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Advice on Lowering a Manual Tranny

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prossett

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OK, I need to take out and then re-install the SM465 4-gear manual transmission on my 1983 Jimmy. Hopefully I can then find someone to replace the 3rd gear synchro.

My Haynes repair manual gives clear instructions, and I've had a good look underneath, and it's doable at home mechanically, but it seems the problem is the sheer weight of the metal piece.

There seems to be one tricky step when the final bolts come off the clutch bell housing, where the manual says I should take off the top bolts first and insert bolts with their heads removed to support the tranny while I take off the bottom bolts. Then I pull the tranny to the rear and it should slip off the two upper headless bolts. It says that's to avoid damage to the clutch bell housing.

So I guess it means that if I just remove the bolts, the tranny drops onto the bell housing.

The problem is how do I balance the tranny on the floor jack while I pull it to the rear and then lower it down? Is there a 'sweet spot' under the tranny where it stays in perfect balance?

Anybody used or heard of using an air jack? It's like a heavy-duty balloon that gets inflated by the exhaust. I'm thinking I could inflate it under the tranny, unbolt, and let the tranny sit on the inflatable jack while I let the air out...

I've never taken out anything as heavy as a tranny, so any advice would be appreciated.
 
well if you use a tranny jack then you can lift / tilt till all the weight is on the jack and when you remove the bolts....all weight will be on the jack... :wink1:
 
If you leave the transfercase bolted up, just put a floor jack under the crossmember, unbolt the bellhousing, then the crossmember, and have fun getting it down.

The problem with removing the tranny is typically that you have to drop it down in the rear far enough to clear the floor pan where the shifter sticks through, once you are that far its easy. You can't back the assembly up before you start angling down or you hit the body. Watch the distributor to firewall clearance as well. If you are worried about it falling you can always stack up wood or blocks of some type to "catch" the assembly if it slips off the floor jack. But I had no problem doing this in my driveway by myself with just a floorjack.
 
So, just to confirm, the floor jack under the crossmember without unbolting, then the bell housing bolts up front, then unfasten the crossmember to frame bolts, and then lower the rear of the tranny still bolted onto the crossmember?

Can you hold up the front yourself as the rear goes down on the jack?
 
When I took the 5 speed out of my F250 diesel (yes its a ford :D ) I used an engine lift. I just removed the tranny hump and stuck the lift through the door and ran a chain down through the hole in the floor board. Doin it this way u can go up and down and needed to take the pressure off the bolts. Make sure you block up the back of the motor so the dizzy dont hit the firewall.
 
prossett said:
Guys, I live on the edge of the desert, and I've got a floor jack, 4 jack stands, and the stock jack.
Click to expand...

Get help! Yes the with the 4 bolts removed from the bellhousing the trans will be loose, but until you pull back on it, the input shaft is still splined to the clutch and the pilot bearing on the flywheel. It's not like its going to fall out if you pull the 4 bolts. Here is a very redneck way to do it, but should work given your limited supply of tools.

#1 Unbolt the turtle shell on the floor. Get the rest of the trans ready to remove (with or without the t/case attached). I would rather pull the t/case apart just to take away the extra wieght and ackwardness to lower/lift. Support the Trans with your floor jack. You may need to add some scraps of 2x4's to stablize it. (Note pull the ditributator cap, just in case as the engine might rotate down when the trans is pulled and crush the cap on the firewall) Pull the 4 bellhousing bolts. With your buddy inside the truck, have him hold onto the shifter to stabilize the trans and start slowly lowering the jack while pulling backwards to get the input shaft out of the flywheel and clutch. You will need to tilt it at the rear to clear the floor but with the turtle shell off you should have a little more room. Keep moving the trans down and back in small increments. Eventually, the shifter handle will be in the way of the floor so it will finally have to come out. Your buddy should then join you underneath and help hold the trans on the jack while you keep lowering and pulling back. remember you just need to pull it back enough for the input shaft to clear the bellhousing. Its not easy with limited tools, but still doable if you attack it in the right manner.

Just make sure your floor jack works smoothly to release and lower. Mine is somewhat sticky and would make a more interesting time to remove. Just be aware that you are working to try and remove a HEAVY chunk of iron and it can and will hurt when dropped on fingers, toes, hands, arms, ect.....

Best advice, take it slow. Don't rush.
 
I just put in a SM465 adn NP 205, it was frickin heavy. I used an engine hoist through the cab to get it in place. However, I did NOT use the hoist to get the TH400/NP205 out. I used a motorcycle jack with a big piece of plywood on it for more surface area and a buddy to get it out. I got the jack wedged in there pretty good, unbolted everything, decided I was willing to sacrafice three knucles, yanked on the tranny and then lowered it VERY VERY slowly.

Get a buddy to help you balance the tranny once it is off the truck.
 
I recently pulled my sm465 to replace a broken clutch fork, all i had was a floor jack. I let the air out of the tire to lower the truck closer to the ground, removed the driveshafts, and the transfercase, and the crossmember, then i put the floor jack under the tranny, the i took a RACHET STRAP and wraped it around the tranny and the floor jack.

Then removed all the bolts, and slid the tranny back, and down.

to get it back up, i put the tranny on the jack, then i ran the rachet strap from the drivers side frame rail, around the tranny adapter (the end where the transfercase bolts to) then to the passenger side frame rail. then i was able to jack the front of the tranny up, and use the rachet strap to lift and position the rear of the tranny, and slid it home..;)
 
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