Turbo 350 vs TH 700r4

[crazy4offroad]

Cool I thought a lockup (RV) converter would be the hot ticket in a mud truck, especially a racer since grabbing gears it would be like a standard. I dont think the one I have is lock-up, since there is no plug on it. It does have the big "K" on the bellhousing, and it was bolted to a NP203 with the front flange output for the dshaft, so that puts it between 78-81 I think?

 

[89Suburban]

Excellent point to bring up 89S. Don't ever fall for that . You should change your fluid and filter every 50K miles. Some will say more often, but they are usually trying to sell fluid and parts. If you tow alot or abuse your trans, you might wish to do it more often, say 35-40K. But, if you maintain your tranmission properly, YES you should change your fluid at those intervals no matter what the mileage is, even high mileage. In the event you have 120-140K and now you decide its time to change the fluid and filter, now you might have a problem. Because you may do is clean out gunk and junk out of the transmisison that has became a part of the transmisison and its tolerances. So now you clean the junk out, and your tolerances are much looser and you might start having problems. So the rule is. If you have always properly maintaned your trans, then continue to do so and you should get good life out of it. If you have NOT maintained your transmission and have let it go high mileage without maintaining it, then don't bother doing it now. Leave well enough alone and drive it until it quits. And btw, for all of those who have a slipping trans and think changing the fluid and filter will help, NO, don't waste your money on the new fluid and time for the job. The damage is done, its to late.

Sunnnuva bitch. That's the omly thing that sucks about buying pre-tested vehicles, you never know if the previous owner religeously maintained the trans and I expect a lot of people just run them and don;t give a **** about the trans if it's working fine. Maybe I should leave mine alone then, I don;t know. I hate this ****...

 

[Old77]

Great thread and GREAT info for when I start scouring the yards and CL for a 700R4 to build and put in the 77! I just know the OD will make the truck even more enjoyable to drive. We should make this thread a sticky because I know the question will come up again in the future was we get more new users (i.e. newbies! )

 

[89Suburban]

Great thread and GREAT info for when I start scouring the yards and CL for a 700R4 to build and put in the 77! I just know the OD will make the truck even more enjoyable to drive. We should make this thread a sticky because I know the question will come up again in the future was we get more new users (i.e. newbies! )

****, that will be a nice trans for your ride hoss, smooth highway rpm'n dawg.

 

[Swims350]

nice info and write up.


I'll stick with my th350's though.

 

[Old77]

****, that will be a nice trans for your ride hoss, smooth highway rpm'n dawg.

No doubt! I'd love to just cruise at 2200 rather than 3000 especially with my 40 series flowmasters. Those things are LOUD at 3000+ RPMS! Nearly impossible to hold any kind of conversation while driving on the highway especially in the summer when the windows are all open.

 

[Old77]

nice info and write up.


I'll stick with my th350's though.

Why?

 

[HotRodPC]

Cool I thought a lockup (RV) converter would be the hot ticket in a mud truck, especially a racer since grabbing gears it would be like a standard. I dont think the one I have is lock-up, since there is no plug on it. It does have the big "K" on the bellhousing, and it was bolted to a NP203 with the front flange output for the dshaft, so that puts it between 78-81 I think?

OK, that takes the guess work out of tht one C4. KEEP IT KEEP IT KEEP IT. DON'T LET GO OF IT. No lock up is weaker and DEFINATLY, not stronger. For a mud truck you want strength. That big K, is a good thing, and a bit more rare. Some make a big deal of the K, and true, it has an advatage. The K case is stronger in the bell housing bolt bosses. Great for offroad, that is why the 4x4 cases are usually K case. But many times they are not. KEEP IT. Even if the hard parts are rusty, you can find a donor 350 for the hard parts IF your are rusted up. I have picked up a few T350's that a guy was throwing away. Or find one that has a broken bell housing. I have acquired most of my cores, but telling people in CL that are selling broken transmisison and wanting $50-$150 for them, hey partner, I build transmissions, and I do buy cores, but cores these days are only $25, so if you don't sell it and it needs to go, before you go scrap it for $3-$5 call me up, and I'll give you $25 for it. About a month later they usualy email and ask if I am still interested. If its close, I'll go get it, but they are so common, not gonna spend an hour and $15 in gas to go get it. So hit up a few CL adds til you get you a good core. And for hard parts, it don't matter 2wd or 4wd, or the size of the tailshaft housing. Just get the core. Try to avoid the lock up though since the input shaft and pump are differant. But do KEEP THAT ONE YOU HAVE. Don't cut loose of it.

