Background: After I had my car for about 20 years it started leaking transmission fluid from the hole in the torque converter cover.
I figured there are only a few gaskets involved, so I bought those gaskets from the local Chevy dealer.
After taking the transmission out of the car and getting it on the workbench, I opened the shop manual.
The first step in the pump removal process is, "TOOLS REQUIRED: J-23772-A Oil Pump Remover", which of course I didn't have.
I looked at the pump and thought, "I can get it OUT of there, one way or another, but I don't think I can get it back IN without damaging something".
So I went to a local transmission shop and talked with the owner. Two of his guys came and picked up the transmission.
He rebuilt it and I went to his shop to pay for it. The first thing I noticed was that he used a cork pan gasket.
They ALWAYS leak, which I mentioned to him. He said, "We've never had any complaints".
I thought, "Yeah. From mini-van drivers who park their car in the street".
After I put the transmission back in the car it immediately started leaking at the pan gasket, so I bought a new gasket and installed it.
Now it was leaking at the front, even worse than before and I was out $950 for the rebuild plus a lot of pain and strain getting the trans out and back in.
I decided to live with the leak because it was too much hassle to take the trans out again.
The leak has really irritated me and I was tired of dealing with the puddle of trans fluid on the garage floor so
five years later I started doing some research online and I found out that there is a well-known problem with the 700r4
front pump seal that was fixed in mid 1987, when the transmission was redesigned. It seems the front bushing tends to walk out of the pump, blocking the drainback passage and
pushing the seal with it, thus causing the leak. GM fixed this problem by machining a lip in the pump to keep the bushing from moving.
I decided to buy a newer pump and just replace the pump, thus fixing the problem. Then I remembered that one of the guys in my Corvette
club had taken the 700r4 out of his '89 Corvette and replaced it with a ZF 6 speed manual trans. I figured he probably had the trans sitting
in the corner of his garage gathering dust. He did. I told him I wanted to buy it and he said I could have it for free (which is what I was
hoping he would say). Cool. The improved version with the valve body upgrades, too. He even gave me a transmission jack that he no longer needed.
I rented a U-Haul van to get the transmission. I brought lots of ropes and we tied the transmission down really well.
I didn't want it flying around in the van and getting damaged. Going around the third corner on the way home the trans
jack tilted and the transmission tipped up on its nose and transmission fluid poured out everywhere. Why this happened later...
After getting it home, I decided I had better rebuild it since it had about 95,000 miles on it. That turned out to be a
good decision, since he had upgraded his engine to a high output 383 and burned out the clutches. I did a lot of research
on rebuilding 700r4s and since I was unemployed with lots of time and little money I decided to buy a rebuild/upgrade kit
from Dana Wilkes at Pro-Built Transmissions
. The advantage of his kit is that all
the parts needed are included with the appropriate heavy-duty components. He even included a DVD video that shows how it's done.
This article is a little different from the usual 700r4 rebuild article. Others have done a great job of documenting the
process in great detail, so I didn't want to repeat what has already been said quite well. Here are a couple of links:
Pete's Transmission Threads
janarvae's 700R4 Transmission Rebuild
The reason the transmission tipped over in the van was that the jack is a cheap Harbor Freight unit and the too-thin sheet
metal bent from the tension on the trans holding strap and allowed the jack to come apart. This is the trans cradle (upside down).
The sides are supposed to be vertical, but they spread apart and the U-shaped guides came off the rollers.
I drilled holes in the cradle and added a long bolt across the bottom to prevent the spreading in the future.
Some preliminary pics before the meat of the article. Here's the victim. Note that the trans will not normally stand up
like this because of the way the bellhousing is shaped. It has a couple of blocks of wood under the front of the pan.
These passages in the case are known as worm tracks. Very appropriate name.
This is looking into the case with the pump and input clutch housing removed. The output shaft is also out.
You're supposed to use the fancy tool to take the pump out,
but you can actually pop it out quite easily by prying on the back with a long screwdriver. I saw that in a YouTube video.
There are several springs that need to be compressed in order to remove the snap rings that hold them is place. Since I didn't
want to spend over $100 for a tool I would only use once, I opted to make my own spring compressor. Here's what it takes to get
the rear spring out of the case. The spring to be removed is in the back of the picture, with the snap ring on the left.
