700r4 Overdrive

[Subourbon]

@Ricko1966
Yeah the kit ive got has a thermostatic switch to kick fan on at 185f and off at 175f if im not mistaken.

So, in your comment you mention going to aux cooler first, then back to stock rad, and back to trans.

Heres a pic off the kit, it does the opposite, stock rad first, then aux cooler.

because if we gonthe way you mention, the atf will be at the temp ofnthe engine coolant (or around there) taking into account efficient heat transfer.

And other way, itll be whatever thermostatic fan switch i end up installing (there are many availble)

I almost wonder if the gains in cooling at gained just by extra volume in the system. At which point, get a deep pan and finned for extra volume

hmmm

 

[Subourbon]

Oops forgot to attach pics, my bad.

 

[Ricko1966]

No they make a thermostatic valve to bypass the cooler below a certain temp not just turn on a fan. My gut says the cooler manufacturers recommend that routing because they can take an already cooled( by the radiator) fluid then bring it down some more even if it brings it below optimal. Guys that aren't thinking about too cold isn't good either can see the dramatic difference. Where as if they had been watching a gauge forever and thier temp was 195* and they put on a cooler and bit was still 195* then people would call thier coolers junk,they don't do anything.

You must be registered for see images attach

 

[Subourbon]

Yeah yeah i get what youre saying.
I dont doubt the efficiency of the aux coolers, I am concerned about winter though. Either I warm up the truck for 5 mins minimum before going anywhere or, I route it the way you suggest and the coolant regulates it at its designated temp.

It was all stock when I burnt out 3rd gear clutch pack though and it was end of September too when it happened. I'm still confused as to why that happened.

Geez I might look into a thermostat for my poor engine oil cooler, oil pump definitely won't like pumping molasses from the aux in january lol

 

[Ricko1966]

Yeah yeah i get what youre saying.
I dont doubt the efficiency of the aux coolers, I am concerned about winter though. Either I warm up the truck for 5 mins minimum before going anywhere or, I route it the way you suggest and the coolant regulates it at its designated temp.

It was all stock when I burnt out 3rd gear clutch pack though and it was end of September too when it happened. I'm still confused as to why that happened.

Geez I might look into a thermostat for my poor engine oil cooler, oil pump definitely won't like pumping molasses from the aux in january lol

I edited my last post to put up this Pic. They also make thrmo bypasses for oil coolers

 

[Subourbon]

Yep, I think I'll be safer with one of those. Otherwise next post will be how do I change blown up oil pump in the winter lol. Have one for trans too at the same time.
It's not uncommon where I'm at to drop down to where celsius and Fahrenheit meet at -40. Lok i jad the truck plugged in and at minus 40 it was not having it. At all.

Nice I appreciate the heads on the thermostatic valves. Hopefully the fittingd are compatible

 

[gmbellew]

I have aux cooler only, but winters in KC are a little more mild. maybe some single digits to negative 10 for a few days. mostly between 0 and 30 for the lows. I figure the transmission makes enough of its own heat that I dont worry about it being too cold. not many transmissions die because they are too cold...but if you are in the -40f range, I'd probably route it thru the rad first...

 

[Subourbon]

Yeah, the thread got a bit off topic for a bit there coz we were discussing exactly that, cooler placement and routing and thermostatic valves...

 

[Steelbuddha]

No need to take it out of OD unless you're towing. I've never had trouble with shift points on a 700R4.

Just don't be like my friend who melted his Toyota Tundra transmission by thinking you were supposed to drive around in 3rd gear all the time, but put it in overdrive for towing. Doesn't work so well. (He is still my friend, but he required an extensive lecture on transmissions and gear ratios .)

 

[Mike_82_Shortbox]

So basically guy said yeah shift it in (D) and leave it there all day, doesn't hurt coz OD won't kick in until it's needed on the highway and that's that.

But now I read that it's not good, wears out trans faster and messes with shift points.
Is this true?

 

[Mike_82_Shortbox]

There are some different ideas of what overdrive means on a 700R4. The 700R4 is essentially just a four-speed automatic transmission that is good for about 350 foot-pounds of torque. It is 100% mechanically governed; no solenoids, no vacuum, no TCU. It's the original plug-and-play transmission. It is sometimes thought the 700, not being related to either horsepower or torque, refers to the 0.7:1 gear ratio of fourth gear. The R stands for rear wheel drive, and the 4 stands for four forward speeds.

