is on the suction side of the outer pump gear. Do you as an engineer think the placement of this groove is critical? I noticed that the groove in the 400 pump body in the picture does not go to the bottom of the pump gear pocket. I remember that they did. Maybe my memory isn't very good. Do you think it should or is it not critical to the actual function. The location of the "Pocket" in terms of placement (the same as going around the Outer Gear like a Clock) is indeed very important. Not to sound too crude... but the Gears get shoved in one direction as an effect of the pump design/ pressure increasing. The "pocket" allows oil to go on the side of the Gear that needs help pushing back in the opposite direction.
-Why not use it in all performance units? It certainly can be used in all units. I was only saying that I consider it mandatory in a Fixed Line-Pressure or Trans-Brake Transmission.
Answers to your questions are high-lighted in RED.
I do Not see you often on the Forum... But Obviously you are reading from time to time.
Thank you for all of your own contributions to both the THM200-4R and the 4L80E (that now has your shop super busy!)
I am very Glad to see your success with all the 4L80E work!
I've been meaning to tell you this is an awesome thread. I don't actually login often anymore but occasionally read.
Very well done technical post. Most don't realize the effort it takes to write these.
I have pretty much quit participating online with trans tech. Too many internet experts so I'll let them argue and I'll just run my shop. I've spent the last year prepping to move, moving, and getting things smoothed out from the move of my shop and house. It's time to get some new parts rolling.
Finish it when time allows. You have done an excellent job. If you need any pics just let me know, we probably have anything you need on the bench at the shop at any given moment.
Thanks for clarifying this some. My apologies about the "You said GM added it to all production 400 pump bodies" quote. You are correct you did say the late 895 body and that was how I took it. I did not clarify my understanding of the only 895 bodies. It was in the 90's when I was with the "Transmission Factory". Hence the clouded memory of some pump bodies and not others. I haven't touched a 400 in 20 years, it's been 350's 700's and 4L60E's only since my retirement from the trade in 2007 @ 55. with that said, I just built two rock crawler 400's with manual VB's and fixed line pressures 2 weeks ago. I don't think either pump body were "895's" and this part of the post really got my attention.
Continuing with the Pump, for both Early and Late designs...
Next a small hole/ bleed is going to be drilled in the Front half of the Pump.
The images above are showing the location in the Front half of the Pump; where the hole/ bleed will be drilled.
This hole/ bleed will benefit the Lube-Circuit by allowing some of the Pump output/ Line-Pressure into the Lube-Circuit.
Below is an image showing the diagram/ passages of the Front half of the Pump:
The hole/ bleed will connect the small passage #7 to the large passage #2.
The #2 passage is the output of the Pump/ Line-Pressure.
The #7 passage is Converter-Feed Oil... which will become cooled Lube-Oil.
In a post I made further up in this Thread, I had mentioned "Pressure Regulator Valve Balance".
This modification hole/ bleed has to do with "Pressure Regulator Valve Balance".
I am not going to discuss this topic at this time, as "Pressure Regulator Valve Balance" could be it's own Thread by itself.
When building the 4L80E for performance oriented purposes... the Line-Pressure will be increased to 180 - 190 Psi...
Or 200 - 210 Psi for units behind 1,500 HP engines.
When the Line-Pressure becomes this high, correcting the natural "Pressure Regulator Valve Balance" with this hole/ bleed becomes very important.
When I mentioned "Pressure Regulator Valve Balance" in a Post further up in the Thread is a Hyper-Link to a Sonnax article.
I suggest you guys take a look at it, and read it.
Regarding increasing the Line-pressure for the 4L80E Transmissions... the builder must take care not to increase Line-Pressure too much.
180 Psi is a small increase over stock... and is adequate for a 1,000 HP engine.
Too much Line-Pressure can, and will eventually case hard-parts damage...
Sometimes severely!
A firmer Pressure Regulator Valve Spring or a Boost Valve Assembly can be used to increase Line-Pressure.
At times both the Spring and the Boost Valve will be replaced to increase Line-Pressure.
The two images show a popular product from Sonnax.
Included is the Pressure Regulator Valve Spring, and the Boost Valve Assembly.
The last image also shows an O-Ringed End-Plug at the top of the Pressure Regulator Valve.
It is always a good idea, when vacuum testing the Pump... To inspect this area.
In higher mileage units, it is common to find some leakage here.
In general, replacement End-Plugs with O-Rings are good to have...
They can help significantly seal-up some leaking circuits in the Pump and Valve-Body.
Also in both the Early and Late design...
The Bushing that is inside of the Over-Drive Sun-Gear can be replaced with a Bushing that is normally used for the Late design Sun Gear Shaft.
Here is an image below, of this type of bushing again in the Sun Gear Shaft:
Below is an image of the Over-Drive Sun-Gear with the original Bushing installed (Blue arrow):
Installing one of the grooved Bushings instead, will increase Lube-Oil flow through this area.
The Red arrow in the image above show the location of the Lube-Passage for Over-Run and Over-Drive.
This hole/ passage can be enlarged/ drilled for an increase of Lube-Oil to a size of 0.125".
The rear part of the Stator Support Tube in the Rear half of the Pump, can also have the Lube passage/ hole for Over-Drive enlarged.
