84 GMC C2500, V12 powered

[steemin_ehman]

Theres a plastic gear drive system adaptor to replace the electronic speedo sensor. you remove the tailshaft housing, pop off a retaining clip, remove the stuff for the electronic speedo, and install a plastic gear style one in place. Very simple to do, the hardest part is knowing whether you need a 34-39 series, or 40-45 series.

40-45 series:
http://www.bowtieoverdrives.com/cata....php?ITEMID=14

34-39 series:
http://www.bowtieoverdrives.com/cata....php?ITEMID=19

Bowtie Overdrives is a good place to get information and parts. You can also get different speedo gear ratios to factor in rear end ratio, tire diameter, etc to make your speedo accurate.

[steemin_ehman]

found another great site:
http://texasz.net/allan_and_rosanne/...nformation.htm

it has more information pertaining to the series you'll need (# of teeth on drive gear), as well as other things that are helpful to know regarding the swap.

[cayoterun]

Lot's more great stuff. Printed it all off to take with me with the other info to study while gone.
These computors are great stuff, if you know how to use them. I don't! You guys are a great help. May check in now and then if I can find a computor while down there.

Need to go to Ark. due to family illness for a week or 10 days. Hope to find things much improved, but news now not the best. Nephew has a brain tumor.
Thanks,
Cayoterun

[dabels23]

Hope your nephew gets better!

I love the project!

[cayoterun]

Looking toward 2011, Since last post in Oct., things has been hectic in my wife's family.
Lost a nephew and bro-in-law, Funerals same day. It's said that it's darkest before dawn. Hope so.

But in our 5,500 miles, we have gathered some parts, and was good to be in the shop this evening, lining up, checking fit, and dreaming.

Looks like we have a complete drive-line except shaft.
Flywheel cover adapter:
Flywheel/Flexplate adapter: designed and machined by Locomotive Breath
3.42 14 bolt rear end: Bartered from Locomotive Breath
700-R4 tranny:

At 2400rpm, that combination should give us around 90mph, which is fine with me. If we can run 70mph around 2100, that would be great.
Now, if I can get it set in the '84 frame and all adjusted, then we can decide whether we make another long-nose, cut the firewall and let motor back in the cab, or what.
We did get the '84 titled, and current tag on it.

Happy and prosperous new year all, and help me build a truck.
Thanks,
Cayoterun

[locomotive breath]

Sorry to hear about the family. Never a good time to lose loved ones but this time of year seems to make it even tougher.

Glad to see your getting back out in shop. It's always the best therapy for me.

[cayoterun]

Could someone give me a service manual link to the ring-gear/pinion swap on a '84 GMC 2500 14bolt rear-end?

I thought I had a service manual, but learned, I don't.
Thanks,
Cayoterun

[1985-GMC]

FYI that's a 14B with the 9 1/2" ring gear opposed to a 10 1/2". I think you've mentioned before that your out in the boonies or else I would say just find one with the gear ratio that you want. Sorry I don't have a link, what do you want to re-gear it to?

[cayoterun]

I have a complete rearend/w 3.42s, and wanted to pull the 4.11s out of the rearend that's in the truck now. Might save fighting the rusty U-bolts, brake lines, etc. Will have the bed off, so room to work. If it was a direct swap.
I've never worked on anything that you pull the guts out the rear.
I was always lucky enough to change the ones that all the 3rd member dropped out the front in one chunk.
3.42s are the ones I wanted in the truck. The 4.11 rearend looks to have better brakes, emergency cables, etc., so might save some work.

Yes, I am out in the boonies, so a friend found this one in Dallas and I picked it up at his place.
Our closest salvage yard is 125mi. away.
Thanks,
Cayoterun

[cayoterun]

Pulled the bed on the '84 GMC 2500 yesterday. Found this, never seen one before. WHAT IS IT?? I think it's obvious, but curious to be sure.

It looks to be an additional proportioning valve to control fluid to rear brakes depending on weight/height on the rear axle.

Started the dirty job of stripping the frame. It must have a ton of dried mud in all the nooks and crannies. So far, I've found no serious rust thru. (lots of surface rust, tho).

[1985-GMC]

Yep that's exactly what it is.

[cayoterun]

Decisions, decisions: I'm a long ways from having to decide, but can't make up my mind.
The motor is too tall to extend back in the cab without using at least a 4" body lift, OR moving the cab back 30" and shortening the bed.

Could someone use the '84 pic on page #1, post #21 and photo-chop it with a 4-6" body lift/with running boards? If so, I'd appreciate it. It would look alot more stock, but 1/2 the motor would be inside the cab, then a insulated cover over it.
Opinions appreciated, too.
Thanks,
Cayoterun

[Jonboy]

I haven't seen a 4" body lift (unless you made your own). They are usually 2" or 3" pucks.

