bl85c

iTrader: (2)

Like most owners of pre-'87 th700's I find the factory 'safety features' to be very annoying. Early models can't upshift from 3-4 at wot, can't downshift from 2-1 at wot, won't cruise in lockup or 4th gear above ~1/2 throttle, have the annoying tendency to 'hunt' between 3 and 4 while cruising on the highway and of course there's the plesant clunk when shifting from park/neutral to drive or reverse. What I hope to achieve here is a guide to eliminating the driveability problems found with early th700's.

First thing to do is install a quality shift kit or transpak. Often times a good shift kit will eliminate or reduce many of the problems found with early th700's. After installing mine the clunk from shifting from park/neutral to drive or reverse was considerably reduced and I was able to cruse at higher speeds in lockup and 4th with much less 'hunting' between 3rd and 4th on the highway.

Early pre-'84 models that only have 7-vane oil pumps are often plagued with poor shift quality and can always benefit from the later 10 vane pumps. Most companies do offer performance pumps, but the best option is to upgrade your existing pump to a 10 or 13 vane setup available as a kit from Raptor. Although completely replacing the pump with a later 10 vane model requires plugging the auxillary valvebody port and changing the reverse drum and torque converter with it, using an '87-up assembly will also eliminate the clunk when shifting from park/neutral to reverse or drive.

Now that the trans has sufficient oiling and more holding power, the 3-4 shift problem is easily solved by installing a later 3-4 shift valve assembly from an '87-'93 Iroc or Corvette. This valve enables a wot 3-4 shift and limited (e.x. passing someone) wot operaton in 4th. Extended wot operation in 4th with early models could damage the trans and should be avoided. B&M, Raptor, Transgo and Bowtie overdrives also sell it.

I haven't been able to find an easy solution to the 2-1 downshift problem. I have found conflicting opinions that the later 1-2 shift valve assembly from '87-'93 th700's (which enables wot 2-1 downshifts) can and can't retrofit into earlier models. Supposedly there are aftermarket 1-2 shift valves available that fix this problem, but I haven't found one. Maybe someone can clear this up for us?

To further enhance the trans' holding power (ability to stay in a particular gear) larger servos can be installed. C4/C5 Corvettes and LT1 Camaros were equipped with better servos that improve the trans' holding power and also eliminates the 2-3 shift flare on older models. Many aftermarket servos are available with greater holding power, however some of the larger ones may be too harsh for street use as they also affect shift quality.

The final step is to install a better throttle valve to enable cruising at higher speeds in lockup and 4th. Some Corvettes and Iroc's had a better tv (stamped 94 on the plunger valve) that enabled lockup and 4th gear operation at a higher throttle position (60%?), however most aftermarket valves can further delay downshifting up to 75% throttle.

After modifying an early model with these parts the result is a transmission that's plesant as a daily driver, yet crisp and responsive under load. The life of your transmission will be significantly extended, however this does not compensate for wear or many of the design flaws found in early models. This setup will suit a daily driver or cruiser that sees relatively little wot operation and is therefore less likely to stress weaker components. Those wishing to build a performance oriented transmission should consider starting with an '87-up trans and building from there or a professionally built unit.

bl85c

iTrader: (2)

After calling a few performance shops and comparing the valvebodies and 1-2 shift valve assemblies from my trans and an '89 I've found that it is most likely possible to install the later valve. I'll install one in mine as soon as I get the time to do so and post the results here.

bl85c

iTrader: (2)

Well, I finally had time to put the later 1-2 valve in, but it wasn't a straight swap. The earlier valvebodie's 1-2 valve port narrows from .8" dia. to .768" where the first segment of the valve sleeve assembly separates from the second. So that means that you either have to have your valvebody's valve port honed out to .8" for the entire length, or lathe the later valve sleeve down to .768" dia. (lathe 1.777" back from the open end of the valve sleeve) to fit. I opted for the second option so I could put the original valve back in if things didn't operate correctly. It's also neccecary to plug the unused retaining pin hole to prevent pressure loss. So after finally getting a chance to drive with the new valve I can say that it operated flawlessly, providing a crisp 2-1 downshift after opening it up while cruising in second. With this valve you'll never have to suffer from being unable to downshift into the powerband while cruising again.

speshulldroo

excellent thread. i can see myself using this for sure.

