84 GMC C2500, V12 powered

[Palf70Step]

Whoa! That will get you some looks. Hot Wheels are alive!

[cayoterun]

I had to post this one. This old boy could overhaul one of these motors at night with a flashlight in his mouth in front of his pickup lights. Have it fired up and pumping by daylight. (maybe stretched the truth a little, grin). He bought this motor new in '65.
Thanks, Don, for being my neighbor and friend all these years,(58 to be exact). Always did all his own overhauls and mechanics except machine work.

[spudz]

Nice!!!!!!

[AceX]

Originally Posted by rod86

nice!
oh an by the way that 55 chevy that was built in australia you mentioned has a rolls royce merlin v12 in it...

YouTube- Merlin V12 Powered 55 Chevy

That's my buddy Charlie's car. Alot of engineering went into that thing...

[cayoterun]

Neat car and lot's of engineering AND WORK!!! Thanks for posting.
Cayoterun

[locomotive breath]

Looks like you and Rap-Em-Pappy had a great time, wish I could have made it.

[rod86]

Originally Posted by AceX

That's my buddy Charlie's car. Alot of engineering went into that thing...

yea, i heard it got sold to someone in the states..

[Rap'em Pappy]

Locomotive Breath I wished you could of made it to the get together. We talked V12's all day and night. You could of gave Rap'em Pappy a drive. It is running real smooth. I let Cayoterun take her for a cruise. First person other than me that has driven it. Don was amazed what I did with his pile of old
iron. I am also amazed it came out that good my self. I would hate to count my hours.
I will be going to Chicagoland Nationals Sept 16-19 next. I am thinking of running with the hood off for that. That is to keep people from falling off there chairs trying to look under the fender. It has happen!! The best part of the trip was putting the two longnoses head to head. Thank you Cayoterun The
pictures came out great. Your next project truck looked good and solid, go for it.....

[cayoterun]

IMO, This is the best part about this truck: We wonder where our project names come from.
Rap 'em Pappys tailgate says it all. The name of the plane was "Rap 'em Pappy". Bob's uncle was co-pilot. On the 19th or 20th mission over Germany, she was shot down. After his uncle jumped, he was never heard from again. Quiet a tribute!!
Cayoterun

[jb1016]

Wow, what a story. Very cool tribute.

[cayoterun]

I'm getting some parts ordered and gathered up. I'd like to fit all adapters and tranny while the motor is still in the stationary stand. Then bench run them.
I'm going to gamble on a 700-R4, since this truck isn't going to be hammered around. It's from a '91 Chev 1500.

Dumb questions:
1: What function is the 12volt wire going to the tranny?
2: Can it be spliced into any 12v source when ignition switch is on?
3: What happens if it's not hooked up at all?

Thanks,
Cayoterun

[steemin_ehman]

Originally Posted by cayoterun

1: What function is the 12volt wire going to the tranny?
2: Can it be spliced into any 12v source when ignition switch is on?
3: What happens if it's not hooked up at all?

First of all, cool build!!! Looking forward to how this one turns out!!

If it goes into the transmission on the drivers side, into a plug with 4-pins (one blank one), then it sounds like its the torque converter lock-up wire. Its supposed to be energized unless the brake pedal is pushed, or the brake lights are on. Thus you either need to run a relay to turn the 12V off when the brake lights are on, or run a normally closed brake light switch hooked to your brake pedal specifically for the tranny.

This engages the locking torque converter in 4th gear only. If you dont wire it up you risk burning up your torque converter, and tranny.

Hope this answers your questions!!

[cayoterun]

Thanks, that explains a bunch.
I'm pulling the tranny from a '91 GMC 1500, so now I know what all to look for and make sure I get the stuff I need.
I'm gambling with a used tranny, but by using it, I at least get a core, tv cable, brackets, and all the stuff that I'd need. Buying a rebuilt, most or all don't have even a filler tube or dipstick. A friend let me have this one on the barter system, so can rebuild later if I need to.
I have all the other adapters located or in hand. Another friend is letting me have a 3:42 14bolt rearend, so I should have a top speed of around 90mph @ 2400. 60mph @ 16-1700.
The purpose is not go-fast, but hold rpm down.

edit: If I understand, By tying into the brake lights/pedal switch, It disables the converter lock until it drops out of overdrive, then when brake pedal is released, the wire is reenergized until brakes are applied again?? Correct me if that's not the way it works.

I learned alot of things on the other truck I wish I'd done different, so hope this can be an improved version.
Thanks again for your explaination.
Cayoterun

[bluex]

Read through this, should help you answer any 700r4 related questions.

http://700r4.com/faq/faq.shtml

You also need a vacuum switch, which should be on the firewall of the donor truck. This will unlock the converter allowing the trans to downshift when you step on it. Or you can avoid all this and buy a non-lockup converter and be done with it.

Bowtie overdrives is a great source for 700r4 stuff. I purchased my TV setup from them when I converted my '78. Great customer service and they really know these trannys.

