transmission questions..350/700r4

[bigblaze76]

I apologize if this has been covered a 1000 times but when i did a search there were so many posts i didnt know which way to go..

my 350 tranny burned up last night and i am trying to decide what to do next...

is a 700r4 the best option or should i just stay with a 350?

next question is it best to buy a new unit on line or just have mine re-built?

my wheeling is a mild a little in the mud and a little on the rocks..

the truck is a 84 k5 with a 383 and a 205 t-case.

is a 700r4 a direct bolt, oh and i dont have a computer in the truck anymore that went out when i put a new painless harness in the truck.

sorry so many questions but i want to do this right the first time

thanks for any advice

 

[sweetk30]

BUILT 700r4 is nice and gets you lower first gear only over the th350 .

and overdrive is nice if you have the gears to use it with your tire size.

700r4 can be easy to setup for bolt in simple hook up use.

and 700r4 is close to bolt in . but few little things and its longer by almost 2" over the 350 . so drive shafts need reworked for length . rear shorter / and front longer .

need special non stock tail shaft for 205 to 700 tranny . but best to use spacer ( fitzall ) to space tcase away from 700r4 as 205 front output gets to close to tranny pan if direct bolt on .

search in the garage section for a lot more info .

 

[Greg Ducato]

Normally I am a huge advocate of installing a 700R4 for all the benefits associated with this trans. As Sweet K30 pointed out, there are several installation obstacles to overcome, plus the set up and adjustment of the tv cable, wiring for converter clutch operation and the expense of a WELL BUILT 700R4 to make all of the pain worth it. If you have the funds and time then the rewards are your for the reaping but the 350 is a very sturdy little trans and will plug right in where the old one came out, and that can be a huge plus here.

 

[goathearder]

I bought a "rebuilt" 700R4 K case from craigslist at the beginning of the year to do this exact swap and I have been super happy with it. My intention is that I would always eventually get a built unit when this one blows up but I wanted to get it done and have the overdrive and lower first gear as soon as possible. So far, its been holding up well.

A couple of issues I ran into if you do it

1) The spacer to bolt the 205 up is great but forces you to screw studs into the output of the 700r4 and when I tightened the nuts on the other side they pulled the studs right out of the aluminum on the tranny and ruined the threads. I used "time-serts" to fix the holes and now I can torque the heck out of those nuts with no issues.

2) The spacer shipped with 1 o-ring and crappy directions. You are supposed to have an o-ring on BOTH sides of the spacer but since it only shipped with one, I only used 1 and the damn thing leaked like crazy till I figured out you needed two. Start with two and you should be good.

3) I bought an aftermarket lockup kit that was supposed to screw into a pressure port on the tranny to engage the lockup but I had a later tranny that didn't have that port. Greg actually helped me wire it up myself without the kit and it works awesome!

4) I had a deep pan but apparently deep pans need spacers for the filter and mine didn't have one. This cause the filter to keep falling out and some serious weirdness on the tranny. Stick with a stock depth pan or make sure you have a filter spacer with your deep pan.

5) You'll need new driveshafts so if you plan on doing a doubler or anything else in the future, try to do it all at once so you only need driveshafts made once.

6) Stay away from Monster transmissions. Worst customer service I have ever experienced in my life.

In the long run, those were all super small issues and I would never go back to a 350 after having the 700. Again, I fully expect to spend 1500 bucks in the future on a built one but I am gonna run the current one till it explodes.

 

[blazinzuk]

1) The spacer to bolt the 205 up is great but forces you to screw studs into the output of the 700r4 and when I tightened the nuts on the other side they pulled the studs right out of the aluminum on the tranny and ruined the threads. I used "time-serts" to fix the holes and now I can torque the heck out of those nuts with no issues.

this is good advice on any of the popular chevy trans. I always put some sort of heli coil or time sert in those holes. Aluminum just simply does not hold threads.


I have had a 350 and a 700 I would take the 700 every single day. But remember you might need to regear your axles to take the best advantage of the 700. In my diesel Jimmy with 3.08 gears I never ran in overdrive. Now with 4.56s I always run in overdrive.

Same experience when swapping a 700 into a 74. He needed to go from 3.73 to 4.88s for the most benefits to happen.

May I suggest finding a 700/241 arrangement. Hard to find yes and more expensive but the 241 coupled with the 700 gives nearly the crawl ratio of a doubler with a 350 in front of it

 

[jekquistk5]

this is good advice on any of the popular chevy trans. I always put some sort of heli coil or time sert in those holes. Aluminum just simply does not hold threads.


I have had a 350 and a 700 I would take the 700 every single day. But remember you might need to regear your axles to take the best advantage of the 700. In my diesel Jimmy with 3.08 gears I never ran in overdrive. Now with 4.56s I always run in overdrive.

Same experience when swapping a 700 into a 74. He needed to go from 3.73 to 4.88s for the most benefits to happen.

May I suggest finding a 700/241 arrangement. Hard to find yes and more expensive but the 241 coupled with the 700 gives nearly the crawl ratio of a doubler with a 350 in front of it

Hmm may go to a 700 on the next project.