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I liked what frank did with the 4l60e thread on tips/tricks/mods and figured since he's putting in the work there, I'll put in some work for the 700r4 platform.
I'll kick it off later tonight with some tech regarding some of the misunderstood valves in the valve body. TV limit, MTV, Line Bias, etc
What their function is, how modifying them can change trans behavior, and why we might make one change or another.
Then we can get into some topics like WOT 4th gear shifts, pump mods, etc
Anybody else that is willing PLEASE chime in. I don't want this to be me just sounding off. Share your own mods. Ask questions. Debate. Etc.
I'm usually better at answering a question than I am at just doing a bid ol data dump.
Excellent While mY FIRST overdrive was the 200-4r as my best friend bought a Grand National , The 700r4 was my second. I was young but remember so many builders of the time were afraid of it, Built and tried to put on in my 1973 caprice 2 door coupe with built 454 unfortunatly it was 1984 and well its snapped the input shaft , I then softened the shifts and it killed what was at the time bizzare looking input sprag I have a photo of one some place ill post later ON MY FIRST WOT kickdown. Then tried one last time after I figured out the overun clutch was on in D3 and then I snapped the sunshell and I remember for the moment I gave up lol , But thought it would be so cool to have OVERDRIVE particulary with my 411 gears. Then I tried the 200-4R and learned what happens when you block the 4th accum and do a WOT at 5000 rpm unlike the 700 they HIT hard when you do that and i left the entire back half of the trans on the road behind me. FUN TIMES LOL .
Then I gave up for a couple years till better parts came out and just built the 700 for stock apps .
But this will be an interesting thread I feel sure as not many talk of the 700r4 anymore and it has many tricks and such cool stuff I will in particular look forwward to your post and may add a few of my own too. Though I do still build them I generally try and steer away not because they are not strong or good enough , But because so many seem to have such a hard time with the TV cable which I have never understood why but they do.
And the Timings perfect as my next build happens to be a 700R4 maybe I can pick up some new tricks too
__________________ Frank formerly of Performabuilt, Now just me, What can I build for you today? Call or message me. Click sig pic for my facebook
I'll try to break this out into sections so that it's easier to digest, and helps keep this thread organized.
I'll start by going systematically through the basic valve body functions and I'll mention some mods but won't really get into them until questions are asked or until we make it through the conceptual/understanding bit.
First up: TV Limit valve
The TV limit valve is akin to the AFL valve in a 4l60e for any who are familiar with that.
The TV limit valve is a spring-regulated valve that's purpose is to LIMIT the amount of oil pressure that is delivered to the TV valve which feeds oil to a myriad of valves after that. (Accum, Line Bias, MTV up, MTV down, all shift valves, and the converter clutch valve)
This valve is fairly simple in operation. Line pressure comes right from the pump to the 3rd port in the valve (counted left to right. 1st port would be exhaust as you can see in the drawing)
The spring holds the valve to the left and oil can flow from port 3 (line) into port 2 (tv feed).
Oil from port 2 is then orificed back into port 4. port 4 has a larger land on the right side which will hydraulically stroke the valve out against the spring. As the valve strokes out, it closes the feed from 3 to 2. Limiting the oil.
The spring rate is setup such that this limiting action happens in a position that will limit the pressure in the TV feed circuit to 90psi
The TV limit valve's only job is to regulate the oil pressure being delivered to the TV valve at around a steady 90psi max (in factory form)
This 90psi max is usually met any time there is enough pump volume to sustain 90psi of line pressure.
The 700r4 may idle around 55-65psi which is fine. Oil will just be delivered to the TV valve at line pressure during operation under those conditions. But as soon as pump volume rises and line pressure is 90+, the limit valve will regulate oil at the TV valve to 90psi.
This sets a steady base pressure that can then be metered by the TV valve.
If there was not a TV limit valve, there would be a nasty feedback loop in the TV/Boost valve circuit.
Line pressure would go up-so then TV pressure would go up (even at the same throttle opening) as TV pressure goes up, the line pressure goes up...which starts the loop over.
We would get into a runaway line situation until you're maxxed at whatever the boost valve and PR spring are capable of producing.
The limit valve prevents this, and sets a solid steady feed pressure to work off of.
It is not common in any "off the shelf" kit to modify this spring.
This spring and valve really acts like the conductor for a whole orchestra. It sets the tempo and controls the volume. If you were to increase the spring rate, you'll change the entire tv oil curve up or down. that would change shift points. line pressure, shift firmness, etc
When I would come across a Valve-Body and Governor that did not have the Shift Timing/ RPM that was desired...