[cayoterun]

Thanks for the additional info. Your post came in while I was replying to Steemin Ehman.
This is the first time in my life I have ever tried to understand an auto. Always took them to a shop if they didn't work.
Teaching an old dog new tricks is hard.
Cayoterun

[steemin_ehman]

Originally Posted by cayoterun

If I understand, By tying into the brake lights/pedal switch, It disables the converter lock until it drops out of overdrive, then when brake pedal is released, the wire is reenergized until brakes are applied again?? Correct me if that's not the way it works.

Thats pretty much it yes.. the way the transmission is set up from factory, it will only lock in 4th gear. So as soon as the transmission downshifts, the torque converter will not lock, even when the wire is energized. Basically, as soon as you turn on the ignition, the wire is energized until the brakes are applied.

....you can also wire in a manual switch for the lock-up if you so desire. In the end, with the lock-up, i see around a 500rpm decrease with my truck. = better fuel mileage, less drivetrain power loss. I hope you can get it all working!!

PS. On a used tranny, test it to see if the locking solenoid is working. It's easy and cheap to change yourself anytime, but even easier when the transmission is out of the vehicle, and empty of fluid.

[steemin_ehman]

Heres some good info as well:

http://www.73-87.com/7387garage/drivetrain/lockup.htm
http://www.purplesagetradingpost.com...o/700R4p1.html

[cayoterun]

Thanks, Guys:
Great info.

I may not get a wink of sleep tonight. Learning alot tho.
Cayoterun

[cayoterun]

Printed off alot of the info. in the links. Lots of good stuff. Sure helps.
Thanks for posting.
Cayoterun

[cayoterun]

Been studying the info. printed from the links.

Low vacuum switch? How important is it for my use? As said before, my torque is 630#@2400rpm max. It will take a hard load or quick stab on the throttle to drop my vacuum much. From the info, I understand the most important thing about all these controls is to get the torque converter to unlock in 4th (od)? If so, I can deal with that by manual shift to 3rd with shift lever. In short, stay out of 4th except easy hiway driving, since that is the only time I want od.

I think I understand what's necessary concerning the TV cable and carb bell-crank adjustment and can get there by using a pressure gauge. Also understand the need for the brake switch to kick out of od. I have to fabricate the bell crank for the propane carb and and cable mount on block. The measurements needed were in the links. Thanks to you guys and the links you've posted.

The motor and all are still in the donor '91 GMC truck, so if I can trace the wiring, switches, etc and get them removed intact, then try to copy it on this motor, except necessary adjustment changes it will create.

I'm just puzzled how I can deal with lack of quick vacuum changes, if staying in third except on hiway won't protect the torque converter and tranny.
Cayoterun

[jeffspower]

Plenty of people will say "oh no, don't do that" but...

If you don't want to hassle with all of the electrical stuff- don't. You can put a 1/4" checkball under the lockup solenoid and it will lock under load late in second gear, giving a direct coupling feel like a manual trans as it shifts up thru 3rd & on to 4th. It will unlock on it's own on deceleration. I've done this many times including one behind a 6.2 diesel, and 500 Cadillac in heavy pickups pulling a 7,000 lb. trailer. It doesn't work worth a darn behind a low torque engine, as there is no torque multiplication when locked. Doing it this way will give a shift feel kind of like the old 4 speed Hydramatic had... remember the chug you would feel on the 2-3 shift with those?

I've only done this on the 1990 and older 700R4, not the 1991- up 4L60 which was computer controlled. I'm not sure if you can checkball the latter.

[cayoterun]

How do I identify the tranny I have?
I ordered an ATSG General Motors 1987-1993 Tecktran 700-R4 manual, also marked 4L60, (no E). It seems pretty detailed. It shows internal schematics on 10 different TYPES. Type 18,19,22,& 23 are specified for '93. Type 15 is specifed for '87. They all have 3 letter id codes such as mwm, jxm, etc.
Type 3,4,6,9, &10 have id codes with 2 letter codes such as yp,tr, etc.

Where would I find the id codes on this tranny? I can't find an id tag on the case or data plate. Are they stamped internally?
Cayoterun

[jeffspower]

I could be way off on this- but I think 91-93 the computer only controlled the lockup. In 94 it went full electronic.

I think the ID is stamped somewhere on the case on the pan rail.

[cayoterun]

Found some papers in the tranny donor truck today. It's an '89 instead of '91.
Cayoterun

[cayoterun]

I learned my 700R4 had been taken from a Chevy van and put in the donor '89 1500. Supposed to have been rebuilt not many miles ago.
It has an electronic speedo drive, Does that give us any clue what year it is?
Can the rear tail casting be removed and the elec. plastic drive gear on tail shaft be changed to old style spiral drive gear with out changing or removing the tailshaft?

I have it home and cleaned up. Found these numbers:
Cast on case: #8663549
Stamped on case, left side: #33 937 0801
Stamped on right side pan rail: #CHF 395721


Does these help us any for id?

Thanks,
Cayoterun