Being that the input shaft of the transmission rotates 7/10 of a revolution for every revolution of the output shaft in fourth gear, fourth gear truly is overdriven, thus the term overdrive. But there really isn't anything else special about it; it's just another gear. The other confusion about overdrive in this transmission is the presence of the lockup torque converter. Some people call that overdrive. It can sometimes feel like the vehicle is hitting fifth gear when the torque converter locks up on the freeway, because all slippage in the torque converter is eliminated, and the engine generally jumps down 50 or 100 RPM depending on the terrain. At that point the engine is also rotating at exactly the same speed as the input shaft of the transmission, thus the engine itself is rotating at 7/10 of a revolution for every revolution of the output shaft of the transmission.

A lot of car and truck models had different gear selector indicators, for example, I have one in my 82 Chevy C10, and I have been driving it in Drive for 20 years. My indicator says PRND321. The torque converter lockup has never worked, until recently. I put a high-performance small block 400 in my truck, installed a 12-bolt rear end with a 3.73:1 posi-track gear set, and took my transmission to a guy who rebuilt it and made it slam into every gear. He also rewired the lockup system somehow so all I had to do was put 12 volts to a wire, while the transmission was in fourth gear, and I got lockup. So while I am cruising on the freeway, all I have to do is flip a switch, and I have lockup overdrive.

The 700R4 is a great transmission. And because of the fourth gear ratio, I can run my 3.73:1 rear end, and still cruise at 70 mph on the freeway. The 700R4 is simple, tough, and if you adjust the Throttle Valve (TV) cable properly - only about 1/32 of an inch at a time in either direction - it will shift the way you want, and it'll last forever.

 

[Subourbon]

@Mike_82_Shortbox
Wow, that's like more in depths than a Wikipedia page on the 700r4, that's really cool, I appreciate the history and the break down of the name of trans and what it all means.
And yeah ive heard of the torque lock up but not on these, I think dodges have the OD torque lock up
I'll be honest, transmissions to me are a magic box between the engine and drive shaft.
I have lots of question on engine stuff too, but typically I understand way faster and easier than transmissions. I dunno why, theyre just intimidating to me. A bit like wiring, you know, a mistake can be quite dear.

The TV cable, adjust it 1/32 at a time, see when I took off the bracket for the TV cable, when I replaced the glow plug controller, (it's an 82 so I've got thst grey monolith controller that threads directly into the block). I fi wished the job started the truck and no pedal reponse.

I read inline, push that plastic tab on TV cable bracket, and stomp on the accelerator pedal. I did that, and it worked. So 1/32 sounds like some precise engineering, meanwhile I ugga dugga'd it like a caveman. But it worked!

Coz I have this noise a low speed while parking or turning, reversing. Low speed maneuvers, at first only when turning the wheel, but now it's intermittent at low speeds....

So ok, i thought diff, prompted an oil change and doff inspection. Everything looked fine.

So steering, new u joints tie rods etc... still does it.

I mentioned earlier the trans was rebuilt since I burnt out the 3rd gear clutch pack.

And it still does it. This tack tack tack kinda popping/grinding noise. Sometimes fast sometimes slow depending on vehicle speed.

So that leaves torque converter and flexplate. I think? But again it's only low speed. Wouldn't a higher speed be more detrimental to a flywheel/torque converter issue.

Notr: i don't even know if it is that. I need to investigate further.

I have no issues starting.
I'd wouldn't say the engine vibrate or shakes anymore than normal, at idle, jt runs smooth, all of which wouldn't be the case is the flexplate was being beat up.

 

[Long Rider]

I was the service manager at a Chevy dealership when the 7ooR4 came out. We are in a farming ranching community. We started getting grumpy customers nearly right away because of the trans going out. At first Chevy told us that they didn't know of any problems, but shortly after that they sent us a two-page addition to the owner's manual for our customers. It stated that the OD, should not be used if they were towing or hauling a load. Our problems came from doing what farmers and ranchers do every day. Lesson learned. Only use OD when your traveling without a load. I still have a 1986 Chevy C20 with a 700R4 that has over 100k on it. Just my opinion but I also use D for around town.

 

[NickTransmissions]

Thats really helpful, as well as other comments, cheers everyone.

There's still seems to be a split between driving daily in OD vs taking care to city drive in D and highway in OD.

Well, I've been doing it in OD, no matter where, for years. I'll try it the other way, see if there's a difference.

Outside of towing moderate to heavy loads, there is zero harm or exposure risk to the transmission by simply keeping it in the primary drive range position. I have never heard of anyone's transmission failing just because they keep it in drive. None of the thousands that I have built over the past 15 years have ever came back due to not manually shifting it all the time (which is a pain in the ass for an auto trans).

If towing or hauling heavy weight, manual shifting helps spread the load over more applied elements in the transmission. This prevents any one of those elements from being overstresswd by the load.

Beyond that, keeping it in drive is perfectly fine.

Please share the link to whatever site or page where you read that driving your vehicle in D4 all the time is bad and damages the transmission.