700R4 Information Thread

[AuroraGirl]

I experienced something very similar with an '86 700r4 in a TPI Camaro that had just been rebuilt by an unknown shop in South Dakota, maybe the same issue that @mibars spoke of.

Under light to moderate throttle, it would run out first gear in a normal fashion, then after shifting to second, the converter would almost immediately lock up, then short shift to 3rd and then also short shift to OD... then lug it's way up to speed. If you applied heavy throttle from a start, it would shift through all the gears as it should, then go into OD and lock the converter when you let off the throttle.

I never did find out why it shifted that way. I bought the car in the winter, then in the springtime, it fragged the reman converter and sent debris all through the trans.

might have fragged because of the torque during shifts and early 2nd gear lockup + being an old 700r4 which generally had reliability issues anyway

 

[NickTransmissions]

I experienced something very similar with an '86 700r4 in a TPI Camaro that had just been rebuilt by an unknown shop in South Dakota, maybe the same issue that @mibars spoke of.

Under light to moderate throttle, it would run out first gear in a normal fashion, then after shifting to second, the converter would almost immediately lock up, then short shift to 3rd and then also short shift to OD... then lug it's way up to speed. If you applied heavy throttle from a start, it would shift through all the gears as it should, then go into OD and lock the converter when you let off the throttle.

I never did find out why it shifted that way. I bought the car in the winter, then in the springtime, it fragged the reman converter and sent debris all through the trans.

The stack-shifting can be due to improper set up, mal-adjusted TV cable or incorrect TV cable geometry (not saying that was the case with yours but those are common reasons for stack-shifting)...Other reasons include wear/cross-leaks in the forward drum's apply circuits, weak pump, worn TV boost valve, sleeve or plunger or even simply not enough fluid in the trans. If the TCC was engaging super early, that could have been anything from mechanical issues w/the TCC enable/control valve (rare), TCC solenoid partially stuck on/energized, etc.

 

[bucket]

The stack-shifting can be due to improper set up, mal-adjusted TV cable or incorrect TV cable geometry (not saying that was the case with yours but those are common reasons for stack-shifting)...Other reasons include wear/cross-leaks in the forward drum's apply circuits, weak pump, worn TV boost valve, sleeve or plunger or even simply not enough fluid in the trans. If the TCC was engaging super early, that could have been anything from mechanical issues w/the TCC enable/control valve (rare), TCC solenoid partially stuck on/energized, etc.

It's been so many years, I can't remember for sure if I messed with the TV cable or not. I "think" I did, but who knows. I simply changed the broken converter after limping it home 25 miles and that's when I found out the rest of the trans was hurt. (I also removed the engine, did heads, cam, etc and set the TV cable when I replaced the converter) Once it shifted out of first, it wouldn't go back to first unless you stopped and parked the car. It also wouldn't downshift at all, no matter what. Punching it at 65mph resulted in an OD pull all the way up to "highly illegal speeds" and I'll just leave it at that, lol.

Anyways, I guess none of that is related. I drove the car that way for a few hundred miles while I had another 700r4 built by a local shop.

 

[mibars]

What year 700r4?

Only the 1982-E87 in some models had the TC lock up in 2nd gear...Plus the TCC wouldn't drop RPMS that drastically...More than likely, there's a partial tie-up during the 2-3 shift due to the band not releasing completely before the 3-4 clutch pack applies. This happens when either the third accumulator check ball capsule is not completely sealing or the large scarf-cut sealing ring on the very front of the servo assembly is worn out. It can also happen if the band release hole is significantly smaller than the 2-3 feed hole in the spacer plate.

Have you ruled out potential mis-fires or other engine/fuel delivery related causes?

We can assume that transmission is original to the vehicle, the video:

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It doesn't short shift to 3 or 4th gear. It'slike this:
1-2 at 1600 rpm, with like two steps resulting in a drop to 1000 rpm. It sounds like lugging a bit.
2-3 at 2000 rpm meaning that it stays quite long in 2nd
3-4 also about 2000 rpm with no more drops in rpm.