 

[HotRodPC]

Sunnnuva bitch. That's the omly thing that sucks about buying pre-tested vehicles, you never know if the previous owner religeously maintained the trans and I expect a lot of people just run them and don;t give a **** about the trans if it's working fine. Maybe I should leave mine alone then, I don;t know. I hate this ****...

A good tell tale sign if its been maintained is look at the color of the fluid on the dipstick. If its pretty red, its likely been maintained since with high mileage by now, it would be brownish red from all the diluted clutch fibers. So if its red, maintain it, if its brown, drive it til she blows, then rebuild it and make it better than new !!!

 

[crazy4offroad]

WV is one of the shittiest states for CL, I hardly ever see anything worth getting, and when I do it's too far of a drive to justify. The local Ad Bulletin is a better place to find things, which I forgot to get a new one this week. I went down and checked, it doesnt have the input shaft like the one you showed in the pics, but trying to turn it, it's froze up solid. I wanted to start tearing into it when I got it but I was in the middle of the axle upgrade, and figured with all those different parts laying around something would get lost or misplaced, but I should have at least took the pan off and made sure it wasnt holding water. It sat under the eve of a garage with no dipstick tube and rain water running on it, so I know the bottom is full. I think I did turn it over at the guys place and try to get some of the water out but fluid was coming out too so I flipped it back upright and took off with it before he could bitch about making a mess and not let me have it lol.

 

[HotRodPC]

No doubt! I'd love to just cruise at 2200 rather than 3000 especially with my 40 series flowmasters. Those things are LOUD at 3000+ RPMS! Nearly impossible to hold any kind of conversation while driving on the highway especially in the summer when the windows are all open.

Yes, I don't always reccomend going 700r4, but your truck, its purpose etc, its a good candidate for 700r4. Sounds like you got a low rear gear already too. Which as mentioned earlier. That is one of the advantages to a 700r4. Run low rear gear and OD to compensate so you got the better of both worlds. For the guys who have 3.08 or 2.73 gears in the rear, I don't reccomend a 700r4. Stick to the T350. That tall gear 3.08 or 2.73 puts a strain on the trans too, espeically if going to be pulling a trailer or carrying heavy weight. You'd likely also seee a bit of mpg gain too, where the guys with a 3.08 or 2.73 gears won't. There comes a point when your RPM's at cruising speed are to low, and also putting a bigger strain on the 3-4 clutch pack in the 700r4 causiing excessive heat and coning of the clutch pack. One of the upgrades I do to the 700r4 is the Z pack. Its a 14 single sided clutch pack instead of the OEM 5 or 6 cluthes, that get hot and start to curl. The Z pack eleimates that and is about 50% stronger. Using the right servo to hold the 3-4 clutch pack tighter, and the use of the Z-pack, you can acutally use OD to tow about 4000lbs. You damn sure won't have a trans last towing that weight in an OEM build in a 700r4.

 

[HotRodPC]

WV is one of the shittiest states for CL, I hardly ever see anything worth getting, and when I do it's too far of a drive to justify. The local Ad Bulletin is a better place to find things, which I forgot to get a new one this week. I went down and checked, it doesnt have the input shaft like the one you showed in the pics, but trying to turn it, it's froze up solid. I wanted to start tearing into it when I got it but I was in the middle of the axle upgrade, and figured with all those different parts laying around something would get lost or misplaced, but I should have at least took the pan off and made sure it wasnt holding water. It sat under the eve of a garage with no dipstick tube and rain water running on it, so I know the bottom is full. I think I did turn it over at the guys place and try to get some of the water out but fluid was coming out too so I flipped it back upright and took off with it before he could bitch about making a mess and not let me have it lol.

