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73-87 Chevy _ GMC Trucks => Engine/Drivetrain => Topic started by: Breadvan on September 06, 2014, 01:34:15 pm
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I apologize for really not understanding automatic transmissions in advance.
If I have a 2WD '83 C10 with a stock 700R4 in it, and I put in a diesel engine pulled from a commercial vehicle, like a tractor, it has the torque, and it has the horsepower, but they only rev up to about 2500 rpm.
So I have a torque converter, and I believe the stock stall speed is around 1200-1500rpm, so that means my engine has to go this fast for the transmission to start transmitting the power to the driveline. Is this going to be enough? Will it change gear OK? If I'm in top gear ie. 0.70 overdrive, and I let the revs drop below 1200, does it change down automatically?
I'm looking to have a nice diesel cruiser, something where I can fill the truck with band gear, take it on the highway, and it maybe takes a little while to get it up to 60-70, but once there it's going to sit happily and chug along. The problem with the breadvan was it had two tall a gear in the rear it was like 4.5 or something, I think the C10 is like 2.73? Plugging the tire size, revs, diff ration and stock 700R4 ratios into a calculator make it look reasonable, but is that the whole picture?
| RPM | 1st Gear | 2nd Gear | 3rd Gear | 4th Gear | 5th Gear | 6th Gear |
| 500 | 5 | 10 | 16 | 22 | | |
| 600 | 6 | 12 | 19 | 27 | | |
| 700 | 7 | 14 | 22 | 31 | | |
| 800 | 8 | 15 | 25 | 36 | | |
| 900 | 9 | 17 | 28 | 40 | | |
| 1000 | 10 | 19 | 31 | 45 | | |
| 1100 | 11 | 21 | 35 | 49 | | |
| 1200 | 12 | 23 | 38 | 54 | | |
| 1300 | 13 | 25 | 41 | 58 | | |
| 1400 | 14 | 27 | 44 | 63 | | |
| 1500 | 15 | 29 | 47 | 67 | | |
| 1600 | 17 | 31 | 50 | 72 | | |
| 1700 | 18 | 33 | 53 | 76 | | |
| 1800 | 19 | 35 | 57 | 81 | | |
| 1900 | 20 | 37 | 60 | 85 | | |
| 2000 | 21 | 39 | 63 | 90 | | |
| 2100 | 22 | 41 | 66 | 94 | | |
| 2200 | 23 | 42 | 69 | 99 | | |
| 2300 | 24 | 44 | 72 | 103 | | |
| 2400 | 25 | 46 | 76 | 108 | | |
| 2500 | 26 | 48 | 79 | 112 | | |
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You need the Diesel converter in the trans you can't use one from a gas motor.
It governs you stall speed to allow you to stop in gear and the motor not die.
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So I want a lower speed stall converter? Can I have the current one rebuilt?
(http://amishrobots.freeforums.org/download/file.php?id=122&mode=view)
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For anyone reading this in the future. I talked to a pro transmission shop that specialise in the 700R4, and they said more or less, no amount of rebuilding would make the 700R4 suitable for this.
Shame, I still sorta want to get the engine, but now I have nothing to put it in. Back to working on the 350 for now.
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What engine were you going to put in front of it?
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Was a JD 6329, ended up not getting it, family fun.
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The 700R4 can be built to suit your needs.. It's a great trans as long and you fix the normal problem areas
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Check out precision of new Hampton, they can pretty much specialize any converter to fit your needs
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That's odd, as I contacted the 700R4 guys whose name escapes me, the ones that pop up first on a google search, they said it wasn't suitable for something with such a low rev and high torque. Part of the reason why I didn't bother with the engine.
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You could always run a Turbo 400 and a Gearvendors overdrive unit.
I would love to run this combo behind a 4 BT.
Keep in mind that with a 700R4 you would have to fab up the bracket for the TV cable.
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Why not just use a 6.2/6.5 diesel that was available from the factory ?
It's a bolt in deal
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700R4's have a lower first gear, which would be great for low end torque and towing.. Teckpak also makes a universal TV cable that will make it easier to adapt to your application
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