Hello,

I have a question concerning the line pressure boost valve, I have drilled the pump housing lube to line and am now installing the 4l80e-lb1 booster kit. I read that I best use the stock pressure regulator valve, but do I use the stock stock spring as I read that there are problems with the sonar spring ?

Thanks

 

I believe there is/was a problem with the spring quality and some of the high end builders were seeing pressure drop off at higher loads. in reality, you dont need the extra pressure until much higher HP, I want to say 600+ but it could be even approaching 800hp mark. The stock spring is fine, easier on the pump, etc. It's easy to get caught up in "well i might make more power later" or the more mods I do the better, my advice is just recalibrate the transmission later if you ever upgrade engine.

 

Thanks for the info and confirming what I was thinking , I will install it with the stock spring .

 

On all my 4L80E builds I use the stock spring and add a 4l60e SPRING. I always end up with about 70 to 80 lbs at idle and arround 230 at WOT .
I even do this with my stock builds. It fits in perfect .

 

Thanks Frank, your video's are a enormous help for me. I must have missed it when you went over this.

 

I would highly discourage that method. 230 psi in a stock case is asking for the intermediate band lugs to be aluminum chicklets in the pan and totally unnecessary unless your making 1800 RWHP.

Years ago we quit using the LB1 in the 4L80Es due to 40+ psi variation in pressure from spring to spring. I like the Sonnax o-ringed boost valve but won't use their LB1 in a 4L80E or 400 due to the springs.

A typical 800-1200 HP combo that we see only needs 185-190 psi and that's got some room for error.

Fluid level and proper pickup are the issues we've seen cause the most issues.

If you need 230 psi, I hope you are an experienced builder and you need a lot of other mods.

 

Ok thank you for the information, but what valve would you suggest using for a '99 model, I see 3 different boost valves... 34200-01K / 34200-03K / 34200-10K.

I did all the oil upgrades to the pump and drums...

 

Stock Boost valve diameter and Stock Spring is plenty of pressure for most setups for DIY guys
Adding an LB1 often will be just fine
I agree very strongly with jake that 230psi is far too much pressure for a build that doesn't have an upgraded intermediate snap ring and "case saver" aka intermediate snap ring support.
If you make 180psi and the rest of the trans is done right. "Dual Fed" direct clutch being the biggest obvious change versus stock. Then at 180 it will take more power than the stock hard parts can handle.

 

Oh geez, you guys got me worried now: I installed the LB1 boost valve on the lube regulated pressure regulator valve (34200-14K) on this beater K3500 truck. Truck surged and stalled when cold when I put it into D or R, but otherwise shifted well. After the install (transmission still on the truck) I lost all gears. I pulled the pan and the boost valve was on the pan. I "think" I didn't seat the boost valve snap ring on the pump body. Not sure. Also found a piece of aluminum casting on the valve and plenty of friction material, so I knew I was done.

I eventually pulled the transmission and just about ALL direct clutch case lugs were broken! Case is junk. One of these pieces of the casting was the one I found on the pan initially. [I'm still not sure how the boost valve falling off would cause the lugs to blow off, but I'm not savvy enough on the hydraulic circuits?]

I rebuilt another transmission I have and used the LB1 and lube regulated valve...I haven't reinstalled it on the truck yet. Should I change the boost valve with something else? In the past, I have had good luck with the boost valve from the Superior shift kit, although I have read here it's not all that great. This is basically just a basic towing transmission. This was my first time using the LB1 boost valve, and too be honest, I don't really like that when you poke it with a screwdriver, it feels too darn still. I was second guessing myself because it almost feels like it's binding on the bore. Is that because of the spring is so stiff? The 34200-14k is okay to use, right?

Sorry OP to hijack your thread, but it may help you out...

 

hmm I have never had the lugs blow out of the INT on any 4l80e I have built and have always used the added 4L60E spring method . But then I do always keep the waved plate and also use the better snap ring . And bear in mind that 230 max is based on 0 EPC current one the dyno which does not happen as 95 percent is the tune /
230 MINUS 5 PERCENT 211 PSI. But again I have never had issue with a build and i have done many the last 30 years or so. Shifts are firm but not overly aggressive.
Now I have seen a number of cores I have torn down that were built with the wave/cushion MISSING and the stock snap ring with the lugs blown out.
All my 80E builds I go for about .030 -.040 clearance intermediate - Heavy duty snap ring - waved plate - stock 2nd feed size-line lube mod.
I guess we each have different ways that work . This is what has worked for me.

 

No problem, we can all learn from this and learn from the people who know these transmissions best.

 

You do you,
I can say with a great amount of experience on 4L80Es (arguably more than anyone in the performance trans industry) that there are multiple reasons why I would avoid 230 psi on a stock case, and most knowledgeable builders aren't building 230 psi into a unit that's not for serious power. Serious power in my world is 1500+..

Besides case lugs, pump life, converter charge pressure, converter flow, and more to consider.

 

For those of you that previously were drilling the line to lube pump mod and using LB1 boost valve/stock spring setup in your fixed line pressure setups, have you tried Jakes adjustable pressure regulator setup? It comes with a modified PR valve such that you no longer have to drill line to lube, and you get a more balanced pressure regulation system that also allows for adjustable fixed main line pressure.

https://jakesperformance.com/shop/ol...sure-regulator