Hmmmmmm.....Now there is a plan...
Actually...Unless you do not want to do your own ...There are several great builders in Cali that can do you a fine job....
Get a "How to do it book" online from one of a couple different publishers and go at it....
This book will let you build a good gear box......
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Even if you have never touched an auto tranny in your life.....They are not the mysterious magic box many would have you believe....
I have read a few of the books by the publisher (Book linked to)
I helped a buddy do a TH200R4 a while back and suggested he get a book and learn to do it...
He got one from these guys.....I read it though.....Good stuff.....
A few things......CLEANLINESS IS AN ABSOLUTE MUST HAVE.
DO NOT USE RED RAGS TO WIPE STUFF (The lint can stick valves) Use lint free paper rags when doing the assembly
DO NOT USE TEFLON TAPE TO SEAL ANY FITTINGS (This stuff can and will find its way into the VB and cause issues)
Stack all the internals on a long dowel to keep the order.....Or place them in order on the bench.....Yeah...The big boys on you tube just toss parts in a pile.....BUT they have done a buttload of these boxes and can almost do an assembly blindfolded.....
Many valve body bolts are different length.....Pay attention......Take pics and keep stuff in groups .....Plastic baggies or small containers are great......
The special tools are minimal for a 700R
A spring compressor to disassemble the clutch packs.....I have made my own....A hydraulic press ...(Harbor Freight) is handy
Bushing drivers....(Harbor Freight)
Basic hand tools.....
Snap ring pliers
Gert the gear box done.....THEN DO THE VALVE BODY (My method....no reason....just how I prefer to do it)
If you get a "Buildable core" and it is toasted......Figure out why....then do the build....
A lot of miles and hardened seals....TV not set correctly.
WHATS IN THE PAN.....????? A thin layer of black sooty looking stuff in the pan is normal on a high mile unit.
A lot of metal flakes...NOT SO MUCH.....
Auto trannies chew up metal junk.....Clutch plate wear.....Gear wear....
Metal flakes....Bearing failures....Converter clutch failure......
Large chunks of crap .....Bad JU JU
Broken planet carriers....
Case damage......
Case lugs that are badly worn.....Junk case.....
Core suppliers can be a good source..
YOU PULL IT YARDS
Yank the stick.....If it smells like burnt dog poop....try a different one.
Craigs list
Same story
Yank the stick....Oil red or somewhat red..(Good thing)
DO NOT TURN THE BOX UPSIDE DOWN....
Remove the pan bolts and get the pan off with the case right side up.....
Then you can see whats in the thing.....Any piles of debris will likely be right under where it came from
Doing a good "Post mortem" can tell you a lot about your new little prize.......
If you flip the box over...any and all the junk in the pan goes into the gear train....Then it is harder to tell where the junk came from.....Rear planetary, front planetary ????? Clutches
Clutch plates are usually a paper material on the steel plates....Burnt clutch plates (BLACK and smell bad) and the steels all blue and chewed up (Source of metal)
Look the exterior of the case over (Bell housing) for cracks.....If I bell housing is cracked....It does happen....Usually only in 4x4 trucks that have been thrashed....and bad wrecks.....
Give a good look at threads in the case.....Tail housing, pan rail.....Stripped threads can be fixed with a helicoil easily....
With a good "How to book" and a weekend.. (Subjective) you should be able to whip out a good little tranny.
Do the Autopsy......Then decide how far you want to go....$$$$$$$$$$$$$
Get the parts ordered and then while stuff is coming...Get the unit all cleaned up and ready....
Don't mix and match shift kit parts......If the book you are using describes a particular plan of attack ....stick with how they did it......Drilling holes in passages to accomplish a particular oil feed remedy and then using a different shift kit can result in less than stellar results.....
At this late date....Many trannies have been apart....maybe multiple times...And gawd knows what was done to them
Many shops simply clean things, replace seals, clutches, band, thrust washers and such.....new gaskets and leterip...
This will/can restore a factory function.....But will not solve the many issues that need to be taken care of.
Thrust washers on some of these boxes were plastic.....The steel backed brass...BETTER.
Never use a used converter.
Get a unit that has been rebuilt by a reputable outfit.
The converter in the 700R is small inside....The lockup clutch can be upgraded to a much stronger piece.
Also the stator one way clutch needs to be upgraded...New torrington thrust bearings too...
Getting an "RV" TYPE converter with brazed fins is a real plus.
Wiggling and flexing of the fins in the drive and driven torus is what makes a lot of the fine metal "SOOT" looking stuff in the pan.....
A brazed fin converter is far better....
When they installed the lockup clutch the Drive and driven torus parts had to be made smaller to allow room for the clutch assembly......BIGGER PARTS ARE USUALLY STRONGER.....
NOW
There is another avenue you may want to look at.
The bigger 4L80E tranny.
Same bell housing bolt pattern....
An after market electronic controller will get the big box working.
The 4L80E is a TH400 with the OD added....Stout....even in factory trim......
Some options.
The big thing......
When you do your own build ....YOU KNOW what shape stuff was in and what you did inside.....
Besides this....IT CAN BE A LOT OF FUN ...AND SATISFACTION in doing it.....