Below is an image showing the rear part of the Stator Support Tube in the Rear half of the Pump:
The image above shows the existing small hole/ passage found at the rear of the Stator Support Tube.
The hole/ passage is located between the Sealing-Rings, and the Bushing Journal.
Drill this hole/ passage on a 45 degree angle to a size of 0.125".
The next modification will be on the Front half of the Pump.
It is not a necessary modification on a 4L80E, but it also does not hurt anything.
I personally prefer to do this modification on MOST GM Transmissions.
The image below shows the Front half of the Pump with the Torque-Converter Seal removed.
In this location is the Lube-Oil return passage.
Enlarge this passage to 0.250" (this is done to help prevent seal blow-out from increased pressure... not needed for the 4L80E):
The Late 4L80E Transmissions are particularly harsh on many of the Bushings...
Lets just say that the Late design Lube-System does nothing to help the situation.
The two Bushings for the Sun-Gear Shaft suffer significantly.
Again, here is an image of these Bushings:
I will say it again and again... The Early 4L80Es did not have Bushing wear issues like the Late units do.
The next topic will involve using a hollow Intermediate-Shaft (as used in the Early 4L80Es) in the Late Lube-System instead of a solid Intermediate-Shaft.
When using the hollow Shaft; the Sun-Gear Shaft can use non-grooved/ non-fluted Bushings (from an Early 4L80E).
These Bushing tend to last much longer than the grooved/ fluted Bushings.
I very much like to use a complete set of Durabond Coated Bushings in the Late 4L80E units...
They by far outlast the OEM Bushings.
I personally install Durabond Coated, grooved/ fluted Sun-Gear Shaft Bushings in all 4L80E units (Early and Late).
As I had posted further up in the Thread... I use three of these Bushings for every 4L80E.
They hold-up very well:
While not necessary... I do recommend this Bushing set for the Early 4L80E units as well.
Last edited by vorteciroc; May 7, 2021 at 11:07 PM.
Good stuff!
One note to make...I'm not the only one to have this issue...A pro tipped me off to it and then I set out to scaling some 4l80e pressure regulator springs, I noticed just as they did...there are HUGE swings in spring pressure in the LB1 kits for the 80e from sonnax. One might make 170 and the next will make 210 just based on the spring pressure.
I've moved away form using the sonnax springs but I will still use their boost valves
What an awesome thread! Thanks Vorteciroc for taking the time to post all this information. I dont have much to add to the scrum as I dont have much experience in 4L80 or TH400 platform as of yet, but it sure is fun to read
Did you work on this 4L80E tech manual with Chris at CK Performance? He's been posting this information on the yellowbullet forum back in 2012 when he was close to printing. I think he posts it on his website.
Did you work on this 4L80E tech manual with Chris at CK Performance? He's been posting this information on the yellowbullet forum back in 2012 when he was close to printing. I think he posts it on his website.
No.
I needed many images to use examples for this Thread.
The diagrams are photos and screen-shots that I took myself.
However the images of the parts and modifications come from Google-Search.
Many of these images come from Jake, Chris, and Cline.
Good stuff!
One note to make...I'm not the only one to have this issue...A pro tipped me off to it and then I set out to scaling some 4l80e pressure regulator springs, I noticed just as they did...there are HUGE swings in spring pressure in the LB1 kits for the 80e from sonnax. One might make 170 and the next will make 210 just based on the spring pressure.
I've moved away form using the sonnax springs but I will still use their boost valves
I have experienced this with many different transmissions and many different Springs/ Boost-Valves.
This is why pressures are always checked on the Run-Stand/ Dyno and then again in the vehicle...
So that adjustments can be made.
This is why Dana started turning the EPC solenoid up on 4L60Es that did not make enough line-pressure after the TransGo Spring and Boost-Valve assembly.
Last edited by vorteciroc; Apr 30, 2021 at 07:48 PM.
i too was having issues with the LB1 springs. at first I thought it was just variances in the pump cavity clearance but I monitor those pretty closely and have kept decent records of what PR configs did what. eventually i just started ordering PR springs from Lee Spring directly, and pressures been a lot more stable.
Great info Vorteciroc, thank you. Guys I had never thought of using springs from another source that maybe better than what comes in the kit. I guess it need to get something to start measuring spring pressure.
i too was having issues with the LB1 springs. at first I thought it was just variances in the pump cavity clearance but I monitor those pretty closely and have kept decent records of what PR configs did what. eventually i just started ordering PR springs from Lee Spring directly, and pressures been a lot more stable.
Doug, do you think the spring in the Superior kit pictured below will have the same issues? Have you used any of these in your builds?
Another thing I was wondering about was the PR valve that comes in this Superior Kit? Is the PR Valve in that kit like the Sonnax #34200-01K in that it doesn't provide a bleed? I know 34200-14K PR valve does create a bleed in stock applications. I guess none of this matters since most builders just drill the lube to line bypass regardless of what valve is being used.
I have used that kit before. IME it results in stable line pressure, but not a significant rise. Around 700 rwhp i move to a spring that allows the pump to put out 180psi. I like the annular ring cut in the boost valve. The line to lube is accomplished slightly different way with with that kit. It's a milled flat on the PR valve itself. if you squint at the grainy picture below you might make it out.
