700r4 tranny question

[fyresq]

So I want to put in a 700r4 tranny into my cruiser with a GM crate sbc ~250-280hp with a D300 4:1 behind it but my tranny guy keeps telling me its a bad idea. He says they are notorious for dumping fluid on incline and cavitating the pump and/or when you level again push big air bubbles thru also cavitating the pump and that the pump is pretty weak in the first place and cavitating will surely blow the pump up. He says I'd be much better off with a T350. I wanted the OD because I do want to drive it on the road every once in a while and be able to drive to long distance trails without running 2800 rpm the whole way. It's loud, gas hogging, and engine wearing and is nice to cruise IMO but I also don't want to be busted in BFE with no tranny. How can I overcome the pump issue and how hard do you guys wheel that run the 700 and am I in for even more suprises with the 700? Oh yeah and mine is out of an 89 3/4 ton.

[Eskimo]

Originally Posted by fyresq

So I want to put in a 700r4 tranny into my cruiser with a GM crate sbc ~250-280hp with a D300 4:1 behind it but my tranny guy keeps telling me its a bad idea. He says they are notorious for dumping fluid on incline and cavitating the pump and/or when you level again push big air bubbles thru also cavitating the pump and that the pump is pretty weak in the first place and cavitating will surely blow the pump up. He says I'd be much better off with a T350. I wanted the OD because I do want to drive it on the road every once in a while and be able to drive to long distance trails without running 2800 rpm the whole way. It's loud, gas hogging, and engine wearing and is nice to cruise IMO but I also don't want to be busted in BFE with no tranny. How can I overcome the pump issue and how hard do you guys wheel that run the 700 and am I in for even more suprises with the 700? Oh yeah and mine is out of an 89 3/4 ton.

Sounds like your trans guy formed an opinion 25 years ago and won't budge. I like my 700R..

[orangefj45]

find a new transmission builder. i have a small block, a th700 and an atlas in my rig ..........

[Waggoner5]

I have run 700R4s behind big blocks with out an issue. It definately is my tranny of choice behind small blocks.

[GreasedPiggy]

The pre-'86 700R4's just killed the reputation of the line. It has the broadest gearing of any stock auto trans made. Less spinning internal parts result in less parasitic drag = more MPG.

A "K" case version can be built to handle over 1000hp. Definitely have to use one with all the post-1986 factory upgrades if you find an earlier one...

[Isotel]

no issues with mine either, Go for it!

[woody]

love mine...I've got about $1k in it, and it's been bulletproof for over 2 years

[4rnr]

This guy I know lent me his 40 with a small black and a 700 and a dana 300 4:1. It takes a bit of a beating with no problem.

[fyresq]

I realize they'll handle the horsepower and can be built tough, but does the "fluid drain on prolonged inclines" have any merit? I know all autos have issues if you flop your rig on its side. Unlike the manuals, it won't work if you try to drive it on its side. The guy was saying that with the 700r4, you will run into the same problem on inclines and declines as well; that the fluid will drain and the tranny will stop working and, without the fluid, the pump will go and even if you tow it to flat the air bubbles may still cavitate and ruin the pump. I know most of you have to wheel pretty hard.......have you felt slipping or lack of response while sitting on an incline for a while? I was told a solution could be a bigger sump, but I would really like a flat belly.

I just want to do this right the first time and not wish I hadn't spent a grand on a transmission that the pump will keep going out on.

Thanks for all the responses so far

[woody]

I laid mine on the passenger side in Rockport in a V-ravine....left tires off the wall, not quite at a 90 flop, but 75 degree-ish....

turned the rig off for about 10 minutes while Wicket and I survey'd my options....

got back in, fired 'er up, and proceeded to move back and forth about 20' on it's side...then gave up and winched over.

no complaints.

[Gumby]

Can't speak for a 700R4 here, but my Th400 runs just fine on it's side. It has a really deep sump.

[orangefj45]

put a deep pan on it and it'll work perfect. or about as perfect as an auto will at severe angles. by the time you loose fluid pickup you'll have bigger problems.....


also, if your "transmission expert" is telling you that air bubbles in the pump or air in the pump will cause pump failure, then you really should think about consulting a real expert.
of course prolonged pump operation without fluid for lubrication and cooling can cause the pump vane washer (plastic star washer that spaces the vanes properly) to heat up and distort which can/will ultimately cause premature pump failure, but you'd have to run it without fluid going thru the pump for a while. nobody with any kind of respect for their vehicle and equipment should ever have to worry about that possibility. common sense tells you to shut off the rig when the pump is sucking air. chances are you'll be upside down at that point in time so the engine won't run long enough to cause any pump damage no matter what.


i love "transmission experts"!


fwiw, i have built/assisted numerous th700 builds and conversions, including woody's and isotels as well as customers' vehicles and my own. we also run one in our hendrix buggy behind a healthy small block (currently being replaced by an LS1) in front of an atlas with 42"s. it's been up and running for 2 years plus. we've had it at the hammers, rubicon, moonrocks, fordyce, katemcy, moab, the trails around phoenix,.......... and the only time we lost pump pressure was when the rig was laying on it's side and we tried to drive out of it. after about 15 seconds it did loose pressure. so we shut it down, winched it out and drove it the rest of the day, the rest of the month, the rest of the year. guess what?! lotsa air got in the pump and it's still working to this day.

so please put your unfounded fears aside and have some faith in autos. i do.

