Transmission swap- TH350 to 700R4

[beanious]

Hello all, I'm in the process of doing a 700R4 swap and I wanted to start documenting my en devours for the benefit of the community.

The truck is a 71 K10, 350 SBC with a TH350 and a NP205, pretty common. In swapping to the 700R4 I am looking for reduced highway RPMs, as a result of the lower highway RPMs reduced heat from the engine, and (I doubt it but will happen) but better gas mileage.

Stay tuned...

[beanious]

Rebuild parts list below:

Based on a 2nd Gen 700R4 from 1988 K case
Summit rebuild kit that includes Alto red clutches and high end band
TransGo Pump Valve
Hardened Pump Shaft
Beast Sunshell
TCI Corvette Servo (Red aluminum cover, fancy...)
TCI Stainless Servo Cover, fancy...
PATC #2x torque converter with 1800 stall and balloon plate
TCI 5 gear input planetary
TCI 5 gear output planetary
Shortened hardened output shaft for 4x4 from Advanced Adapters
Hardened input drum and shaft
Molded aluminum-rubber pistons
Doorman 4L60E steel trans pan
TCI constant pressure valve body kit
Lokar loktite filler tube
Case Saver
Painless torque converter lockup kit
Lokar floor mounted shifter
Advanced Adapters aluminum TH350 to NP205 Adapter (Got it free)
300 PSI gauge temporarily mounted in the diagnostic port to be sure it has the correct pressures

[beanious]

So, I want to throw out a disclaimer that doing this swap has taken a considerable amount of time. There have been a few hang ups and speed bumps, it's not the hardest project in the world but it is NOT for the first timer. Gain a good working knowledge of auto transmissions and plan this thing out. Have a second vehicle to take you to work and get parts in, especially if it is a weekend project. That being said I'm sure it will be totally be worth it, also what choice did I have my TH350 3rd clutch started slipping. No point in putting back in the same transmission...

[Jcfcamaro]

I'm planning on doing this on my 72 k10

[beanious]

Something that I have learned with the 700R4 is there are a billion aftermarket parts to remedy design flaws with the transmission and increase longevity. It's kind of like looking for aftermarket parts for a Colt 1911, just too many to choose from. The worst part is that unless you know someone that has tested that part and ran it through the paces you have no assurance it is better than stock. Hopefully the list of parts above can help future re-builders to cut down the research required.

[beanious]

Trans with bad 3rd gear removed..

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[Ram-Man]

Couple things I would suggest are a bowtie overdrive TV made ez kit to be able to adjust the cable correctly it's nearly impossible to set it right without it. You will probably also need a governor kit to adjust your shift points because whatever trans you got the governor was set the gearing of the vehicle it came out of. On my swap knowing this in advance would have saved me a lot of headaches.

[beanious]

Ram-man, thanks for the reply. I am starting off with the 700R4 carb arm, I purchased the TV EZ setup but if the pressures arent right or if it doesn't set quickly I'm going to put it on. I'm definitely interested in the governor kit, I saw a video on YouTube of a guy that totally changed the shift points with it. I can't wait to get it on the road and start testing it!

[beanious]

Here is a couple pics of 700R4 trans after rebuild, ready to go in...

[beanious]

So, one of my favorite replacement parts I got for the transmission is the TCI-376020 Constant Pressure Valve Body. I can not rave enough about this kit. It comes with way more than just the valve body. It includes a Torque Converter vac lockup kit, servos for firm shifting, wiring for the Torque Converter lockup and a bunch of other little stuff. The best part is that it comes with extra small parts that give you the option to rebuild it as: Heavy Duty (Firm), Street (Extra Firm) or Street Plus (Competition). If you want to go back and change the shifting at a later date, just change out a few parts. Really a good bonus.

Also, as a side note in researching I found out the the firmer (within reason) the shifts are the longer the clutches last. The shorter transition time for a firm clutch means less slip, less heat and less friction material falling to the wayside.