I could increase the TV Limit Pressure to schedule Shifts up higher in the RPM Range along with Governor Changes.
Or I could decrease it and lower said changes.
If the TV Valves and Springs for each Shift Valve-Train (1-2, 2-3, 3-4) were not allowing for the desired Shift Timing...
Changing the TV Limit Pressures, would allow for fine adjustments.
I'll also Note that excessive TV Pressure at Low Engine-Speeds/ Idle will often result in 2nd-Gear Starts, instead of 1st-Gear Starts.
So don't get too greedy with it!
Next up is the TV aka Throttle Valve
I'll do my best to not say "TV Valve" as that would just be Throttle Valve Valve
This one will be fairly short and sweet to describe its function as a standalone.
We will later on get into how it affects EVERYTHING else in the transmission...but for now we will just stick to putting the TV in a box and focusing on how it works standalone
The throttle valve is basically just a 1:1 relay of throttle position to the trans.
It takes the throttle position given by your foot, and turns that into hydraulic pressure.
There is always a little bit of tension on the cable at 0% throttle *let's say that's 5psi in the TV circuit*
And at WOT the TV is "wide open" and delivering however much oil the TV limit valve discussed above will deliver. Typically 90psi.
Assume a linear relationship between Throttle position and TV
This acts as the "brain" of the transmission.
TV oil acts on lots of other valves to relay the information from your foot.
It can be used to increase line pressure, delay shifts, force kickdown shifts, adjust shift firmness, etc
This is why TV adjustment is SO critical. And having the proper TV geometry on your bracketry at your carb/throttle body is also critical.
With the wrong linkage setup, that 1:1 relay might not get properly transmitted.
Maybe it's a 1:0.8
Meaning even at 100% throttle...the trans only sees that as 80% throttle (hydraulically speaking)
That's going to mean incorrect shift firmness, shift timing, detent timing, etc
Improper cable adjustment can mean that maybe you have the cable "too loose"
Thus there will be a delay between when you move the throttle, and when the TV in the transmission actually moves.
So you might be at 20% throttle...but the trans hasn't had the TV move yet so as far as it knows...you're at 0% throttle
Then when you get to 50% throttle...it's still behind by 20%...so it's going to only have enough line pressure for 30% throttle.
You can see how this could cause all kinds of funky behavior and worst case scenario...a burnt up transmission!
Just think of the TV as a TPS sensor...for the trans.
If you have the wrong TPS information to an engine...it won't get the proper fuel. It won't run right.
If you have the wrong TPS information to an electronically controlled transmission like a 4l60e, 6l80e, etc...it won't have the right pressure, it won't shift at the right time. It will just be all out of whack!
Be sure to get proper cable bracketry with accurate geometry. And be sure to properly adjust the cable.
Attached is a representation of how the TV works hydraulically. As well as a great drawing for proper bracketry dimensions if you have to check yours!
Up next is Line Bias
This is a very commonly misunderstood valve. And there's lots of guesswork across the net if you go searching.
I hope we can help make some sense of it here.
The line bias valve is very similar in operation to the TV Limit valve...It's just a limiting valve. But in this case, the Line Bias valve is placed between the TV and the Boost valve & accumulator valve.
The line bias valve turns TV oil into MTV oil. MTV oil is what's fed to the boost valve in the pump to control line pressure.
The Line Bias is intended to help give a quick initial line pressure rise, then taper off into a more gradual line pressure rise.
We want the pressure rise to taper after a certain point in stock vehicles because otherwise the shifts at heavy throttle would become unnecessarily firm.
Stock vehicles don't want/like/need to be unnecessarily firm.
BUT...they do need a quick initial rise to be capable of holding the tq the engine is producing.
In stock form, the Line Bias valve allows pressure to rise linearly until about half throttle...then it begins to taper off.
This is because Engine tq is not linear to throttle position. It follows a curve with a steep slope initially that tapers off.
At 50% throttle you might have 75% of max torque.
We want line pressure and shift firmness to follow the engine tq, not the throttle position.
This poses a problem with the Throttle Valve. Remember from above the TV is linear.
So, how do we make sure line pressure rises differently than TV rises? With the Line Bias Valve!
The line bias valve acts like a bouncer at a party.
When the party is empty, the bouncer will just let anybody in the line walk right in.
As the party starts to fill up and the venue is nearing capacity...he has to slow the number of people he can let in.
