Maybe some of you transmission gurus out ther could answer this for me. I have th400 im rebuilding for my camaro and id like to know if i could use any parts out of a 4l80e. Ive read some where that they have 5 gear planetarys and 34 element sprags in the erlier ones. I have one out of a 90 chev 1-ton that ill never use cause of the cost of the controller and torqe convertor. Sooo i figured why not try to get some use out of it. Thanks

the 4l80e won't have 5 pinion planets in it.
the 34 element sprag could be used on top of the direct(3rd) drum if the inner on yours is smooth. some of the TH400's used the smooth inner on the drum and some didn't. Teardown of the th400 would be necessary to determine. The 4l80e drum has a molded piston in the direct drum and won't be used for the th400. I've personally never seen the 5 pinion in anything but the 4l60e in the escalades and ss trucks. at the most the planets may be straight cut gears for towing but I doubt that also. the planets in the th400 rarely wear at all. the sprag upgrade is where I would focus if I was making the th400 better as that is what second gear upshifts is counting on (even though it is on the 3rd drum) because it is for the intermediate clutches(2nd).

ok thanks. do you have any other suggestions? the tranny is already torn apart to check it out and mabe rebuild it.im goung to do the diy shift kit mods i found on a 500cad site to it.

1971 and earlier units had the correct drum that will use the 34 element sprag. Use the aluminum piston setups from the earlier transmission, much better than the late stuff. Do not leave any springs out in the drums. Use the Borg Warner Hi-Energy clutches in high/reverse drum, Borg Warner stock clutches for 2nd and forward. DO NOT remove the waved steels. Add a waved steel to the high/reverse drum. Use two 2004R low/reverse housing to case plugs on the center support. The TransGo 400-2 is the Shift kit to use here. Make sure you remove two splines on the input shaft 180 degrees apart, this will prevent the torque converter from balloning and destroying the thrust bearing. Use teflon sealing rings on the center support and the front pump. Use cast iron sealing rings on the servo and accumulators. The 2nd accumulator spring (it is the one that sits under reverse apply piston) should be orange, yellow or plain in color. Flat sand all of the thrust washers as you will find that are not very flat. The inner race on the high/reverse drum should be in very good condition, and have a very smooth surface. DO NOT sand with anything rougher than 600 grit, and in direction of rotation only. The outer race can be rough. I carry everything that is needed to do this tranmission, give me a call at909-795-1876 and go to https://www.700r4l60e.com/store/home.php?cat=15 Dana

I prefer kolene steels for all as they resist burning
remove the wave if it has it from the third drum-you want all the friction possible for third gear
the blue clutches have a high coefficient of friction and grooves to help cooling.
remove the spring from the accumulator piston in the valveboy as it has a tendency to break the snapring-install the piston and snapring back in with no spring
remove the wave from intermediate(2nd) and install flat steel
definately upgrade the intermediate sprag with the 34-find a drum from your core or another-they are pretty common and easy to find locally as the drum needs to have the smooth inner race
if the three tab washer in the rear of the case is wearing the case replace it with a aftermarket bearing repair as that is where the 400case wears.
I like the more expensive B&M kit as it provides a 1-2 shift valve so you can hold the trans in first-or you could modify your stock one by grinding the land with a bench grinder
I agree use teflon on the center support
I agree use cast rings on the accumulators and servo
the metal v.s. aluminum pistons not a real issue for the forward and direct drums unless the inner is the "D" type which burns up clutches

if you're gonna spray it update the input shaft v.s. modify it, and upgrade the forward hub so it doesn't shatter.

DO NOT remove the waved steel from the intermediate pack. This prevents the snap ring from breaking the snap ring case lugs, also it loads the sprag first before it brings on the clutches, thereby making the sprag last longer. Use the HD snap ring in the TransGo Performance Shift kit for the intermediate clutch, or the Torqueflite .106" - .108" high/reverse clutch snap ring. I have never seen a 3rd accumulator spring break in 31 years, leave it in. It takes the shock out of the 2-3 shift, the waved in this clutch pack will do the same. Kolene steels are fine for 2nd and 3rd gears, not necessary for the forward clutch, waste of money. The TransGo Performance Shift kit has the ability to hold 1st gear to any rpm. It also offers a "dual feed" for high gear. Make sure you install all three lip seals in the direct/reverse drum. If you do not do this, you aggrevate the centrifuge problem that occurs here in the top of of 1st gear, and can start to burn the 3rd gear clutches here. If you have over 750-800 FWHP, then you might consider the steel input hub, if over 900-950 FWHP, then you might need the HD input shaft & input drum. Clutch clearances, forward .030" - .055", direct .060" - .080". DO NOT sand the steels. The Blue Plate Specials are fine for Strip only use, but do not do well on the street. The grooves in the clutch only help in the clutch apply, to bring on the clutches faster. The Borg Warner clutch material has the ability to hold a good amount of oil, this allows for better heat dissipation on the 1-2 or 2-3 shifts, therefore the clutches last longer.

WOW thanks guys... thats a TON of info. thi is only the second trans ive torn into. the first was a 4l60e that i rebuilt for my caprice.i didnt think it was too bad.
so i shouldnt remove the center lip seal in the direct drum? i believe thats wat there talkin about? here is the diy shift kit link that i got the info from: http://www.cadillacpower.com/forum/i...0&topic=9735.0
i was hopin that i could just add the clutches to the intermediate(mine only has 3) and replace the bearings and seal and clutches. plus a shift kit. this should handle 450hp? im going to do as many of youre guys suggestion as i can afford.
biggest reason i want to use the 400 is it seems to be cheaper to build than a 700.(burnt up on the first pass.. it was stock w a transgo reprogramming kit..)
my buddy has a ton of old cadillac 400s(or 425s) that ican prob find the right parts for the sprag an maybe a few other things..
thanks guys.....

so-- pro built,youre 400rkedss kit pretty much has all the things i need except the older sprag parts or will the 34 element fit into my drum? its an 86 model

the early drums came with the smooth inner-most likely not in yours-source it locally as it is in lots of early's and will allow the 34 upgrade and save a lot of money. i've attached a pic-look at the drum not the outer race and you'll see at the top it is round(smooth) to match the round sprag.

could i just machine down mine? mine is actually only an 8-spag... Ialso work in a machine shop that id have no prob doing this with the right dimensions.Ive tried to look locally, but seems all the circle track guys pretty much used them up.

i've got one if you want it. pm me. you can't machine it down. it is a fundamental part to a stout th400 build. v.s. a 16 element stock it has 110% more holding power into second gear. I'd take the waves out-they were for cushioning shifts not for holding power/pro guy was right that it might help with some of the shock of the sprag into second to help prolong the life, but most people break that part in the water box by not doing their burnout properly not as suggested by mr built with it "loading". Besides you'll be upgrading the sprag anyway. I run 9.2's at 146 this way for years with 330 shot of nos. not bad eh. also written was to take the spring out of the valvebody-definately do this- if pro would have read correctly he would see that I said the snapring breaks not the spring, and when this happens it trashes the snapring groove in the valvebody making the whole valvebody junk so take the spring out again I say.