It's different from how it shifts in my '90 square body with transmission that was overhauled by Jasper back in the USA. I don't have tachometer so by sound it feels like this

light throttle:
1-2 between 10 and 15 mph
2-3 between 25 and 30 mph
3-4 around 40 mph with a large, 2-step drop of RPM (I assume converter + gear change, don't know the order of thigs)

At super light throttle I can get it to change RPM below 35 mph (e.g. 30 mph) and then to do another change of RPM just above 35 mph. I'm saying "change of rpm" as I can't tell which is a 3-4 and which is a TC lockup.

 

[NickTransmissions]

We can assume that transmission is original to the vehicle, the video:

xc_hide_links_from_guests_guests_error_hide_media

It doesn't short shift to 3 or 4th gear. It'slike this:
1-2 at 1600 rpm, with like two steps resulting in a drop to 1000 rpm. It sounds like lugging a bit.
2-3 at 2000 rpm meaning that it stays quite long in 2nd
3-4 also about 2000 rpm with no more drops in rpm.

It's different from how it shifts in my '90 square body with transmission that was overhauled by Jasper back in the USA. I don't have tachometer so by sound it feels like this

light throttle:
1-2 between 10 and 15 mph
2-3 between 25 and 30 mph
3-4 around 40 mph with a large, 2-step drop of RPM (I assume converter + gear change, don't know the order of thigs)

At super light throttle I can get it to change RPM below 35 mph (e.g. 30 mph) and then to do another change of RPM just above 35 mph. I'm saying "change of rpm" as I can't tell which is a 3-4 and which is a TC lockup.

Didn't watch the video but your description seems to indicate either governor, 2nd gear servo or valve body issues (perhaps 1-2 throttle and/or shift valve sticking), if it's the transmission (still don't know whether you've tested and ruled out engine-related causes). The sizable RPM drop from 1st to 2nd gear is somewhat normal for these transmissions - keep in mind that first gear has a ratio of something like 3.08-1 while 2nd gear is 1.49 to 1 or something very similar...It's one of the main complaints that racers have about these transmissions; Sonnax makes an updated front planetary set that changes the ratio (2.80-1 in first, 1.60-1 while in 2nd).

Check line pressure w/ a trans pressure gauge at min and full TV - assess condition of the cable itself, make sure it's not worn, torn or otherwise damaged (replace if so)

Check your servo in-board travel...Shouldn't be more then about .075"-.125" max:
step 1: remove servo assembly from case
step 2: remove the large scarf cut sealing ring on the front of the 2nd gear servo piston and two large blue / red or green o-rings
step 3: reinstall servo with large return spring and large case snap ring
step 4: push servo inboard until it won't go any more
step 5: assess travel, if too long - acquire and install a Corvette (093) 2nd gear servo ($15-$20) & Transgo SK700-JR shift kit ($40 or so); if travel is acceptable, move to the valve body (drop pan, assess condition of fluid, etc.)
step 6: If fluid is nasty, lots of burnt friction material, etc at bottom of pan, put pan back on with a few bolts, yank it out and overhaul the transmission
step 7: If fluid, pan bottom is unremarkable, proceed with valve body removal and inspection - take note of any sticking 1-2 shift and throttle valve(s)
- If you have an 82-87 unit, you will have a 1-2 low range up and downshift valve set in a small sleeve appx 2/3rd the way to the rear of the 1-2 bore in the valve body

Doesn't seem like TC to me but will know more once you have done the above.

 

[AuroraGirl]

You must be registered for see images attach

this is potentially helpful too

 

[NickTransmissions]

You must be registered for see images attach

this is potentially helpful too

80-95 inch lbs is an ideal range, in my own personal experience, for all valve body and aux valve body or rear hold down plate bolts as well as the TCC Solenoid bolts. I do 105" on the 1-2 accumulator housing and 15 ft lbs on the larger 13mm bolt for the detent roller.

