I need some education on 700R4's. Going behind a small block and in front of an np205 (I think). I want minimum wiring and good durability. What years should I look for? Anything to avoid? What kind of rebuild upgrades should I plan on? Thanks in advance - D

Use that red star and search:flipoff2:

Thanks for the input. You can now add one more post to your post count.:flipoff2:

I'm running one in the pig and love it. I think for some reason you need to find an earlier year model like a pre '96. Not for sure though.

Daryl,

I think you'd want a 87 to 92 model. These should have many of the fixes that makes them more reliable. Georg (orangfj45) would know the specifics.

Charles

Thanks guys. I had heard the 87 and newer were the more desirable ones. I'm waiting for Georg to chime in - OH Wise One!

I got an early 700R4 and had a 13 vane pump, larger sun gear/ basket, case saver, corvette servo, extra clutches, stock GM convertor and some valve body work done at a local trans shop

as mentioned, you really should start with the "auxillary valve body th700" which was produced between 1987 and 1992. these units had all the factory upgrades incorporated in them. some of the tranmission suppliers like to boast about their transmissions having "several HD upgrades". those would be all the factory upgrades........
part of these upgrades are:
a better pump design
better valve body and servo
better input drum
better input shaft ( upgraded from 27 to 30 spline)
accordingly, a better converter ( partially due to the spline count increase)
better rear sprag setup
amongst a few other odds and ends

the "auxillary valve body" actually referrs to a a small auxillary portion of the valve body that bolts to the indise of the trans towards the rear. it supplies much better clutch holding power for fourth gear versus the earlier designs. and it's one crutial upgrade that can not be achieved by "updating" an earlier unit. sure you can put in a shift kit, but you don;t get the same results.

th700s are great transmissions. they got a bum rap because the very early models, 1982-83 had lots of problems when put to severe use. the aux vb units usually go 100k miles in full size trucks. at least that's what we wanted to get out of them when we rebuilt them at the trans shop. and the vast majority of them did. that can not be said for most automatic overdrive transmissions.

if you're going to have on built for your rig, then i would definetly install a MILD shift kit, like the one offered by transgo. do not make it shift too firm or it'll break the aluminum lugs right out of the case. and then you're back to square one.
i would also highly recommend using a kevlar band 9 to cope with the heat and extra load ) as well as an HD sun gear shell, commonly referred to as 'the beast". besides that, get a good quality torque converter with the HD torrington bearing upgrade and kevlar or ceramic lockup-clutch liner. stay away from B&M converters, or it'll be a mistake you won't make twice ( ask me how i know ).

last but not least, find somebody who's well versed in these transmissions and insist on them using high quality components like borg warner or raybestos frictions and oem planets, not the cheap chinese crap......
it'll be money well spent in the long run.

also, make sure you run a quality transmission cooler. use a twisetd fin style, not a tube and fin 9 they're not very efficient at all ).

as far as wiring goes, there are several outfits that can supply you with a 'stand alone" lockup harbess. painless, jags that run, e-z wiring and others are all good.

alright, my 5 minutes are up and i have a two week old that's crying.

best of luck and always remember:

autos rule!:flipoff2:

As always Georg - you offer a wealth of knowledge and I, for one, appreciate it! I printed this list of do's and don'ts and will be discussint this with my builder once I find an acceptable core. Thanks again - Daryl

BTW - enjoy each minute with that little one - they grow up far too fast!

anytime dude! just "paying back" for some of the info i've gotten from the board!:beer:

I quickly looked for this kit on Summit and I found this "TransGo's Performance shift kits give you the hard-launching, tire-blazing shifts you want" This seems to contradict "i would definetly install a MILD shift kit, like the one offered by transgo" Are there options within this kit to tone down the shift a little? I just want to be on the right page when the day comes to move to the dark side of shush boxes. :D

transgo makes a series of shift kits. they do offer at least two for the th700. the one you want comes in a green and black box and should cost about $30. the larger kit in the blue box is for competition vehicles and shifts way too hard. they also cost closer to $100. overkill for sure.

I'm running the same thing.. SBC/700R4/NP205.

The output shaft in the $$ AA adapter is just a 4wd TH350 shaft from what I've been told. Have that installed when you rebuild the trans, and then you can use the factory adapter for a TH350 to the NP205...

I would HIGHLY recommend making a crossmember to mount to the NP205's factory adapter. hardmount the adapter to the crossmember, then mount the crossmember to the frame with bushings. ALSO (this is important), run a bracket up from that crossmember and utilize the 2wd mounting pad to your crossmember. This will take the stress off the 4 10mm bolts (a 700R4 is ALL metric) on the tail, and help keep from breaking the case, as I've seen happen more than a few times.

(Yes, the foot on the TH350-205 adapter is not flat, it's angled)
http://rnrfab.com/rich/fj/07build/5-13-07/images/xmember2_jpg.jpg
http://rnrfab.com/rich/fj/07build/5-13-07/images/xmember1_jpg.jpg

Installed, to give you an idea of what it looks like. That's a clocking ring from DD Machine, and I wouldn't run a NP205 without one..
http://rnrfab.com/rich/fj/07build/6-11-07/images/205side_jpg.jpg

rich makes a good point and it's very important. the rear of the th700 case is definetly the weak spot.


building a sturdy cross member to support the assembly from the bottom is ultra important. using not only the adapter but also the th700 case mounting bolts is almost a must. if you want to go for overkill, then you can also incorporate the two large threaded bosses on the passenger side of the 205, towards the frame. they can clearly be seen in the last pic rich posted above.

...... i have a two week old that's crying.




Maybe he finally opened his eyes(both of them) and saw who his Daddy is!