Technical 700R4 OD question

My trans is in the car, and pan is on it. So I'd have to drain and pull the pan if I needed to see what the wiring inside looks like.
All pressure switches I looked at were two terminal. Do you mean 3 terminal with one input, and two outputs terminals? If so, couldn't you splice two wires off the output of the pressure switch.
And another question, if you don't mind? None of these drawings show anything on the "B" terminal. They show the "D" terminal as being used to either power or ground the coil on the solenoid. So are we talking about the two outputs of the pressure switch going to A and B, or to A and D?

 

Please reread my last post about ohming out the terminals.

 

Because it will prevent a chug-a-lugging or trailerhitching feeling when using the brakes or letting off the gas while lockup is engaged.

Bill

 

After you let of the gas, does the RPM go way higher than it was while crusing at 70, when you get back into the gas, during the time you say it feels like the engine is catching up to the trans?

And after it does catch up what does the RPM do? If it is roughly the same RPM as crusing at 70, it's probably normal.

Reason I am asking this is it could be possible the trans is downshifting out of OD to 3rd and severely over running.
The RPM needed to catch up with the speed would be much higher.
What does it do, to get back to the same RPM at 70?
Does the RPM go way higher and then drop to the cruise RPM? If it does, most likely the trans is downshifting to 3rd and then re-upshifting to OD.

If it is doing that, the first place I would suspect is the TV cable geometry is incorrect.

 

Link to instructions
https://documents.holley.com/70244.pdf

49 Ford Coupe, I'm learning something today, " lock up clutch and solenoids" section of the instructions describes what youre saying. Lock up is controlled hydraulically OR by ecm, depending on year of transmission. Describes how to wite the 4 pin connector for each.

 

No offense, Bill, but do you really think a vehicle would chug-a-lug at 70? In addition, the governor along with the TV valve tells it when to downshift.

I'm running an '85 Jag IRS with 2.88 gears and the only time it does any chug-a-lug at all which is so slight it's barely perceptible is when I have my Dash switch set on lock up in second third and fourth as I'm slowing to a stop. When it's set on normal or overdrive lockup only there is zero chugging with no brake switch. As soon as you slow enough to disengage lock up which is about 40 miles an hour with the TV cable pushed back in it drops out of lockup. And it's perfect.

The related subject it looks like that B&M thing locks up based on speed only. Looks like the driver would have to be constantly running that potentiometer up and down depending on how he's driving a complete waste of money.

By the way the B&M instruction sheet does not show a two-pole 4th gear switch for a 700r4.

 

Thanks justpassinthru. At 70, I completely left off the gas, the engine immediately goes to idle. I press the gas, the engine revs up to catch up to the trani, at some slightly slower speed as it is like being in neutral at that time.

I don't think anything is engaged when I let off the gas. Total idling engine. Seemingly no connection between the engine and the train.

 

Hey, Lovin'..., why don't you call Dana at Probuilt Automatics.. take notes because he can talk kinda fast... He knows EVERYTHING about 700R4's...
That "going into neutral" ain't right...but explain to him that you haven't worked out your lockup scheme yet, if you haven't..
https://probuiltautomatics.com/

 

I really doubt the trans is neutraling out when you let off the gas. There would be other symptoms of problems than just when letting off the gas in OD@ 70MPH.

I really thing the trans is downshifting out of OD back to 3rd gear. Because the overrun clutches are not applied in OD range, the input sprag will just freewheel and overrun. It will feel like its in neutral but is really not. The input of the trans will now have to catch up to the output speed before it feels like its pulling again.

What speeds does the trans shift from 1-2, 2-3, 3-4 under normal (light to moderate) acceleration. At this point for all I know the trans is going into OD at 65MPH

Throttle pressure cable geometry is critical in a 700R4, is yours correct and how is it set up?

Bill

 

At 70MPH or even lower OD speeds, you are right, it wont chug-a-lug.
I was basically describing why it was designed to work that way from the factory.
Many if not most vehicles from the factory got TCC before OD. Even mid 1980s Corvettes got TCC in 2nd gear to help meet CAFE standards. Those really feel like crap and we used to modify the trans to only get it in 3rd and 4th.

Lovin has more than one issue with his trans. The first is TCC is not hooked up properly, and the second is the issue at 70MPH, which is not related to TCC not working. We dont have enough info at this time to properly diagnose the issue.