The snap ring pliers are made by Lisle. It has interchangeable bits that can remove internal or external snap rings.
Unfortunately the junko spring retainer that holds the bits allows the bit to wobble around, making the tool worthless.
A screw and nut fix that problem. Next to the spring is a piece of angle iron that I bought at Lowe's. It was two feet
long and I cut off an appropriately-sized piece. I taped a couple of plastic spacers on it with masking tape. The long
bolt also came from Lowe's. In the front is part of a harmonic balancer removal tool that I bought several years ago.
It's Interesting that when I went to the transmission shop they had an almost identical tool that they had made.
The Lisle snap ring pliers with the worthless spring-loaded pivot. It allowed the tips to wobble so much that the tool was
unusable. A stainless steel bolt and nut fixed the problem.
Another problem with the snap ring pliers was they wouldn't open far enough to remove some of the snap rings.
I ground away some of the material near the rear pins to let the pliers close further so the tips would open more.
It turned out that the harmonic balancer removal tool fit perfectly in the back of the transmission.
The tool in action.
I drilled these holes in my workbench to mount various tools. I have holes for the big vise in the background, a drill
press vise, a drill press and a bench grinder. The mounting bolts and wing nuts are stainless steel. They spin on and off very nicely.
It's traditional to drill a hole in your workbench to put the input clutch housing in while you're working on it. I didn't want to do
that so I drilled a hole in a piece of 2x4 instead. It's mounted to one of my tool mounting holes.
Here's the input clutch housing mounted in the hole. Trans fluid drips out of holes in the shaft so it's good to have something below to catch it.
You can get really cheap pie tins at the grocery store...
Early in the disassembly process. Notice the surprisingly small number of tools needed.
The 3-4 frictions were shredded, with chunks of friction material missing. The steels are burned (the dark areas).
This shows a lip seal guide and protector I came up with. It's a piece of "Transparency Film", for making slides for overhead projectors.
It comes in 8-1/2" x 11" sheets and I cut it down to a useful size.
Here is my custom made 2x4 wood spring compression tool. Cheap but effective. An idea I got from a 700r4 rebuild article online.
Here is my drill press spring compressor. This did NOT work. Even with the 20 pound piece of railroad rail on top of the drill press.
The springs were too strong. I ended up using the 2x4 with the railroad rail on top and leaning on it pretty hard. I had to take the
drum apart about 4 or 5 times and it would have been a LOT easier if I had made a real spring compression tool. I had the idea to use
a C clamp and cut it and weld the screw part to an appropriate piece of angle iron, but I never got that far.
You need a lot of transmission oil during the assembly process. My initial thought was to put it in a condiment bottle, but I didn't have
one so I put it in this Suave shampoo bottle. I ended up using a whole quart during the assembly.
The white cap from the carb cleaner spray can was also handy for dipping my finger in trans oil.
I needed to make a wood spring compressor adapter because the lip on the spring retainer was too high for the angle iron
spring compressor I used in the case. This is made out of a piece of pressed wood I had lying around. That turned out to be a
mistake, as it shedded bits of wood constantly. I ended up painting it with polyurethane to keep the wood bits where they belonged.
My improvised bushing driver. This turned out NOT working. I couldn't get the bushing to go in straight. After about 10 unsuccessful
attempts I took all the bushings and the parts they go into to a transmission shop. The owner was surprised when I told him what I
wanted. He said, "You want to replace ALL of them"? Apparently they usually only replace the ones that are worn. Yes, he did replace ALL of them.
I was amused by the removal technique. They used an old screwdriver at the bushing parting line and pounded on it with a hammer until the
bushing bent and came out. I thought it was interesting that he had a set of bushing drivers that he used with an arbor press to press in the bushings.
NONE of the drivers he had fit any of the bushings. He also burnished the reverse input drum in the background where the band wraps around it.
This is what I used to compress the spring in the servo. The instructions say to use a regular vise but mine wouldn't open far enough.
The C clamp was just barely big enough with the servo pin stuck in one of my handy dandy workbench holes.
