you might consider blocking the 3rd accumulator. i found it hard to get any shift feel on the 3rd shift even at WOT in a friends 3/4 ton that he hauls a landscaping trailer with. I dual fed with transgo's crappy separator plate from the HD2 kit, but dual feeding acts as an accumulator of sorts. I ended up blocking the 3rd accumulator and went .093" on the shift hole. it was better but i would have gone to .101" or .106" if i went back into it again, YMMV. For 2nd drilled @ .082" was nice and i blocked the 4th accumulator which i wouldn't recommend for a heavy/work vehicle. jakes recommendations are likely spot on.

ps:i used the sonnax LB1 boost valve with OEM spring & I didn't touch the accumulator valve spring.

 

Thanks Tay,
Yeah it's kinda hard to muddle thru the mods here as most are going for performance with lighter vehicles and braked VB's. This thing is 30 feet and 12-12.5 k pounds and maybe towing a small car up in the mountains so I am trying get as much info to keep this thing alive and off a tow truck. Happened one before with the TH 400/475, took 3 hours to get a tow company that would come and lift it and the tow plan only tows you to the nearest repair facility. So $3900 later for a 400 overhaul back in 2015 - I got soaked but I had no other options.
Would the spring included in Jakes kit be good enough in lieu of the boost valve ?

 

Yes I understand! Make sure to vac test the AFL valve. if you dont have vac test equipment just get the transgo reamer and replace it. you may be able to find a local trans shop that will do it for you cheap. i also like the drop in TCC from sonnax. the handful i've done have vac checked ok, but i threw this in for cheap insurance. i think theres a few end plugs you can replace in the valve body and pump if you have it removed (again Sonnax). I do not keep updated on Jake's products but I know at one point he used the LB1 boost valve & spring and then switched to his own spring. the way i understand the oem spring is good to 800-1000whp range, no point making the pump work harder unless it has to.


ouch on the Th475 rebuild.... is that US dollars?

 

Yup all in Gringo dollars. Had no forward and 100 miles from home Probably should have had it towed to the house and do it myself but didn't want to deal with it. Looking at the receipt now
new front pump = $195, new fwd drum $211, new valve body= $224, separator plate $92, piston $110, bushing kit $85, master assy kit = $595 , new filter $45 ( doesn't the filter come with a master kit?) rebuilt TC $359. and $1456 labor including replacing the motor mounts.
The fwd drum or clutch was the issue but they said the valve body or something else was the the wrong one and didn't belong in there - possible the prior owner had a shift kit or something done to it? But they got it done by the weekend and my anus eventually healed