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71C trans swap in my 720 4x4


Madkaw

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I’ve been reading until my eyes burn, but still have questions .

 

I have a 5/83 4WD . Currently using a 2WD trans that works great , but leaks at the center plate. I have a chance to get a late 80’s 71c  trans. It measures 30” approx. Of course my truck has the 26” trans. 

 

So I know these trucks ran both short and long trans. The floor hole is the easy part for the shifter. My understanding from reading is that I will have to:

 

shorten the DS to the transfer case- but are the splines the same ?

adapt the trans crossmember to use the 71C

Should bolt straight up if the trans was from the Z motor?!

 

Bell housing is interchange also if need be? 

Id be willing to make a custom DS to use the better trans . Being so short will it cause issues?

 

Anyone have this combo?

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25 minutes ago, Madkaw said:

Should bolt straight up if the trans was from the Z motor?!

 

Bell housing is interchange also if need be? 

 

 

It will 'bolt right up' if the 71C is from another Z24i or either KA series engines.

 

 Too much machine work to swap a front case unless desperate. Z and KA engines use the same bolt pattern and orientation.

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9 hours ago, bottomwatcher said:

Yep! Been running it 15 years no issue and that was after 4b failures. Splines the same. Shorten driveshaft, back in the day cost me $100. Did have to trim the shifter hole and make a simple adapter from 1/2" plate and 1/2" spacers to drop the crossmember so driveshaft was stock but that was basically it. 

So the adapter was to lower crossmember because the trans is actually bigger in diameter ? I’m also figuring the non of the holes lined up for the crossmember ? I’m used to this process since I put a T-5 in my early Z . 

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9 hours ago, datzenmike said:

 

It will 'bolt right up' if the 71C is from another Z24i or either KA series engines.

 

 Too much machine work to swap a front case unless desperate. Z and KA engines use the same bolt pattern and orientation.

That’s what I read , so that’s why I am jumping on this trans 71C  

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9 hours ago, bottomwatcher said:

Yep! Been running it 15 years no issue and that was after 4b failures. Splines the same. Shorten driveshaft, back in the day cost me $100. Did have to trim the shifter hole and make a simple adapter from 1/2" plate and 1/2" spacers to drop the crossmember so driveshaft was stock but that was basically it. 

Trimming shifter hole since the 71c is even longer than the long 71 B ? Can you use the long shifter console from the 720 ? 

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6 hours ago, Madkaw said:

Trimming shifter hole since the 71c is even longer than the long 71 B ? Can you use the long shifter console from the 720 ? 

 

The 71C from a 240sx is longer than a long 71B but the truck 71C is slightly shorter than the 71B.

 

S13 (240sx) top (34-35" long) and D21 Hardbody (30"?) bottom

 

gsDA75o.jpg

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Thanks for the pics . It’s kind of a bummer that the shifter doesn’t fit better in the console . I actually thought it would the other way around . Hate to cut my console up but hate more to have transmission issues . 

It is a truck transmission so it will be the 30” type .

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6 hours ago, bottomwatcher said:

 Shifter is fwd but new lever allows shifting without leaning forward. Console, steel adapter to line up trans mounting holes with trans crossmember. Then the spacers to drop crossmember so trans sits at stock level. I have pics but they won't upload right now. Will try later 

Is that the long console you cut up?

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1 hour ago, bottomwatcher said:

Yep that would be a lot better. What did that come out of Mike? I always intended to build something better. Someday!

That is simply the short 720 console.  It came in any 720 with the short trans, so its easily found in most 4x4.

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Easily found! I hadn't seen another 720 like mine in 15 years in Florida. Now that I dragged the old girl up to Maine I can't  get gas without  someone running up and saying I had one but haven't seen one in 20yrs. My buddy has a junkyard where I got my KAe from. He keeps an eye out for anything 720. They are long gone! Nothing here on the east coast! No worries the old girl will spend the "salt days" snug as bug in my shop until spring!

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17 minutes ago, bottomwatcher said:

Easily found! I hadn't seen another 720 like mine in 15 years in Florida. Now that I dragged the old girl up to Maine I can't  get gas without  someone running up and saying I had one but haven't seen one in 20yrs. My buddy has a junkyard where I got my KAe from. He keeps an eye out for anything 720. They are long gone! Nothing here on the east coast! No worries the old girl will spend the "salt days" snug as bug in my shop until spring!

There’s a guy parting out one here that has the short console . I might grab it when I get some other stuff from him . 

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  • 1 year later...
On 9/29/2019 at 9:20 AM, bottomwatcher said:

 Shifter is fwd but new lever allows shifting without leaning forward. Console, steel adapter to line up trans mounting holes with trans crossmember. Then the spacers to drop crossmember so trans sits at stock level. I have pics but they won't upload right now. Will try later 

Reviving this thread in hopes you can load up pics of your trans adapter mount ?!

About ready to this swap . What’s odd is other research I’ve done has shown the shifter moving rear - not forward . Measuring the shifter is definitely further back on the C compared to B . 

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Trans "adapter" was a piece of steel plate which I drilled to bolt to crossmember. Then drilled and bolted the trans to the plate. Then put spacers the same thickness between the crossmember on the frame dropping it so the trans ended up the exact elevation it started as. Hope this makes sense.

20210713_115142.jpg

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1 hour ago, bottomwatcher said:

Trans "adapter" was a piece of steel plate which I drilled to bolt to crossmember. Then drilled and bolted the trans to the plate. Then put spacers the same thickness between the crossmember on the frame dropping it so the trans ended up the exact elevation it started as. Hope this makes sense.

20210713_115142.jpg

Thanks . So that pic is looking from the rear to front ?

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