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700r4 woes and question

I'm running 37"s with 4.56's and am also having probs with my BTO stage 2. My lock up kicks in and out with a mild accelleration in overdrive. In your case with 38's and 4.10's. I would probably run it in 3rd gear and not even worry about OD. My next move is 38's and 4.10's with a 465/205 combo. With the 37's and 456's, I'm only turning about 1900-2000 rpm. I think that is a hair low at 65mph. I think I'd like to be closer to 2400rpm at 65mph. I don't know if that is the right thinking or not. I feel for you though, I've been through that alot. Right now I have $ 2000 into my BTO tranny and have driven about 5000 to 6000 miles and it still isn't right. I went 4 months with out my truck last year. I've owned it 1 year now and have only put those miles on it. My last 88 burned the tranny up running 2.72 gears with 35's. Went to a th350 and blew that one 2 weeks before my honeymoon. The 465 was my answer and have had no probs with it since. My summer project is to tear out the 60/14ff/205/465 out of my rusting 88 and put it in my 89 rust free truck. Good luck with your case!
 
The overdrive works fine and it locks out fine in overdrive turning about 1800 going probably 65-70, but it slips or something right as you're starting out. Like as soon as you start moving it shifts gears or something. But if I flip the switch and turn the lock out off, it shifts perfectly fine but it runs hot and of course no lock out. Could it be the torque convertor??
 
I highly recommend that you talk to a laywer before having anymore work done to the tranny or before having anyone else mess with it. It wouldn't hurt to have another shop drive it and advise you of what they think the issue is but whatever you do, DO NOT have any work done until you seek legal advice and probably not until after you've had your day in court.

Now with my calculations, 4.10 gearing and a true 38" tire you will be spinning 1649 RPM's @ 65 MPH while in OD and 2356 RPM's @ 65 MPH while in drive (3rd gear). Ideally you want to be between 2200-2500 at your cruise speed (whatever that is for you).
 
Yeah, 4.88 is what I'm wanting to put in it, but this has been consuming all of my time for months now. Got a fraternity brother that's a lawyer, gonna call him in the morning and see if he has any advice on what to do next.

I know I don't know that much about trannys but I know they haven't done something right. I was running 36s on it for a while with 3:08 gears and it didn't have that prob, so I don't understand why it would have a problem with 4.10 and 38s
 
It's possible that all of these problems are related to the torque converter lockup.

Without a locking TC, the 700 gets hot fast, but mostly just in overdrive. Putting it in D instead of OD really cuts the heat. The fact that they initially disconnected the lockup and added a switch to get rid of the "bogging" tells me that the lockup is trying to engage all the time, which is abnormal. It should be wired through a vacuum switch as well as the brake pedal switch. Plus, there is a hydraulic valve that controls lockup internally based on TV pressure. They might have messed this up when the tranny was serviced. Maybe they swapped in a different year/model transmission or changed the valve-body?

Getting rid of the lock-up could be an acceptable "band-aid" for uversized tires / undergearing with a TH350, but doing it to a 700 is bad news.

There is a kit available to turn lockup on/off based on vehicle speed, which would be a much better solution than that stupid switch.
 
I know. I don't know much about trannys but I know that the switch was not the way. I know they did have to change the valve body cuz something was wrong with the original. Put in another used one I'm sure. Also, the tranny was originally out of an 86 K5. Truthfully, I now believe that they just pieced together this tranny to make a bunch of profit. Like I think i mentioned before, the torque converter might be the old one and they didn't put in a new one. An ex co-worker who quit that shop told me he believed that's what happened but isn't entirely sure
 
They put in a 86 tranny in your 89?
If they did you have the old style 700. By 1989 700s had all the upgrades that dealt with overheating, lubrication, and strength issues.
Also 1989 700s TC lock up is completly controlled by the ECM. There is no vaccume or manual switch anywhere in the system, Lock up is controled totally electronically.
IIRC The TBI 700s use a difefent TC lock up solenoid than the old Carb 700s.
If you live in a smog state what they did is most likely illeagal.

IMO that shop screwed you. They gave you an older ,weaker tranny that was never designed to be in your year of K5 and operate correctly with your ECM
They should have rebuilt your trans or installed a later (post 1987} model trans with all the needed up grades.
Also Installing an old Torque convertor in a new or rebuilt trans is a big No No.
 
It definitely sounds like an issue with the TC lock-up control, as based on your description it sounds like the TC is trying to lock-up almost immediately after you start to accelerate.

I don't have any experience with an older model tranny in a newer truck in regards to the difference in TC lock-up control as explained above, but that does make sense.

The one thing you could do is try to borrow a stock-ish size set of tires and wheels, install them on the truck, and see if the problem is still there.......I'm guessing it will be.
 
An 86 tranny is a downgrade for you. There are a lot of changes required to give the ECM control of lockup in an 86. This could be why the changed valvebodys. It can be done, but it's not straightforward. This is the cause of your problems and the shop should have known...
 
ah. Never knew that. I knew the post 87 700s where stronger and more desirable but I never knew that they wouldn't match up like that. the shop didn't install an '86 700 in my truck, I already had it in it. Couple years ago, the original 700 burnt up and I put in this 86 700r4 in I had left over from my previous k5 (an 86). Ran it for about a year or more before the 10b blew and that's when the tranny got screwed up. I never had a problem with it before, but then again I was never running big meats and what not. I actually asked the shop if it would be better to rebuild my original tranny I took out and they told me it really wouldn't make a difference.

So, how did this '86 run perfectly fine before in my truck? Most of it's life it was in my Blazer in stock form and then it was in it when I was running 36 and 3.08s for a few months until the rearend and then it went out? It shifted fine and never had a problem. Course, I didn't have a temp in it then to see if it was getting hot or not
 
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