 

[HotRodPC]

You basically have to block the TV Boost valve so it's wide open and same with the TV limit valve. You also need to modify the reverse boost valve to avoid a severe overpressure condition when in Reverse. I think I have some instructions Chris at CK gave me a few years ago so if I can dig them up, will post them here.

That said, I wouldn't do a CP VB for street use - that much pressure is generally harmful for the pump. If it's race only, it's good to go since trans periodically comes out for refresh in racing applications.

Isn't it the older valve bodies needed to make a constant pressure vb? Or am I thinking of something else? I know there's a 700r4 hack that can be done and why it's wise to save the older valve bodies. Is it maybe manual lock up on the converter? My memory....

 

[NickTransmissions]

Isn't it the older valve bodies needed to make a constant pressure vb? Or am I thinking of something else? I know there's a 700r4 hack that can be done and why it's wise to save the older valve bodies. Is it maybe manual lock up on the converter? My memory....

You can convert either style into a 'constant pressure VB' but unless you're drag racing, it's not recommended...Having the VB generating 175PSI full time is extremely hard on the pump, results in extremely harsh shifts, especially the 1-2 shift and usually results in premature pump failure in street-driven vehicles. Race transmissions typically come out once per season or so thus remanufacturing or replacing the pump each time is part of the refresh.

 

[bucket]

You can convert either style into a 'constant pressure VB' but unless you're drag racing, it's not recommended...Having the VB generating 175PSI full time is extremely hard on the pump, results in extremely harsh shifts, especially the 1-2 shift and usually results in premature pump failure in street-driven vehicles. Race transmissions typically come out once per season or so thus remanufacturing or replacing the pump each time is part of the refresh.

You just reminded me of another 700r4 experience I once had. Sorry for the foggy memory and extremely vague details, but here goes...

I had a very trustworthy trans shop rebuild the 700r4 in my '88 Suburban. I brought it to them because it suddenly started shifting soft and slipping a bit at times. They tore into it and could tell that someone had been in it before (something about a "z-pack" maybe?), they recommended a full rebuild and I approved of it. When it was all done and put back together, they called and said "It's ready to go, but we tried a [my memory is super foggy here, they may have said something else] new shift kit and it shifts very harsh, you probably won't like it". So I went and drove it and it was a very very firm 1-2 shift, along with positive shifts in all other gears. I told them "No it's great! I love it! Call it done!" and I drove it home. I did enjoy driving it like that too, it was so much fun... like a high performance machine, lol. But after 10 or 20k miles it suddenly lost all movement in either direction and they rebuilt it again for free. There was a bunch of broken internal stuff, I don't remember what all there was, but I for sure remember the 4-pinion planetary was broken. When I got it back, it still had a good positive shift, but it wasn't like before.

I kind of wonder if they had tried the "constant pressure" vb thing.

 

[HotRodPC]

You can convert either style into a 'constant pressure VB' but unless you're drag racing, it's not recommended...Having the VB generating 175PSI full time is extremely hard on the pump, results in extremely harsh shifts, especially the 1-2 shift and usually results in premature pump failure in street-driven vehicles. Race transmissions typically come out once per season or so thus remanufacturing or replacing the pump each time is part of the refresh.

So do you recall what the reason is to save the older valve bodies for? I know there's a hack and you need a very early vavle body to do it. Maybe it's manual lock up? It's just totally slipped my mind, but I know there's a reason why to save the older vb.

 

[NickTransmissions]

You just reminded me of another 700r4 experience I once had. Sorry for the foggy memory and extremely vague details, but here goes...