The two halves of the pump. The halves need to be aligned perfectly before being bolted together or the pump won't
go into the case. I read somewhere that you can put the pump in the case and bolt it together, using the case itself
to align the two halves.
I used two long hose clamps linked together and clamped around the outside, an idea I got from a YouTube video.
The tips on the snap ring pliers were too short to reach the C clips in the pump, so I had to resort to desperate measures.
I mangled the C clips when I took them out. The large one came in the valve body kit and happened to fit but I had to buy
the small one. I would have liked to see both of these in the rebuild kit.
This is what it took for me to get the stator shaft screws out of the pump. On the right is a hammer driver, a manual impact wrench
that you hit with a hammer. I've used it many times to take apart my various Honda motorcycles, but in this case it didn't work.
I got it apart with the multiplicity of adapters on the left. Dana supplied the Torx bit in his rebuild kit.
It seems like everybody who rebuilds an automatic transmission has a picture of the valve body with all the various valves and
springs spread out on the workbench, so here ya go.
The separator plate was warped in the area where the accumulator springs press against it so I decided to replace it.
Another view of the warped area.
Another reason to replace the separator plate. Worn holes where the check balls seat.
The new separator plate, a TransGo 700P. They said it had a "protective coating", but I didn't expect it to be galvanized.
The circled holes will be drilled out with the drills supplied by Dana, according to the instructions.
Check balls and flow restrictor. The new torlon check balls at the top will supposedly never wear out the separator plate.
The flow restrictor is pounded into one of the oil passages with a pin punch.
You absolutely HAVE to have one of these magnetic pickup tools. It works really well to pull the valves out of the valve body
and is generally useful for a lot of things.
These guys may be cheap tools from AutoZone, but you really need them to get O-rings and lip seals out of their grooves.
My improvised parts washer. An ancient oil drain pan I've had since the '60s and a weed sprayer filled with paint thinner.
I used carb cleaner for the final rinse.
The old (on the right) and new wiring harness connectors. I thought it might be nice to use a 4 pin connector and put a
trans oil temperature sensor in the trans, but I didn't do that. The new connector was REALLY hard to get into the case.
The video made it look so easy...
This is what I came up with to extract the thimble filters -- a drywall screw.
I tried for about an hour to get this piston into the drum. I was using a 0.010" feeler gauge to guide the lip seal into place,
but the piston kept getting cocked and the sharp edges on the feeler gauge were slicing off little bits of the lip seal.
I finally got the idea to use the overhead transparency film, which worked really well. A little trans oil for lubrication
and the piston slipped right in.
The reaction gear support had a lot of wear where it rides in the bushing so I bought a new one.
The new reaction gear support is a beautiful piece thanks to numerically controlled machining.
All the frictions need to be saturated with transmission fluid. I just rubbed it on with my finger until it soaked in.
The books tell you to use Vaseline liberally during assembly to lubricate the various seals and to hold the check balls in place.
I've had this jar a LONG time. It's real glass. You don't see that nowadays. The circle on the top has "27¢" rubber stamped in it.
Checking the servo travel with a dial indicator. This is critical to the life of the band. There is a small piece of sheet aluminum
under the C clamp to protect the pan gasket surface. The trans is sitting on a bar stool that my next door neighbor threw away after
her dogs chewed it up. I cut off the legs and drilled a 1-3/8" hole in it that the output shaft fits in.
The rebuild kit comes with a new spring that is added to the servo stackup. It's REALLY strong and it took a lot of effort to
compress it. This kludgy setup actually worked quite well and is based on a rebuild series I saw where the author welded up a
bracket to do this. I don't know if I would have thought to use a crow bar without the hint from his web site.
I started cleaning the torque converter cover and it got shinier and shinier as I cleaned it. It surprised me that it's aluminum.
I put some metal polish on it and now it looks great, even though nobody but me will ever see it.
These are the parts replaced during the rebuild and upgrade process.
The transmission weighs about 150 pounds and I was afraid I might drop it when I moved it from the workbench to the trans jack.
I bought a Harbor Freight rope hoist to do this job. The idiot who wrote the instructions didn't understand how pulleys work
and I had to thread the rope a different way in order to get the maximum multiplication of effort.
