adi4

As the title says my 83 700r4 has developed a major problem.

I was driving down the road yesterday when I had to stop at a set of lights when they changed I floored it and pulled away, she changed up from 1st to 2nd then into 3rd then I let go of the gas and slowed back down to about 45 mph, when I squeezed the gas to hold the speed she reved up as if she was in N.
Now it does'nt matter what gear I select ( R, D, 3, 2, 1, ) she does'nt feel like the box has engaged but if you bring the revs up ( 3000 to 4000 ish ) she will slowly pull away in what ever gear you select and eventually gain speed, it feels like all of the gears are still there and engaging but it kinda feels as if it a manual gearbox and the clutch is slipping.
I have checked the TV cable and it is within adjustment and the oil level is correct and the oil looks clean, I belive she has had a shift kit fitted sometime in the past cos she upto now has allways shifted positively and never slipped.

TIA
Adrian





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CFI-EFI

It may have been built in 1983, but there was no 1983 model year designation. It is a 1984. Your transmission is fried.

RACE ON!!!

Pete K

Sad but true.
When overhaul time comes, try to start with an 87 1/2 -92 core. You will be better off in the long run.

adi4

I was only reading the year off the data plate on the drivers door, its the only true reference to the cars age once it has been imported into the UK






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adi4

I had a feeling that was going to be the answer






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AFogleman

Sounds like the clutch packs are gone.Do you still have reverse?Sorry to hear this.

CFI-EFI

It surprises me that there is no documentation indicating the year of the vehicle. No titles in England? My 1984 was built in June of 1983.

Sorry about your trans.

RACE ON!!!

adi4

I still have all of the gears, Ive just got to rev the motor right up to get any movement




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Corvette86

clutch packs

adi4

The only thing that is bugging me is that before I pulled away from the lights there has never been ANY problems with the box, and if it was clutch packs surely 1&2 3&4 and reverse would'nt give up all at the exact same time seeing that prior to this the gearbox has never missed a beat or shown ANY signs of slippage at all

Hopefully tomorrow I can get her on the ramp and get the pan off and make sure that something daft has'nt happened.

Thanks for your advice

Adrian






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Pete K

If the foward clutch packs are the problem it would explain it. Another term for foward clutch is direct clutches. The input housing contains 3 clutch packs. Over runs(used for engine braking) foward and 3/4. You may have broken the foward sprag.

Randy93

It could also be the impellar, I had mine go out on my van and it had the same symtoms.

rodj

"I was only reading the year off the data plate on the drivers door, its the only true reference to the cars age once it has been imported into the UK"
You should still have the factory VIN plate visible at the base of the windscreen ,LH side of the car.The VIN will tell you everything about the car as far as production .
Check idavette.net for details.
The door plate is more likely a import or compliance plate fitted locally to the car like we have here after a car has been converted.

CFI-EFI

Mine has the plate on the drivers door with the build date. I could never understand how so many people knew their build dates, until someone told me to look for that plate. It is below the belt, on the trailing edge of the left side door and therefore faces somewhat downward. I had to get down on the ground to read it.

You are right about the VIN. It should read something like, "1G1AY0783E51XXXXX". The "E" in my example designates the 1984 model year.

Muffin

Adrian, before you start removing various pieces and parts you need to have someone run pressure tests on the unit. A sudden failure like that could be a malfunction in the pump or the pump control valves in the valve body. No matter the cause I suspect you are in for a rather costly rebuild.

tonymax2

Sounds right from my latest experience. The 700R4 in my '86 Astro dumped it's blood all over I70 a few weeks ago- talk about a smoke bomb!! I just got around to fixing the problem (after a short talk with my friend the tranny man). Seems the earlier 700's are prone toward pushing the TC neck bushing forward which fouls the front seal. My bushing was about 3/16 in out from where it was supposed to be.

He also said they sometimes have a similiar catastrophic leak problem because the return oil hole (right behind the front seal) is too small under some conditions-causes pressure build-up and blows the seal out. Mine had an external keeper cliped to the nose of the pump as a running "fix". My friend said they corrected these problems about mid-'87.

Pete K

Good advise. The auto trans does not easily repair. Most times to find a problem, total removal and disassembly is needed then, at a minimum, a soft kit, fluid, filter and labor is needed. Parts are minimally expensive in the transmission. Labor is huge. I typically spend 25-30 hrs to build a solid 700r4, 4l60 or 4l60e. I don't mean to ramble, just explain and justify why these things cost so much to do.

Brimis

One fine day I drove my car to work and it was fine, it was on the way home when the transmission went south. No indications, I got off the ramp, hit the gas and nothing. I had to race the engine just to get the car home.

Good luck

Pete K

This was a huge, common problem. The earlier pumps can be used with a mod to the pump housing. It involved careful drilling out the passages in the pump to relieve the pressure. I always locktite the front and case bushings in place when freshining them. The 87 1/2 and up units had hundreds of minor (and some major) upgrades. They are worlds better in these years.

Muffin

There are many very important upgrades between the date yours was built and July 86. Seals as mentioned,pump,sprag,forward clutch to name a few. To have yours upgraded may be so expensive that a new one would be less costly. BTW the build date of your trans is stamped on the right rear of the pan rail. Good luck.