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Old 05-11-2019, 10:37 AM   #1
Xavier
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Any tips for 4-speed manual transmission removal?

Long story short the trans is dead and needs to come out of my truck.

It's a 68 C20 with a NP435. I'm trying to drop it in the driveway and it seems the easiest option would be to unbolt it from the bell housing but I can't get anything on the two bolts inside the bell housing.

Just looking for any tips or advice from people who may have experience doing this before.
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Old 05-11-2019, 11:05 AM   #2
AussieinNC
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Re: Any tips for 4-speed manual transmission removal?

Long story short here....even if you got the internal bolts out you will have another issue with top of trans shift housing hitting the cab floor.

Sounds counter intuitive but its easier to pull the engine and trans out as a unit, then disassemble the bell housing/trans from the engine...then the bell housing from the trans.

Suggestions....

Replace all engine mounts while you are doing the job, two on engine, two under bell housing to cross member.
Replace the clutch kit including new pilot bushing.
Make sure clutch release bearing height is same as original one fitted.

Make sure Z link is in good condition and fully lubed on pivot points while you have it apart.

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Old 05-11-2019, 11:09 AM   #3
gmc684x4
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Re: Any tips for 4-speed manual transmission removal?

I am going to say your tranny is Sm420 if its a 4 speed possibly a Sm465 if changed from a 69 and up truck unless its a 3 speed

Undo the bell house to the motor there a 9/16 head 3/8 bolt pull the bell housing with the tranny

Remove the shifter boot on a 4 speed from the floor slide it up push down on the ball cup on the shifter turn counter clockwise release and remove shifter by pulling up best doing this with it in neutral

I have always leave the engine in the vehicle when doing a clutch job why make more work and replace all that antifreeze if you do not need to
and having an extra jack to support your engine with a block of wood on the cup to help from denting the oil pan
I did that last with my sentra everyone says pull the engine. too much extra work for little gain

and to the comment pull the engine do you have an engine hoist to do that extra work ?
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Old 05-11-2019, 11:39 AM   #4
Xavier
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Re: Any tips for 4-speed manual transmission removal?

I've already removed everything else, including the transmission hump in the cab. After some scrubbing I revealed the part number on the case, C-95948F, which appears to be to a Dodge.
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Old 05-11-2019, 01:11 PM   #5
weim55
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Re: Any tips for 4-speed manual transmission removal?

The NP435 was an option over SM465. Itís a very rare option that you seldom see. The ratio spread in the 435 is much better and a lot more enjoyable to drive overall than the 465. If thereís any chance you can save that new process unit I would, itís worth the effort.

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Old 05-11-2019, 01:19 PM   #6
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Re: Any tips for 4-speed manual transmission removal?

But to answer your questions: not sure why those two lower bolts in the bell housing would be difficult to get out, I can use a medium depth three-quarter inch socket with my half inch drive ratchet and remove them just fine. I’m wondering if there something unusual about your particular bell housing that makes those bolts difficult to get to (??)

A poor man’s method for removing the transmission: if you have two strong friends and a strong pole or 4 x 4 that’s about 8 feet in length you can suspend the transmission with rope or chain from the top inside the cab and not use a transmission jack at all. If you cut the 4 x 4 post the exact length to clear the open doors and measure the proper distance to the ground for your chains, you can remove the bolts from the bell housing and with one person underneath break the transmission loose guide the transmission back while your buddies support the weight and then carefully lower The transmission to the ground. Reverse procedure to reinstall. It’s been 35 years since I used the above for Procedure on my 69K 10, but it worked like a champ in my broke teenage years......

Thinking further there could be an issue with my idea as a 2 Wheel Dr. application has the engine forward about four more inches compared to a four-wheel-drive truck, not entirely sure there’s enough room to manipulate the 4 x 4 post inside the cab with the doors open. The transmission might be too far forward and the post will hit the doors (??)

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Last edited by weim55; 05-11-2019 at 01:26 PM.
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Old 05-11-2019, 01:48 PM   #7
RustyPile
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Re: Any tips for 4-speed manual transmission removal?

Quote:
Originally Posted by Xavier View Post
Long story short the trans is dead and needs to come out of my truck.

It's a 68 C20 with a NP435. I'm trying to drop it in the driveway and it seems the easiest option would be to unbolt it from the bell housing but I can't get anything on the two bolts inside the bell housing.

Just looking for any tips or advice from people who may have experience doing this before.
As other's have stated: Don't add work to an already difficult chore.. Leave the engine alone.. Unless you plan a clutch replacement, leave the bell housing attached to the engine also.. I won't go into all the details as proper removal has been covered by others.

That transmission is HEAVY, use a suitable transmission jack. And one of these should work to remove those 2 bolts..

https://www.harborfreight.com/8-piec...set-32041.html
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Old 05-11-2019, 02:08 PM   #8
weim55
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Re: Any tips for 4-speed manual transmission removal?

One thing thatís really nice about these trucks, through 1972 the original bell housing is an open bottom unit. The entire clutch assembly and flywheel can be removed through the bottom of the bell housing with the transmission out. No need to remove the bell housing or engine in anyway for transmission or clutch removal.

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Old 05-11-2019, 03:01 PM   #9
Xavier
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Re: Any tips for 4-speed manual transmission removal?

Quote:
Originally Posted by weim55 View Post
But to answer your questions: not sure why those two lower bolts in the bell housing would be difficult to get out, I can use a medium depth three-quarter inch socket with my half inch drive ratchet and remove them just fine. Iím wondering if there something unusual about your particular bell housing that makes those bolts difficult to get to (??)

Steve weim55 Colorado
I can barely fit a socket on them without hitting the clutch, let alone a ratchet as well.
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Old 05-11-2019, 03:46 PM   #10
Jason Banks
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Re: Any tips for 4-speed manual transmission removal?

See if you can turn the rotate the crankshaft to move to clutch to a place that makes it easier to get a wrench on.

I don't have a 4sp but my 3sp was a little difficult to get the inside ones off and on.
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Old 05-11-2019, 05:00 PM   #11
weim55
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Re: Any tips for 4-speed manual transmission removal?

Thanks for the pic to clarify. With a smaller 10 1/2" clutch there is room for a socket. With larger clutches such as yours I use a 3/4" offset box wrench. If the bolt is too long the bolt head will still hit the clutch before you can remove the bolt completely. Leave the top two bolts in place a couple threads out (loose) and pry the transmission out from the bellhousing a bit to get the last couple turns to remove the lower bolts.

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Old 05-11-2019, 05:02 PM   #12
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Re: Any tips for 4-speed manual transmission removal?

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Old 05-11-2019, 05:04 PM   #13
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Re: Any tips for 4-speed manual transmission removal?

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Old 05-12-2019, 09:45 AM   #14
Xavier
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Re: Any tips for 4-speed manual transmission removal?

Yeah, an offset wrench ended up being the ticket. Once I had it loose I didn't know how to get it out from under the truck so I picked it up through the hole the transmission hump covers and took it out through the cab. It's definitely heavy.

I'll have to learn a little more about transmissions now but it looks the the 3-4 sleeve/synchro detonated and is the cause of my issue.
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Old 05-12-2019, 05:47 PM   #15
AussieinNC
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Re: Any tips for 4-speed manual transmission removal?

Just looking at those oil soaked lower bell housing mounts....time now to replace em and look for the oil leak source.

And can almost guarantee the front engine mounts are oil soaked as well...

Typical for a well used truck....either do em now or go looking for alignment or vibration issues down the road...

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