We dont know if the TV geometry is right or even what speeds the trans is upshifting at. I would venture to bet the geometry is not correct. Most modified cars we get in the shop are wrong.

Your wiring schematic for TCC will work fine also. Thats labor intensive to install though. (A lot of wiring, vacuum hoses, switches etc.) It has been in my experience, that the vacuum/electric switch is prone to problems also.

Here in Chicago @ $120.00 per hour labor rate, it would be too time consuming for me to do that way to do that way.
The system I use for TCC control is from Bowler Transmission at around $190.00
Its very easy to install, one wire hook up to the car, change the solenoid and pressure switch, and you can either install the 2 stage brake switch or not. Using the brake switch is recommended though.
Has a little micro processor that engages TCC 8 seconds after the 4th shift. That way you dont get a 3-4-TCC stacked shift, that some setups will do, and feels better with TCC spaced out a little after the 4th shift. Trans will stay in TCC only in 4th. The only issue I dont like about it, is during a OD gear forced downshift to 3rd, it can be pretty harsh due to it going from OD with TCC applied to 3rd with no TCC. Forced downshift is sorta like going from 4th to 2nd.

Bill

 

Bill, thank you for saying that my wiring diagram is fine..but I must disagree that it is difficult to install. As long as a transmission has a Two pole 4th gear pressure switch and even if it doesn't then pulling the pan and putting a 2 pole in and rewiring it is the worst part. other than that the addition of a three position toggle, a vacuum switch in a couple of feet of vacuum tubing and a few terminals, it's very easy and straightforward for anybody who has any skills at all. As I've mentioned more than once above that system works just damn perfect for a whole lot less money then the cheapest lock up kit anywhere including the one you mentioned in your post.

 

OK.. had some MiL "opportunities" that side tracked me, but got back to it this evening.

I got the relay (brake signal) connected (yellow wire in the B&M Schematic) properly (I'm pretty sure). Took it for a test drive. This was certainly an improvement in the overall operation of the trani and converter lock-up. The "issue" is still prevalent when in 4th. I would like to ride in a car with this trani. I don't believe mine is right. It is still like instantly putting the shifter in neutral when taking the foot off the gas at 70 mph.

I've read input here where up to 500 rpm may be noticed when the converter engages. I'm seeing about 100rpm change. I don't know if this is a clue.

I've left a message with Dana. Waiting to hear back. He does sound like the expert on the 700r4.

Still open to exploring possibilities. Is there a valve that is specific to the 4th gear that could be leaking?

 

a resent question about the TV cable. I'm using a Lokar cable. I've taken the pan off to confirm the full range of motion between the throttle position and the cable. There is a very slight bit of slack at idle position, and more taunt at full throttle. There is not limitation in the throttle when the TV cable is removed. It very much appears to be working thru it's full potential range. If there is another way to set this let me know, please.

 

If when you're at full throttle wide open the TV cable should be completely pulled to its fullest extent in the transmission. And I'm sure you've got the correct linkage at your carburetor so that everything matches up , right?

But that's unrelated to your issue about going back to idle when you let off the gas. Dana will tell you what's the matter. And have a pen and paper handy and be sure that you write down everything that he says even if you don't understand it that's what I did. Better yet get a call recorder for your cell phone and record the call so you can review it later

 

What carburetor do you have? The tv geometry has to be correct.
You can't just hook up the cable at the carburetor.
Google tv cable geometry.
Some newer aftermarket carbs have the correct geometry, older ones do not.
We're talking about the throttle lever on the carb. The rate and distance the TV cable moves is critical for proper operation.

Bill

 

I have an edelbrock carb with the Lokar cable. I removed the TV cable at the carb when the pan was off. I opened the throttle to wide open, and could clearly see and feel the cable was fully extended to the carb linkage when the cable was pulled by hand. This was also confirmed, again when I had the pan off and could see the linkage was fully opened. Or fully closed in the idle position. the trani shop had also confirmed this linkage set-up.

I've watched https://m.roadkillcustoms.com/how-to-adjust-a-700r4-transmission-tv-cable/ I have not adjusted the cable based on general driving acceleration and MPH. I don't have a spring at the cable clamp. I would say mine is currently set tighter than loser based on this video example. I will have to take note what MPH when it is shifting and adjust the cable accordingly.

