Has anone here actually done a 4wd to 2wd conversion?

Nad_Yvalhosert · Jun 5, 2023

Like Doc Brown said: "You're just not thinking 4th dimensionally"

There is more than just slapping in a manual tranny... There's the clutch master cyl and line assy, and bleeding it
there's the clutch, flywheel, pilot bushing,
there's the clutch pedal and rod,
there's the smaller brake pedal,
there's the neutral safety switch,
there's cutting the floor and installing the double shifter boots,
there's removing the shifter arm on the column,
there's rewiring the reverse lights,
there's the VSS relocation,
All of which should come from an entire donor truck...

And yes, it's gonna need a custom 2 piece driveshaft to clear the torsion bar x-member.

You neglected to inform us of the year, so either a PCM reflash or a custom burnt chip.

And as for removal, if you remove the non-functional front diff, you'll need to retain the outer CV shafts to hold the wheel bearings together.

You're looking at close to 8 grand if you piece together all the parts, maybe 6 grand if you buy a donor truck.
It's gonna be MUCH cheaper just to have a properly built 4L60 installed and all OE components left in operational condition.

Nad_Yvalhosert · Jun 5, 2023

evilunclegrimace said:
I don't think it would have a 2 piece drive shaft. It is a 131.5 Wb same as and RCLB .

2wd 131" should be a 2 piece on a pickup.
4x4 131" is a 1 piece.

Suburban generally are expected to see less suspension articulation, and have a rear fuel tank. So a 1 piece drive shaft could be fine.
On my 2wd RCLB pickup, the carrier bearing is combined on the fuel tank cross member.

Caman96 · Jun 5, 2023

Nad_Yvalhosert said:
Like Doc Brown said: "You're just not thinking 4th dimensionally"

There is more than just slapping in a manual tranny... There's the clutch master cyl and line assy, and bleeding it
there's the clutch, flywheel, pilot bushing,
there's the clutch pedal and rod,
there's the smaller brake pedal,
there's the neutral safety switch,
there's cutting the floor and installing the double shifter boots,
there's removing the shifter arm on the column,
there's rewiring the reverse lights,
there's the VSS relocation,
All of which should come from an entire donor truck...

And yes, it's gonna need a custom 2 piece driveshaft to clear the torsion bar x-member.

You neglected to inform us of the year, so either a PCM reflash or a custom burnt chip.

And as for removal, if you remove the non-functional front diff, you'll need to retain the outer CV shafts to hold the wheel bearings together.

You're looking at close to 8 grand if you piece together all the parts, maybe 6 grand if you buy a donor truck.
It's gonna be MUCH cheaper just to have a properly built 4L60 installed and all OE components left in operational condition.

Agree, and still why I feel just finding the correct(same)transmission would be best. If money is an issue.

evilunclegrimace · Jun 5, 2023

Nad_Yvalhosert said:
2wd 131" should be a 2 piece on a pickup.
4x4 131" is a 1 piece.

Suburban generally are expected to see less suspension articulation, and have a rear fuel tank. So a 1 piece drive shaft could be fine.
On my 2wd RCLB pickup, the carrier bearing is combined on the fuel tank cross member.

Not unless they make two different designs. 131.5 2WD pickup is one piece. I have 2 sitting here. They both have Aluminum drive shafts.

Nad_Yvalhosert · Jun 5, 2023

evilunclegrimace said:
Not unless they make two different designs. 131.5 2WD pickup is one piece. I have 2 sitting here. They both have Aluminum drive shafts.

They must. The 131 in my driveway is a two piece. Maybe because mine is a 2500 with a 4L80 and the carrier bearing mounted at a 45°angle?

jjester6000 · Jun 6, 2023

Nad_Yvalhosert said:
Like Doc Brown said: "You're just not thinking 4th dimensionally"

There is more than just slapping in a manual tranny... There's the clutch master cyl and line assy, and bleeding it
there's the clutch, flywheel, pilot bushing,
there's the clutch pedal and rod,
there's the smaller brake pedal,
there's the neutral safety switch,
there's cutting the floor and installing the double shifter boots,
there's removing the shifter arm on the column,
there's rewiring the reverse lights,
there's the VSS relocation,
All of which should come from an entire donor truck...

And yes, it's gonna need a custom 2 piece driveshaft to clear the torsion bar x-member.

You neglected to inform us of the year, so either a PCM reflash or a custom burnt chip.

And as for removal, if you remove the non-functional front diff, you'll need to retain the outer CV shafts to hold the wheel bearings together.

You're looking at close to 8 grand if you piece together all the parts, maybe 6 grand if you buy a donor truck.
It's gonna be MUCH cheaper just to have a properly built 4L60 installed and all OE components left in operational condition.

I guess I left out some details, but I'm not so inept.

The truck is a '98 Chevy Suburban K1500 with a 4L60E, NP241, and 319,000 miles.

I've had the trans rebuilt twice, and I don't really want to deal with it again.

I understand everything else I need, and I do actually have some of the parts already on hand (Clutch, flywheel and pressure plate).

I don't know where you got 8 grand from? If I looked around I could probably find a rusty doner truck for less than 2K, but I think piecing together the parts may be cheaper since I know of several local junkyard trucks with standard transmissions I can get all the clutch components from.

Also, I have a workaround for the ECM problem that I've successfully used before that involves locking the neutral safety switch in neutral and zip tieing it out of the way.

The only thing I'm having a hard time turning up is a Transmission/Tcase. That's why I was considering a 2wd swap, since I knew of a 2wd Nv3500 someone I work with has laying around.

jjester6000 · Jun 6, 2023

Caman96 said:
Agree, and still why I feel just finding the correct(same)transmission would be best. If money is an issue.

It would, but I think this truck deserves it. I understand that if I go this route, this truck probably won't be on the road for several months since money is a bit of a factor (Not that I don't have it, but I don't like spending it. That means that I'm going to sit around and look for deals.)

Pinger · Jun 6, 2023

I'm assuming the torsion bar crossmember is some distance aft of the manual gearbox tail shaft and thus the question is one of clearance between the propshaft and it. Whatever that distance is divided into the distance from the gearbox tail shaft to the rear axle centreline as a fraction used as a factor (ie, a numerical multiplier) when applied to the axle travel (bump and droop - easily measured) will give the range of movement of the propshaft in the vicinity of the crossmember. Isn't that enough to gauge if there is the required clearance?

Nad_Yvalhosert · Jun 6, 2023

jjester6000 said:
I don't know where you got 8 grand from?

Shop labor. I never assume people have a lift or a high capacity gantry in their driveways.

The last manual tranny I priced out was $1200. I'd be hard pressed to put in a 5 speed someone else abused for 100k.

Schurkey · Jun 6, 2023

jjester6000 said:
finding a 4x4 NV3500 complete with T-Case is proving very difficult.

I know of a 2wd one I can get very cheap,

I'm no stranger to crazy transmission swaps having successfully swapped a 4l60E for a Th350 in my '95 Suburban.

If you're tearing-up 700/4L60/60E, what do you think you're gaining with an NV3500? Swapping one failure-prone automatic for a failure-prone manual isn't much of an "upgrade".

At least the TH350 is more reliable than a '60E. Sucks for fuel economy and emissions, but it's at least strong enough.

Has anone here actually done a 4wd to 2wd conversion?

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