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Transmissions and Rear Ends Three on the tree or four in the floor? Shift it all here.

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Old April 28th, 2020, 04:02 PM
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Default Trans is swapped!

Ok, after a lot of fits & starts and Covid-19 delays we finally got to where we could all meet up and do the trans swap from the hydramatic to the 700R.


WHAT a journey, before I get into the nitty gritty, I want first shout-out to the following members for their help, knowledge and assistance in giving me pointers and suggestions. ED SNYDER for helping me located the need OEM adaptor setup. LEWIS MACKLIN and PETE CHRONIS for their encyclopedic knowledge of the 305 and the hydramatic. I'm highly doubtful that anyone knows more about these engine than these guys posted above! And that's no Bullcrap.


Ok, here what I did to remove, install and modify the trans swap. Some of this will mundane, but since a little knowledge goes a long way it can't hurt.


First, as has been repeated a few times you need to locate a complete OEM automatic trans. bolt adaptor setup, which will allow you to bolt up a later model automatic where the manual or Hydramatic trans sits. If you cannot luck out and locate this OEM setup, you can buy the needed parts from Bendstsen Transmission Adaptors. The adaptor comes with all the items needed including a new starter and flexplate/flywheel combo.


If you go the OEM route like I did, you will have to get the bolt adaptor, the correct flywheel (their is a major difference in the flywheel design), the flexplate and the spacer plate.


The Removal- The Hydramatic version!
First you will ABSOLUTELY need a transmission jack. The hydramatic weighs in at about 450 lbs, (about 100 lbs heavier than a Duramax trans) youor your buddies cannot manhandle this.


Disconnect the positive battery lead. Drain the fluid, remove the trans hump cover and the upper trans firewall cover you will need so in order to access the bellhousing bolts 3/4" bolts. The top of the bellhousing will have a 4" x 4" access plate at the top and bottom of the bellhousing, you simply pop them off. Once removed you will see 30 3/8" bolts, these bolts hold the Torus cover to the flywheel. (Historical note, before GM designed/invented the modern torque converter we know now, they used a fluid coupling torus adaptor), close to the same principal.


As you remove the bolts, you will need a helper to turn the crank bolt to rotate the the Torus Cover to get to all the bolts. While turning it, you will find a square headed nut; you need to remove this in order to drain the fluid from the Torus assembly.


Now you and remove the gear selector rod linkage, carb bellcrank shift linkage (I will also explain the new accelator linkage you'll need to change also). Now remover the propeller shaft if you have not done so already. If you are happy with you rear u-joint good, but but why not put on a new unit while you have this torn down?


With the truck elevated, setup your adjustable engine stand using a large of world that will span the entire width of your oil pan bottom (we used a 4x4). We realized early on that we had to remove the muffler as well, so we did. Now lift the engine a bit to get the weight off of the rear cross brace. There are 2 3/4" bolts that reach up from the bottom of the crossmember and bolt into the bottom of the bell housing, these have lock tab so you bend them back and remove the bolts, make sure you remove the tube sleeve as well. Now you will need to remove the rear motor/bellhousing cross member (the new 700 will not need that). Mine was bolted in place and we saturated the bolts (4 on each side) with kroll oil to help ease in removal (bolts have not moved in 60 years). You will need 2 wrenches one to loosen and one to act as a holdback, you have a small area to work in. (Some cross member are said to be riveted in place, if so, you'll need to grind the heads and drive the bolts out or but them out with a torch?) Once the bolts are out, you will need to beat the cross member down and forward to remove. I'd save it as another members my need it?


Ok, now setup your trans jack, strap/chain her down TIGHT! and take up some load, remove the 5 bellhousing bolts from the block and walk the trans backwards. Once lose, the is where you need a few people, because of the size of the bellhousing it will have to really be worked at a very steep angle. We also secured the trans to the stand with a short piece of 12/2 romex so the trans would not slide forward. We secured through the bottom access hole to the trans jack as well.


You need to adjust your stands till angle to the max it can go. While you have that angle let down on the stand, you may have to raise the engine a bit as well. We works off a hydraulic vehicle lift and needed to also lift the entire truck at the same time we lifted on the motor. Once you get the trans out of the way. Sit down take a brake, gave a beer and a cigar. That part of the battle is over!


The Flywheel-
Ok, breaks over, you think this is a UNION shop . You can now unbolt the 6 flywheel bolts, you need to keep the double washer/spacers as well. Once the bolts are out, take a good hold on the 30lbs flywheel and her off the crank. Now you can access and remove the 4 bolts which would the spacer plate to the block.

While you can access the rear of the block, now is the time to check for and address any main seal leaks if you have them, I did not.