[cayoterun]

Now, maybe we can get down to some serious knuckle bustin'. This time I'm using a complete junker motor for fitting. Heavy and bulky to work with, but gives a complete picture of height, length, and width. I hope to rough fit the motor, tranny, and drive-shaft in the frame mounts. Then maybe we can decide whether we have room to let motor extend back in cab or what, before we put the good motor in. Using the '84 GMC frame seems to offer more options, and more parts to choose from than "Balaur" with the '62 components and 1ton Ford frame.
Measurements are coming out much better on this too. The flywheel housing came out almost exactly where the rear tranmission crossmember was.
Was glad to find this '78 Chevy 1ton crossmember will be easy to make work for the rear motor mount crossmember.
I did a rough lay-out this evening using the drop-center 1ton crossmember. It will let the flywheel housing drop 3+- inches below the bottom of the frame.
The verticle sticks will be where the steel legs from the crossmember will bolt to the original mount locations on each side of the flywheel housing.
Cayoterun

[cayoterun]

Originally Posted by 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.

I got the motor and tranny crossmembers and mounts in place and motor mounted in frame.
Now I'm back into the 700R4 classroom. I am reading and rereading the info. from earlier posts.

BlueX: If I used a non-locking converter, What functions do I lose, and does this eliminate the electrical wire-ups for the tranny?

I understand that the TV cable will always be needed and well adjusted.
Thanks,
Cayoterun

[cayoterun]

Felt good to sit the good motor in the frame. Hope it don't have to come back out anytime soon. I'll be hassleing you guys with more 700R4 questions now for awhile.
I left the irrigation control panel on the motor so I can hook battery/ fuel to it and run in frame as we go along. I may hook up a temp radiator.
If I put the cab back on the original mounts, it looks like the firewall will be about halfway between the carbs. May have an air cleaner on the inside of the windshield. Time will tell.
The weight of the motor only dropped the frame to ground clearance by 1-1/2inches. Was glad it wasn't more.

Cayoterun

[bluex]

Originally Posted by cayoterun

I got the motor and tranny crossmembers and mounts in place and motor mounted in frame.
Now I'm back into the 700R4 classroom. I am reading and rereading the info. from earlier posts.

BlueX: If I used a non-locking converter, What functions do I lose, and does this eliminate the electrical wire-ups for the tranny?

I understand that the TV cable will always be needed and well adjusted.
Thanks,
Cayoterun

I believe that will do away with the electrical portion of the swap. You will only lose the 4th gear lockup which gives me about another 3-400 rpm drop when crusing the highway. The lockup does away with any and all converter slippage at crusing speed. You will still get the OD, but will lose just a little without the lockup. I am not an expert on this but its really not that hard to wire up. BTO helped me out alot with my swap and with their help and TV kit, I have not touched any of the settings in 8 yrs. Give them a call I'm sure they will be glad to help you and give you definate answers....

Motor/trans looks killer in the frame. I say section the cab and have it riding inside with you!

[cayoterun]

Tomorrow may be the day I chain "Doc" down to the tractor and pickup, with the rear wheels blocked off the ground and static run it. Don't plan to run motor more than 800-1000 rpm max.
I did put a Bowties overdrive shift kit in the 700R4.
I only have a temporary elec. on/off switch hooked to the tranny.
I have the tv cable hooked up, and adjusted according to the instructions in the factory shop manual. At least close, I hope.

Some questions:
1: On startup and idle speed the elec. switch should be on, correct?
2: After light acceleration, and the tranny shifts thru the gears and into overdrive, I then turn the switch off, so it will fall out of overdrive when I reduce rpm. When it drops out of overdrive, then turn the switch on as long as it's in lower gears at lower rpm.
3: If all that works ok, then I'm not at risk of ruining the tranny?
4: Is it ok to manually shift the tranny in each gear with shift lever? If I do this, does the switch need to be on or off?

Thanks,
Cayoterun

[thirdstreettito]

Lookin good guy! Keep it up!

[cayoterun]

Spent the day in the butcher shop with the trusty saw-zall.
There's barely enough room, but will go. The cab is still on 3" blocks, but need to do some trimming before sitting it down on the mounts. By using shorter air filters, it looks like it will be below dash.
The rabbit was behind the seat when I stripped it out, so I guess he may as well be the mascot.
I found a late 70? van that I can cut all the firewall and floor out and try to scab in to use it and the cover in this.
Buckets seats are on the list for sure. A bench might go, but would be close.
Maybe tomorrow I can get it down on the mounts.
If the motor ever needs to be pulled, the cab front may have to be lifted a little. Hope not.

Tried to save the glove box and heater controls, but they have to go. Not wide enough between them.
Haven't a clue what to do about the dash, but maybe can use a van dash???
Cayoterun

[thirdstreettito]

Looks great!

About the dash; tell Kert at DIY4X your measurements and about the project, he can fab up the PERFECT dash for you, then you can get it covered, or paint it or whatever.

http://diy4x.com/cart/index.php?rout...product_id=148

[cayoterun]

That went into the favorites. Sure looks like a simple answer for what I'll need. The basic dash he has displayed makes the price seem reasonable. That project is still some months down the road, but I can focus on something else now, mainly the "doghouse".
That's what they called them when I drove cabover road trucks, what do they call them in vans?
I sure thank ya' for the lead.
Cayoterun

[jb1016]

I think it's still called the doghouse...or maybe the bunny pen in this case.

It's coming together pretty nicely.

[thirdstreettito]

As far as I know it's always been a doghouse. I'm not sure how a husband would sleep there though....

[1985-GMC]

Good progress! This way you can set the timing while driving down the road.