I installed the rebuilt transmission in my car and found out I had a big problem. Fortunately I had the foresight to buy a transmission
pressure gauge. I found that my line pressure was about 70 PSI and did not go up when pressing on the gas pedal or when shifting
into any of the gears. I did the TV cable extend test and the pressure went DOWN about 5 PSI (it's supposed to go up). This can cause
major problems in the transmission because the low pressure doesn't clamp the clutches tight enough and they slip. This causes
a lot of heat and the clutches burn up very quickly. I wasn't going to let that happen to me, so I resolved that the car was
going to stay up on blocks with the wheels off the ground (minimum load on the transmission) until the problem was resolved.
Based on my experience, I recommend that you ALWAYS ALWAYS ALWAYS
use a pressure gauge to verify
proper pressures after rebuilding a transmission.
After some Internet research into low pressure problems I found that there is a rather common mistake that rookie rebuilders
make. It's known as the "boost valve in the pan" problem. I dropped the pan and mine wasn't there. This really bothered me because
I thought I had some serious internal problem and I would have to take the transmission out, which is a major pain in a
Corvette because of the C beam that joins the transmission and differential (there is no rear motor mount).
The boost valve had slipped and ALMOST came out. Most of the fluid was blowing out the gap instead of going into the internal passages
of the transmission. It looked like this:
I couldn't get the boost valve to go up into the pump where it belonged, so I decided it had to come apart.
One of the problems with working on a transmission in the vehicle is that transmission fluid drips out constantly. The whole
transmission is full of fluid when it's running and fluid leaks out because of clearances. Moving the shift lever opens up
various passages and fluid pours out. No matter how careful you are there will be puddles of fluid on the floor.
Even after wiping up the puddles, there is still some fluid on the floor and since I was lying on my back while working on
the trans I got fluid in my hair.
I decided I needed to protect the back of my head from the fluid and the first
idea I had was to wear a baseball cap. I don't like wearing hats and only have two baseball caps and I didn't want to
sacrifice either one, so I came up with a "do-rag" solution. Dodge was giving out these bandanas in
their goodie bags at the Cruisin' For A Cure (for prostate cancer) car show. Actually I use this one to dust my furniture, but
it came in handy for this.
This is what we're dealing with. The part labeled .296" is the reverse boost valve and it sits down inside the part below it (the
intermediate boost valve) and sticks out the bottom about 3/8".
It rests on top of the TV boost valve stem, which sits down inside the bottom of the boost bushing.
The instructions for the pump upgrade kit (TransGo SK 700-Jr.) say, "This kit installs easily with trans in the vehicle
or on the bench". EASILY? They LIED.
There several big problems here. The first
one is gravity. When you put these parts up inside the pump they fall right back out again. The second one is that the valves
have lands on them and fit very tightly in the bore. The lands get hung up in the internal passages as you insert them into
the bore. They feel very solid like they're all the way in, but they're not. That's what caused the problem in the first place.
The stackup wasn't far enough into the bore when I put in the snap ring.
The third problem is that all these parts are separate pieces so you can't hold one in place while you put the next one in.
What happens is that you put in one piece and then it falls down when you try to put in the next piece. Then the lands get hung
up in the bore and you can't get the first piece back into the correct position.
The classic DIY method for holding parts in a
transmission is Vaseline. In this case the PR (Pressure Relief) valve is steel and fairly heavy. I put lots of Vaseline on it
and pushed it up into the bore. After a LOT of wiggling around I finally got it to go in fully and stay in place.
As I was finding the spring the PR valve would fall out. Then I got the brilliant idea of putting a big glob of Vaseline on the top of the
spring and inserted the PR valve and spring together. This worked somewhat better but I still had problems with the spring and/or
PR valve falling out and it still took a lot of wiggling to get the PR valve all the way in. My solution was to squeeze the top coil of
the spring to make it smaller and then force it over the tapered bulge just below the large diameter land, so it was retained on the PR
valve. At least they now fell out as an assembly.
Now another big problem became apparent. When I tried to put in the reverse and intermediate boost valve I was pushing against the
spring. It was very difficult to get the lands in the bore plus the spring was trying to push it out. In this case the tight fit
actually helped because it tended to get stuck in place.