700R4 Install-
Ok, mount up the new trans on the stand, strap her down as good as the last one (because you need to go the same steep angle, also the 700 is about 4" longer depending on what tail shaft the trans has, I have the long shaft model.

Now, we bolted up the new spacer/backing plate. The OEM flywheel has a thin spacer that has to be used between the flex plate and flywheel that all 6 crank bolt must pass though, you have to pre check this because the tolerance is extremely tight and only fits one way. We mocked it up and marked it with whiteout. Then reset the new Flywheel in place with the flexplate.


While we got the trans in position and angled up, we noticed that the torsion bar bolts interfered with us getting it in position by about an inch. So we sat back and gave this some thought and reliEs we could loosen the 1/2" nuts that held the torsion bar cross member on and drop it an inch. The tension is still on the bar, but the back of the rod is ONLY pushing again the cross member. We took the short bolt out and replaced it with a longer bolt so we could loosen and still have the bolt secures with a nut, BUT we also put a large C-clamp in place as an address safety measure (belt and suspenders!). Once the cross member was lowered an once the trans slid right in. We we set the cross member back in her original position and walked the trans to the block.


We got her bolted up to the block and called it a day!


DAY 2-
Ok, remember we had to remove the trans/bellhousing cross member? you will now need to ADD a new rear trans cross member to support the rear of the 700R. In all my research, I discovered that no one makes a direct bolt in replacement cross member, this is because on the 60 model year and some later, we have the 'X' frame. So we had to make one up. Another member who did this swap already explained that all we needed to do was simple install a span of metal so the the rear of the trans can bolt to and read or the cross member. We used 2 pieces of 6" long 2" x 2" angle and bolted it up to the inside of the frame, splitting the l distance where the mount would fall. Then we used a a a 2 foot long piece with the holes matched to the rubber trans support. We bolted the new cross member to both the new angle mount AND the truck frame. We could have use just 1 but why not use both.

And She's in!

We have to remount the exhaust but she's done .

Last edited by jbgroby; April 28th, 2020 at 04:17 PM.
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Old April 28th, 2020, 05:16 PM
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Default Re: Trans is swapped!

Good to hear. I have a 700R4 in one of my trucks. How did you get the Throttle Velocity Cable to hook onto the 305's carburetor? I have an Edelbrock carb so it was easy to connect and correctly adjust.
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Old April 28th, 2020, 10:19 PM
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Default Re: Trans is swapped!

I have a 500 CFM Holley as my carb. The bracket from Bowtie overdrive is designed to hold both the tv cable and the wire throttle.
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Old April 29th, 2020, 04:00 PM
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Default Re: Trans is swapped!

We used the same company. I liked the way Bowtie takes actual pressure readings before sending transmission to the customer.
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Old May 7th, 2020, 02:01 PM
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Default Re: Trans is swapped!

Well we got a little closer to rolling. I had to have the propeller shaft cut to 63.25" and rebalanced, the Driveline Shop did a good job and a quick turnaround; I dropped it off Friday afternoon and picked it up Wednesday, we installed it last night.

We also started the installation of the trans cooler lines. I have one more to go. Next up is connecting the new Terry Cable for the throttle (I screwed up the other one by NOT having better cutting pliars.....
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Last edited by jbgroby; May 8th, 2020 at 10:24 AM.
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Old May 8th, 2020, 10:25 AM
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Default Re: Trans is swapped!

Next
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Old May 10th, 2020, 04:11 AM
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Default Re: Trans is swapped!

One thing that you may want to check is your driveshaft angle now that you have fabricated a new cross member and used a transmission foreign to this vehicle. You mentioned it was longer so the angle would have increased. You want to get the angle at the universal close to being the same at the transmission end and at the rear pumpkin. You may have to raise or lower the transmission at the cross member to get an angle that will not induce vibration into the drive system. I think the specs call for it to be <3 degrees, you could check the with folks that did your driveline for their input.
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Old May 10th, 2020, 01:03 PM
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Default Re: Trans is swapped!

Thank you. She falls within the angle.
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Old May 10th, 2020, 01:10 PM
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Default Re: Trans is swapped!

Ok, we a little more done yesterday. We finished up the trans cooler lines, I'll dust the cooler a bit more with black so we won't stand out quite a much. The next project was the shift linkage. The summit kit I ordered will work, except the rod is 24" long and I need 26. So I picked up an iron rod at Homedeopt and will thread it to 5/16-24 to fit the summit pivot.
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Old May 16th, 2020, 10:38 AM
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Default Re: Trans is swapped!

Got the exhaust system back bolted in place. Hope fully today we should finish up.... I need to install the new shift linkage and solder a longer wire into the lockout switch to go to my accessory plug on my ignition (I need 12 volt key on power.
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