[warpdriv]

No probs out of mine. Give http://bowtieoverdrives.com/index.shtml a call for a point of reference. Nice people to talk to.

[fyresq]

Have no doubt that this advice is making me more confident in using the 700r4 I have........now to find a tranny guy. I'd love to try and do a tranny myself but I'm pretty much retarded when it comes to tranny's. After all, I almost let a tranny shop owner talk me out of putting one in the cruiser.

[warpdriv]

I have found that when building a vehicle, talk to a lot of people and see what works. That is what I did before I started building my 40 and 60. That is what is great about this forum.

[Cruisertime]

Ummmmmmm your trans guy does know that a 700R4 is a TH350 with over drive right? Yes, the R4 sucked when the came out in trucks cause they were stripped directly from the GM car parts bin. Since then over built solenoids, overbuilt internals, and high flow pumps are avail......there are tons of places selling hop up parts out there for this tranny. I bought a "raptor in a box" for around $600 and just had a local shop build it. Little over $900 and the 40 was happy.

I

[orangefj45]

Originally Posted by Cruisertime

Since then over built solenoids, overbuilt internals, and high flow pumps are avail

the electrical components in the th700 have stayed virtually the same truout the years.

the main parts that did change were:
the input shaft was strengthened by going from 27-30 spline models
the input drum was updated also
the pump was updated from 7 to 10 vane rotor (13 vane model available also and standard in the "E" version)
the valve body has gone thru numerous chages, the best version being the latest 700s from 88-92 with the 'auxillary" valve body for 4th gear
low sprag assembly was updated from the th350 version

one mod certainly worth doing when rebuilding a th700 is to replace the sun gear shell with the HD "the beast" version.

hope that helps.

[Eskimo]

Funny thing about deep pans, they don't come with deeper pickups. I just run mine 1 quart overfilled.

Anyway, I've had my LS1 lose oil pressure, the trans was still pulling, sitting just about vertical. I've never had it slip while going downhill, and the atached picture shows that it handles off-camber just fine. I drove out of this.

[orangefj45]

some of the deep pans do come with a longer pickup or a tube adapter. do some shopping around......

although the extra volume alone normally takes care of any fluid pickup problems.

[RVBtruck]

I'll have to call bullshit on this one. As stated earlier in the thread, the early units had problems with their pumps that can be easily rectified during a build. The later 700's are gtg from the factory for most purposes. I've put out at least 5 units for serious off road & 3 in "hardcore" rigs and not one problem from them. Great unit and it is actually my preferred unit behind a chevy motor for ALOT of applications. On and off road it's hard to beat the excellent 1st gear(3.08 iirc) and having the OD.

[RVBtruck]

[quote=Eskimo;2445583]Funny thing about deep pans, they don't come with deeper pickups. I just run mine 1 quart overfilled.]

Careful with that it will cause foaming if you go too far, more of a problem than cavitating it at times.

[RVBtruck]

The actual "best" way to insure good transmission life and dependability is to use an Accusump type system in the transmission cooler lines. This ensures pressure and lubrication at all times even during brief moments of cavitation. But really only necessary in extreme uses.

[Eskimo]

Originally Posted by RVBtruck

Careful with that it will cause foaming if you go too far, more of a problem than cavitating it at times.

I have heard this, and I believe it, though not so much as I do on an engine, BUT.. A guy who is extreeemly hard on parts runs a 400hp LS1 and a TH350 behind it, and he fills it "until it pukes out the vent", and then it's good to go. His transmissions are holding up well.. He never has issues at any angles, nor has is cavitated and not put the power to the output shaft.

If we were street driving, desert racing, etc, filling it till it pukes isn't a good idea. I doubt a quart over will kill it.. Just my $.02

[orangefj45]

they'll puke out the extra fluid either way. just makes a big ass mess. that's why i run a length of rubber tubing from the vent down to the frame.............

[fyresq]

I certainly appreciate all the input. It has kinda sealed the deal for me as far as using it. Funny thing is - my dad has a t400 in his heep and it's starting to slip and make noise, so after talking to him about the 700r4 he wants to throw one in his rig bad. I had to change the code on my doors to keep him out and away from mine....

Thanx again