The line bias valve starts in the open position. It will allow TV oil to freely pass into the MTV circuit. For this stage of Line Bias operation, MTV is equal to TV. This gives the quick
MTV oil is fed to the end of the valve and tries to move the valve against spring pressure.
As TV pressure (and MTV pressure) starts to rise the valve begins to close against the spring. As the valve closes MTV will no longer be equal to TV. It will be less than TV.
This gives the "taper off" effect we're looking for so that the shifts and pressure don't get out of control.
MTV oil acts on the boost valve which controls line pressure
MTV oil also acts on the accumulator valve. This valve is used to control shift firmness. As MTV pressure tapers off...so will the accumulator oil pressure...which will keep the shifts firm but not let them "run away" and get too firm.
Now...how/why might we modify the line bias valve? Anybody that's installed a shift kit and paid attentiion to the instructions will notice that the line bias valve is one of the most commonly modified valves across any and all kits from whichever brand.
Some brands have you install a stiffer spring. Some have you block the valve entirely.
This is done because the line bias valve can limit the maximum achievable line pressure. So increasing the pressure allowed by the line bias valve will increase the max pressure the trans is capable of making.
Increasing the MTV pressure also means accumulator oil pressure can continue to rise for longer which leads to firmer and firmer shifts.
MTV oil is often modified because most performance or heavy duty based kits are OK with having more and more pressure with firmer and firmer shifts as throttle continues to increase. The kits aren't worried about a grandma in her 83 monte carlo complaining about a firm shift on the way to church.
A stiffer spring will allow MTV to match TV pressure for longer. It will also allow max line pressure to be higher.
Some kits have you block the line bias valve entirely. This means that MTV will always equal TV pressure.
I've attached some graphs that demonstrate how different springs can affect the MTV oil pressure vs TV pressure. And how that will affect line pressure in the trans.
These graphs are not gospel truth, TransGo I'm sure has EXACT spring rate charts but I haven't been able to source them, so this is data I gathered weighing and comparing different springs from Kits I've used over the years. There's a little variance for sure, but you'll get the visual which is the real goal.
Stock Form MTV oil raises quickly then tapers off at around half throttle (just like stock engine tq)
Red transgo spring raises quickly then continues to raise for alot longer until it finally starts to taper off. At around 85% throttle.
Blocking the Line Bias valve open means MTV will just track linear with TV oil.
I know that was really long winded...maybe even turned into rambling.
No Magazine editors here to help make sense of my rambling. But I hope somebody can gain something from it.
If anyone has questions or comments please don't hesitate to chime in! Thanks to those above who already have chimed in and shared some good tidbits.
What should we cover next?
MTV up and MTV down valves?
Accumulator valve and accumulators?
3-2 control?
Governor/shift valves/tv and their combined role in shift timing?
Yes good idea, AIso would like to see his thoughts, Personally I do not like them and do not use that set up as I do not see a way to do this and not cause excessive strain on pump and hard parts, To me its a cop out not to take the time to properly set up the TV cable , But thats my opinion.
And Most shops who use the just do not want to take the tiem to go through the TV set up with customers, Again just my opinion on the matter.
__________________ Frank formerly of Performabuilt, Now just me, What can I build for you today? Call or message me. Click sig pic for my facebook
What should we cover next?
MTV up and MTV down valves?
Accumulator valve and accumulators?
3-2 control?
Governor/shift valves/tv and their combined role in shift timing?
Honestly I would like your thoughts on the MTV up and down, MTV (VIDEO KILLED THE RADIO STAR ) Sorry could not resist.
__________________ Frank formerly of Performabuilt, Now just me, What can I build for you today? Call or message me. Click sig pic for my facebook
Yes good idea, AIso would like to see his thoughts, Personally I do not like them and do not use that set up as I do not see a way to do this and not cause excessive strain on pump and hard parts, To me its a cop out not to take the time to properly set up the TV cable , But thats my opinion.
And Most shops who use the just do not want to take the tiem to go through the TV set up with customers, Again just my opinion on the matter.
I agree with Frank here!!! I have an extensive TV set up page I print & hand out to my customers. I don't even put a pan gasket on the 700R4 or 200-4R transmission when they pick it up. That way they have to pull the pan off, then at least they will look at it...
Here is my 700 one. I made my own because none of the pictures or information was proprietary. The pictures at the end are all mine and anyone can copy them or the document and distribute with my permission expressed here.
What should we cover next?
MTV up and MTV down valves?
Accumulator valve and accumulators?
3-2 control?
Governor/shift valves/tv and their combined role in shift timing?
My vote is 3-2 control.