They are stiff by nature and hard to turn bare handed. If it got some water in the pan, big whoop, no severe harm should be done. If it sat in water submerged about 6 inches deep, then there might some rusted hard part and some stuck servos, but even then, it still a good case and the case is not affected since aluminum doesn't rust. Its definalty a builder worth keeping and having built.

 

[nxtlevl]

Excellent info.... My truck has the 700r4, which apparently was built by MadDog Transmissions confused according to the decal on top of the housing...Never heard of them before, so I have no idea how strong their builds are...
Haven't had any issues yet, but from the sounds of things I just might have to make the 4 hr drive to OKC when the time comes......

 

[HotRodPC]

700r4 TV (Throttle Valve) Cable

One other HUGE point about a 700r4 that can not be stressed enough is the TV CABLE MUST BE CONNECTED and ADJUSTED PROPERLY. Most people think its just a kick down cable, so I'll hook it up later when I get my linkage modded. But NO, in as low as 100-200 miles you can cook your transmission. Very common when people do Eddy carb upgrade that does not have provisions for the TV cable, so they leave it unhooked. DON'T DO IT.

On a 350 the Detent cable (known to most as Kick Down cable) is used to help determine shift points as well as kick down. So if you have a T350 and its shifting way early, its likely becuase the cable needs adjusting or isn't hooked up. But no harm is done by not having it hooked up.

On a 700r4, the Throttle Valve cable gets info from the thrttle likage as to what you are doing, light throttle, medium throttle, or wide open throttle etc. With that information, the trans decided how much pressure to apply to compresses a given clutch pack. So if light throttle, light pressure, if wide open throttle then higher pressure means holding the clucth pack tighter. WO the cable hooked up, the trans thinks light throttle so it does light pressure, and if you are doing WOT or medium throttle with low pressure, you are slipping the clutches and creating alot of heat which cooks the trans. Makes sense huh??? So, if you are in a situation where your cable isn't hooked up. You can drive it, but keep in mind the trans thinks you are being light on the throttle, so do that. Be light on the throttle, slow takes off etc, and I would sure not use OD without the cable hooked up. I only suggest this to use in a pinch or a bind to get home, but I suggest avoiding it at all possibities.

 

[HotRodPC]

Excellent info.... My truck has the 700r4, which apparently was built by MadDog Transmissions confused according to the decal on top of the housing...Never heard of them before, so I have no idea how strong their builds are...
Haven't had any issues yet, but from the sounds of things I just might have to make the 4 hr drive to OKC when the time comes......

Great Trans nxt !!! Mad Dog Transmissions are good. I actually have learned some of my tricks and upgrades from him. He's a biggo ugly dude, must be where he gets his name Mad Dog. But he does know transmissions.

BTW, these upgrades and building a 700r4 isn't a secret really. Eveyone who builds good transmisisons, does about the same things. Its the pricing that makes the differance. Some polsih the case the make it to pretty, some have big advertising, like Monster. Who has heard of Monster transmission? Noone !!! Its all a matter of what upgrades to do and for what, and what kind of use. But as bad as a reputation as 700r4's have in an OEM fashion, a 700r4 can easily be built to handle 600hp with the right mods. And even more with some more expensive mods. Also don't always think more is better. Example being a 700r4 comes with options of 7 vane pump, 10 vane and 13 vane. Many builders go with the 13, some don't. Its an opinion thing. I agree with going with the 10 Vane. You get to many vanes in the rotor, then that is less meat between the vanes and can make them weak. Yes stronger for pressure, but weaker for strenght in the rotor. A good quality 10 vane rotor should be sufficient, espeically if using a .500 boost valve in the pump to increase pressures.