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GM 700R4 Trans. Info

The 700R4 is a good transmission for a retrofit into an older car. It has a 0.7 to 1 overdrive ratio making even 4.11 gears great on the street. The following information is what I've found out over time and what I encountered installing it in a 1979 Z28 Camaro.

The 700R4, 4L60, and 4L60E have the same external dimensions and case. The 4L60E is the electronic controlled version of the 700R4 / 4L60. The transmission has the following dimensions and gear ratios

Case to ext Housing Overall Length Bellhousing to mount
23 3/8" 30 3/4" 22 3/8"

Transmission 1st Gear 2nd Gear 3rd Gear 4th Gear OD
Turbo 350 2.52 1.52 1 N/A
Turbo 400 2.48 1.48 1 N/A
2004R 2.74 1.57 1 0.67
700R4 /4L60 3.06 1.63 1 0.7
4L80E 2.48 1.48 1 0.75

I recommend to get an 1987 or later 700R4. 86' and older 700's have a reputation for problems. If you stick with 87' and newer the tranny will have a 30 spline input shaft and a 27 spline output shaft. This allowed me to re-use my drive shaft yoke from the Turbo 350.

The mounting pad on the 700R4 uses the typical TH350 / manual trans 3.75 inch bolt spacing. The bolts going into the 700R4 are M10x1.5x (length required). Metric torque converter bolts are also required to bolt the converter to the flexplate, GM (PN 1261968).

The 700R4 uses a lockup converter. I love my lockup. The person I spoke to at Art Carr doesn't recommend using a lockup converter, I guess that's why I bought a TCI 3000 rpm stall lockup converter. The lockup converter allows me to have a high stall and cruise on the highway. With 3.73 rear gear and a 28" tire 2500 rpm is about 80 m.p.h.. If I didn't have a lockup converter I would be constantly slipping with my converter on the highway. I don't use the lockup in any other gear than overdrive and I disengage the lockup under full throttle. It's great you can have your cake and eat it too, high stall for good launch, lock up the converter on the highway and cruise home.

700R4 wiring diagram

I control the lockup on the converter manually. The wiring diagram shown is how I wired my car. I got the toggle switch from the junk yard out of an older Nissan Maxima, it's lighted and says O/D on it. It's simple I push the switch and the tranny locks the converter. In a braking situation the brake switch disengages the converter for me. Sometimes I forget the converter is locked up and I'll bog the motor...ooooops press the button to disengage the converter. I've never used one of the kits for controlling the lockup but I'm the type who likes to control when I want the converter to lock. I hate it when a tranny keeps going in and out of lockup. If this is not for you all of the major tranny companies offer a lockup kit for the 700R4, B&M, TCI, Art Carr, etc.

For mounting the 700R4 the cross member had to be slid back approximately 3". I was able to re-use my TH350 cross member and just drill extra holes in the front sub frame. I used the orginal back bolts as the front bolts for the 700R4 and drilled the sub frame to match the crossmember back bolts. The drive shaft also had to be shortened by approximately 3".

I installed a B&M Megashifter which allows for 4 forward gears. The one I put in is the unit made for the Camaro center console. The shifter is a little hard, requires a lot of force, but it's nice. I love the ratchet action.

The stock 700R4 has low shift points because it typically came with a TPI motor that runs out of steam at 4500 rpm. My motor turns on at 3500 rpm and I like to shift at 7000 rpm for first to second and 6500 rpm for second to third. The one bad thing about the 700R4 is the big gear drop between the 1-2 shift. So I hold first longer to put the motor in more of a sweet spot for second. The point I'm trying to make is , buy a kit from B&M which you can adjust the shift points. It's for the governor and it's different weights and springs, unfortunately you have to experiment to figure out the shift points. For mine I have to pull the tranny out to get at the governor, Oh well.

The only other modification that I had to do is to cut off a section of the case to clear my headers. The piece I removed is on the passenger side.

The 700R4 transmission in the Camaro recently blew up. With my luck the tranny let go on the highway around midnight with no one around. I had to walk a few miles to the nearest phone to call for help. The tranny let go when I was accelerating up to highway speed from the on ramp. The funny thing is that night I went to the shop to examine the drive line because I heard a SNAP when I hit the nitrous racing someone. I was planning on going to the track the next day and I wanted to make sure everything was OK. Needless to say I didn't see anything that would lead me to believe anything was going to let go. Well it did in a big way. Check out the pictures below.

The pictures are of the aluminum input drum. This drum is a splined piece that connects to the input shaft. As you can see from the pictures all the splines on the drum are sheared off and this piece just shattered. This is the weak link in the 700R4 tranny and I found it the hard way. When this thing let go it leaves you with no gears at all. No forward gears and/or reverse.

What's the Fix?
After calling around to all the big name transmission companies that advertise in the magazines and anyone else I could find I came up with nothing. They all basically said that they never heard of the input drum failing like that and they have these transmissions behind mega horsepower big blocks. YEAH RIGHT!!! Oh yeah, and that they would be happy to sell me one of their 700R4's that will handle the power I'm making.

What to do?
For lack of anything better to do I decided to do nothing, yet anyway. I put in the 700R4 from the parts 89 Firebird Formula, completely as is with the stock converter just so the cars is drivable. A note the stock converter is so tight and has no slip it is weird to drive. What I'm going to do is to send the converter back to TCI and have them do a rebuild as required because of all the metal pieces in the transmission. Who knows what's in the converter. Then I'm going to pull the tranny out and rebuild it with the billet servo pump, extra clutch packs, and kevlar band. I am also looking into having a new drum machined out of steel but it looks like that won't happen because the quotes from the machine shops are not cost effective. I'm also looking into the idea of getting another 700R4 to rebuild to keep as a spare in case I blow this one up.

Why not rebuild the blown up tranny?
I'm not rebuilding the 700R4 transmission I blew up because the output shaft egged out the case of the transmission so I would have to machine it and I it's cheaper to get a good used case.

Why stick with the 700R4?
The reason I'm staying with the 700R4 is I want an overdrive transmission. I think the 700R4 is stronger than the 2004R from what I've heard. I could be wrong on that because I've never had a 2004R transmission. Please don't send me any hate email saying that the 2004R is the best tranny since sliced bread. If however you know how to build it to handle the power please let me know.
The other choice is the 4L80E and the reason I'm not running out to buy one is because it's too much money.

4L80E Pricing:
4L80E Transmission, Approx. Prices $2000
Torque Converter $250 - $500
Transmission Controller $1000
Total: $3500

Don't forget the cost of the new driveshaft. Will the tranny will fit in the car? Will the tranny clear the headers? etc.

This picture is the input drum. It's aluminum! The piece in the middle of the drum is what broke off and shattered. I wish I had a picture of what one should look like but both pieces should normally be one piece. Input drum
This shows the sheared off splines. This is what the main input shaft slides into. Input Drum
The is the piece is part of the piston assembly that goes inside the above drum. The picture doesn't really show it but the piece is cracked and has a lot of metal shavings from the destruction. Input Drum

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