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88-98 Chevy sbsc 4x4 mt driveshaft length

3K views 3 replies 3 participants last post by  cerial 
#1 ·
I have a sbsc with 305 nv3500 c1500.

I want to pull out the drivetrain and set a v8 500 6-8" back into the firewall. Behind the v8 will be a sm465 then a 8" prop shaft then a 12" aux transmission then the driveshaft in question then a ff14 bolt.

Now I believe a nv3500 mated to the transfer case is 47" long. If that is the case my 8" bell, 12" transmission, 8" prop and 12" transmission lets me set the back of the engine block back 7" and still use a factory rear shaft.

Although harder to find. If I can bolt in a factory shaft vs having one built I'm
going to try and find it.
 
#2 ·
Assuming aux. transmission means a "divorced" transfer case... I would think the rearmost driveshaft length would be among the least of your problems on that deal, in any event because you're using parts that would normally be found on a long-bed truck you'd likely be shortening things rather than needing them longer. Shortening is easy to do, just finding something heavy-duty w/ the right ends would be the main thing.
 
#4 ·
It is a aux transmission. Mine is a Watson 5531A. They are sometimes wrongly called brownies or brown lipe transmission. Brownie is used as a general term for any aux transmission pre 70 now a days.


My unit has 3 speeds. 1.52/1, direct, and .72/1. The sm465 has 6.55, 3.15, 1.7 and direct. The rear axle has 4.56 gearing.



I really have no need for the low gearing and because I am not using it I am able to switch between direct and high by moving just one of the two shift rails on the aux forward or backward with a solenoid. I will select high or low then have it activate the high or low signal to the solenoid when I push the clutch in avoiding a second shiftier. Shifting from 3D to 3H for instance will only require me to flip the switch up before slamming the clutch down for a second then releasing it. While shifting from 3H to 4D will require me to flip the switch down before shifting the shiftier into 4th. I can also just throw the thing in High leaving it in high and turn the 4.56 rear into a 3.28 rear if I'm feeling like driving slow.:rolleyes:

The brownie will let me split the gears of the sm465 for
1H 4.71
24%
2D 3.58
28%
2H 2.58
34%
3D 1.70
28%
3H 1.22
18%
4D 1.00
28%
4H 0.72

Notice the percentage drops between the shifts. They are similar to many transmissions the difference is that I can rebuild both the sm465 and Watson for under $200 in a weekend with no special tools. The downside is that the two transmissions weigh in at 320lbs. I am figuring 350lbs with brackets. Still being able to slam down that pedal and dump 550-600lbs into the clutch without worry is worth the 100-150lbs it is going to cost me.
I fought myself on using the full floater 14 bolt. But at around 400lbs(axle only with disc conversion) and able to take the torque that weight is also justified. Being able to grab a broken shaft and switch it out in around 10 minutes is kind of nice. Having the option to bolt on some 15“ wide slicks is a bonus. Having the option to run dually street tires and air them down to 6 psi is also a nice bonus.


Here is the two sides of the case. The actual case is only about 8“ long




Here is the rough layout I want to use. I was trying to mate the aux right up to the sm465 in this picture but the shift rails really do not make that happen easily. Besides I want to use the prop shaft to make pulling the engine and sm465 easier. Ignore the aluminum piece that is for the project that I decided to set aside for a while.





The inside contains a mix of spur and other gears in good condition



Back to the drive shaft in question.

I think I have a issue where I believe the driveshaft in question in the short bed nv3500 4x4 trucks used 1350 joints. I am not sure of this. But if they did use 1350 joints that is out. A conversion u joint is not going to cut it. I need 1410 joints both for ease of maintenance and availability. I will probably run a special 1410 joint. But I will carry a 1410 standard in the glove box as I have had the grease fittings decide they are going to rip before I decide to take a 300mile weekend trip. Get to where I am going and I hear a clunking at low speeds. I did not even need to look. I did it right at NAPA in 20 degree weather. 10 minute job took me over a hour but I was back on the road and added another item to my emergency parts list.

I am still looking at this. But worst case I end up having a driveshaft built/shortened. I just tend to abuse the crap out of my toys. I tend to get 12,000 out of my tires, and around 20,000 out of an engine if you catch what I am saying. The motor is tough, the transmission tough, the prop shaft tough, and the 14 bolt is tough. Clutch is going to be the thing I pay big money for but it should be tough. The driveshaft in question is the weak link here.

I know they made a standard cab short box manual 1500 4wd truck I just need to know the driveshaft length so I can find more of them easier.
 
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