I had a very trustworthy trans shop rebuild the 700r4 in my '88 Suburban. I brought it to them because it suddenly started shifting soft and slipping a bit at times. They tore into it and could tell that someone had been in it before (something about a "z-pack" maybe?), they recommended a full rebuild and I approved of it. When it was all done and put back together, they called and said "It's ready to go, but we tried a [my memory is super foggy here, they may have said something else] new shift kit and it shifts very harsh, you probably won't like it". So I went and drove it and it was a very very firm 1-2 shift, along with positive shifts in all other gears. I told them "No it's great! I love it! Call it done!" and I drove it home. I did enjoy driving it like that too, it was so much fun... like a high performance machine, lol. But after 10 or 20k miles it suddenly lost all movement in either direction and they rebuilt it again for free. There was a bunch of broken internal stuff, I don't remember what all there was, but I for sure remember the 4-pinion planetary was broken. When I got it back, it still had a good positive shift, but it wasn't like before.

I kind of wonder if they had tried the "constant pressure" vb thing.

Very cool recollection...Do you remember installing, adjusting a TV cable? If not or one was never installed, it's a good bet that a CP valve body was involved. Also, the fact it lasted only 20k miles lends more credence to one being on that trans since that's about how long they typically last (5-20k miles) in a street driven application. Pump rotor/rings/slide likely shattered.

So do you recall what the reason is to save the older valve bodies for?

Yes, their main draw is the mechanical TCC lock up control capability...no need for an electro-mechanical internal/external lock up kit for non-stock applications...My resto-mod customers love that sine they don't want to spend time and money monkeying with electrical stuff on a 30s,40s,50s,60s vehicle and the 1st gen valve bodies let you control the converter clutch automatically via the forth bore on the shift valve side of those 1st design valve bodies.

The 2nd design and 3rd design, 88-92, 93 respectively, don't have that 4th bore - it was casted over entirely...

The preferred approach for any performance application involving a 700R4 is to use an 88+ core with an 82-87 valve body to give you the best of both worlds...The 88+ 700R4s have the most updated input drum, 29 element input sprag, wider low roller clutch/center support, 10-vane pump assemblies, aux valve bodies for softer garage engagement into drive and a better engineered low-reverse circuit.

 

[Wumbo]

Ugh. I've been going back and forth on whether or not to use an early valve body with mechanical lockup or make my own TCC lockup control for the 89 700r4 I'm about to build. It's going into a 600+ hp big block Camaro. Mainly street driven, with an occasional trip to the strip. I'm not really impressed with the aftermarket lockup controls I've looked at.

On that matter, does the mechanical lockup apply in 4th gear only? Because my goal is for lockup in 4th at cruising speed above 45 mph. And if I did swap to an early valve body, can I use the 89 separator plate?

One more question, does anybody currently make a performance output shaft for a 2wd 700r4? I have a Sonnax input shaft and drum, smart shell, and about every other performance part I can get, but I can't find an output shaft.

 

[NickTransmissions]

Ugh. I've been going back and forth on whether or not to use an early valve body with mechanical lockup or make my own TCC lockup control for the 89 700r4 I'm about to build. It's going into a 600+ hp big block Camaro. Mainly street driven, with an occasional trip to the strip. I'm not really impressed with the aftermarket lockup controls I've looked at.

On that matter, does the mechanical lockup apply in 4th gear only? Because my goal is for lockup in 4th at cruising speed above 45 mph. And if I did swap to an early valve body, can I use the 89 separator plate?

One more question, does anybody currently make a performance output shaft for a 2wd 700r4? I have a Sonnax input shaft and drum, smart shell, and about every other performance part I can get, but I can't find an output shaft.

Mechanical lock up applies in 4th gear only as far as I know. The Superior Tech kit comes with five or six different lock up springs; the stiffest spring will provide the latest lock up road speed. You will likely need to use the Transgo 700P spacer plate and follow their instructions for set up. Im not sure (can look tomorrow) if the 88-92 spacer plates will work as is with a first design valve body with the mechical lock up functioning.

I dont know of anyone who makes a billet output shaft for the 700 either (sucks) but the factory shaft has lived in 700+ hp TT LS1 applications that I'm personally aware of so it may be ok for your Camaro. Plus they're cheap so if it snaps you can go get another....sounds crappy but that's the only shaft I know of for those (not sure why Sonnax doesnt make one).

 

[Wumbo]

Thanks Nick