Pro Built Automatics

Except for the installation of the later 1-2 shift valve, I have been doing most of what you have brought up and other modifications for many years now when doing an older version (1982-1986).

Shagwell

great thread! Very informative.

That will bring the early model up to the operating level of the later unit, and with the addition of the aux valve body and later 30-spline input drum you start bringing up the strength as well.

EGG

Is there a way to tell under the car if it's an earlier 700R4? I've got an '88, but it has most of those problems (refuses to change to 4th at WOT, hunts between 3-4 on hills, clunks between P/N - D/R).

Before this I had a Holden Commodore sedan with a buick 3.8 and a 4L60E. The transmission in that was fine, clunked a bit between P/N - D/R, but it held higher gears through corners, didn't hunt around for gears like a hippy chick in a bra shop and changed to 4th at WOT.

The #$%$^$ 700R4 also once dropped out of 4th to 3rd at what was definitely not a 3rd-gear speed, one of the tappets on the left bank has been a bit noisy since that.

RacinMadns

This thread is very helpful to me, Thank you. I have a 84 Camaro that I put a mild 355 in to bracket race(low 13 sec. car). I am in the process of rebuilding it. it is a 30 spline and I put a trans-go shift kit in it. My question is I want to make it a full manual but when putting shift kit in I set it up to not be manual. Can I make it a manual without having to get another valve body or can I use a valve body out of 87-89 700R4?

Pro Built Automatics

The way to identify the year is on the passenger side of the transmission just above the pan rail torward the rear is a flat area that has the ID of the unit. The first digit is the year. 7 would be 1987, 1 would be 1991, etc. The hunting in 4th gear (this is assuming that the TV cable is adjusted correctly) is because the TV plunger sleeve has two 4-3 downshift passage holes in it. The placing of where the hole is in the TV plunger sleeve, has a lot to do with how easy or how hard it is to make a 4-3 downshift. The other is how much torque the engine is putting out. If you have a lot of torque, it will take less throttle to do anything, then you will not uncover the 4-3 downshift passage as easy. You can change the location of where the 4-3 downshift passage is, by using a different TV plunger sleeve with a different 4-3 downshift passage location from another transmission such as a Corvette. By moving the 4-3 downshift passage further away from the top of the TV plunger sleeve, it will take more throttle to make the 4-3 downshift, and the transmission will not be as likely to hunt for which gear it wants to be in. You can eliminate the 4-3 passage by using two Allen screws to block these passages. This will prevent the 4-3 downshift at anything above apx. 75 mph in the most cases, and will allow you to hold 4th gear at WOT.

Mikz86TA

iTrader: (4)

Hmm..well thats a cool trick! I have an 86, but its had a few trannies and the one now has an aux VB. So Im guessing 87-up from what I read. I need to verify by the ID though what exactly it is. Here is my issue. I have no 2nd or 4th. If you drive it through 1st in D or OD, it will never shift. If Im flooring it, it doesnt shift to 2nd like it should but there is a way to et it to shift by heavy throttle and letting off and on. But it draggs like its in 3rd. It will not go into 4th either when you get going. When in 3rd (seemingly) I can try to manual downshift to 2nd (this is at a reasonable road speed where it would do this B4) and it doesnt go in. Back to cruising when its finally in 3rd, I can upshift to OD and its almost like neutral slipping but still seems like its in 3rd at the same time...no pull. I can put it back in D and it feels like 3rd...responsive again. On a side note, it did seem like the 4th gear symptoms were acting up B4 the no 2nd gear symptoms were going on. I didnt really pay attention since I rarely used OD and 4th (not a daily driver nor road trips) and I thought it was the TQ converter clutch malfunction (no ECM..I was told if I wanted the TCC lockup, I would need to buy the kit or make one or use a manual switch). But now the issues seem 2B related to bad Band, Servo malfunction or VBody malfunction of those circuits. Anyone got any helpful or useful inputs?? Ive heard of a way to use compressed air in a hole under the pan lip to test the servo actuation...can you see the band from the front hole and is this an on-car test I could do?? Im about through with the 700R4...been through many, spent alot of $ on something I couldve learned myself anf f-ed up cheaper by now. Plus the tranny guys dont listen. I wanted the self-lockup or a non lockup converter, and wanted to be able to hold the gears manually (never was able to hold 1st) and the 1st shift happened way too early. Please help ?? =)

bl85c

iTrader: (2)