"In order for manufacturers to get a smooth shift for the general public, they have to make the transmission slip into each gear slowly. They have studied and tested and compromised to get the balance between slipping, smooth shifts and a long lasting transmission. They have done fairly well to get both. As you start increasing HP the slipping smooth shifts will eat the transmission clutches in short order. This is one reason why people install shift kits. It allows the shifts to become firmer with less slip. This will last longer with the added HP.

As HP keeps going up more mods are needed to keep the clutches alive. Added hydralic pressure, added clutchs with better heat resisance, high temp bands, manual valve bodies to speed up shift time. At this point the trans will require more maintainance.

As a general rule, a firmer shift will allow the clutches to live longer. On the other hand if the transmission "bangs" into gear on a road driven street car, the u-joints will need more maintainance. So firm is good and banging is bad."

http://www.fordmuscleforums.com/c4-t...nsmission.html

[beanious]

One thing to note with the TCI kit, for transmissions that are already together. When removing the Boost Valve, sometimes after removing the c-clip the valve can stick. Usually it will move 1/4" up and down but it might get stuck in the up position. It took me 45 minutes of playing with it to finally get it out due to a really tight fit. Just be patient and tap the bottom of it with a screw driver in various positions until you can feel 1/4" of travel while pushing up with your finger. Then bounce it out and free of the debris, a magnet will also help as it gets closer to removal. The video below also helped...

https://www.youtube.com/watch?v=WLfBZeOS2W8

[randy500]

Beautiful k case trans...is it in yet?

[beanious]

So, the 700R4 is installed!!! It took a bit to get everything the way I wanted it but it was totally worth it. Boy, the little things stack up making it take longer, driveshaft cut and re-balance, making new trans lines, TV cable adjustments etc, that racetrack figure 8 pattern designed by a sadist. In the end the cross member had to be pushed back 1-3/8 " and strangely enough the driveshaft had to be cut the same amount. I checked 5 times, once installed I verified it was dead on. Anywho, below is a picture of it being installed. More pictures to follow tomorrow, tired.

[beanious]

So, I wanted to take some time to document some things I went through after the transmission was installed that might help with anyone making the swap for a TH350 to the 700R4 or 4L60. Some of these things may seem obvious, but having another person confirm what you are going through and seeing is priceless. So here we go.

First off the transmission took forever to fill to the proper level. I wanted to make sure no damage was done to the transmission as a result of an ATF starvation issue. So, I disconnected the coil to the distributor before I started. I filled the transmission with 5 quarts and then cranked for 5 seconds, another quart, cranked for 5 seconds, repeated until I got to 9 quarts. At that point I changed to running the engine for 10 seconds and adding half a quart of fluid each time and checking the levels. I have a larger external cooler, so I got up to 12 quarts. It took forever, but it was safe.

Cooling and temperature monitoring: If you live in a warm climate, you cannot have enough cooling. I am unfortunate and get 100 to 120 degree summers; as a result I need to over engineer the cooling on most of the systems in my truck. Also after talking with the transmission repair shop he recommended that I do not run the trans ATF through the radiator as he sees them come in all the time for coolant leak contamination. If that happens, your transmission is smoked. So I only ran an external cooler. Also I would not run a rebuilt transmission without a temp gauge, which is cheap and effective and a great trouble shooting device. You want your trans to run between 160-170 F, any hotter and it’s taking miles off the lifespan.

YOU NEED A REMOTE MOUNT TRANSMISSION PRESSURE GAUGE. This is critical because if you have a malfunction inside the transmission or a Throttle Valve (TV) adjustment issue you can burn up your transmission quick, I mean quick! I thought I would be a cool guy and install one on the transmission itself but that only allowed me to read the gauge when stationary, terrible. So I duct taped a Logitech web cam to the frame with a laptop in order to read it while drive testing. Not the classiest thing, but it got the job done.

