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Old 10-11-2018, 12:19 AM   #1
andyh1956
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Driveshaft Question

Am about to start working on my '94 2500 single cab pickup soon. It has a two piece driveshaft in it.
Anybody ever use a one piece shaft in their truck?
My truck has a NV4500 trans.
Thanks
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Old 10-11-2018, 10:34 AM   #2
mikebte
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Re: Driveshaft Question

My single cab 93' GMC 2500 had a single drive shaft in it. Just tossed it last week. I would given it for free. Kind of a bumber.
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Old 10-11-2018, 11:55 AM   #3
andyh1956
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Re: Driveshaft Question

Thanks. I don't know if the two piece is a 5 spd deal or what.
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Old 10-11-2018, 09:45 PM   #4
Keith Seymore
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Re: Driveshaft Question

It’s a top speed/shaft rpm thing.

It affected by engine, trans, rear axle ratio and tire size. If the combination of those factors causes a one piece shaft to exceed its critical speed then a two speed shaft is released.

K
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Old 10-12-2018, 12:03 PM   #5
andyh1956
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Re: Driveshaft Question

Yeah this truck is kinda an odd duck. Gotta 6.5TD & NV4500 & 3.42L rear. This truck would get 21 MPG when it was running.
I think I'm gonna get a one piece shaft built when I put it back together.
Thanks
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Old 10-16-2018, 07:57 AM   #6
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Re: Driveshaft Question

The use of the two-piece may also have been to take some load off the transfer case tail housing and prevent tailshaft yoke pull-out under extreme suspension travel on 4x4 models. It may also have something to do with U-joint maximum angles being exceeded with the shorter driveshaft on the 4x4's too. All the 4x4's I have owned have been 2-piece and the 2wd's have all been one-piece. That doesn't mean jack as far as reality goes but it's a possibility

They made no sense as to when they put the larger diameter driveshafts in vs. the smaller ones either.

My 94 K2500 ECLB camper special had the same 454 and 4L80E as my 95 K3500 ECLB DRW truck also with the camper special option code but the 94 came with a 3-1/2" diameter 2-piece driveshaft and the dually came with only a 3" diameter version. The only real difference between the trucks besides the DRW was the 94 having 3.73 gears & NP241 and the 95 having 4.10's and the B-W transfer case that came in the 1-tons. You would think the DRW truck with its 1400 pound greater GVW would get a bigger diameter driveshaft but it didn't. Both had visible GM part number tags on them under the dirt leading me to believe they were original parts to the trucks and the fasteners looked like they had never been removed so they were probably not installed from another vehicle.

It turned out the rear section of the two-piece from the 94 K2500 was a perfect fit as a one-piece driveshaft for my 89 RCSB project truck when I built it with a 9.5" 14-bolt and used the medium length tailshaft T-400 that was in the 89 RCLB donor truck I got the cab from once I put the right transmission slip yoke on it to match the trans. Thanks GM, no custom length driveshaft required
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Old 10-16-2018, 02:39 PM   #7
andyh1956
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Re: Driveshaft Question

While I am building the engine for the 2500 I'm driving an '89 S10 LWB std cab pickup.
It has the vibrating 2-peice driveshaft also.
If I was gonna keep this truck I would chuck this driveshaft also.
Been looking for a one piece S10 shaft but all have been damaged by Mr Forklift driver!
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Old 10-17-2018, 06:56 AM   #8
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Re: Driveshaft Question

Quote:
Originally Posted by andyh1956 View Post
While I am building the engine for the 2500 I'm driving an '89 S10 LWB std cab pickup.
It has the vibrating 2-peice driveshaft also.
If I was gonna keep this truck I would chuck this driveshaft also.
Been looking for a one piece S10 shaft but all have been damaged by Mr Forklift driver!
Same problem here. I have even brought that up to them at my local yard and they don't want to take the time to disconnect the pinion yoke and tie it up so it stays undamaged by the fork lift even though it would be another good part they could sell. That makes no sense to me. They can't possibly pay the guys that prep the vehicles so much per hour that taking an extra two minutes to save a driveshaft isn't profitable.
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