With the symptoms you've listed it sounds like you've burned the 2-4 band. If you see a lot of metallic-black sludge in your trans fluid (particularly on the pan magnet) you've definately burned it up.

Extensive work has to be done to the valvebody to convert it to a transbrake (manual) valvebody, I'd suggest getting a professionally built one. Likewise, to eliminate the tcc lockup you have to have the valvebody modified and get a non-lockup converter to prevent overheating and trans damage. I can't help you with that though, because I've never needed (or wanted) to do it. It's much easier to get a kit to manually lock the converter.

I'm glad to see so much interest in this thread, I was starting to think noone gave a crap about the older models. Eventually I'm going to modify my trans to retrofit the aux valvebody onto it and outline the proceedure so anyone can do it. It doesn't seem to need much machining work, mostly just part swapping. We obviously can't all have '87-up th700's, so we might as well upgrade the early ones.

EGG

Thanks Pro Built, I'll see if I can have a look under it tomorrow.

IROC-You

If you live close to me (Virginia Beach, VA) I will give you a case from an 89 V6 for free. Then you can have your very own 87+.

bl85c

iTrader: (2)

Wish I did, I'm half way across the country in colorado.

bl85c

iTrader: (2)

I was just thinking we should get this stickied so it doesn't get lost in old thread land. Anyone else think so?

bl85c

iTrader: (2)

...

klause83z28

I agree, this should become a sticky.

87zjeff

iTrader: (4)

btw, the channels in the pre '86 cases and the channels in the 87-up cases are significantly different. i doubt you can modify an earlier case to accept an aux. valve body.

bl85c

iTrader: (2)

I haven't had a chance to look at it closely yet, so thanks for the info.

Pro Built Automatics

Unlkess you are good at heliarcing....... The passages are different in the area of where the forward accumulator valve body sits.

bl85c

iTrader: (2)

Or maybe an adapter could be made...

camaro91boy

ok heres a question for you trany people. when i bought my 91 camaro it had a bad trans so i went to local junk yard and bought a 700r4 from i think a 84 or 85 camaro rs. recently iv'e noticed the symptoms of what was described before. but when i was driving down the high way for quite a distance it what felt like slipped into neutral. then the shift points spread way out and i never reached my 4th again. i added some lucas tranny fix fluyid and it fixed it for awile but tonight the tranny made a lot of funny noises rattling and then it didn't shift or catch it stopped and wont move unless you push it then you feel something grab and it takes off. its loosing fluid somewhere but i can't find it and now will drive when ever it wants while in gear. basically from what iv'e read i need a 87 and up but did i fry my tranny or am i jumping the gun?

bl85c

iTrader: (2)

The trans that came in your car had electric tcc lockup, your ecm should be throwing a code for that, but in general I don't suggest reverting to pre-'85 models unless many improvements have been made. I would never use a junkyard trans as-is, if they offer any kind of guarantee I suggest taking it back and getting a post-'87 replacement and having it rebuilt, or buying a new one altogether.

camaro91boy

yeah i don't have the $ for new or rebuilt ones so that solves that option but i did find a trans in the junkyard out of a 92 trans am will this fit better and how can i expect it to shift and drive compared to the last one iv'e never drove one that was correct. the one that was in it shifted real hard from first to second and then mellowed out through the gears. as for the codes it dosen't through any unless i shut off my speedometer. i was begining to be quite the reliable car until this happened. when i got home today i tried to put it in gear it made godawful rattling noiseses but did move forward. i checked the fluid and it was well over full. its almost like it sucks up all of the fluid puts it some where and then after you park it it fil;ls back up? im so confused and down right agrivated any ideas of what happened. also any pros and cons for a shift kit?