Stock TV and valve bodies malfunction, and malfunction all the time. These transmissions are OLD, mine was manufactured in 1988 and is currently at 29 years. To put it kindly, my TV-valve body was b-roke. I tried adjusting the TV and doing the neutral TV jerk-clear-clean method so many times. I actually spent 3 days doing that while monitoring the gauge perplexed why it wasn’t responding correctly. In the end I installed the TCI constant pressure valve body and BAM. Absolutely no issues and perfect pressures right out the get go. I wish I hadn’t spent half a week wasting my time with the stock setup. Sure it cost me a couple bucks but with incorrect TV pressures the trans would be smoked and would have to be rebuilt within a week.

After you have the transmission up and running for a while drain the fluid, change the filter, clean the pan and fill with new fluid. To me this seems like an obvious step, but no one talks about it. When you rebuild a motor you change the oil after 100 miles. With auto transmissions it should be the same thing. It is a wet clutch system and anything that comes off the clutches, pressure plates, band, bearings, pump, and gaskets gets circulated right back into the system. Literally liquid sand paper going through your expensive rebuilt transmission. When I pulled the pan to change the valve body and saw that there was already debris in there, I was so glad I did.

[beanious]

If anyone has any picture requests, please let me know.

[Jcfcamaro]

So did you leave the engine in the stock position? And that's why you moved the cross member and shortened the rear drive shaft. I've read where guys are moving the engine forward so everything lines back up on the cross member and driveline .

[beanious]

Jcfcamaro, you hit it on the head. I left the engine in the stock location and moved the cross member back. I plan on running A.C. and possibly a crazy belt setup, so I wanted the room. Also, I plan on putting in a 73+ front cross member for the sway bar option. So much to do I used the short rear shaft instead of the TX-TC extension spacer to try to reduce the length. It would have been nice to do curb weight before and after to see if moving it back made any difference.

Bryan B.

[beanious]

More pictures of the install!



In this one you can see the standard pan dent I had to create in order to clear the driveshaft, I also trimmed the pan rail as much as possible and used a button head bolt for safe measure. Need to paint the dent

[67 chevelle]

Im not completely happy with my constant presure valve body from tci , it does work well , BUTTTTT , it clunks downshifting from second to first , its annoying ,called tci ,they said they all do it , they should tell their customers about it first . I would never use one again , besides the fact I was chasing it down for months , guessing about mounts bearings , suspension and sutch

[beanious]

67 Chevelle, I'm getting exhaust installed today and haven't even gotten to really road test it yet. It was a hoot driving it down the street to the exhaust shop with only headers... Thanks for the heads up that doesn't sound like a feature... Maybe you can change out the 1-2 accumulator springs for softer ones or remove a shim? That is supposed to soften shifts from what I read.

A question for you, what boost springs and shims did you use and what low and high pressures are you experiencing? Mine are a little on the high side, I used the silver spring and the washer. I'm considering either taking out the washer or changing back to the stock spring. Thanks.

[beanious]

Here's a good link with info and explinations on TV and the Valve body kit.

http://www.hotrod.com/articles/0801s...-transmission/

[Bigdav160]

I moved my engine forward to install my 4L60. While I couldn't use the factory 4x4 fan shroud it seemed easier to lengthen the exhaust and move the gear linkage.

I have A/C but decided to go the serpentine belt route to clear the TPI manifold.

I was a transmission man at GM dealers for more than a decade. I didn't use much in the way of aftermarket parts in my build. Shifts perfect and it's a pleasure to drive.

I should add, I did not have front driveshaft interference. Perhaps because I have a 2" lift.

[beanious]

Forgot to mention I've been given the nickname overkill by those who know me well

[cleszkie]

Maybe a dumb question, but why don't you plumb the pressure gage with some hard line to mount in the cab so you can see it while driving? Seems like having a gauge on the tranny case isn't the best for monitoring pressures (unless you use a camera like you did), and leaves it open to the possibility of leaking if the relatively delicate gauge gets hit by road debris. Nice work on the tranny BTW.

[beanious]

Yeah, bone head move with the gauge on the trans. When I started I didn't know much about line pressures. I'm waiting for the dash mounted gauge to come in from Summit. They also make temporary test gauges similar looking to a compressionor fuel injection test gauge.