I do need to ( I believe) work with the governor weights/springs to increase the shift points at WOT. I've wondered if that being too low would effect it. I'm barely at 3000 when it shifts during WOT. Again, I need to take it out to see when it shifts.

I don't know if this is playing a role at this time, but my speedometer is way off, 30% high. I've been using a gps app to verify my MPH. I've got the lock-up engagement speed set at 45MPH (gps) at this time.

I'm still appreciating the help!! Waiting on Dana's return call.

 

While you are crawling around on the concrete, you may as well try the first step to correct your speedometer that changing your gear in the transmission. Have you Googled how to do that yet? Your first try will probably be wrong. When I took my first swipe at it. Checked and double-checked and watched YouTube videos Etc and it still came out about 10% off so then I had to order another gear and now it's right on. I will send some links you need them.

You may have noticed in the pictures of my chapter 2 gallery on my website that I eventually used a blue gear to get it correct that I got from Dana. I think I remember that if your ratio is way off you may even have to change the drive gear on the tail shaft to get it to come out right.

 

The TV cable isn’t just on/off, its range of motion matters as well. You need to achieve:



Depending on exactly what carb you’re running, you may need something like:



to do so.

 

One more morsel of information, the trani does not downshift at any speed or gear when accelerating. I have attributed this to the low shift points at general acceleration. Again, I'm thinking governor adjustments to help this. I'm I thinking about this correctly? Happy Friday!!

 

Even if you use a calculator, which I did, you will be lucky if you get it right the first time. You need to confirm your drive gear tooth count first, then take your PERCENTAGE off, then check if a different driven gear will work with the drive gear, if not, then you may have to replace the drive gear. The higher the tooth count on the driven gear, the slower it turns


Skip forward to the 3 minute mark on this one


Here is a calculator. Plug in your known numbers and see what the answer is, then adjust for the percentage you are off, then plug in new numbers for closer selection.
http://www.bgsoflex.com/speedo1.html

 

If you have been driving it without kick down you may have already smoked the clutches.

 

I've been very careful. I'm sure I don't have 20 mi on the rebuild. Very very little hwy, unless doing the on-off ramp to get to speed for test drives. Always, shifting out of OD after "test" to be extra cautious.

This isn't my first ride. Just my first ride trying to work with a 700r4. Give me a break, unless you have something to helpful to add. Thanks.

I really appreciate the helpful replies. Always appreciated.

 

not to mention the two times I've replaced fluid in the 20 miles while checking the TV.

 

thanks for the info. how would You describe "no overrun braking, manual 3-2-1"?

 

No engine braking when you let off the throttle.

 

When the converter is locked you have engine braking. Unlocked you do not. At lower speeds you notice the engine needs to "catch up with the trans" after coasting down some while unlocked, this is normal. With a 3.91 rear and the low 700r4 gear you are probably in 3rd pretty quick so in traffic you will notice it a lot. Mine with a 3.20 rear picked up mileage by 18% over a turbo 350 and 2.42. I just wired it with a toggle switch thru the cruise control side of the brake light switch and engage it over 45mph. Just be sure it is unlocked when you stop. Best money I ever spent.

 

thanks 1320 Fan. Maybe some of my concern is not warranted?!?! Could be. But I still have a couple of lose ends to take care of.
Today, I will fix my speedo, just because it needs to be, as noted. I am going to change the weights on the governor, because I believe these may be aiding the trani to shift at low speed, as I know WOT has very low shift points from a quick test each outing. They are easy enough to change back.

I've got the brake signal corrected now with a universal relay switch from O'Reilly. I'll put a small spring in the TV cable as in videos above. Then take her out with a fresh mental perspective, and re-evaluate the TV cable set-up based on normal accelerations noted in instructions above. Let's see where I'm at then.

Thanks for everyones help!!

I'm Slow, but moving forward.....
Cheers Guys!

 

I can build a ratio adapter to correct your speedometer, 30% is hard to correct with the speedometer driven gear. If you don't want to mess with changing the drive gear the ratio adapter is the way to go. PM me or check my website to contact me.

 

Thanks. It looks like I can get stock gears to fix it based on 5speed.com calculator. I'll be at the local trani store Monday to pick-up a 15/45 combo, hopefully.