Since I was having so much trouble, this called for some tools. On the right is an old screwdriver that the handle broke off of. I've
saved it for probably 20 years and finally found a use for it. I put it into the spring on the PR valve and it helped me wiggle and guide the
PR valve into place. The middle tool is a deep socket on a 6" 1/4" drive extension. The socket fit over the end of the reverse boost
valve that stuck out of the intermediate boost valve and also provided some wiggle. The snap ring pliers have interchangeable tips
and the ones in there are extended as far as I could get them. The boost bushing sits very deep in the bore so I needed all the
length I could get.
Since I was taking my car apart to swap in the newly rebuilt transmission, I decided to replace the
front Y pipe because I had a problem with one of the cats getting plugged up. I took the new Y pipe to a muffler shop to have a
second O2 sensor bung welded in so I could have a wideband O2 sensor for tuning. While I was there I happened to pick up a 6"
steel rod that was lying on the ground and looked interesting. They apparently use these for making muffler hangers.
I knew there was going to be a lot of slipping, sliding, bumping and general chances for things to slip up and I needed a solid
method to hold everything in place while I put in the snap ring. I saw in a thread somewhere
that somebody suggested measuring from the bottom of the boost bushing to the ground and then cutting a rod that length. That
sounded kind of iffy to me and I wanted something more sophisticated. The 6" steel rod was sitting on my bench and looked like
the ideal start of a new tool. Here is my solution. An old cheap floor jack that's semi-retired because it leaks.
I found a 3/4" socket fit tightly over the bolt
that holds the cradle and used a lot of 2" masking tape to hold it in place. I found a socket that the rod fit snugly and
inserted the socket inside the 1/2" drive part of the larger socket. My boost valve holder:
I was concerned that I might be jacking up against a PR valve or boost valve that was hung up in the bore and not really fully
inserted into the correct place. I was very careful to make sure the snap ring groove was exposed below the bottom of the boost
bushing. The opening in the snap ring turned out to be just large enough to fit over the rod.
The way the boost valve bore is machined, there is a tapered step about 1"
into the bore. The snap ring groove is about 1/4" deeper. This step is what
causes the "boost valve in the pan" problem. Since the snap ring groove is so deep in the bore, the snap ring pliers won't go
in far enough. The snap ring is inserted in the bore and then pushed in until it bottoms against the tapered step instead of
in the groove where it belongs. There is nothing to hold
the snap ring in position and the whole assembly gets blown out of the pump when it's pressurized for the first time.
Now another problem arose. With the jack and various transmission parts in the way, I couldn't get the snap ring very far
into the bore with the snap ring pliers. I got the snap ring partly in and after a lot of futzing around was finally able
to get it into the snap ring groove.
This is what the boost bushing looks like when everything is in the correct position. You can see that the snap ring has
seated in the groove. The black ring above the snap ring is the tapered step that causes the problem.
Success! Now I've got correct line pressures.
But wait... There's more.
I put in a Boss Hog converter (~$200) when I did my 700r4 rebuild. After 150 miles it started whining. At 170 miles I figured
it was grinding itself to death and sending metal particles throughout the trans, so I stopped driving the car. One thing I noticed
(didn't know it was a problem at the time) was that there was a very large gap between the flex plate and the torque converter, at least 1/4".
I just bolted it up and found out later that this could be a problem.
Here's the inside of my trans filter. All the sparkly stuff is metal particles:
Anyhow, I bought an Edge torque converter (~$350) because Dana of Pro-Built recommended them. One thing I noticed was that the gap
between the flexplate and torque converter was very small and the torque converter actually grazed the flexplate as I spun it.
I think this says something about the quality of the Edge converter, which obviously fits much better. Hundreds of miles later everything is fine.
One small complaint. I asked for a stock stall speed and they sent me one that is slightly higher than stock. I don't like the loose
feel off the line. On a slight incline I can take my foot off the brake and the car won't creep forward. This is a daily driver and
I don't need a high torque "launch" every time I pull away from a stop. I like the tighter feel of the stock stall speed better.