As some of you may remember, I tried doing some upgrades on the TH700 in my R1500 Suburban last year, and my results were not as I expected:
Hope you dont mind MaroonMonster but thought I would copy paste this from my thread as it applies as well to the 700R4 If you do mind please feel free to let me know.
Setting band clearance---
Ok I am not going to go into what that clearance should be as each builder has different ideas on that (I myself like it to be as close as possible but with no rubing pump installed)
But this is about methods, Ideally using the longer sonnax pin is IMO best and as I am noting more and more cases are leaking in the servo pin bore and they do address that with the teflon rings, Though I am looking for a better seal type because while they do improve the situation they do not totally seal it from observational test I have done, Or I may eventually get the sonnax boring tool and just start using the oversized pin they offer. "NOTE KEEP EYE OUT FOR THESE I FOUND ONE IN A CORE RECENTLY AND LUCKLY I AIR CHECK AS THE STOCK SIZE PIN REALLY REALLY LEAKS WITH THE OVERSIZED BORE"
But again this is about hows not whats, Someone ask about flipping the stock 4th servo if they could not get the longer pin and yes this can be done , I have done it no issues in the past though not in any way a preferred method . But again theyre more to it. Using washers or flipping or even longer pin with the 4th servo still leaves something un-adressed (SECOND SERVO CLEARANCE/TRAVEL) Just setting the 4th travel does not mean the second will be correct even with the pin in particular with aftermarket servos.
You can have perfect 4th servo travel and still have way to much second this must be addressed separately. To do this leave 4th servo piston out and install servo assembly and check clearance with clip installed and ajust accordingly by adding washers between second servo and pin. Also before installing make sure cap. separator and second servo meet when placed together outside bore if needed use one of the transgo spacers or similar to take up any gap but not more than the gap. (this is with 4th servo still in place)
Again put all in bore and install clip and see what clearance you have and ajust accordingly (Again each has own ideas about this. Mine are based arround years of dyno time and tear down and the realization the band does indeed stretch a little and comform to the drum after a few applies and getting hot.)
This clearance has particular importance as the travel against the servo cushion spring plays into it also. So you have the Measured or observed clearance and the cushion spring travel to consider when figuring second servo travel to solid against band.
Once you have this set then you can reinstall the 4th servo and use spacers AKA washers if needed to ajust 4th travel which should IMO be 0 till hits the pin and washer but not more than. Doing it this way will insure proper travel for both servos As I stated each has own ideas on what that travel should be , To me it is as close as possible with 0 drag of band on drum.
Note with aftermarket 4th servos, the travel can be very critical and because they generally do not have the raised area under the 4th servo the actual travel they have before colliding with the spacer and second servo can be very very limited . I personally have always wondered why aftermarket servo manufacturers do not add or keep the raised area for this reason as it would make this setting much less critical. The superior servos are probaboly the worse offenders with this by design and any pancake style servo and its particularly bad with a superior / sonnax second/ fourth servo combination.
__________________ Frank formerly of Performabuilt, Now just me, What can I build for you today? Call or message me. Click sig pic for my facebook
we did one at my shop once. It was in a stone stock 1992 truck, drove great. We wired the lockup to the 4th pressure switch so it shifted 1-2-3-4LOCKUP right as it went to 4th, that's not ideal but it was sorta the best we could do.
we said our praises it worked, the customer was grateful we worked on his antique truck, and then never really worked on that older stuff every again unless it was a MVB th400.
I'm all for "copping out" if it works. I own a transmission shop (well, half of one. lol) and the thing that matters more than anything else to us is a finished product that works and goes away for as long as possible for the most amount of money.
03-05-2024, 09:35 AM
700r4 Tips and Tricks Master Thread 
While mY FIRST overdrive was the 200-4r as my best friend bought a Grand National , The 700r4 was my second. I was young but remember so many builders of the time were afraid of it, Built and tried to put on in my 1973 caprice 2 door coupe with built 454 unfortunatly it was 1984 and well its snapped the input shaft , I then softened the shifts and it killed what was at the time bizzare looking input sprag I have a photo of one some place ill post later ON MY FIRST WOT kickdown. Then tried one last time after I figured out the overun clutch was on in D3 and then I snapped the sunshell and I remember for the moment I gave up lol , But thought it would be so cool to have OVERDRIVE particulary with my 411 gears. Then I tried the 200-4R and learned what happens when you block the 4th accum and do a WOT at 5000 rpm unlike the 700 they HIT hard when you do that and i left the entire back half of the trans on the road behind me. FUN TIMES LOL .
