1985 700r4?

[62step]

Well need yall's advice on a transmission, I need one, so I went to the junkyard 2 days ago and found a 1985 chevy truck and looked at the cluster, saw it had an overdrive. Well, I want an overdrive in my truck, but it seems to some people I have gotten the wrong year, people say 1986-up is the stronger transmission.

I'm not planning to put 900 hp to this thing, I want to do a couple of burnouts here and there and maybe drag strip every couple months. Just debating whether to put money into this trans or not. Just a good rebuild (the high friction clutches and maybe a shift kit?) and call it done. I'll also have to get a stall converter (274h comp cam).

Did I make a good choice or not?

Thanks, any advice will be appreciated!

[Chevy Fleetside]

It takes alot of upgrading. I think an 85 year model will have a 3 pinion sprag and the laters have 4 and they sell a 5 as an upgrade. Something with the sun drums also. I built an 84 year model and ran in behind my small block for 4 years before selling the eingine and tranny. I think I put a shift kit in it also. It will hold up if built right.
I am sure you will get alot more answers. And as for year models.. You want 88 and up.

[62step]

Ok, thanks, so I should look into purchasing a 4 sprag atleast?

[Captainfab]

If you are going to rebuild it, then you can make the upgrades necessary for it to live under your intended useage. But yes the '88 and up are a better trans to start with. There are many, many ,many threads in the 'Engine and Drivetrain' section on the 700R4.

[clinebarger]

Originally Posted by 62step

Ok, thanks, so I should look into purchasing a 4 sprag atleast?

He is referring to the Planetaries, I think?, All 7004R's have 4 pinion planets, They hold good on mild street strip vehicles. The planets die from lack of lube most of the time.

The good thing is '85 has the bigger 30 spline input shaft (earlier unit have a 27 spline input), But '87 & up had a lot of improvements that can cost a few hundred dollars to add them to the '85.

[stsalvage]

the rules with 700R4 are get them out of trucks Cars don't use torq The best one to get with out having to update the trans is the early 1993 before they went to computer.

In the 1980--86 they have piss poor oiling the 1987--93 have drilled oil cases with more check bearing in the case if you have a older case it will cost you a extra 3-$500.00 for a person to read the book and know where to Drill the case you drill it wrong time to buy another case.The alum sprage where the clutches go in to best off to get the metal Corvette one way stronger.If you can witch i doubt you will if you can take a 700 apart check for missing teeth Plus see if some one has put in a case saver.

700R4 had a ton of problems they where the only trans that had over 11 to 17 upgrades done to the trans Ford never had that many nether did dodge.

The 200R4 way better trans as long as your not planing on pulling a 3 ton dump trailer behind it 200R4 are a simple trans mostly used in the V6 - 305 V8 and light duty 350 for a daily driver the 200R4 will work plus its one peace no removable tail shaft housing.

[D13]

700r4 is a perfectly good trans for what it is designed for. It's NOT designed for the drag strip or towing in 4th gear.
You would be better off with 87 up. If you can't return it, assuming it wasn't the reason the truck was in the yard, I'd be tempted to do fluid / filter/ seals and use it as a set up trans for the drive shaft and mount mods you'll needs, then drive it while saving my cash for an upgraded one.
BTW the TV cable is critical on these, be sure you have one and it is hooked up right. Absolutely not an option like a kickdown cable on a TH350.

[Bigdav160]

I remember the days as a transmission tech at the local Oldsmobile dealer. TH200's, 200-4R's, 440T4's, TH125's; they were my bread and butter. Then I moved to a Buick-GMC dealer and, because of the pickup truck line, saw more 700R4' broken. Later, I moved to a large Chevrolet dealer where I had the lowest warranty cost and the highest "fixed right the first time" scores in the zone.

All I'm going to say is there is a lot of misinformed in this thread. There's nothing wrong with a '85 700R4. It doesn't have a forward accumlator, so what?

[D13]

Nothing wrong with an 85, just the 87 up have some improvements. Preference is to start with the best you can get for the money.

[clinebarger]

Originally Posted by Bigdav160

All I'm going to say is there is a lot of misinformed in this thread.

I agree, Lots of wrong info.
Changes to the '87 4L60/7000R4....

Change: New design 2nd/4th/Forward Accumulator pistons & seals
Reason: Improved shift consistency & smoothness.

Change: Low/Reverse Roller Clutch-Rollers increased in length by .150"
Reason: Increased Torque capacity. (82-86 used a TH350 center support & Sprag)

Change: Overrun Clutch lubrication (15 lube holes in the overrun clutch hub in place of the previous 3)
Reason: Improved durability of the Overrun clutches)

Change: Larger diameter Forward Sprag assembly.
Reason: Vastly Improved Torque Capacity (In my opinion this was the MOST important change)

Change: Auxiliary Valve Body added (Aux. VB)
Reason: The Low Overrun Valve in the Aux. VB provides a smooth 2-1 manual downshift, It also regulates the pressure applied to the low/reverse clutch to a lower pressure.
The Abuse Valve in the Aux. VB protects the forward clutch during rock cycles (Quick reverse to drive shifts when the vehicle is stuck) Any throttle above idle opens the abuse valve & bypasses the feed orifice to speed up forward clutch apply time.
A Forward Clutch Accumulator, Provides smooth garage shifts to drive.

Change: One piece Turbine/Input shaft seals.
Reason: Improved sealing over Scarf Cut.

Change: Increased Input Drum wall thickness around the Forward Clutch backing plate.
Reason: Improved 3-4 clutch life, The Drum will Distort when the Forward & 3-4 clutch are applied. This improvement didn't eliminate the issue altogether, But still a large step forward!

Change: 10 Vane Front Pump (Added 3 vanes)
Reason: Increased pump capacity.

Change: Revised Reverse Input Drum
Reason: I have no earthly clue (GM states it's for softer reverse). 82-86 had a stronger reverse. The Low/Reverse piston was also redesigned for softer apply.

Change: Seal Rings on 2/4 band apply pin eliminated.
Reason: Seals get damaged during service, I have never cut one?

Change: Thicker 3-4 Apply Plate (Longer Input Drum)
Reason: More evenly applies pressure to the 3-4 clutches, Allows use of a 4L60E single piece apply plate to be used along with 9 frictions & a thick backing plate, The 82-86 Input Drums will take 8 with a thin backing plate, I usually run 7 with an early Input drum.

Change: Revised Out-Put Shaft Oiling Circuit, Revised Shaft Seal in the Input Drum.
Reason: Improved Input & Reaction Planetary oiling